Fluke MOLBOX RFM User Manual

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molbox™ RFM™

(Ver 1.10 and Higher)

Reference Flow Monitor

Operation and Maintenance Manual

Page 2

High pressure liquids and gases are potentially hazardous. Energy stored in these liquids and gases

can be released unexpectedly and with extreme force. High pressure systems should be assembled and operated only by personnel who have been instructed in proper safety practices.

Information in this document is subject to change without notice. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without the express written permission of DH Instruments, a

Fluke Company 4765 East Beautiful Lane Phoenix AZ 85044-5318 USA.

DH Instruments makes sincere efforts to ensure the accuracy and quality of its’ published materials; however, no warranty,

expressed or implied, is provided. DH Instruments disclaims any responsibility or liability for any direct or indirect damages resulting from the use of the information in this manual or products described in it. Mention of any product does not constitute an endorsement by DH Instruments of that product. This manual was originally composed in English and was subsequently translated into other languages. The fidelity of the translation cannot be guaranteed. In case of conflict between the English version and other language versions, the English version predominates.

Products described in this manual are manufactured under international patents and one or more of the following U.S. patents: 5,142,483, 5,257,640, 5,331,838, 5,445,035. Other U.S. and international patents pending.

DH Instruments, DH, DHI, molbox, molbox RFM, molbloc, molbloc-L, molbloc-S and CalTool are trademarks, registered and otherwise, of DH Instruments, a Fluke Company.

LabVIEW is registered trademark of National Instruments Corporation. Swagelok is a registered trademark of the Swagelok Company.

Document No. 550107f 050512 Printed in the USA.

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AABBLLEE

OONNTTEENNTTS

TABLE OF CONTENTS ...............................................................I

TABLES.................................................................................. V

FIGURES................................................................................VI

ABOUT THIS MANUAL............................................................ VII

1. INTRODUCTION ................................................................. 1

1.1 PRODUCT OVERVIEW.................................................................................................................................................................1

1.1.1 MOLBLOC FLOW ELEMENTS ........................................................................................................................................................... 1

1.1.1.1 MOLBLOC-L FLOW ELEMENT....................................................................................................................................................... 1

1.1.1.2 MOLBLOC-S FLOW ELEMENT...................................................................................................................................................... 1

1.2 SPECIFICATIONS.........................................................................................................................................................................2

1.2.1 GENERAL SPECIFICATIONS ............................................................................................................................................................. 2

1.2.2 REFERENCE PRESSURE TRANSDUCER (RPT) SPECIFICATIONS .............................................................................................. 2

1.2.2.1 UPSTREAM AND DOWNSTREAM RPTS...................................................................................................................................... 2

1.2.2.2 DIFFERENTIAL RPT (MICRORANGE OPTION)............................................................................................................................3

1.2.3 TEMPERATURE MEASUREMENT SPECIFICATIONS......................................................................................................................3

1.2.4 FLOW MEASUREMENT SPECIFICATIONS.......................................................................................................................................3

1.2.4.1 MOLBLOC-L .................................................................................................................................................................................... 3

1.2.4.1.1 MOLBLOC-L FLOW MEASUREMENT SPECIFICATIONS, MICRORANGE OPTION............................................................. 4

1.2.4.1.2 MOLBLOC-L PRESSURE DEPENDENT CALIBRATION TYPES............................................................................................. 4

1.2.4.1.3 MOLBLOC-L RANGES WITH LOW PRESSURE CALIBRATIONS........................................................................................... 6

1.2.4.1.4 MOLBLOC-L RANGES WITH HIGH PRESSURE CALIBRATIONS..........................................................................................7

1.2.4.1.5 MOLBLOC-L DIMENSIONS....................................................................................................................................................... 8

1.2.4.2 MOLBLOC-S.................................................................................................................................................................................... 9

1.2.4.2.1 MOLBLOC-S RANGES............................................................................................................................................................... 9

1.2.4.2.2 MOLBLOC-S PRESSURE DEPENDENT CALIBRATION TYPES.......................................................................................... 11

1.2.4.2.3 MOLBLOC-S DIMENSIONS.....................................................................................................................................................12

1.2.5 FRONT AND REAR PANELS............................................................................................................................................................ 13

1.2.5.1 FRONT PANEL..............................................................................................................................................................................13

1.2.5.2 REAR PANEL................................................................................................................................................................................ 14

2. INSTALLATION ................................................................ 15

2.1 UNPACKING AND INSPECTION ...............................................................................................................................................15

2.1.1 REMOVING FROM PACKAGING...................................................................................................................................................... 15

2.1.2 INSPECTING CONTENTS ................................................................................................................................................................. 15

2.2 SITE REQUIREMENTS............................................................................................................................................................... 15

2.3 INITIAL SETUP............................................................................................................................................................................ 16

2.3.1 PREPARING FOR OPERATION ....................................................................................................................................................... 16

2.3.2 POWER CONNECTION ..................................................................................................................................................................... 16

2.3.3 MOLBOX RFM TO MOLBLOC CONNECTION.................................................................................................................................16

2.3.4 GAS SUPPLY AND FLOWPATH CONNECTIONS........................................................................................................................... 17

2.3.5 VACUUM SUPPLY (MOLBLOC-S ONLY) ........................................................................................................................................ 18

2.3.6 COMMUNICATIONS CONNECTIONS .............................................................................................................................................. 18

2.4 POWER UP AND VERIFICATION.............................................................................................................................................. 18

2.4.1 POWER UP.........................................................................................................................................................................................18

2.4.2 CH E CK P ROPER PRESS URE MEASU REMEN T OP ERATI O N .......................................................................................... 19

2.4.3 CHECK PROPER TEMPERATU R E M EASUR E M ENT OPERATIO N..........................................................................................19

2.4.4 LEAK CHECK.....................................................................................................................................................................................19

2.4.5 CHECK/SET SECURITY LEVEL ....................................................................................................................................................... 20

2.5 ADDITIONAL PRECAUTIONS TO TAKE BEFORE MAKING FLOW MEASUREMENTS .......................................................20

2.6 SHORT TERM STORAGE...........................................................................................................................................................20

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

3. OPERATION..................................................................... 21

3.1 GENERAL OPERATING PRINCIPLES ......................................................................................................................................21

3.1.1 MOLBLOC-L AND MOLBLOC-S OPERATION................................................................................................................................ 21

3.1.2 MOLBLOC-S BPR LIMITS................................................................................................................................................................. 21

3.1.3 FLOW READY/NOT READY INDICATION ....................................................................................................................................... 22

3.1.3.1 MOLBLOC-L OPERATION............................................................................................................................................................22

3.1.3.2 MOLBLOC-S OPERATION............................................................................................................................................................ 22

3.1.4 SOFT [ON/OFF] KEY ......................................................................................................................................................................... 23

3.1.5 MICRORANGE OPTION (OPTIONAL).............................................................................................................................................. 23

3.1.6 REFERENCE PRESSURE TRANSDUCER (RPT) OVERPRESSURE ............................................................................................ 24

3.1.6.1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS................................................................................................................ 24

3.1.6.2 DIFFERENTIAL RPT, MICRORANGE OPTION........................................................................................................................... 24

3.2 MAIN RUN SCREEN................................................................................................................................................................... 25

3.2.1 MOLBLOC-L OPERATION................................................................................................................................................................ 25

3.2.2 MOLBLOC-S OPERATION................................................................................................................................................................ 26

3.3 MANUAL OPERATION............................................................................................................................................................... 27

3.3.1 KEYPAD LAYOUT AND PROTOCOL............................................................................................................................................... 27

3.3.2 SOUNDS............................................................................................................................................................................................. 28

3.3.3 SOFT [ON/OFF] KEY ......................................................................................................................................................................... 28

3.3.4 DIRECT FUNCTION KEYS SUMMARY ............................................................................................................................................ 28

3.4 DIRECT FUNCTION KEYS.........................................................................................................................................................29

3.4.1 [K] ....................................................................................................................................................................................................... 29

3.4.2 [GAS] .................................................................................................................................................................................................. 31

3.4.2.1 MOLBLOC-L OPERATION............................................................................................................................................................32

3.4.2.2 MOLBLOC-S OPERATION............................................................................................................................................................ 33

3.4.3 [UNIT]..................................................................................................................................................................................................34

3.4.3.1 MASS FLOW VS. VOLUME FLOW...............................................................................................................................................35

3.4.3.2 VOLUMETRICALLY BASED MASS FLOW UNITS....................................................................................................................... 36

3.4.3.3 VOLUMETRICALLY BASED MASS FLOW UNITS AT VARIOUS REFERENCE TEMPERATURES (UXXX) ........................... 37

3.4.3.4 VOLUME FLOW UNITS (VLM)......................................................................................................................................................37

3.4.3.5 CUSTOMIZING FLOW UNITS AVAILABLE UNDER THE UNIT FUNCTION.............................................................................. 38

3.4.4 [TARE] ................................................................................................................................................................................................ 39

3.4.4.1 <1TARE> ....................................................................................................................................................................................... 40

3.4.4.1.1 MOLBLOC-L OPERATION.......................................................................................................................................................40

3.4.4.1.2 MOLBLOC-S OPERATION....................................................................................................................................................... 43

3.4.4.2 <2PURGE>.................................................................................................................................................................................... 44

3.4.4.3 <3LEAK CHECK>.......................................................................................................................................................................... 46

3.4.4.3.1 LEAK CHECK MOLBOX........................................................................................................................................................... 47

3.4.4.3.2 LEAK CHECK SYSTEM........................................................................................................................................................... 49

3.4.4.4 <4AUTOZ>.....................................................................................................................................................................................53

3.4.4.4.1 EDIT AUTOZ.............................................................................................................................................................................55

3.4.4.4.2 RUN AUTOZ............................................................................................................................................................................. 56

3.4.4.5 <5BPR> (MOLBLOC-S OPERATION ONLY) ...............................................................................................................................58

3.4.5 [P&T] (PRESSURE AND TEMPERATURE)......................................................................................................................................59

3.4.6 [DISPLAY] .......................................................................................................................................................................................... 61

3.4.6.1 <1RATE> ....................................................................................................................................................................................... 62

3.4.6.2 <2AVG> (AVERAGE) .................................................................................................................................................................... 63

3.4.6.3 <3 HI/LO>....................................................................................................................................................................................... 64

3.4.6.4 <4TOTAL> (TOTALIZER).............................................................................................................................................................. 64

3.4.6.5 <5UNIT>......................................................................................................................................................................................... 66

3.4.6.6 <6DEV>.......................................................................................................................................................................................... 66

3.4.6.7 <7FREEZE>................................................................................................................................................................................... 67

3.4.6.8 <8CLEAN>..................................................................................................................................................................................... 68

3.4.7 [MICRO] (OPTIONAL)........................................................................................................................................................................ 68

3.4.8 [MOLBLOC]........................................................................................................................................................................................70

3.4.8.1 MOLBLOC-L AND MOLBLOC-S SIZE AND RANGE DESIGNATIONS.......................................................................................70

3.4.9 [RES]...................................................................................................................................................................................................71

3.5 [SETUP].......................................................................................................................................................................................72

3.5.1 <1FLOWU>......................................................................................................................................................................................... 72

3.5.2 <2PRESU>..........................................................................................................................................................................................73

3.5.3 <3TEMPU> ......................................................................................................................................................................................... 73

3.5.4 <4MOLBLOC>.................................................................................................................................................................................... 74

3.5.5 <5STAB> ............................................................................................................................................................................................ 74

3.5.6 <6ADJ>............................................................................................................................................................................................... 75

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TABLE OF CONTENTS

3.6 [SPECIAL]................................................................................................................................................................................... 76

3.6.1 <1RESET>.......................................................................................................................................................................................... 77

3.6.1.1 <1SETS>........................................................................................................................................................................................ 78

3.6.1.2 <2UNITS>...................................................................................................................................................................................... 78

3.6.1.3 <3COM>......................................................................................................................................................................................... 79

3.6.1.4 <4CAL>.......................................................................................................................................................................................... 79

3.6.1.5 <5ALL>........................................................................................................................................................................................... 79

3.6.2 <2LEVEL> .......................................................................................................................................................................................... 80

3.6.2.1 SECURITY LEVELS...................................................................................................................................................................... 80

3.6.3 <3UL> ................................................................................................................................................................................................. 83

3.6.3.1 UPPER LIMIT ALARM AND SEQUENCE.....................................................................................................................................84

3.6.4 <4CAL>............................................................................................................................................................................................... 84

3.6.5 <5PREFS>.......................................................................................................................................................................................... 84

3.6.5.1 <1SCRSVR>..................................................................................................................................................................................85

3.6.5.2 <2SOUND>....................................................................................................................................................................................85

3.6.5.3 <3TIME>......................................................................................................................................................................................... 86

3.6.5.4 <4ID>.............................................................................................................................................................................................. 86

3.6.5.5 <5LOG>.......................................................................................................................................................................................... 87

3.6.6 <6REMOTE>.......................................................................................................................................................................................87

3.6.6.1 COM1 AND COM2......................................................................................................................................................................... 88

3.6.6.2 IEEE-488........................................................................................................................................................................................88

3.6.6.3 RS232 SELF-TEST........................................................................................................................................................................ 88

3.6.7 <7MICRO>.......................................................................................................................................................................................... 89

3.6.8 <8HEAD>............................................................................................................................................................................................ 90

3.6.9 <9BPR>............................................................................................................................................................................................... 91

4. REMOTE OPERATION ....................................................... 95

4.1 OVERVIEW..................................................................................................................................................................................95

4.2 INTERFACING.............................................................................................................................................................................95

4.2.1 RS232 INTERFACE ........................................................................................................................................................................... 96

4.2.1.1 COM1.............................................................................................................................................................................................96

4.2.1.2 COM2.............................................................................................................................................................................................96

4.2.2 IEEE-488 (GPIB).................................................................................................................................................................................97

4.3 COMMANDS................................................................................................................................................................................ 97

4.3.1 COMMAND SYNTAX ......................................................................................................................................................................... 97

4.3.2 COMMAND SUMMARY ..................................................................................................................................................................... 98

4.3.3 ERROR MESSAGES..........................................................................................................................................................................99

4.3.4 COMMAND DESCRIPTIONS...........................................................................................................................................................101

4.3.4.1 IEEE STD. 488.2 COMMON AND STATUS COMMANDS.........................................................................................................101

4.3.4.2 MOLBOX RFM COMMANDS...................................................................................................................................................... 104

4.4 STATUS SYSTEM.....................................................................................................................................................................129

4.4.1 STATUS REPORTING SYSTEM ..................................................................................................................................................... 129

4.4.1.1 STATUS BYTE REGISTER.........................................................................................................................................................129

4.4.1.2 STANDARD EVENT REGISTER................................................................................................................................................. 131

5. MAINTENANCE, ADJUSTMENTS AND CALIBRATION ...........133

5.1 PRODUCT OVERVIEW.............................................................................................................................................................133

5.2 CALIBRATION OF REFERENCE PRESSURE TRANSDUCERS (RPTS)..............................................................................134

5.2.1 PRINCIPLE....................................................................................................................................................................................... 134

5.2.1.1 PA AND PM COEFFICIENTS...................................................................................................................................................... 135

5.2.2 EQUIPMENT REQUIRED.................................................................................................................................................................135

5.2.2.1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS.............................................................................................................. 135

5.2.2.2 DIFFERENTIAL (MICRORANGE) RPT....................................................................................................................................... 136

5.2.3 SET-UP AND PREPARATION.........................................................................................................................................................136

5.2.3.1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS.............................................................................................................. 136

5.2.3.2 MICRORANGE DIFFERENTIAL RPT......................................................................................................................................... 136

5.2.4 VIEWING AND EDITING RPT READINGS AND CALIBRATION INFORMATION........................................................................ 137

5.2.4.1 VIEWING RPT OUTPUTS...........................................................................................................................................................138

5.2.4.2 VIEWING AND EDITING RPT PA, PM AND CALIBRATION DATE...........................................................................................140

5.2.5 RPT CALIBRATION/ADJUSTMENT PROCEDURE WITHOUT USING CALTOOL FOR RPTS SOFTWARE ............................ 141

5.3 OHMIC MEASUREMENT SYSTEM VERIFICATION................................................................................................................142

5.4 RELOADING EMBEDDED SOFTWARE INTO MOLBOX RFM FLASH MEMORY.................................................................143

5.5 RELOADING MOLBLOC EEPROM FILE.................................................................................................................................144

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

5.6 OVERHAUL...............................................................................................................................................................................144

5.6.1 INTERNAL VIEW..............................................................................................................................................................................145

5.6.1.1 UPSTREAM ABSOLUTE RPT ....................................................................................................................................................146

5.6.1.2 DOWNSTREAM ABSOLUTE RPT..............................................................................................................................................146

5.6.1.3 DIFFERENTIAL MICRORANGE RPT (OPTIONAL)................................................................................................................... 146

5.6.1.4 DISPLAY......................................................................................................................................................................................146

5.6.1.5 POWER SUPPLY........................................................................................................................................................................ 146

5.6.1.6 MICRO BOARD........................................................................................................................................................................... 146

5.6.1.7 VALVING MODULE..................................................................................................................................................................... 146

5.6.1.8 MAIN BOARD ..............................................................................................................................................................................147

5.6.1.9 COOLING FAN ............................................................................................................................................................................147

6. TROUBLESHOOTING .......................................................149

6.1 OVERVIEW................................................................................................................................................................................149

7. APPENDIX ......................................................................155

7.1 CONVERSION OF NUMERICAL VALUES...............................................................................................................................155

7.1.1 PRESSURE ...................................................................................................................................................................................... 155

7.1.2 TEMPERATURE...............................................................................................................................................................................155

7.1.3 FLOW................................................................................................................................................................................................ 156

7.2 WARRANTY STATEMENT....................................................................................................................................................... 159

8. GLOSSARY .....................................................................161

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TABLES & FIGURES

AABBLLEES

Table 1. molbloc-L Pressure Dependent Calibration Types........................................................................5

Table 2. molbloc-L Ranges with Low Pressure Calibrations.......................................................................6

Table 3. molbloc-L Ranges with High Pressure Calibrations ...................................................................... 7

Table 4. molbloc-S Flow at Various molbloc Upstream Pressures ...........................................................10

Table 5. Minimum molbloc-S Critical Flow (slm) at Various molbloc-S Downstream Pressures ..............10

Table 6. molbloc-S Calibration Types........................................................................................................11

Table 7. molbox RFM Parts List.................................................................................................................15

Table 8. Summary of molbox RFM Direct Function Key Operations.........................................................29

Table 9. Available molbloc-L Gases .......................................................................................................... 32

Table 10. Available molbloc-S Gases........................................................................................................33

Table 11. Available Flow Units...................................................................................................................39

Table 12. Flow Units and Corresponding Total Mass or Volume Units.....................................................65

Table 13. molbloc-L Size and Nominal Range Designations .................................................................... 71

Table 14. molbloc-S Size Designation and Pressure to Flow Conversion Ratio (KF)................................71

Table 15. Pressure Units of Measure Available.........................................................................................73

Table 16. Security Levels - Functions NOT Executed Per Function/Level................................................81

Table 17. Security Levels - Functions NOT Executed Per Function/Level (Continued)............................82

Table 18. COM1 and COM2 Available Settings ........................................................................................88

Table 19. COM1 DB-9F Pin Designation...................................................................................................96

Table 20. COM2 DB-9M Pin Designation..................................................................................................97

Table 21. Command Summary..................................................................................................................98

Table 22. Error Messages........................................................................................................................100

Table 23. Status Byte Register ................................................................................................................129

Table 24. Standard Event Register..........................................................................................................131

Table 25. Troubleshooting Checklist .......................................................................................................149

Table 26. Pressure Unit Conversions......................................................................................................155

Table 27. Temperature Unit Conversion..................................................................................................155

Table 28. Conversions From kg/s To sccm At 0 °C For Various Gases .................................................156

Table 29. Conversions From sccm At 0 °C To Other Volumetrically Based Flow Units .........................156

Table 30. Conversions From Volumetrically Based Flow Units At 0 °C To

Table 31. Conversions From kg/s To mole/s For Various Gases............................................................157

Table 32. Conversion From mole/s To pccm...........................................................................................158

Table 33. Conversion From sccm At 0 °C to Volume Flow Units At Another Pressure

Table 34. Authorized Service Providers ..................................................................................................159

Corresponding Units At Another Temperature (uxxx)...........................................................157

And Temperature...................................................................................................................158

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

IIGGUURREES

Figure 1. molbox RFM Front Panel............................................................................................................13

Figure 2. molbox RFM Rear Panel ............................................................................................................ 14

Figure 3. molbox RFM Internal Pneumatic Schematic – MICRORANGE OPTION RPT

Figure 4. Keypad Layout............................................................................................................................27

Figure 5. molbox RFM Internal Pneumatic Schematic – TARING, UPSTREAM

Figure 6. molbox RFM Internal Pneumatic Schematic – TARING molbloc-S OPERATION..................... 44

Figure 7. molbox RFM Internal Pneumatic Schematic – PURGING ......................................................... 45

Figure 8. molbox RFM Internal Pneumatic Schematic – LEAK CHECK molbox.......................................48

Figure 9. molbox RFM Internal Pneumatic Schematic – SYSTEM LEAK CHECK –

Figure 10. molbox RFM Internal Pneumatic Schematic – SYSTEM LEAK CHECK –

Figure 11. molbox RFM Internal Pneumatic Schematic – molbloc-S OPERATION, BPR ON..................92

Figure 12. molbox RFM Internal Pneumatic Schematic – molbloc-S OPERATION, BPR OFF................ 92

Figure 13. Status Byte Register...............................................................................................................130

Figure 14. molbox RFM Internal Pneumatic Schematic – RUN UPSTREAM OR DOWNSTREAM

Figure 15. molbox RFM Internal Pneumatic Schematic – RUN MICRORANGE DIFFERENTIAL

Figure 16. molbox RFM Internal View......................................................................................................145

Figure 17. molbox RFM Valving Assembly Schematic............................................................................147

ACTIVE/INACTIVE..................................................................................................................23

molbloc-L OPERATION...........................................................................................................41

CHECKING OFFSET AND STABILITY molbloc-L operation..................................................50

CHECKING OFFSET AND STABILITY molbloc-S operation .................................................52

ABSOLUTE RPT CALIBRATION..........................................................................................139

RPT CALIBRATION ..............................................................................................................139

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ABOUT THIS MANUAL

BBOOUUTT

This manual provides the user with the information necessary to operate a molbox RFM, Reference Flow Monitor. It also includes a great deal of additional information provided to help you optimize molbox RFM use and take full advantage of its many features and functions.

Before using the manual, take a moment to familiarize yourself with the Table of Contents structure: All first time molbox RFM users should read Section molbox RFM operating principles. Section 4 is for provides maintenance and calibration information. Section 6 is a quick troubleshooting guide. Use troubleshoot unexpected molbox RFM behavior based on the symptoms of that behavior.

Certain words and expressions have specific meaning as they pertain to molbox RFM. Section 8 is useful as a quick reference for exact definition of specific words and expressions as they are used in this manual.

For those of you who “don’t read manuals”, go directly to section 2.3, initial setup, to set up your

molbox RFM. Then go to section 2.4, power up and verification. This will get you running quickly with minimal risk of causing damage to yourself or your molbox RFM. THEN… when you have questions or start to wonder about all the great features you might be missing, get into the manual!

HHIISS

AANNUUAAL

2. Section 3 provides a comprehensive description of general remote operation from an external computer. Section 5

Manual Conventions

it to

(CAUTION) is used in throughout the manual to identify user warnings and cautions.

(NOTE) is used throughout the manual to identify operating and applications advice and

additional explanations.

[ ] indicates direct function keys (e.g., [RANGE]).

< > indicates molbox RFM screen displays (e.g., <1yes>).

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

OOTTEES

Page 11

1. INTRODUCTION

11.

NNTTRROODDUUCCTTIIOON

1.1 PRODUCT OVERVIEW

molbox RFM is a support unit for making low mass flow measurements using molbloc mass flow elements. molbox RFM reads calibration data off the molbloc EEPROM and measures molbloc upstream and downstream pressure using built-in high accuracy Reference Pressure Transducers (RPTs). An ohmic measurement system reads the resistance of the molbloc platinum resistance thermometers from which molbloc temperature is calculated. Using the molbloc calibration data, pressures, temperature and gas properties stored in memory, the flow rate of the gas flowing through the molbloc is calculated. A microrange option is available to increase resolution and accuracy below 10 % FS of the molbloc-L flow range.

Internal molbox RFM valving supports on-board PRESSURE TRANSDUCER TARING, LEAK TESTING and SELF PROTECTION functions as well as a gas purge routine.

molbox RFM provides a local user interface via a front panel key pad and display and includes advanced on-board functions. Remote communication capability is supported with RS232 and IEEE-488 interfaces.

molbox RFM is intended for applications in which a highly compact presentation, high range ability and lower cost are the primary considerations. A second model, molbox1, is available for applications where higher accuracy is the most important requirement.

1.1.1 MOLBLOC FLOW ELEMENTS

Two different types of molblocs may be used with molbox RFM; molbloc-L (laminar) and molbloc-S (sonic).

1.1.1.1 MOLBLOC-L FLOW ELEMENT

molbloc-L is the original molbloc laminar flow element. molbloc-L covers the lower portion of the molbloc/molbox system flow range. The key molbloc-L measurement is the differential pressure across the element, which is roughly proportional to the mass flow rate through it. molbloc-L elements are calibrated to be used at an absolute pressure that remains nearly constant, while the differential pressure varies with flow rate. Different operating pressure options and their effect on molbloc flow range are described in Section 1.2.4.1.2.

1.1.1.2 MOLBLOC-S FLOW ELEMENT

molbloc-S elements use critical (sonic) flow venturi nozzle technology to measure flows, which overlap with the higher molbloc-L ranges and extend the high end of the molbloc/molbox RFM system flow range. The mass flow rate through a molbloc-S element is roughly proportional to the upstream absolute pressure when the flow is “choked”, so the molbloc-S operating pressure can vary widely as the mass flow rate is changed throughout the flow range. The limits of molbloc-S operating pressure and flow ranges are defined by the molbloc-S calibration type, described in Section 1.2.4.2.2.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2 SPECIFICATIONS

1.2.1 GENERAL SPECIFICATIONS

Power Requirements

Fuse

Operating Temperature Range

Storage Temperature Range

Vibration

Weight

Dimensions

Microprocessor

Communication Ports

Reference Pressure Transducers

(RPTs)

Ohmic Measurement System

Gases Supported

Pressure Connections

Pressure Limits

Flow Ranges

CE Conformance

85 to 264 VAC, 47 to 440 Hz, 18 VA max. consumption 1A/250V, slow blow, 5x20mm, NSN: 5920008930491 15 to 35 °C

-20 to 70 °C Meets MIL-T-28800D

2.55 kg (5.6 lb) max. 8 cm H x 22.5 cm W x 20 cm D

(3.1 in. x 8.9 in. x 7.9 in.) approx. Motorola 68302, 16 MHz

RS232 (COM1), RS232 (COM2), IEEE-488 Standard: 2 x 600 kPa (87 psia) calibrated range piezoresistive silicon

Microrange option: 12.5 kPa (1.8 psid) piezoresistive silicon Resolution: 0.004 Ω

Accuracy: ± 0.02 % of reading Accuracy of 100 and 110 Ω reference resistors: ± 0.01 % Stability of 100 and 110 Ω reference resistors: ± 0.005 % per three years With molbloc-L Nitrogen (N2), Air, Argon (Ar), Butane (Butn), Carbon

Monoxide (CO), Helium (He), Oxygen (O2), Carbon Dioxide (CO2), Carbon Tetrafluoride (CF4), Octofluorocyclobutane (C4F8), Ethane (C2H6), Ethylene (C2H4), Fluoroform (CHF3), Hexafluoroethane (C2F6), Hydrogen (H2), Methane (CH4), Nitrous Oxide (N2O), Propane (C3H8), Sulfur Hexafluoride (SF6), Xenon (Xe)

With molbloc-S Nitrogen (N2), Air (dry and humid) Quick connectors equivalent to Swagelok QM Series (-QM2-B200)

Maximum working pressure 600 kPa absolute (87 psia) Maximum pressure without damage 800 kPa absolute (115 psia) NOTE: The microrange option includes a 12.5 kPa (1.8 psi) differential

RPT which may be damaged by differential pressure greater than 100 kPa (15 psi).

See Sections 1.2.4.1.3, 1.2.4.1.4and 1.2.4.2.1 Available. Must be specified.

1.2.2 REFERENCE PRESSURE TRANSDUCER (RPT) SPECIFICATIONS

1.2.2.1 UPSTREAM AND DOWNSTREAM RPTS

Type

Range

Resolution

Repeatability

Accuracy

Piezoresistive silicon 0 to 600 kPa absolute (0 to 87 psia)

6.0 Pa (0.0009 psi) ± 0.01 % FS Absolute measurements: ± 0.05 % FS for one year

Differential measurements: ± (20 Pa + 0.05 % ΔΡ). Taring sequence eliminates zero error on measurement of difference between the two RPTs.

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1. INTRODUCTION

1.2.2.2 DIFFERENTIAL RPT (MICRORANGE OPTION)

Type

Range

Resolution

Repeatability

Accuracy

Piezoresistive silicon 0 to 12.5 kPa differential (0 to 1.8 psid)

0.14 Pa (0.00002 psi)

± 0.01 % FS ± 0.05 % FS for one year. Taring sequence eliminates zero error.

1.2.3 TEMPERATURE MEASUREMENT SPECIFICATIONS

Specifications are for molbloc mounted Platinum Resistance Thermometers (PRT) combined with molbox RFM resistance measurement system and temperature calculation.

Range

Accuracy

Resolution

0 to 40 °C ± 0.05 °C

0.01 °C

The molbox RFM internal resistance measurement system is automatically calibrated using reference 100 and 110 Ω (± 0.01 %) resistors (see Section

5.3).

1.2.4 FLOW MEASUREMENT SPECIFICATIONS

molbox RFM measures the flow through molbloc flow elements. There are two different types of molblocs, molbloc-L (laminar) (see Section 1.1.1.1) and molbloc-S (sonic) (see Section 1.1.1.2). Flow measurement specifications, calibration types, ranges and dimensions are detailed separately for each molbloc type in Section 1.2.4.1 and 1.2.4.2.

1.2.4.1 molbloc-L

The flow range, useable operating pressure and absolute and differential pressure associated with molbloc-L operation depend on the molbloc used and its pressure-dependent calibration options (see Section

Measurement Update Rate

Range

Resolution

Linearity

Repeatability

Precision

Stability

(1 year)

Measurement Uncertainty

(1 year, N2 and any molbox RFM

supported gas for which the molbloc

1 Precision: Combined linearity, hysteresis, repeatability. 2 Stability: aximum change in zero and span over specified time period for typical molbox RFM and

molbloc used under typical conditions. As stability can only be predicted, stability for a specific molbox RFM should be established from experience.

3 Measurement Uncertainty (Accuracy): Maximum deviation of the molbox RFM flow indication from

the true value of the flow through the molbloc including precision, stability and DHI calibration standard measurement uncertainty.

in use is calibrated)

1 second 0 to molbloc full scale depending on gas and molbloc

pressure dependent calibration type (see Section 1.2.4.1.2).

0.01 % FS

± 0.23 % of reading from 10 to 100 % FS, ± 0.023 % FS under 10 % FS

± 0.1 of reading from 10 to 100 % FS, ± 0.01 % FS under 10 % FS

± 0.25 % of reading from 10 to 100 % FS, ± 0.025 % FS under 10 % FS

± 0.15 % of reading from 10 to 100 % FS, ± 0.015 % FS under 10 % FS

± 0.5 % of reading from 10 to 100 % FS, ± 0.05 % FS under 10 % FS

1.2.4.1.2).

Page 14

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2.4.1.1 molbloc-L FLOW MEASUREMENT

SPECIFICATIONS, MICRORANGE OPTION

The microrange option (see Section 1.2.2.2) improves molbloc-L flow measurement specifications below 10 % FS of the molbloc range. With the microrange option, the affected measurement specifications below 10 % FS become:

Resolution

Linearity

Repeatability

Precision1

Stability

(1 year)

Measurement Uncertainty

(1 year, N2 and any molbox RFM

supported gas for which the molbloc in

use is calibrated)

1 Precision: Combined linearity, hysteresis, repeatability. 2 Stability: Maximum change in zero and span over specified time period for typical molbox RFM and

molbloc used under typical conditions. As stability can only be predicted, stability for a specific molbox RFM should be established from experience.

3 Measurement Uncertainty (Accuracy): Maximum deviation of the molbox RFM flow indication from

the true value of the flow through the molbloc including precision, stability and DHI calibration standard measurement uncertainty.

0.01 % of 10 % FS (0.001 % FS)

± 0.23 % of reading from 1 to 10 % FS ± 0.1 % of reading from 1 to 10 % FS ± 0.25 % of reading from 1 to 10 % FS

± 0.15 % of reading from 1 to 10 % FS

± 0.5 % of reading from 1 to 10 % FS

1.2.4.1.2 molbloc-L PRESSURE DEPENDENT CALIBRATION

TYPES

See your molbloc’s Calibration Report to determine the calibration type of

the molbloc you are using.

Different pressure dependent calibration options for molbloc-L elements determine the range of operating pressures over which a molbloc can be used within its mass flow measurement specifications. The calibration option also affects the molbloc flow range and the differential pressure associated with the flow range.

Measurement uncertainty (accuracy) specifications for molbloc-L are valid only for gases with which the molbloc has been calibrated. All molbloc-L elements are calibrated for N2. Calibrations with other gases are optional. DHI calibration capability is not maintained at all times for all gases on all molbloc designations. Check for availability before ordering calibrations.

Page 15

1. INTRODUCTION

The molbloc-L pressure dependent calibration types are summarized in Table 1.

Table 1. molbloc-L Pressure Dependent Calibration Types

CALIBRATION TYPE

Full mod, low pressure

Full mod, high pressure

Downstream

Single P, low pressure (non-N2 gases only )

Single P, high pressure (non-N2 gases only )

OPERATING PRESSURE

200 to 325 kPa absolute (29 to 48 psia) upstream of molbloc

325 to 525 kPa absolute (48 to 76 psia) upstream of molbloc

Atmospheric pressure (95 to 105 kPa, 13.8 to 15.2 psia) downstream of molbloc

Any specified single molbloc upstream pressure between 200 and 325 kPa absolute (29 to 48 psia)

Any specified single molbloc upstream pressure between 325 and 525 kPa absolute (48 to 76 psia)

NOMINAL DIFFERENTIAL

PRESSURE AT MAX. FLOW

1E5

MOLBLOC

5 kPa

(.725 psi)

Not available 50 kPa

12.5 kPa (1.8 psi)

5 kPa

(.725 psi)

Not available 50 kPa

ALL OTHER MOLBLOCS

50 kPa

(7.5 psi)

80 kPa

(12 psi)

50 kPa

(7.5 psi)

Differential pressure values are nominal and may vary by up to 15 % with the

actual molbloc used.

Page 16

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2.4.1.3 molbloc-L Ranges with Low Pressure Calibrations

Table 2. molbloc-L Ranges with Low Pressure Calibrations

- full mod, low pressure

- full mod, downstream

- single P, low pressure

SIZE

Nitrogen N2 Argon Ar

Helium He Sulfur Hexafluoride SF6

INERT

Xenon XE

Butane C4H10

Ethane C2H6

Ethylene C2H4

Hydrogen H2

FLAMMABLE

Methane CH4

Propane C3H8

Carbon Tetrafluoride

Hexafluorethene C2F6

FLUORO-

CARBONS

Trifluoromethane CHF3

Air Air Carbon Dioxide CO2

Carbon Monoxide CO Nitrous Oxide N2O

OTHER

Octafluorocyclobutane

Oxygen O2

A bold value indicates that the maximum flow is limited by the maximum Reynolds number value of 1 200 which is reached before the normal differential pressure range is reached. In that case, the second value gives the minimum flow for which relative accuracy is ± 0.5 % of the measured value. With the microrange option, this value is divided by 10 (see Section

1.2.2.2). Where there is no value in the field (--), this indicates that the maximum Reynolds number is reached before the differential

pressure reaches 5 kPa (1 kPa in the case of the 1E5 molbloc), therefore calibration with that gas is not useful. [1] Due to low vapor pressure, only downstream calibration type is available.

GASES

[1]

C4F8

CF4

SIZE

1E1

5E1

10 50 100 200 500 1 000 5 000 10 000 30 000 100 000 10 50 100 200 500 1 000 5 000 10 000 25 000 80 000

10 50 100 200 500 1 000 5 000 10 000 30 000 100 000 10 50 100 200 500 1 000

10 40 80 150 400 800

20 100

20 100 200 400 1

16 80 160 320 800 1 600

20 100 200 400 1

16 80 160 320 800 1 600 8 000 16 000

20 100 200 400 1

10 50 100 200 500 1 000

10 50 100 200 500 1 000 5 000 10 000 30 000 100 000 10 50 100 200 500 1 000 5 000 10 000

10 50 100 200 500 1 000 5 000 10 000 30 000 80 000

molbloc-L SIZE AND FULL SCALE FLOW (sccm)

SIZE

1E2

130

609 65

SIZE

2E2

270

130

5E2

670 140

000

330

SIZE

1E3

2 300

2 000

2 000 10

2 000

1 100

175

SIZE

5E3

2 000

500

3 500

500

2 200 1 400

6 000 1 000

7 000 1 000

000

3 000 1 000

4 000

600

2 000

600

4 000

600

1 050

840

SIZE

1E4

6 000 1 000

8 000

7 000 3 000

18 000

2 000

16 000

20 000 60 000 200 000

10 000

2 000

10 000

6 000 1 200

10 000

3 400 1 700

6 000 4 000

11 000

18 000

20 000

40 000

10 000

12 000

20 000

SIZE

3E4

3 000

---

6 000

5 000

7 000

3 000 6 000

4 000

--- ---

SIZE

1E5

---

30 000 20 000

---

60 000 50 000

70 000 40 000

120 000

40 000

---

36 000 25 000

---

38 000 30 000

60 000 30 000

Page 17

1. INTRODUCTION

1.2.4.1.4 molbloc-L Ranges with High Pressure Calibrations

Table 3. molbloc-L Ranges with High Pressure Calibrations

- full mod, high pressure

- single P, high pressure

SIZE

GASES

Nitrogen N2

SIZE

1E1

5E1

20 100 200 400 1 000 2 000 10 000 20 000

molbloc-L SIZE AND FULL SCALE FLOW (sccm)

SIZE

1E2

2E2

SIZE

5E2

SIZE

1E3

SIZE

5E3

SIZE

1E4

SIZE

3E4

40 000

SIZE

1E5

N/A

7 500

Argon Ar

20 100 200 400 1 000 2 000 10 000 17 000

35 000

N/A

6 000

Helium He

INERT

Sulfur Hexafluoride SF6

Xenon XE

[2]

Butane

4H10

Ethane C2H6

Ethylene C2H4

Hydrogen H2 Methane CH4

FLAMMABLE

Propane C3H8

Carbon

CF4

Tetrafluoride Hexafluorethene C2F6

FLUORO-

CARBONS

Trifluoromethane CHF3

Air Air

20 100 200 400 1 000 2 000 10 000 20 000 65 000 N/A 25

100

120

20 100 150 350 650 1 700

250

* * * * * * * * * N/A

40 200

350

700 100

40 200 350 700 2 000 4 000

600 150

1 800

200

2 000

300

4 000

2 000 1 400

3 350

950

6 000 2 300

7 000 2 000

6 200 2 800

11 000

1 900

20 000

4 500

22 000

4 000

11 000

5 700

20 000 13 000

22 000 12 700

40 200 400 900 2 000 4 500 22 000 45 000 130 000 N/A 35 175 350 700 1 700 3 500

13 000

2 000

50 200

20 100 200 400 1 000 2 000

200

400 100

1 000

250

3 500

500

3 500 2 600

3 700 1 200

100

120

25 125

240

250

450

600 150

1 200

150

2 000

300

2 500

1 800 1 500

4 000 1 500

20 100 200 400 1 000 2 000 10 000 20 000

33 000 42 000

12 000

11 000

5 400

12 000

2 400 6 000

3 000

12 000

3 000

12 000

7 300

12 000

8 800

40 000

N/A

7 200

Carbon Dioxide CO2

Carbon Monoxide CO

25 125 250 500 1 250 2 500

6 600 1 400

20 000

2 500

20 000

8 800

20 100 200 400 1 000 2 000 10 000 20 000 40 000

N/A

7 500

OTHER

Oxygen O2

20 100 200 400 1 000 2 000 10 000 20 000

40 000

N/A

6 500

Octafluorocyclobutane

[2]

C4F8

Nitrous Oxide N2O

Where there is no value in the field (--), this indicates that the maximum Reynolds number is reached before the differential pressure reaches 5 kPa (1 kPa in the case of the 1E5 molbloc), therefore calibration with that gas is not useful.

* * * * * * * * * N/A

25 125 250 500 1 250 2 500

11 000

1 500

20 000

3 000

20 000

9 000

N/A

[2] The operating pressure range is greater than the vapor pressure value for the gas.

Page 18

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2.4.1.5 molbloc-L DIMENSIONS

5E3 AND LOWER 1E4, 3E4 1E5

58.50 (2.303) 74.50 (2.933) 74.50 (2.933)

16.00 (0.630) 24.00 (0.945) 24.00 (0.945)

32.00 (1.260) SQ 48.00 (1.890) SQ 48.00 (1.890) SQ

68.84 (2.750) 80.00 (3.150) 80.00 (3.150)

19.06 (0.750) 28.00 (1.102) 28.00 (1.102)

124.00 (4.881) 157.00 (6.181) 164.00 (6.458)

1/4 in. VCR M 1/4 in. VCR M 1/2 in. VCR M

molbloc-L SIZES [mm(in.)]

Page 19

1. INTRODUCTION

1.2.4.2 molbloc-S

The flow range and operating pressure associated with molbloc-S operation depend on the molbloc used and its calibration options (see Section 1.2.4.2.2)

Measurement Update

Range

Resolution

Linearity

Repeatability

Precision

Predicted Stability

(1 year)

Measurement

Uncertainty

With SP molbloc-S

calibration

Measurement

Uncertainty

With LP molbloc-S

calibration

1 Precision: Combined linearity, hysteresis, repeatability.

2. Stability: Maximum change in zero and span over specified time period for typical molbox RFM and molbloc used under typical conditions. As stability can only be predicted, stability for a specific molbloc and molbox RFM should be established from experience.

3. Measurement uncertainty (accuracy): Maximum deviation of the molbox RFM flow indication from the true value of the flow through the molbloc including precision, stability and DHI calibration standard measurement uncertainty.

1 second

Rate

Depends on molbloc-S pressure dependent calibration type (see Section 1.2.4.2.2)

0.01 % of FS

± 0.25 % of reading ± 0.10 % of reading

± 0.30 % of reading

± 0.2 % of reading

± 0.5 % of reading from 50 to 500 kPa

± 0.5 % of reading from 50 to 200 kPa

± 0.5 % of 50 kPa flow from 20 to 50 kPa

1.2.4.2.1 molbloc-S RANGES

molbloc-S flow ranges are defined by the molbloc’s Pressure to Flow Conversion Ratio, K downstream pressure and the acceptable back pressure ratio (see Section

3.1.2). K

between mass flow and the absolute upstream pressure delivered to the molbloc-S. molbloc-S sizes are defined by the nominal K nozzle, using scientific notation, for example a 1E3 molbloc-S has a K sccm/kPa. To differentiate from molbloc-L size designations, this molbloc size is designated 1E3-S.

The molbox RFM pressure range, the molbloc-S calibration type (see Section

1.2.4.2.2) and the back pressure ratio (BPR) requirements (see Section 3.1.2)

limit the pressures, and flows, over which a molbloc-S can be used within known measurement uncertainty limits. In practice, the usable range of a molbloc-S in a given application also may depend on the available gas supply pressure, the presence and flow capacity of a vacuum pump downstream or the allowable back pressure on an upstream DUT.

The flow ranges for each molbloc-S size at various typical operating pressures are summarized in Table 4 and the BPR limits are in Table 5.

, the absolute pressure that can be delivered upstream of molbloc-S, the

is expressed in units of sccm/kPa and defines the relationship

of the molbloc-S

1 000

Page 20

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

Table 4. molbloc-S Flow at Various molbloc Upstream Pressures

[1][2]

250 kPa

(36 psia)

500 kPa

(70 psia)

molbloc-S

DESIGNATO

5E1-S 1E2-S 2E2-S 5E2-S 1E3-S 2E3-S 5E3-S 1E4-S

FLOW [slm @ 0°C] WHEN molbloc-S UPSTREAM PRESSURE IS:

[sccm/kPa]

20 kPa (3psia)

50 kPa

(7 psia)

100 kPa

(15 psia)

Minimum

without

vacuum

]

150 kPa

(22 psia)

200 kPa

(30 psia)

50 1 2.5 5 7.7 7.5 10 12.5 25 100 2 5 10 15 15 20 25 50 200 4 10 20 28 30 40 50 100 500 10 25 50 67 75 100 125 250

1 000 20 50 100 129 150 200 250 500 2 000 40 100 200 248 300 400 500 1 000 5 000 100 250 500 596 750 1 000 1 250 2500

10 000 200 500 1 000 1 173 1 500 2 000 2 500 5 000

[1] When volumetrically based mass flow units with reference temperatures other than 0°C are used, flow values

will generally be higher; for example, the flow values for a given molbloc and upstream pressure are approximately 7% higher when expressed in slm @ 20°C. Flow values at a given pressure may vary by up to

2% due to flowpath machining tolerances. [2] Flow values in table are valid only when critical flow is established. [3] Minimum upstream pressure to achieve critical flow with atmospheric pressure (approximately 100 kPa)

downstream of molbloc-S (no vacuum).

Table 5. Minimum molbloc-S Critical Flow (slm) at Various molbloc-S Downstream Pressures

molbloc-S

DESIGNATO

5E1-S 1E2-S 2E2-S 5E2-S 1E3-S 2E3-S 5E3-S 1E4-S

250 kPa

(36

psia)

[1]

300 kPa

(44

psia)

MINIMUM molbloc-S CRITICAL FLOW [SLM @ 0°C] WITH molbloc DOWNSTREAM PRESSURE OF:

≤ 5 kPa (0.7

psia)

1 2

4 10 20 40

100 200

kPa

(1.5

psia)

[2]

1.7 3.4 4.7 7.7 8.4 9.4 11 14 17 20

[2]

3.4 5.9 8.4 15 16 18 21 27 33 38

[2]

5.9 9.8 16 28 31 34 40 51 63 74

[2]

12 20 37 67 72 80 95 122 149 179

[2]

100

[2]

200

25 kPa (3.5

psia)

[2]

39 69 129 139 154 184 239 294 349

[2]

73 131 248 268 298 358 468 578 687

[2]

173 317 596 646 746 871 1 145 1 420 1 694

[2]

347 615 1 173 1 273 1 442 1 741 2 240 2 789 3 338

kPa

psia)

100

kPa

(15

psia)

110 kPa

(16

psia)

125 kPa

(18

psia)

150 kPa

(22

psia)

200

kPa

(30

psia)

[1] When volumetrically based mass flow units with reference temperatures other than 0 °C are used, flow values

will generally be higher; for example, the flow values for a given molbloc and upstream pressure are approximately 7 % higher when expressed in slm @ 20 °C. Flow values at a given pressure may vary by up to 2 % due to flowpath machining tolerances.

[2] Limited by 20 kPa minimum calibration pressure rather than back pressure ratio.

Page 21

1. INTRODUCTION

1.2.4.2.2 molbloc-S PRESSURE DEPENDENT CALIBRATION TYPES

See your molbloc’s Calibration Report to determine the calibration type of

the molbloc you are using.

Measurement uncertainty (accuracy) specifications for molblocs are valid only for gases with which the molbloc has been calibrated. All molbloc-S elements are calibrated in one standard gas, either air or N2, and may be calibrated in other gases. Calibrations with other gases are optional. The set of gases which can be measured by molbloc-S is separate from the list of molbloc-L gases, and may be more limited. DHI calibration capability is not maintained at all times for all gases on all molbloc sizes. Check for availability before ordering calibrations.

molbloc-S calibrations are performed over flow ranges corresponding to one of two pressure ranges, summarized in Table 6.

Table 6. molbloc-S Calibration Types

CALIBRATION TYPE

LP low pressure

SP standard pressure

OPERATING PRESSURE

20 to 200 kPa absolute (3 to 30 psia upstream of molbloc

50 to 500 kPa absolute (7 to 70 psia) upstream of molbloc

molbloc-S flow measurements are valid only when the ratio of pressure

downstream to pressure upstream of the nozzle is high enough to assure a critical (choked) flow (see Section 3.1.2).

Page 22

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2.4.2.3 molbloc-S Dimensions

5E1-S 1E2-S 2E2-S 5E2-S 1E3-S 2E3-S 5E3-S 1E4-S

48.0 (1.89) SQ 48.0 (1.89)SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 80.0 (3.15) SQ 80.0 (3.15) SQ

24.0 (0.94) 24.0 (0.94) 24.0 (0.94) 24.0 (0.94) 24.0 (0.94) 24.0 (0.94) 40.0 (1.57) 40.0 (1.57)

48.0 (1.89) SQ 48.0 (1.89)SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 48.0 (1.89) SQ 80.0 (3.15) SQ 80.0 (3.15) SQ

80.0 (3.15) 80.0 (3.15) 80.0 (3.15) 80.0 (3.15) 80.0 (3.15) 80.0 (3.15) 176.0 (6.93) 176.0 (6.93)

28.0 (1.10) 28.0 (1.10) 28.0 (1.10) 28.0 (1.10) 28.0 (1.10) 28.0 (1.10) 44.0 (1.73) 44.0 (1.73)

167.5 (6.59) 167.5 (6.59) 171.0 (6.73) 171.0 (6.73) 171.0 (6.73) 175.0 (6.89)

KF16 FLANGE KF16 FLANGE KF16 FLANGE KF16 FLANGE KF16 FLANGE KF16 FLANGE KF40 FLANGE KF40 FLANGE

100.0 (3.94) 100.0 (3.94) 84.0 (3.31) 84.0 (3.31) 84.0 (3.31) 84.0 (3.31) 154.0 (6.06) 154.0 (6.06)

128.0 (5.04) 128.0 (5.04) 128.0 (5.35) 128.0 (5.35) 128.0 (5.35) 128.0 (5.35) 236.0 (9.29) 236.0 (9.29)

73.0 (2.87) 73.0 (2.87) 73.0 (2.87) 73.0 (2.87) 73.0 (2.87) 73.0 (2.87) 106.0 (4.17) 106.0 (4.17)

167.5 (6.59) 167.5 (6.59) 171.0 (6.73) 171.0 (6.73) 171.0 (6.73) 171.0 (6.73) 290.0 (11.42) 290.0 (11.42)

K L

¼” VCR M

[2]

¼” VCR M

[2]

½” VCR M

molbloc-S SIZE [mm(in.)]

[2]

½” VCR M

[2]

½” VCR M

[2]

½” VCR M

[1]

299.7 (11.80)

[2]

1” NPT M

[1]

331.0 (13.03)

[2]

1” NPT M

[1] On some molbloc-S elements,

the venturi nozzle extends beyond the molbloc downstream flange, making the overall length dimension, F, longer than the fitting to fitting length dimension, K.The nozzle overhang may interfere with some molbloc-S downstream connections or the connection of a blank off cap for leak testing, so a 40 mm diameter ISO-KF nipple is supplied with 5E3-S and 1E4S molblocs.

[2] Default connector type is

listed. Additional upstream connector options may be available. Contact your DHI Sales Representative for details.

[1]

[2]

Page 23

1. INTRODUCTION

1.2.5 FRONT AND REAR PANELS

1.2.5.1 FRONT PANEL

The front panel assembly provides a 2 x 20 vacuum fluorescent display, a membrane keypad for local user interface and a SOFT ON/OFF key.

1. Display

2. Multi-function Keypad P

3. Remote Communication Indicator

4. SOFT ON/OFF Key and Indicator

Figure 1. molbox RFM Front Panel

Page 24

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

1.2.5.2 REAR PANEL

The rear panel assembly provides pressure and electrical connections to a molbloc mass flow element, communications interfaces and the power connection module.

1. Quick connectors to molbloc pressure connections (color coded)

2. Electrical power connector (IEC320-313)

3. IEEE-488 (GPIB) connector for host communications

4. COM1 (RS232) connector for host communications

5. Electrical connection to molbloc

6. COM2 (RS232) connector for communications with an external device

7. Product label (on bottom of case)

Figure 2. molbox RFM Rear Panel

Page 25

22.

NNSSTTAALLLLAATTIIOON

2.1 UNPACKING AND INSPECTION

2.1.1 REMOVING FROM PACKAGING

molbox RFM is delivered, along with its standard accessories, in a corrugated container with polyurethane inserts to hold it in place.

Remove the molbox RFM and its accessories from the shipping container and remove each element from its protective plastic bag.

2.1.2 INSPECTING CONTENTS

Check that all items are present and have NO visible damage. A molbox RFM includes:

2. INSTALLATION

Table 7. molbox RFM Parts List

DESCRIPTION PART #

molbox RFM Reference Flow Monitor FAM0005 Report of Calibration 550100

ACCESSORIES, INCLUDING:

1 Operation and Maintenance Manual 550107 1 Power Cord (7.5 ft.) 100770 1 Set of (2) molbox to molbloc pressure connecting

tubes

1 molbox to molbloc electrical/data connection

cable 2 straight through quick connector stem 101889* 1 General Accessories CD (white)

(Important: Includes system support software

and documentation.)

* Equivalent to Swagelok P/N SS-QM2-S-200

2.2 SITE REQUIREMENTS

Install molbox RFM on any stable surface at a convenient height. The front feet are extendible so that the unit can be inclined for easier viewing.

The molbox RFM can also be mounted in a standard 19-in. rack mount using the optional rack mount kit (P/N 401465). For additional information, contact your DHI Sales Representative.

401125

102096

102987

When installing molbox RFM, consideration should be given to where the molbloc flow measuring element and associated hardware will be located. molbox RFM may be placed on a shelf or cart at a different height than the molbloc, but the distance between the molbloc and molbox is limited by the length of the cable and pneumatic lines connecting them. If you will locate the molbox at a different height than the molbloc, the small errors that would be associated with the difference in pressure can be removed using the molbox RFM head correction (see Section 3.6.8).

Page 26

molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

If the molbloc/molbox system is being used to calibrate other devices (DUTs), the molbloc may need to be connected upstream or downstream of the DUT to operate within the pressure limits of the molbloc’s calibration type (see Sections 1.2.4.1.2, 2.2.4.2.2) and to accommodate the pressure requirements of the DUT. Se e th e mo lb lo c’ s Ca l ib ra ti on R eport to determine the calibration type of the molbloc you are using.

If the molbloc is connected upstream of the DUT, it is important to supply the molbloc with a stable regulated gas source. The volume present between the molbloc and the device to be calibrated should be minimized for low flows.

In some cases, molbloc-S is used with a vacuum source downstream to reduce the pressure at w h i c h critical flow is reached. Consider the placement of the vacuum pump and connections. Generally, a large vacu u m p u m p i s needed that should be isolated from the work area due to noise and oil vapor considerations. If the vacuum pump and/or vacuum kit was purchased from DHI, see the instruction sheets and/or manuals that are included with the hardware.

Optional molstics are offered for mounting molblocs. They provide a convenient means of addressing supply regulation, filtering and interconnection issues with high quality, configured hardware. For additional information, contact your DHI Representative.

If a DUT is located upstream of the molbloc and is contaminated, contaminates may flow

from the DUT to the molbloc and alter the molbloc calibration. If the DUT must be connected upstream of the molbloc, be sure it is clean before flowing and consider installing a filter between the DUT and the molbloc.

2.3 INITIAL SETUP

2.3.1 PREPARING FOR OPERATION

To prepare molbox RFM for check out and operation:

n Remove the plastic caps from the molbox RFM rear panel pressure connections. o Remove the protective plastic sheet from the front panel display. p Familiarize yourself briefly with the front and rear panels (see Section 1.2.5).

Follow the steps described in Sections 2.3.1 to 2.3.6

2.3.2 POWER CONNECTION

Connect the power cable supplied to molbox RFM and to a power source. Power requirements are 85 to 264 VAC, 50 to 60 Hz, 22 VA max. consumption.

molbox RFM is always powered and active when power is supplied through the rear panel

power connector. The front panel ON/OFF key controls a SOFT ON/OFF (see Section 3.3.3).

2.3.3 MOLBOX RFM TO MOLBLOC CONNECTION

There are two pressure connections (upstream and downstream) and one electrical/data connection between molbox RFM and a molbloc.

For the pressure connections, use the molbox RFM to molbloc pressure tubes (P/N 401125) supplied with the molbox RFM. Following the color coding on the pressure lines, connect the upstream (HI) molbox RFM rear panel quick connector to the upstream port of the molbloc and the downstream (LO) quick connector to the downstream port. Push firmly on the quick connectors until they click into place to assure that the connection is properly completed.

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2. INSTALLATION

For the electrical/data connection, use the molbox to molbloc electrical/data connection cable (P/N 102096). Connect the cable to the molbloc and then to molbox RFM rear panel connector labeled “molbloc”.

Avoid making molbloc electrical connections to molblocs while molbox RFM is plugged in.

Damage to the molbloc EEPROM may result (see Section 5.5.5)

2.3.4 GAS SUPPLY AND FLOWPATH CONNECTIONS

Connect a gas supply to the molbloc. Gas supply requirements are:

• The gas supply must be clean and dry (especially free from oil and particulates) to avoid contaminating the molbloc.

• For correct measurements, the gas must be of the same species as that selected by the molbox RFM GAS function (see Section 3.4.2). Gas purity affects the measurement uncertainty of flow measurements as molbox RFM uses the thermodynamic properties of the flowing gas in its flow calculations. Generally, gases with purity of 99.9 % or better are used for molbloc measurements. Except when using ambient air with molbloc-S, the test gas should be free of any humidity (dew point less than – 40 °C).

• If the molbloc is connected upstream of the DUT, the supply pressure must be regulated and stable within the limits of the molbloc-L pressure dependent calibration type (see Section connected downstream of the DUT, use regulators and

1.2.4.1.2) or molbloc-S calibration type (see section 1.2.4.2.2). If the molbloc is valves to make sure that the

pressure that is delivered to the molbloc will be within the limits of the molbloc calibration type.

• Care should also be taken to make sure that the pressure and flow supplied to the molbloc are always low enough to avoid over pressuring the molbox RFM RPTs (see Sections 1.2.2, 3.1.6). If a DUT upstream of the molbloc is operated at high pressure, a pressure reducing regulator should be connected between the DUT and the molbloc to ensure that even momentary high pressure spikes do not reach the molbox RPTs.

The gas supplied to the molbloc should be clean and dry. Contamination of the molbloc

flow passage with liquids, particulates or any other matter will alter the molbloc calibration and can lead to out of tolerance flow measurements.

NEVER connect a pressure source to the molbloc that is greater than the overpressure

limit of your molbox RFM. molbox RFM overpressure limit is 660 kPa absolute/560 kPa gauge (95 psia/80 psig). Overpressure can damage the molbox RFM internal RPTs (see Section 1.2.2, 3.1.6).

If you are using a DHI molstic: Install the molbloc into the molstic and connect a gas supply following the molstic instruction sheet or manual. The flow through the molbloc must be in the direction of the arrow engraved on the molbloc.

If you are NOT using a DHI molstic: Connect a gas supply to the molbloc according to the molbloc instruction sheet and the pressure limits of the molbloc calibration type. A valve should be installed between the pressure supply and the molbloc to allow flow to the molbloc to be interrupted. The flow through the molbloc must be in the direction of the arrow engraved on the molbloc.

Adaptor kits are available from DHI to make connections from the molbloc or molstic fittings to other common connector types. Ask you DHI Sales Representative about your specific adaptor requirements.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

Operating at pressures other than those of the molbloc-L pressure dependent calibration type

(see Section 1.2.4.1.2) or molbloc-S calibration type (see Section 1.2.4.2.2) may result in out of tolerance flow measurements. Refer to the molbloc Calibration Report to determine its calibration type.

2.3.5 VACUUM SUPPLY (molbloc-S ONLY)

In some cases molbloc-S is operated with a vacuum downstream of the molbloc to reduce the back pressure so that critical flow can be reached at a lower upstream pressure (see Section 3.1.2).

There is no lower limit to the pressure that may safely be applied to molbox RFM RPTs. If you are using DHI supplied downstream vacuum connect kit and vacuum pump:

Install the kit and pump following the supplied instruction sheet or manual. Carefully follow the pump manufacturer’s recommendations for pump operation.

If you are NOT using DHI supplied downstream vacuum connect kit and vacuum pump: Carefully evaluate vacuum pump specifications to be sure that the vacuum source

available has the pumping speed necessary to safely handle the planned flows and to maintain low enough pressure at planned flow rates.

Be sure to provide facilities to avoid flowing into the pump when the pump is not ON as this will cause pressure to build up on the pump and may damage it. Normally, a shut-off valve should be included between the pump and the molbloc-S.

It is preferable to install a check valve with very low cracking pressure between the molbloc and the vacuum shut-off valve.

Operating at pressures other than those of the molbloc-S calibration type may result in

out of tolerance flow measurements (see Section 1.2.4.2.2). Refer to the molbloc Calibration Report to determine its calibration type.

2.3.6 COMMUNICATIONS CONNECTIONS

If molbox RFM is being interfaced to a computer, connect an RS232 cable to molbox RFM COM1 or an IEEE-488 cable (cables not supplied) to the molbox RFM IEEE-488 interface. Configure the interface (see Section

3.6.6).

2.4 POWER UP AND VERIFICATION

2.4.1 POWER UP

Connect the molbox RFM power cable to an electric supply of 85 to 264 VAC (47 to 440 Hz). Observe the front panel display as molbox RFM initializes, error checks, calibrates its internal ohmic measurement system and goes to the main run screen (see Section 3.2). The top left side of the main run screen should display a flow value near zero or <BPR HI>. If <NO BLOC> is displayed, molbox RFM has not been able to identify a molbloc connection and load molbloc information. Verify that a valid molbloc is properly connected (see Section

2.3.3) and press [SETUP], <4molbloc> to load the molbloc data. If molbox RFM is still

unable to identify a molbloc, the molbloc may require reloading of EEPROM information or molbox RFM may require repair.

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2. INSTALLATION

If the molbox RFM fails to reach the main run screen: Service may be required. Record

the sequence of operations and displays observed and contact a DHI Authorized Service Provider (see Section 7.2).

molbox RFM is always powered and active when power is supplied through the rear panel

power connector. The front panel ON/OFF key controls a SOFT ON/OFF only (see Section

3.1.4).

2.4.2 CHECK PROPER PRESSURE MEASUREMENT OPERATION

Check that the molbox RFM pressure measurements are operating properly. Proceed as follows:

n Connect the molbloc to the molbox RFM (see Section o Shut off the gas supply to the molbloc and open one or

2.3.3). both molbloc ends to atmospheric

(ambient) pressure.

p Press [P&T] and observe the display of the pressure measured by the upstream and

downstream absolute RPTs. Observe the upstream and downstream pressures (see Section 3.4.5). These should indicate current atmospheric pressure and be in agreement within ± 0.5 kPa (0.1 psi). If the two readings disagree by more than ± 0.5 kPa (0.1 psi), one or both RPTs may be out of calibration and service may be required. A difference in the RPT readings could also indicate that there is some flow through the molbloc. Check the flowpath valve or disconnect the molbloc to ensure that there is actually no flow.

q If the molbox RFM is equipped with the microrange option, and the option is currently

active, the bottom line left side of the display is <mDP>. Observe the differential pressure value following this indication (see Section 3.4.5). It should be 0, ± 50 Pa (0.004 psi). If the indication is different from zero by more than ± 50 Pa (0.004 psi), the microrange differential RPT may be out of calibration and service may be required. Again, a non-zero differential pressure could indicate an unexpected flow through the molbloc.

r Press [ESCAPE] to return to the main run screen.

2.4.3 CHECK PROPER TEMPERATURE MEASUREMENT OPERATION

Check that the molbox RFM temperature measurement is operating properly. Proceed as follows:

n Connect a molbloc to the molbox RFM (see Section o From the molbox RFM main run

screen, press [P&T] twice to arrive at the temperature

2.3.3).

display screen. Observe the temperature readings of the two molbloc PRTs (see Section 3.4.5). If the molbloc has been in a stable temperature environment for 30 to 60 minutes, the temperature indications should be roughly ambient temperature and the two indications should agree within ± 0.2 °C. If the two readings disagree more than ± 0.2 °C, there may be a problem with the molbloc or the molbox RFM TEMPERATURE MEASUREMENT function and service may be required.

2.4.4 LEAK CHECK

It is recommended that a new molbox RFM be leak checked at start-up to assure that no internal leaks developed during shipping and handling. Run the molbox RFM on-board INTERNAL LEAK CHECKING function (see Section 3.4.5).

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

2.4.5 CHECK/SET SECURITY LEVEL

molbox RFM has a security system based on user levels. By default, the security system is set to “low”, which includes certain access restrictions, and there is no password required to change the security level (see Sections 3.6.2). As part of the molbox RFM startup, set your desired security level and a password.

molbox RFM is delivered with the security level set at low to avoid inadvertent altering of

critical internal settings but with access to changing security levels unrestricted. It is recommended that the low security level be maintained at all times and password protection be implemented if control over setting of security levels is desired.

2.5 ADDITIONAL PRECAUTIONS TO TAKE BEFORE MAKING FLOW MEASUREMENTS

Before using molbox RFM to make meaningful flow measurements, consider the following:

• Be sure that the gas pressure connected to the molbloc is not great enough to overpressure the

molbox RFM internal RPTs.

• For molbloc-L operation, the pressure measuring RPTs should be tared at the operating line pressure

(see Section 3.4.4.1).

• Operating pressure should be within the limits of the molbloc calibration type (see Sections 1.2.4.1.2.

and 1.2.4.2.2).

• The gas type selected should be the gas flowing through the molbloc (see Section 3.4.2).

• For best accuracy, the gas type should be a gas with which molbloc has been calibrated. See the

molbloc Calibration Report or press [SETUP], <4molbloc>, [ENTER] to see if the gas is included in the molbloc calibration gas list (see Section 3.5.4).

• Do not supply a gas or connect a device under test upstream of the molbloc that may contaminate

the molbloc.

• Be sure the flow unit of measure you are using is correct. Many different types of flow units of

measure are commonly used. Before selecting a unit of measure, familiarize yourself with Section

3.4.3 thoroughly.

• Troubleshooting: For information on typically encountered start-up and operational issues, see

Section 6.

2.6 SHORT TERM STORAGE

The following is recommended for short term storage of molbox RFM:

• Vent the molbox RFM pressure ports.

• Disconnect the power supply.

When molbox RFM will NOT be used for some time, it may be left powered. Use the SOFT ON/OFF key to turn OFF the display.

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33.

PPEERRAATTIIOON

3.1 GENERAL OPERATING PRINCIPLES

3.1.1 molbloc-L AND molbloc-S OPERATION

molbox RFM operates somewhat differently depending on whether a molbloc-L or molbloc-S is connected to it. mobloc-L and molbloc-S operation use different displays and flow calculations and some menu items are present for only one type of molbloc.

Most molbox R FM settings, such as gas, units, K factor, etc. , are com mon to bo th molbloc-L and molbloc-S operation. Changes made to these settings while operating one type of molbloc will still be in effect when the other type of molbloc is connected. The only setting that is used for both molbloc types but is stored independently for each type is tare. See section

3.4.4.1 for details on the tare function. Several of the molbox RFM screen displays and functions described in this section are

different for molbloc-L and molbloc-S operation. Where the differences are major, the description of these functions is divided into two parts.

3. OPERATION

3.1.2 molbloc-S BPR LIMITS

To make flow measurements within predictable measurement uncertainty limits with a molbloc-S flow element, critical (sonic) flow conditions must be present. Critical flow exists when the gas velocity reaches the local speed of sound at the throat of the molbloc-S venturi nozzle.

molbox RFM uses the back pressure ratio, or BPR (the ratio of the molbloc-S downstream absolute pressure to the upstream absolute pressure) to determine whether the flow is critical. For venturi nozzles in general, the BPR must remain below a certain value for critical flow to exist. Commonly accepted practice for typical venturi nozzle use suggests that this limiting BPR value, or “choking ratio”, is approximately 0.5. That is, the absolute pressure downstream of the nozzle must be less than one half of the absolute pressure upstream of the nozzle. Empirical study of the venturi nozzles used in molbloc-S shows that the actual choking ratio, or maximum BPR for critical flow, varies between about 0.4 and 0.9 as a function of the Reynolds number (Re) over which the molblocs are used. molbox RFM continually calculates Re during flow measurement and can monitor the BPR to ensure that it does not exceed the choking ratio at the current Re conditions. molbox RFM uses a conservative BPR limit t o indicate to the user when the BPR approaches the choking ratio, to ensure that flow measurements are only made under “safe” critical flow conditions. molbox RFM includes features to measure BPR, automatically alert the operator when the BPR is too high and prevent measurements when flow is not critical (see Sections 3.1.3.2, 3.4.4.5, 3.6.9).

Maintaining a sufficiently low BPR must be considered by molbloc-S users when selecting molbloc-S sizes and hardware setups to use for flow measurements. For example, if a molbloc-S will be used with atmospheric pressure downstream, then the molbloc can only be used over a range of upstream pressures starting at the maximum pressure for its calibration type down to a minimum pressure value at which the BPR becomes equal to the BPR limit calculated by molbox RFM. Since mass flow through molbloc-S is proportional to the upstream absolute pressure, the flow range for the molbloc in this application is defined by this BPR limit. To maximize the range of a molbloc-S element, a vacuum pump can be connected downstream to reduce the downstream pressure while flowing. When the downstream pressure is kept sufficiently low, the upstream pressure, and thus the mass flow rate, can be adjusted all the way down to the minimum value for the molbloc’s pressure dependent calibration type without being limited by the BPR value.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

Depending on the placement of the molbloc-S in relation to the DUT and other hardware, and the availability and capacity of a vacuum pump that may be used, the molbloc-S downstream pressure will vary in different applications. Calculating Re for different molbloc-S sizes and flow rates, and estimating the choking ratio (maximum BPR limit) as a function of Re is somewhat complex, so Table 5 is offered to give the minimum flow that can be achieved with each molbloc-S size, without exceeding molbox BPR limits, when the molbloc-S downstream pressure is known: In actual operation, molbox RFM calculates the Re and BPR ratio and provides an indication of whether the BPR is adequate for measurements to be made.

3.1.3 FLOW READY/NOT READY INDICATION

The character to the left of the measured flow on the MAIN run screen provides a flow Ready/Not Ready indication. This indication is intended to provide the user with a clear and objective indication of when a stable flow has been achieved.

Ready <*> is indicated when the current stability (rate of change) of flow is less than the stability limit. The user can set the stability limit (see Section 3.5.5). The Ready/Not Ready indication is often used when comparing molbox RFM and a test device to help determine when steady state flow conditions are present so that a valid comparison reading can be made.

3.1.3.1 molbloc-L OPERATION

In molbloc-L operation, the Ready/Not Ready indication also helps guard against using molblocs above their valid range by monitoring the Reynolds number of the flow. If the Reynolds number of the current flow exceeds 1 300, the Ready (<*>) indicator flashes. The current Reynolds number value can be viewed using [P&T] (see Section range limits for the flowing gas and the pressure dependent calibration type (see Section 1.2.4.1.2), a Reynolds number of 1 200 will never be exceeded used as the warning limit to allow for individual molbloc differences).

Ready/Not Ready character indications are:

<*> Flow Ready (stable). <*> (Flashing): Reynolds number > 1 300. <↓> Flow Not Ready (unstable and decreasing). <↑> Flow Not Ready (unstable increasing).

3.4.5). If molblocs are used within the pressure and flow (1 300 is

3.1.3.2 molbloc-S OPERATION

In molbloc-S operation, the Ready/Not Ready indication is also used to warn the user when the BPR (back pressure ratio) is too high to ensure critical flow (see Sections 3.1.2). When the BPR is beyond the choking limit, molbloc-S flow measurements may not be valid and the Ready indicator becomes <P>. The Ready/Not Ready indicators based on flow stability are also used in molbloc-S operation, but the <P> indicator takes priority over other indicators.

Ready/Not Ready character indications are:

<*> Flow Ready (stable). <↓> Flow Not Ready (unstable and decreasing). <↑> Flow Not Ready (unstable increasing). <P> Flow Not Ready (BPR high / sub-critical flow)

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3. OPERATION

3.1.4 SOFT [ON/OFF] KEY

molbox RFM is equipped with a SOFT [ON/OFF] key and indicator LED on the bottom left hand corner of the front panel. The purpose of the SOFT ON/OFF key is to put molbox RFM into a dormant mode in which the display is turned OFF but power is still supplied and OVERPRESSURE functions are still active. When molbox RFM is ON, the ON/OFF indicator is ON continuously.

When molbox RFM is SOFT OFF, the ON/OFF indicator blinks every 5 seconds. When molbox RFM is SOFT OFF, receiving a remote command turns it ON. When molbox RFM is SOFT OFF, an overpressure conditions turns it ON.

3.1.5 MICRORANGE OPTION (OPTIONAL)

The molbox RFM offers a microrange option to improve molbloc-L flow measurement specifications below 10 % of full scale of the molbloc being used (see Section 1.2.4.1.1). The microrange option is only active during molbloc-L operation and has no effect on molbloc-S operation or specifications.

The microrange option includes a low differential pressure RPT to improve the measurement of differential pressure across the molbloc below 12.5 kPa (1.8 psi). A three-way valve and on-board logic automatically put the low differential RPT into and out of service. This allows it to be used as the source of differential pressure values whenever differential pressure is under 12.5 kPa (1.8 psi) and bypassed for protection from overpressure when differential pressure exceeds 13.5 kPa (2 psi) (see Figure 3).

With automatic microrange operation ON, the microrange option (if present) is used transparently to the operator to optimize flow measurement resolution and accuracy (see Section 3.4.7). With automatic microrange operation OFF, the microrange option is not used and all measurements are made using the upstream and downstream absolute RPTs only.

When the type of molbloc connected to molbox RFM is changed from molbloc-L to molbloc-S, or molbox RFM power is cycled, the last state of the microrange option (ON or OFF) is retained for molbloc-L operation.

The microrange option can also be controlled manually by pressing [SPECIAL] and selecting <7micro> (see Section 3.6.7).

The microrange indicator on the main run screen (see Section 3.4.7) indicates the status of the microrange option.

1. High Isolation: Open

2. Low Isolation: Open

3. Bypass: Closed

4. Mirorange Bypass: Closed (microrange active) Open (microrange inactive)

Figure 3. molbox RFM

Internal Pneumatic Schematic – MICRORANGE OPTION RPT ACTIVE/INACTIVE

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

To determine if a molbox RFM is equipped with the microrange option, check the model

number on the product label on the bottom of the molbox RFM case. If the model number includes a “-M”, the microrange option is installed.

The microrange option is only active during molbloc-L operation. Mirorange has no effect

on molbloc-S operation or measurement specifications.

3.1.6 REFERENCE PRESSURE TRANSDUCER (RPT) OVERPRESSURE

3.1.6.1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS

Every molbox RFM has two absolute RPTs, one measures molbloc upstream pressure, the other usually measures molbloc downstream pressure and may provide a second measurement of molbloc upstream pressure in molbloc-S operation. In normal operation, they are not used at pressures greater than 600 kPa absolute (87 psia).

Exposing the molbox RFM RPTs to pressures greater than the maximum operating pressure may damage them. molbox RFM has a system of warnings and alarms to protect itself from overpressure (see Section

3.6.3.1).

3.1.6.2 DIFFERENTIAL RPT, MICRORANGE OPTION

The microrange option low differential RPT has no overpressure warnings or alarms in normal operation. It is, to the extent possible, protected from overpressure automatically and transparently as it is put into and out of service using the molbox RFM on-board valving.

In run calibration operation (see Section 5.2.4.1), the microrange RPT has an OVERPRESSURE function whose operation is similar to the absolute RPT overpressure function (see kPa (2 psi) differential.

When an overpressure condition occurs during run calibration of the microrange transducer, the display of microrange pressure indicates:

Be sure the pressure conditions that caused the overpressure to occur have been cleared. Then press [ENTER] to reactivate the microrange RPT.

When using molbox RFM equipped with the microrange option, avoid very rapid

pressurization of one molbloc port. Attempt to open flow isolation valves slowly. The microrange option low differential RPT is protected from overpressure automatically by internal valving. However, dumping pressure very rapidly on one port of the molbloc while the differential RPT is active could cause a very sudden surge in differential pressure that can overpressure it.

Section 3.6.3). Overpressure occurs at about 13.7

Microrange RPT: OVERP! kPa [ENTER]

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3.2 MAIN RUN SCREEN

The molbox RFM MAIN run screen is its home display that is reached upon power up and from which other functions and menus are accessed. It is the top level of all menu structures. It indicates the current measured flow as well as a variety of additional information, if desired.

The appearance of the MAIN run screen differs depending on whether the active molbloc is a molbloc-L or a molbloc-S.

3.2.1 molbloc-L OPERATION

Some items in the molbloc-L MAIN run screen may change or flash at times, to indicate that certain limits are exceeded, as described in the text accompanying the following screen display:

1. <*> Ready/Not Ready indication: <*> when Ready (flashes if Reynolds number of the flow exceeds 1 300 or if flow was not ready for a full averaging period in AVERAGE display), <↑> (increasing) or <↓> (decreasing) indicating direction of flow rate evolution when Not Ready (see Section

2. <FL

3. <UNIT>: Current flow unit of measure (see Section 3.4.3).

4. <k>: Indicates whether a gas correction factor (K factor) is currently being applied to the measured flow (see

5. <m>: Microrange option indicator (see Sections 3.4.7 and 3.6.7). Possible indications include:

6. <GGGG>: Indicates the current molbox gas selection (see Section 3.4.2). This should be the gas that is

7. <D>: Indication of what is being displayed on the bottom line of the display as set by the DEVIATION function

<R>: Current DISPLAY mode is RATE (see Section

< <H> Current DISPLAY mode is HI/LO (see Section 3.4.6.3). <∑> Current DISPLAY <=> Current DISPLAY <D> Current DISPLAY <F> Current DISPLAY Blank, No character Current DISPLAY mode is CLEAN (see Section

8. <DISPLAY

OWWW>: Numerical value and sign of the flow

measured by molbox RFM. Result of last flow averaging cycle if in AVERAGE display (see Section 3.4.6.2). Flashes if Reynolds number of the flow

Section 3.4.1). <k> if a factor is being applied, blank if no factor is being applied.

Blank, NO character: The microrange option is currently OFF or the molbox RFM is not equipped with

the microrange option.

<m>: Automatic microrange is ON (see Section 3.4.7). <d>: Manual microrange is ON and the differential pressure reading being used to calculate flow is

coming from the microrange differential RPT (see Section 3.6.7).

<a> (flashing): Manual microrange is ON and the differential pressure reading being used to calculate

flow is NOT coming from the microrange low differential RPT. It is the difference between the upstream and downstream absolute RPTs (see Section 3.6.7).

flowing through the molbloc.

(see Section 3.4.6.6). Possible indications include:

corner of the display, current DISPLAY AVERAGE screen (see Section

exceeds 1 300.

σ> Current DISPLAY mode is AVERAGE (see Section 3.4.6.2).

mode is TOTAL (see Section 3.4.6.4). mode is UNIT (see Section 3.4.6.5). mode is DEVIATION (see Section 3.4.6.6). mode is FREEZE (see Section 3.4.6.7).

MODE DATA>: Information displayed depends on current display mode (see Section 3.4.6).

3.4.6.2).

3. OPERATION

3.1.3).

*FLOWWW unitkm GGGG D DISPLAY MODE DATA

mode is “average” and this is the instantaneous reading

3.4.6.1); or if <n avg> is in the bottom right hand

3.4.6.8).

When a number is too large to show in the allocated display space, molbox RFM

displays <********>.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

molbox RFM has a SCREEN SAVER function that causes the display to dim if NO key is

pressed for 10 minutes. Pressing a key restores full power to the display. The screen saver activation time can be changed or screen saving can be completely suppressed (see Section 3.6.5.1).

3.2.2 molbloc-S OPERATION

As with molbloc-L there are limits on some of the conditions that may exist if the user expects to make accurate flow measurements with molbloc-S. The key condition that can be monitored is the back pressure ratio, or BPR, which determines whether critical flow through the molbloc is achieved (see Section 3.1.2).

When the BPR is in a “safe” region for critical flow measurements, the appearance of the MAIN run screen is identical to the MAIN run screen for molbloc-L operation (see Section

3.2.1). When the molbox RFM BPR limit is exceeded, there are two possible MAIN run screen indicators. A flashing flow value and unit indicate that the BPR limit has been exceeded. In this condition, the flow may not be critical and flow measurements should not be relied on to meet specifications. When the BPR limit is exceeded by a large margin, the flow is almost certainly not critical and the calculated value may be nonsensical, so the flow value is not shown and is replaced by <BPR HI>.

When molbloc-S is in the BPR OFF mode (see Section 3.6.9), BPR is not monitored and

invalid flow values may be displayed in the molbloc-S MAIN run screen with no indication that a the BPR value is high.

1. <*> Ready/Not Ready indication; <*> when Ready <↑> (increasing) or <↓> (decreasing) indicating direction of flow rate evolution when Not Ready; <P> when BPR is higher than choking limit. (see Section 3.1.2).

2. <FLOWWW>: Numerical value and sign of the flow measured by molbox RFM. Result of last flow averaging cycle if in AVERAGE display (see Section if BPR

is higher than the choking limit. If BPR exceeds the choking limit by a large margin, <BPR HI> replaces the flow value.

3. <UNIT> Current flow unit of measure (see Section 3.4.3). Flashes if BPR is higher than the choking limit.

4. <k>: Same as molbloc-L (see Section 3.4.1).

5. <GGGG>: Indicates the current molbox gas selection (see Section 3.4.2). This should be the gas that is flowing through the molbloc. <AirW> indicates that air is selected and a humidity correction is being applied (see Section 3.4.2.2).

6. <D>: Same as molbloc-L (see Section 3.4.6).

3.4.6.2). Flashes

*FLOWWW unitk GGGG D DISPLAY MODE DATA

7. <DISPLAY MODE DATA>: Information displayed depends on current display mode (see Section 3.4.6).

When a number is too large to show in the allocated display space, molbox RFM

displays <********>.

molbox RFM has a SCREEN SAVER function that causes the display to dim if NO key is

pressed for 10 minutes. Pressing a key restores full power to the display. The screen saver activation time can be changed or screen saving can be completely suppressed (see Section 3.6.5.1).

Page 37

3.3 MANUAL OPERATION

molbox RFM is designed to offer the optimum balance between simple, intuitive operation and the availability of a wide variety of functions with a high level of operator discretion. The local operator interface is through the front panel’s 2 x 20 character alpha-numeric display and a 4 x 4 multi-function keypad. Remote operation by RS232 or IEEE-488 interface is also available (see Section 4).

3.3.1 KEYPAD LAYOUT AND PROTOCOL

Molbox RFM has a 4 x 4 keypad for local operator access to direct functions, function menus and for data entry.

3. OPERATION

1. The Function/Data keys allow very commonly used functions to be accessed directly from the MAIN run screen by a single keystroke. The name of the function is on the bottom half of the key (see Section 3.4). These keys enter numerical values when editing.

2. The Editing and Execution keys are for execution, suspending execution, backing up in menus and editing entries

3. The Menu/Data keys provide access to function menus from the MAIN run screen. The menu name is on the bottom half of the key. The SETUP menu is for more frequently used functions. The SPECIAL menu is for less frequently used and internal functions. These keys enter numerical values when editing.

Figure 4. Keypad Layout

Pressing the [ENTER] key generally causes execution or forward movement in the menu tree. Pressing the [ESCAPE] key generally allows movement back in the menu tree and/or causes

execution to cease or suspend without changes being implemented. Pressing [ESCAPE] repeatedly eventually returns to the MAIN run screen. From the MAIN run screen, pressing [ESCAPE] allows momentary viewing of the molbox RFM identification screen.

Pressing the [+/-] key changes a numerical sign when editing. It also toggles through multiple screens when available.

Pressing the [←] and [→] keys allows reverse and forward cursor movement when editing data entry. These keys are also used to scroll through menu choices.

Menu selections can be made by pressing the number of the selection directly or by pressing

[←] and [→] to place the cursor on the number of the desired selection and pressing [ENTER].

Some screens go beyond the two lines provided by the display. This is indicated by a

flashing arrow in the second line of the display. Press [←] and [→] to move the cursor to access the lines that are NOT visible or directly enter the number of the hidden menu choice if you know it.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

3.3.2 SOUNDS

molbox RFM is equipped with a variable frequency tone device to provide audible feedback and alarms. Sounds are used for the following indications:

Valid key press

Brief beep. Choice between three frequencies or NO sound is available (see Section 3.6.5.2).

Invalid key press

Descending two tone “blurp”. Choice of NO sound is available (see Section 3.6.5.2).

Totalizing time complete Purge time complete Near overpressure limit

Three, 2 second beeps (see Section 3.4.6.4). Three, 2 second beeps (see Section 3.4.4.2). Intermittent 1 second beeps (see Section 3.6.3).

exceeded Overpressure limit

5 second high frequency beep (see Section 3.6.3).

exceeded

3.3.3 SOFT [ON/OFF] KEY

3.3.4 DIRECT FUNCTION KEYS SUMMARY

Local operation of molbox RFM is through the front panel 4 x 4 pressure sensitive keypad. To minimize the u se of mult i-lay ered menu structures, the keypad numerical keys also provide direct access to the most commonly used functions. The function accessed is labeled on the bottom half of the each key. Direct function keys are active whenever molbox RFM is in its MAIN run screen. corresponding manual sections for full detail on each direct function.

It may be useful to keep a copy of Table 8, Summary of molbox RFM Direct Function Key

Operations, near the molbox RFM, especially when first becoming acquainted with its operation.

Table 8 summarizes the operation of the direct function keys. See

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3. OPERATION

Table 8. Summary of molbox RFM Direct Function Key Operations

DIRECT FUNCTION KEYS ARE ACTIVE FROM THE MAIN RUN SCREEN

SEE CORRESPONDING MANUAL SECTIONS FOR FULL DETAIL

Menu of commonly used setup features including unit changes and stability setting.

Menu of less frequently used internal functions and settings including preferences, resets, molbox calibration, remote interfaces, BPR (back pressure ratio) when using molbloc-S.

Turn automatic microrange ON/OFF.

Load the molbloc that is currently connected to molbox RFM. Use this to activate a new molbloc after a molbloc change or to view details on the molbloc that is currently in use.

Set the resolution with which the measured flow and other values are displayed.

Run the TARE, LEAK CHECK, PURGE, AutoZ and BPR functions.

Display the current pressure measurements (first press). Display the current molbloc temperature measurements (second press).

Define the DISPLAY function for the second line of the molbox RFM display. Choices include rate, average, hi/lo, totalize, 2

Set/change a DUT gas correction factor (K factor).

unit, deviation, freeze, clean.

Set flow measurement gas.

Set flow measurement unit. Choice of units can be customized.

3.4 DIRECT FUNCTION KEYS

3.4.1 [K]

 PURPOSE

To cause the flow value calculated by molbox RFM to be multiplied by a factor, K. Generally used to apply a test device’s gas correction factor used when a test device is calibrated with a gas other than its normal process gas.

 PRINCIPLE

Frequently, when testing or calibrating a flow-measuring device, it is not possible to flow the gas with which that device will normally be operated (the process gas). This may be because the

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

process gas is toxic or corrosive or simply because it is not available or convenient to use.

When the process gas cannot be used for calibration, it is common to use a different gas for testing or calibrating (the calibration gas). In this case, a factor representing the relationship between the calibration gas and the process gas for the test device may be applied so that the calibration gas simulates the process gas. The calibration gas that simulates the process gas is often called a surrogate gas for the process gas.

The relationship between a test device’s process gas and calibration gas is frequently called a K factor or gas conversion factor. The factor’s value depends on specific properties of the test device and determining the value is the responsibility of the device manufacturer.

For example, Silane (SiH4) is a frequently used gas in semiconductor processing. SiH4 is highly toxic and requires extensive handling precautions so it is not practical for use in calibration and testing. A major manufacturer of Mass Flow Controllers (MFCs) recommends that MFCs that are to be used with Silane be tested with Sulfur Hexafluoride (SF6), a nontoxic, non-flammable gas, using a conversion factor of 0.970. In other words:

SF6 flow x 0.970 = equivalent SiH4 flow for the MFC

The K function in molbox RFM allows a gas conversion factor to be entered by which flow values measured by molbox RFM will be multiplied. In this example, 0.970 would be entered as K so that the values indicated by molbox RFM when SF6 is flowing through the molbloc simulate the flow of SiH4 for that manufacturer's MFC.

When the K function is active, molbox RFM performs all of its flow calculations normally but multiplies the current flow value by the value of the K factor prior to displaying it.

The gas selected on molbox RFM which is displayed in the upper right corner of the molbox RFM display should always be the gas that is actually flowing through the molbloc.

K factors or gas conversion factors are based on the properties of the device

being tested. Their availability and validity are the responsibility of that device's manufacturer. molbloc/molbox does not use factors or conversion coefficients between gases. Flow is calculated from molbloc characteristics and specific gas properties for each gas supported by molbox. The gas selected on molbox RFM (see Section 3.4.2) which is displayed in the upper right corner of the molbox RFM display should always be the gas that is actually flowing through the molbloc.

If the K function and the ADJ function are both active, the ADJ adder and multiplier are

first applied to the measured molbloc flow, then the result is multiplied by the K factor. This order of operations reflects the fact that the ADJ values are intended to represent an adjustment to be applied to the molbloc flow while measuring the calibration gas that is flowing, and the K factor is a correction related to gas effects on the device under test measurement (See Section 3.4.6).

 OPERATION

To enable a gas conversion factor press [K] from any run screen. The display is:

If <2off> is selected, no conversion factor will be applied. If <1on> is selected, the next screen is:

K Factor? 1on 2off

K Factor:

1.00000

The value of the gas conversion factor can be edited as desired. Pressing [ENTER] returns to the MAIN run screen with the entered K factor active. The letter <K> is always

appended to the flow unit indication in the run screens when the K function is ON (e.g., sccmK). A K factor value of 1 is handled as if the K function were OFF.

Page 41

3. OPERATION

When the K function is ON, as indicated by a <K> following the current flow unit in the

first line of the MAIN run screen, the current molbox RFM flow indication equals:

(flow as calculated by molbox RFM for the selected gas) x (the current K factor)

So the indicated flow is actually in error (biased) relative to the true flow through the

molbloc by the value of the K factor. Care should be taken to ensure that the correct molbloc range is selected for tests when a K factor is used, since the actual flow rate through the molbloc is different from the device under test range in the process gas.

3.4.2 [GAS]

 PURPOSE

To specify the gas that is currently flowing through the molbloc so that molbox RFM uses the correct gas property values in its flow calculations.

 PRINCIPLE

molbox RFM calculates the flow through a molbloc from:

• molbloc geometric characteristics

• gas pressures

• gas temperature

• specific characteristics of the flowing gas

The gas characteristics include:

• gas density under standard conditions

• change in gas density with pressure and temperature

• gas viscosity under standard conditions (when needed)

• changes in gas viscosity with pressure and temperature

Proprietary algorithms are used to calculate gas density and viscosity (when needed) under the actual flowing pressure and temperature conditions from density and viscosity under standard conditions.

The characteristics of molbox RFM supported gases and corresponding algorithms are stored in molbox RFM memory. To correctly calculate the flow of a gas, the correct information for that gas must be used. The molbox RFM GAS function allows the user to specify the flowing gas so that molbox RFM will use the correct gas information in calculating the flow through the molbloc.

The set of available calibration gases that can be used is not the same with molbloc-L and molbloc-S, and the operation of the GAS function is different. They are described separately below.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

3.4.2.1 molbloc-L OPERATION

The molbox RFM gases available for use with molbloc-L at the time of this manual printing are listed in Table 9.

Table 9. Available molbloc-L Gases

<1inert> <2flammable> <3toxic> <4other>

<1N2> Nitrogen <2He> Helium <3Ar> Argon

<Butn> is used to identify Butane in molbox RFM because the chemical symbol for

Butane (C4H10) has more than the 4 characters used by molbox RFM to abbreviate gas identifications.

<1H2> Hydrogen <2O2> Oxygen <3CH4> Methane <4C2H4> Ethylene <5C3H8> Propane <6C2H6> Ethane <7Butn> Butane

<1CO> Carbon Monoxide <1Air> Air

<2C2F6> Hexafluoroethane <3N2O> Nitrous Oxide <4CF4> Carbon Tetrafluoride <5SF6> Sulfur Hexafluoride <6CHF3> Fluoroform <7C02> Carbon Dioxide <8Xe> Xenon <9C4F8> Octafluorocyclobutane

Mixtures of known gases in known concentrations can be measured by calculation

and use of the ADJ function (see Section 3.5.6).

 OPERATION (molbloc-L OPERATION)

To specify the gas flowing through molbloc-L, press [GAS]. The display is:

1inert 2flammable

3toxic 4other

The gases available are grouped in categories to facilitate finding a specific gas and as a reminder to the user when selecting a gas that may require special precautions in use. There is a list of gases under each

1N2 2He 3Ar

category. For example, the <1inert> selection displays:

Select the desired gas. Pressing [ENTER] returns to the last run screen with the newly selected gas active. The selected gas is always displayed in the upper right hand corner of the MAIN run screen.

The gas selected on molbox RFM should always be the gas that is flowing through

the molbloc. molbloc/molbox does not use K factors or gas conversion factors between gases. When calibrating or testing a device with a surrogate gas, molbox RFM should be set to the surrogate gas. The K factor or gas conversion factor, if used,

defines the relationship between the surrogate gas and the process gas for the device being tested, not for molbloc/molbox (see Section 3.4.1, PRINCIPLE). The K factor is

supplied by the manufacturer of the device being tested.

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3. OPERATION

3.4.2.2 molbloc-S OPERATION

The molbox RFM gases available for use with molbloc-S at the time of this manual printing are listed in Table 10.

Table 10. Available molbloc-S Gases

GAS

<1N2> Nitrogen

In addition to dry air, molbox RFM supports measurement of ambient (humid) air flow with molbloc-S. When Air is selected as the molbloc-S test gas, the user is prompted to enter a value of the humidity ratio (also known as the absolute humidity or water ratio) of the ambient air. The humidity ratio, W, is defined as the ratio of water mass to gas mass in the flowing air. It is different from the relative humidity value, which is usually expressed as a percentage. Typical values of W are between zero and 0.06. molbox RFM does not accept an entry for W greater than 0.1.

Typically, humidity measuring instruments report relative humidity, which is dependent on the ambient pressure and temperature. Users who do not have the W value available can use DHI’s free Unit of Measure Converter software utility or COMPASS for molbox calibration software to calculate W from measured pressure, temperature, and relative humidity. Visit www.dhinstruments.com, or se e your DHI sales representative for a copy of the Unit of Measure Converter software utility. Air relative humidity, pressure and temperature are converted to the humidity ratio, W, following Dalton’s thermodynamic principals using water saturation properties:

<2Air> Air (dry and humid)

Rule and

⎛

⎜ ⎝

gamb

100

⎛

⋅−

⎜ ⎝

⎞ ⎟

⎠

100

ambambambg

⎞ ⎟

⎠

CTCTCTCP

+++=

⋅

62188.

P is the water saturation pressure, which can be calculated as:

If dry air will be measured, then the user should enter a W value of zero when prompted. Zero is the default W value.

When a non-zero W value is entered, molbox applies a correction to its air flow measurement for the change in air density due to humidity. If a correction for W is being applied to air flow measurements, a <W> is placed to the right of the <Air> gas indication in the MAIN run screen.

where

⋅=

0649289.0

0528.53

−=

1327760

−=

9.14509

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

The humid air correction applied to the molbloc measured flow is (from ASME FEDSM98-5309):

)( dWcWbWaratioqm +++=

where a b c d

If an incorrect value of W is entered (for example, using any non-zero W value

while flowing dry air), an error will be introduced into the air flow measurement. W, humidity ratio, is different from relative humidity.

 OPERATION (molbloc-S operation)

To specify the gas flowing through molbloc-S, press [GAS]. The display is:

The display is:

Select the desired gas. Pressing [ENTER] returns to the last run screen with the newly selected gas active. The selected gas is always displayed in the upper right hand corner of the MAIN run screen.

0000.1

336872.0

−=

158514.0

131924.0

1N2 2Air

If <2Air> is selected,

The display is:

Leave the value at zero when dry air is being flowed. Enter the appropriate nonzero value (see section immediately above) if humid air is being flowed.

The gas selected on molbox RFM should always be the gas that is flowing

through the molbloc. molbloc/molbox does not use K factors or gas conversion factors between gases. When calibrating or testing a device with a surrogate gas, molbox RFM should be set to the surrogate gas. The K

factor or gas conversion factor, if used, defines the relationship between the

surrogate gas and the process gas for the device being tested, not for

molbloc/molbox (see Section 3.4.1 and 3.4.2 PRINCIPLE). The K factor is supplied by the manufacturer of the device being tested.

Humidity ratio: 0:1

3.4.3 [UNIT]

 PURPOSE

To specify the flow unit of measure in which molbox RFM displays measured flow values.

 PRINCIPLE

molbox RFM calculates the mass flow of various gases in kilograms/second [kg/s]. molbox RFM also supports conversions to a variety of other flow units of measure. The UNIT function allo w s the user to select the flow unit of measure in which molbox RFM displays measured flow. These include units o f mass flow , inc ludin g vol umetr ical ly bas ed ma ss fl ow uni ts (i .e., sccm)

Page 45

3. OPERATION

as well as units of volume flow (i.e., ccm). See Table 11 for a complete listing of the unit conversions available. molbox RFM can also display the measured flow in two different units of measure simultaneously (see Section

3.4.6.5).

 OPERATION

The UNIT function is used to set the unit of measure of the molbox RFM flow display. To change the flow unit of measure press [UNIT].

The display is:

1sccm 2slm 3uccm 4pccm 5mg/s 6vlm

Select the desired unit. For all units except <uxxx> or <vlm>, operation then returns to the run screen with the flow unit of measure changed to the selected unit. When user units (i.e., uxxx) are selected, the reference temperature must be specified before the unit is activated (see Section 3.4.3.3). When “vlm” (volume) units are selected, a menu of volum

e units is accessed. The desired volume unit must be selected and then the temperature and pressure of the flowing gas must be specified (see Section

3.4.3.4).

See Section 7.1.3 for specific molbox RFM flow unit conversion calculations.

molbox RFM supports many more flow units of measure than the six default units of the

UNIT function. The six units available under the UNIT function can be customized to include any molbox RFM supported units in any order (see Section 3.4.3.5).

Many different types of flow units are commonly used including a wide variety of mass

flow units as well as volume flow units. Please read Sections 3.4.3.1 through 3.4.3.5 for additional information on the various unit definitions and how they are handled by molbox RFM before making unit of measure selections.

3.4.3.1 MASS FLOW VS. VOLUME FLOW

COMPASS for molbox software users: conversions to volume (sometimes

called actual) flow units are handled in COMPASS. When using COMPASS, the molbox always operates in mass flow units.

molbox RFM measures mass flow (quantity of material per quantity of time). molbox RFM always calculates flow in terms of kg/second [kg/s]. It also supports conversions of kg/second to a variety of other flow units. These include other mass flow units such as g/s and mole/s as well as volumetrically based mass flow units (i.e., sccm and slm) (see Section 3.4.3). In steady state flow, mass

flow is the same at different points in the flow system independent of gas pressure and temperature. Therefore, the measurement of mass flow made by

the molbloc/molbox represents the mass flow at the same time at other points in a steady state flow system.

molbox RFM can also make conversions to volume fl ow under specific pressure and temperature conditions by dividing the mass flow by the density of the gas under the specific pressure and temperature conditions (see Section

Volume flow is sometimes referred to as actual flow.

3.4.3.4).

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

Volume flow is dependent on the actual temperature and pressure of the flowing gas at the point where volume flow is to be measured. Generally, this

point is not at the molbloc, it is at another point in the flow system (e.g., at the device under test). At another point in the flow system, it is quite likely that the gas pressure and temperature are different from the gas pressure and temperature at the molbloc. Then, even in steady state flow conditions, the volume flow at the molbloc and the volume flow at another point in the system are likely to be different. Therefore, to accurately predict volume flow at another point in the system,

molbox RFM must calculate volume flow based on the mass flow through the molbloc and the gas pressure and temperature at that other point, not at the molbloc. For this reason, molbox RFM requires that gas pressure and temperature

conditions at the DUT be specified for volume flow measurements. Estimating the flowing gas pressure and temperature at the point at which

volume flow is to be measured may be difficult. The relevant gas pressure when measuring volume flow is the gas’s absolute pressure.

In cases in which the volume flow measurement is open to atmospheric (ambient) pressure, the volume flow pressure is atmospheric pressure. In other cases, there may be ways to estimate the pressure at the volume flow measurement point but it probably should be measured.

For temperature, if the volume flow measurement point is very near the molbloc, one possibility is to use the molbloc temperature measurement. By design, the molbloc causes the temperature of the gas that flows through the molbloc to take on the molbloc temperature. Therefore, the temperature of the gas as it exits the molbloc is the same as the molbloc temperature. If the volume flow measurement point is not immediately downstream of the molbloc, the best estimate of gas temperature may be ambient temperature or the temperature of the device or bath used to stabilize gas temperature if one is present.

Because volume flow (sometimes called actual flow) is dependent on gas

pressure and temperature at the flow measurement point, gas pressure and temperature must be specified by the user when selecting volume flow units on molbox RFM. The measurement uncertainty (accuracy) in the volume flow measurement is highly dependent on the measurement uncertainty in the pressure and temperature specified. Typically, temperature errors have an effect on flow of about 0.35 %/°C and pressure errors have an effect on flow of about 1%/kPa (6.8%/psi) if the DUT is used near atmospheric pressure.

3.4.3.2 VOLUMETRICALLY BASED MASS FLOW UNITS

molbox RFM supports a number of volumetrically based mass flow units of measure. Volumetrically based mass flow units should not be confused with volume or actual flow units (see Section 3.4.3.4). Volumetrically based mass flow units define mass in terms of the quantity of gas that occupies a volume under standard conditions of pressure and temperature. Since there is no universally accepted definition of standard conditions, molbox RFM supports the three most common variances.

• Standard units (sxxx): The “s” prefix indicates standard. Volumetrically based mass flow units preceded with the letter “s” (i.e., sccm, slm, scfh) define standard conditions as pressure of 101.325 kPa absolute (14.6959 psia) and temperature of 0 °C (32 °F) and take into account the true compressibility of the flowed gas.

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3. OPERATION

• User units (uxxx): The u prefix indicates user. This option is designed to provide support for volumetrically based mass flow units with a reference temperature other than 0 °C (see Section mass flow units preceded with the letter “u” (i.e., uccm, ulm) define

3.4.3.3). Volumetrically based standard

conditions as pressure of 101.325 kPa (14.6959 psia) with the user specifying the reference temperature. User units take into account the true compressibility of the flowed gas.

• Perfect units (pxxx): The “p” prefix indicates perfect. This option is designed to provide support for volumetrically based mass flow units that assume ideal gas compressibility for all gases. Volumetrically based mass flow units preceded with the letter “p” (i.e., pccm, plm) assume a gas compressibility factor of 1 for all gases and define standard conditions as pressure of 101.325 kPa (14.6959 psia) and temperature of 0 °C (32 °F).

Volumetrically based mass flow units at reference temperatures other than

0 °C (32 °F) can be defined using user units (see Section 3.4.3.3).

In early 1996, SEMI (a semiconductor industry interest group) adopted

standard E12-96, which specifies that perfect units be used for volumetrically based mass flow units. To comply with the SEMI standard, pccm should be used rather than sccm. To purchase a copy of the relevant SEMI standard, contact SEMI at telephone 415.964.5111 or email semihq@semi.org.

3.4.3.3 VOLUMETRICALLY BASED MASS FLOW UNITS AT

VARIOUS REFERENCE TEMPERATURES (UXXX)

Units starting with the letter “u” (user units) are volumetrically based mass flow units (see Section 3.4.3.3) for which a reference temperature other than 0 °C is desired.

When a user unit is selected, the reference temperature desired must be specified. After a user unit is selected, the display is:

Temperature ref? 0ºC

Enter the reference temperature desired for the volumetrically based mass flow unit selected. The temperature unit can be changed between °C and °F by pressing [SETUP] and selecting <3tempU> (see Section

3.5.3). The temperature sel ecte d

applies to all the user units.

Volumetrically based mass flow units, including user units (uxxx) and perfect

units (pxxx), are discussed further in Section 3.4.3.2.

3.4.3.4 VOLUME FLOW UNITS (VLM)

See Section 3.4.3.1 before using volume flow units. Volume flow is

sometimes referred to as actual flow.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

To measure flow in volume flow units (sometimes referred to as actual flow units), press [UNIT], <vlm> under the UNIT function. If <vlm> is not available, see Section

3.4.3.5. This selection accesses the menu of volume units available.

Select the desired volume flow unit:

1. Current volume flow pressure.

2. Current volume flow temperature. Indicates <bloc> if the current setting is to use the molbloc temperature.

To retain the current volume flow pressure and temperature, select <1no> and operation returns to the MAIN run screen with the selected volume flow unit active. To change the volume flow pressure and/or temperature select <2yes>.

The next screen gives the choice of having the volume flow gas temperature be either the molbloc temperature or a user specified temperature. If <2user> is selected, a screen to enter the temperature is presented before continuing. If <1molbloc> is selected, the volume flow temperature will automatically be taken as the molbloc temperature.

P101.325kPa T21.1ºC Edit P&T? 1no 2yes

Gas temperature: 1molbloc 2user

The next screen is to edit the volume flow pressure in the current pressure unit of measure. Pressing [ENTER] accepts the edited value as the volume flow pressure and returns to the MAIN run screen with the selected volume flow unit

Volume unit gas pres

101.325 kPa

and gas temperature and pressure active.

The temperature and pressure units of measure used to specify volume flow

conditions can be changed using [SETUP], <2presU> for pressure (see Section 3.5.2) and [SETUP], <3tempU> for temperature (see Section 3.5.3).

Because volume flow is dependent on gas pressure and temperature at the

flow measurement point, gas pressure and temperature must be specified by the user when selecting volume flow units. The measurement uncertainty in the volume flow measurement is highly dependent on the measurement uncertainty in the pressure and temperature specified (see Section

3.4.3.1).

3.4.3.5 CUSTOMIZING FLOW UNITS AVAILABLE UNDER THE UNIT FUNCTION

The UNIT function provides a choice of six different flow units of measure. The units that are available by default are the six indicated in Section 3.4.3. However, molbox RFM supports many other units. These other units can available for selection by customizing the UNIT function.

be made

To customize the UNIT function, press [SETUP] and select <1flowU>. The display is:

Set up user unit #1

Page 49

3. OPERATION

<#1> corresponds to the first of the six

available selections under the UNIT function. Enter the number of the selection that you would like to change.

Flow unit type: 1std 2user 3perfect 4vlm

The display becomes:

Select the flow unit type of the desired flow unit (see Table 11). Then select the desired unit.

Table 11. Available Flow Units

<1std> <2user> <3perfect> <4vlm>

<1mol/s> <2kg/s> <3mg/s> <4slm> <5sccm> <6scfm> <7scfh> <8slh> <9sm3h>

<1ulm> <2uccm> <3ucfm> <4ucfh> <5um3h>

<1plm> <2pccm> <3pcfm> <4pcfh> <5plh> <6pm3h>

<1ccm> <2lm> <3lh> <4m3h> <6cfm> <7cfh>

The <4vlm> unit selection embeds the selection “vlm” into the UNIT function

rather than a specific volume unit. The “vlm” selection provides access to all of the volume flow units. In summary the unit types are:

<1std> (standard): mass flow units for which “standard” conditions are

temperature of 0 °C, standard atmosphere and using the true compressibility factor of the gas.

<2user>: mass flow units for which “standard” conditions are a

user settable temperature, standard atmosphere and using the true compressibility factor of the gas.

<3perfect>: mass flow units for which “standard” conditions are

temperature of 0 °C, standard atmosphere and assuming a compressibility factor of 1 for all gases.

<4vlm>: volume flow

units.

See Sections 3.4.3.1 to 3.4.3.4 for additional information on flow unit types.

3.4.4 [TARE]

 PURPOSE [TARE] accesses five functions.

• TARE function: To zero the molbox RFM differential pressure readings during molbloc-L operation or verify the two RPTs by comparing them against each other during molbloc-S operation (see Section 3.4.4.1).

• PURGE function: To purge the molbloc connecting lines and molbox RFM internal volume of a first gas with a second gas by flowing the second gas through the molbox RFM (see Section

3.4.4.2).

• LEAK CHECK function: To check the molbox RFM internal pneumatic circuit and/or the external test circuit to which molbox RFM is connected, for leaks (see Section 3.4.4.3).

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• AUTOZ function: To periodically offset the molbox RFM RPTs relative to a reference pressure value in order to compensate for possible changes in the RPT zero between full recalibrations (see Section 3.4.4.4).

• BPR function (present only in molbloc-S operation): To measure and display the molbloc-S back pressure ratio (BPR) while operating in a BPR mode, which does not continuously read and display BPR (see Section 3.4.4.5).

 OPERATION

Pressing [TARE] accesses a display with the choice of four functions (five functions with molbloc-S). Select the desired function. See the following for principles and operation:

1tare 2purge 3leak check 4AutoZ ↓

5BPR

Some screens (e.g., the Tare menu) may go beyond the two lines provided by the display.

This is indicated by a flashing arrow in the second line of the display. Press the [←] and [→] keys to move the cursor to access the lines that are NOT visible or directly enter the number of the hidden menu choice if you know it.

3.4.4.1 <1TARE>

The purpose and operation of the tare function is different for molbloc-L and molbloc-S operation. Tare values are generated and stored independently for the two molbloc types. For example, a tare value generated during molbloc-L operation is not used during molbloc-S operation, but is saved and used again when a molbloc-L is connected to the molbox.

Tare is described separately for the two molbloc types below.

3.4.4.1.1 molbloc-L OPERATION

 PURPOSE

To zero the molbox RFM differential pressure reading at the molbloc operating pressure. Zeros the differential between the two high pressure absolute transducers as well as the microrange transducer if present.

 PRINCIPLE

The molbox RFM TARE function can be considered the equivalent of the ZEROING function performed on many instruments prior to making measurements. molbox RFM calculates the flow through the molbloc from the differential pressure across the molbloc. The differential pressure across the molbloc is measured by taking the difference in the absolute pressure measured by the molbox RFM’s two internal RPTs. One RPT is connected to the upstream molbloc pressure port and the other to the downstream molbloc pressure port. If the molbox RFM has the microrange option (see Section 3.1.5), when the differential pressure is under 12.5 kPa (1.8 psi), the microrange option’s low differential RPT is used as the source of the differential pressure measurement.

If a common pressure is applied to both absolute transducers (and both legs of the microrange option differential RPT if present) the differential pressure indicated should be zero. If a differential pressure is observed, the value indicated represents an offset in the differential measurement, which will appear as an offset or “zero error” on the flow through the molbloc calculated by the molbox RFM. The TARE function allows the differential indication between the two RPTs to be zeroed at the molbloc operating pressure to eliminate the zero error in differential pressure measurement.

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3. OPERATION

When the TARE function is activated, molbox RFM’s internal valves operate to pneumatically connect together the two absolute transducers, and both legs of the microrange option differential transducer if present, at the molbloc operating pressure. The user can select whether this pressure is the upstream or downstream molbloc pressure so that the tare can be made at the pressure that will be held stable during operation (generally by a regulator or because it is open to atmosphere). Activating the tare causes molbox RFM to record the current differential as the tare value. The tare value will be used to correct all subsequent RPT readings. For the absolute transducers the tare value is the difference between the two transducer readings (hi - lo). The upstream RPT will be corrected by (- tare value/2) and the downstream RPT will be corrected by (+ tare value/2). For the microrange differential RPT, the tare value is the differential value read. The differential transducer will be corrected by subtracting the tare value from the current reading.

1. High Isolation: Open

2. Low Isolation: Closed

3. Bypass: Open

4. Mirorange Bypass: Open

Figure 5. molbox RFM

Internal Pneumatic Schematic – TARING, UPSTREAM molbloc-L OPERATION

 OPERATION

At a minimum, the TARE function should be executed whenever the operating

pressure of the molbloc is changed significantly, at the beginning of each test or any time a significant zero error is observed. For best results, it is possible to tare before every reading since taring can be executed while flowing. Best results will be obtained if the TARE function is executed with a stable flow through the molbloc.

To access the TARE function press [TARE], <1tare>.

The display is:

Select tare pressure: 1upstream 2dnstream

Selecting <1upstream> will tare the molbox RFM RPTs at the molbloc’s upstream pressure (see Figure 5). Selecting <2dnstream> will tare the RPTs at the molbloc’s downstream pressure (Low isolation valve open, High isolation valve closed). Select the position where the pressure will remain the most stable during molbloc operation.

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The next display is:

1. The current pressure read by the upstream (left) and downstream (right) RPTs without taking into account the current tare value. These are untared readings in the current pressure units.

2. <T>, flashing, to indicate that this is a TARE display showing the tare between the two absolute RPTs.

3. The difference between the untared upstream and downstream absolute pressure readings (upstream – downstream). This differential value is always in Pascal [Pa].

4. The flow corresponding to the current untared differential pressure in the current flow units.

This display allows the current untared absolute pressures and the resulting untared differential pressure from the difference of the two absolute RPTs to be observed. The flow value represents the current untared zero error in terms of flow. It does not necessarily represent the current zero error on flow measurements as a tare value other than zero is probably already active.

Press [ENTER] when ready. Molbox RFM makes measurements to determine a new tare value. The next display is:

202.347 kPaa 202.311 T 36 Pa 0.06 sccm

1. The tare value currently in use [Pa].

2. The new tare value, resulting from this execution of the TARE function [Pa].

3. Microrange tare value currently in use [Pa}

4. New microrange tare value [Pa].

OldT: 44Pa m 20 NewT: 36Pa m 20

Press [ENTER] to activate the new tare and return to the MAIN run screen. Press [ESCAPE] to return to the [TARE] display without activating the new tare,

leaving the old tare active.

The tare screen shows the upstream and downstream RPT readings

WITHOUT the current tare applied. The [P&T] screen shows the RPT readings WITH the tare applied (see Section 3.4.5).

Limits and Errors

Excessively large tare values can diagnose molbox RFM transducer malfunction, the need to recalibrate or possible poor execution of the TARE function. To protect against improper taring and to alert to possible RPT malfunction, molbox RFM checks the tare values before they are activated and displays warnings when appropriate. In the most extreme case, molbox RFM will not allow the tare value to be activated. The limits checked and their consequences are as follows:

Upstream and downstream absolute pressure RPTs coherence test: When attempting to activate a new tare, molbox RFM checks the coherence between the two transducers and alerts the operator to excessive disagreements. The test has two levels.

If the new tare is 700 Pa < tare > 10 000 Pa, a caution message is displayed. Pressing [ENTER] overrides the caution and activates the new tare. Pressing [ESCAPE] returns to the TARE screen.

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3. OPERATION

If the new tare is > 10 000 Pa, the new tare cannot be activated. Pressing [ENTER] or [ESCAPE] returns to the tare screen. It is likely that molbox RFM needs service or a grossly incorrect adjustment has been made to one or both of the RPTs.

Microrange differential pressure RPT zero drift test (if microrange option present): When attempting to activate a new tare, molbox RFM checks

the zero offset value of the microrange RPT. If the new tare is > 999 Pa, the new tare cannot be activated. Press [ENTER] or [ESCAPE] to go back to the tare screen. It is likely that molbox RFM needs service or a grossly incorrect adjustment has been made to the differential RPT.

If a caution message appears or a tare cannot be activated during the taring

process, repeat the taring process. If the caution persists, the calibration of the RPT(s) should be verified. If the tare still cannot be activated, the RPT(s) should be recalibrated and molbox RFM may require other service.

3.4.4.1.2 molbloc-S Operation

 PURPOSE

To check the molbox RFM RPT absolute pressure readings by comparing them at a common molbloc-S upstream absolute pressure.

 PRINCIPAL

When measuring the flow through molbloc-S, the critical pressure measured by molbox RFM is the molbloc upstream pressure. The downstream pressure is only monitored to be sure that critical flow conditions exist (see Section 3.1.2). To reduce the uncertainty on the upstream pressure measurement, molbox RFM employs internal valving to direct the upstream pressure to both RPTs, and the average of the two readings is used as the measured molbloc upstream pressure. To take advantage of this RPT averaging, the molbox RFM must be in either BPR OFF or Auto BPR mode (see Section 3.6.9).

molbox RFM dynamically tares the two RPT readings when they are connected together, so the user can view the “live” average pressure that is calculated and to allow smooth pressure and flow measurements during valve transitions in the Auto BPR mode (see Section 3.6.9). RPT taring in molbloc-S operation occurs automatically when needed and does not need to be initiated or performed by the user.

The molbloc-S TARE function is available to allow the user to conveniently verify that the two RPT measurements agree within an acceptable tolerance when a common pressure is applied to them. When the TARE function is selected, the molbox RFM internal valves operate to connect both Q-RPTs the active channel UPSTREAM pressure port (see Figure 6). The RPT readings and the difference between the two RPT readings (tare value) is displayed for evaluation by the user. A message is also displayed to indicate to the user whether the tare value is acceptable, or indicates a need for pressure verification or calibration of the RPTs. There is no need for the customer to save a new tare value during molbloc-S operation.

As during molbloc-L operation, the molbloc-S tare value is the difference between the two transducer readings (hi - lo). In BPR modes where the tare value is dynamically calculated and applied, the upstream RPT is corrected by (- tare value/2) and the downstream RPT is corrected by (+ tare value/2).

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Figure 6. molbox RFM

Internal Pneumatic Schematic – TARING molbloc-S OPERATION

1. High Isolation: Open

2. Low Isolation: Closed

3. Bypass: Open

4. Mirorange Bypass: Open

 OPERATION

To access the TARE function press [TARE], <1tare>. The display is:

1. The current pressure read by the upstream (left) and downstream (right) RPTs without taking into account the current tare value. These are untared readings in the current pressure units.

2. <T>, to indicate that this is a TARE display showing the tare between the two absolute RPTs.

3. The difference between the untared upstream and downstream absolute pressure readings (upstream – downstream). This differential value is always in Pascal [Pa].

4. Tare message

<OK> If tare is less than 300 Pa,

<CHECK> if tare is between 300 and 1250 Pa <NEED CAL> if tare is greater than 1250 kPa

201.032 kPa ^201.013 T 19.3 Pa OK

The tare screen shows the upstream and downstream RPT readings

WITHOUT the current tare applied. The [P&T] screen shows the RPT readings WITH the tare applied (see Section

3.4.5).

3.4.4.2 <2Purge>

 PURPOSE

To purge the lines between the molbloc and the molbox RFM and the internal molbox RFM volumes of one gas with another gas by setting up an internal valving configuration in which gas flows through the molbox RFM.

 PRINCIPAL

molbox RFM supports the measurement of flow of a variety of gases. To calculate the flow, the thermodynamic characteristics of the gas must be known. These are stored in molbox RFM memory. For the flow to be calculated correctly, the gas flowing through the molbloc must be the gas that is selected on

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3. OPERATION

the molbox RFM (see Section 3.4.2). When switching from the measurement of one gas to another, the old gas remaining in the circuit and the new gas being flowed may mix for some time so that the gas flowing through the molbloc is not purely the new gas. Erroneous measurements may result. For this reason, it is important to purge the lines upstream and downstream of the molbloc when changing gases. It is also important to purge the molbox RFM itself which, since there is normally no flow through it, may trap and hold the old gas.

The PURGE function is designed to facilitate purging the molbox RFM. It sets up the molbox internal valving so that flow can pass through the molbox RFM (see Figure 7). In this configuration, the lines between the molbloc and molbox RFM and the molbox RFM internal volume can be purged by simply flowing the new gas in the normal flowing configuration. The flow resistance through the molbloc creates a differential pressure, which causes flow through the molbox RFM to occur, purging it with the new gas.

1. High Isolation: Open

2. Low Isolation: Open

3. Bypass: Open

4. Mirorange Bypass: Open

Figure 7. molbox RFM

Internal Pneumatic Schematic – PURGING

 OPERATION

For best results, the PURGE function should be executed whenever the

species of the gas flowing through the molbloc is changed. Prior to activating the PURGE function, set flow through the molbloc to the highest rate that is practical. Then, with the gas flowing, activate the PURGE function. Very small volumes of gas remain trapped (dead ended) in the molbox RFM in the PURGE configuration. Therefore, it may be desirable to execute the PURGE function more than once to clear these volumes by the pressure changes caused by PURGE execution.

To access the PURGE function press [TARE], <2purge>. The display is:

Set purge time: 15 sec

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The purge time can be edited. Pressing [ENTER] causes molbox RFM to set its internal valving to the purge configuration (see Figure 14) and go to the PURGE display:

1. The current pressure read by the upstream (left) and downstream (right) RPTs in the current pressure unit of measure.

2. <PURGING> to indicate that this is a PURGE display.

3. Countdown of purge time remaining in seconds.

molbox RFM remains in the purge condition until the purge time countdown elapses. It then automatically returns to normal operation. When the countdown elapses operation returns to the run screen from which PURGE was accessed.

202.347 kPaa 202.311 PURGING 15 sec

The appropriate purge time setting is dependent on the flow rate and the

volumes upstream and downstream of the molbloc. Typically, 15 to 30 seconds is adequate. The time needed increases as flow rates go down and volumes go up.

To interrupt the PURGE function, press [ESCAPE].

When using the PURGE function, remember that the molbox RFM absolute

RPTs are exposed to the pressure. Do not apply pressure greater than 600 kPa absolute (87 psia).

3.4.4.3 <3Leak Check>

 PURPOSE

To access the molbox LEAK CHECK and SYSTEM LEAK CHECK functions which use molbox RFM’s pressure and flow measurement capabilities to check molbox RFM and/or the system to which it is connected for leaks.

 PRINCIPAL

molbox RFM is used both as a tool to accurately measure unknown flow values and as a calibration standard to calibrate other devices by comparison. Leaks with in the molbox RFM pneumatic circuit can cause erroneous flow measurements. Leaks in the external flow circuit can cause the flow through the molbloc to be different from the flow at another point in the system so that, even with an accurate measurement and steady state flow, the molbox RFM indication is not an accurate indication of flow at the other point in the system.

To obtain valid measurement results, it is important that leaks in molbox RFM and/or the external flow system be identified and eliminated to the extent possible. molbox RFM uses its precision on-board pressure and flow measurement capabilities to help identify leaks with INTERNAL and EXTERNAL LEAK TESTING functions.

 OPERATION

Press [TARE] and select <3leak check> to access the LEAK CHECK functions. Then select <1molbox> or <2system>.

<1molbox> is designed to leak check the internal molbox RFM pneumatic circuit. <2system> is designed to leak check the system to which the molbloc/molbox

is connected.

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3.4.4.3.1 Leak Check molbox

 PURPOSE

To check the internal molbox RFM pneumatic circuit for leaks.

 PRINCIPAL

It is normally not necessary to run the MOLBOX LEAK CHECK procedure frequently. It i s int ended for troubleshooting purposes when there appears to be a leak or other molbox RFM measurement problem whose source cannot be identified by the SYSTEM LEAK CHECK or other troubleshooting means. It is recommended to run the MOLBOX LEAK CHECK after it has been shipped or if it is suspected that the molbox has been exposed to a large shock or liquid or particulate contamination.

 OPERATION

Press [TARE] and select <3leak check>, <1molbox>. If the molbox RFM has a microrange option, microrange RPT <1active> or <2bypassed> must be selected to proceed (see Section 3.1.5). The next display is:

1. The pressure read by the upstream transducer (left), the downstream transducer (right) and the pressure unit of measure (middle).

2. Indicator that the figure that follows is differential pressure.

3. Differential pressure across the molbloc in current pressure unit of measure.

4. Prompt for the action to take when ready.

The molbox RFM internal valving is in its normal measuring configuration (see Figure 3). This display is intended to assist the operator in setting the leak check pressure.

Apply the maximum differential pressure across the molbloc that is normally encountered during flow measurement while working at your typical absolute working pressure. Neither pressure should be less than atmosphere. Use the <DP> indication on the molbox RFM display to set the absolute and differential pressure.

347.458 kPaa 307.455 DP 40.003 <ENTER>

Once the pressure setting is correct, press [ENTER]. The molbox RFM actuates its internal valves to isolate itself from the molbloc and trap the upstream and downstream pressures on its RPTs

Vent molbloc ports <ENTER>

(see Figure 8). The display is:

Assure that both molbox RFM rear panel pressure connections are vented. Since the pressure quick connections on the molbox RFM and the quickconnectors on the molbloc pressure connection tubes seal when disconnected, they cannot be vented by simply disconnecting them. The easiest way to assure that the connections are vented is to maintain the normal connections to the molbloc, shut off the molbloc gas source and open one or both ends of the molb loc so it can vent to atmospheric pressure. Another alternative is to install the non-sealing quick connectors (P/N 101889) provided in the molbox accessories (see Section 2. 1.2) into the molbox quick connectors.

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Figure 8. molbox RFM

Internal Pneumatic Schematic – LEAK CHECK molbox

1. High Isolation: Closed

2. Low Isolation: Closed

3. Bypass: Closed

4. Mirorange Bypass: Closed if Active Open if Bypassed

Once the molbox RFM pressure connections are vented, press [ENTER].

1. The pressure read by the upstream RPT (left), the downstream RPT (right) and the pressure unit of measure (middle).

2. The ratio of the upstream RPT reading to the downstream RPT reading.

3. Leak check count down in seconds.

347.466 kPaa 35.459

1.03579:1 WAIT: 60

molbox RFM counts down for 60 seconds while monitoring the ratio of the two pressures and then determines whether an internal leak was present. A significant leak in a pressure isolation valve or a bypass valve between the two channels will cause the ratio between the two pressures to vary.

The molbox RFM LEAK CHECK function should end with the prompt:

molbox passed the leak check

If any other prompt is present, repeat the process. If the molbox RFM is equipped with the microrange option, run the leak test with the microrange in the opposite condition (active or bypassed). If the leak check fails consistently, note the failure message and contact a DHI Authorized Service Provider.

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3.4.4.3.2 Leak Check System

 PURPOSE

To leak check the external system that is connected to the molbox RFM.

 PRINCIPAL

It is recommended to run the SYSTEM LEAK CHECK whenever critical physical connections in the system attached to the molbloc are broken and reconnected. Critical connections are ones that are between the molbloc and the DUT, which, if they were to leak, would cause the flow through the molbloc and the DUT to differ. Whenever a new DUT is connected to the system, it is a good idea to run the SYSTEM LEAK CHECK.

The SYSTEM LEAK CHECK monitors changes in pressure in a closed system defined by the user to help determine whether a leak exists in the system. One of the ways a leak is detected is by monitoring pressure decay in the pressurized closed system. When the test volume is large, significant leaks may exist without being detected because the pressure decay caused by the leak is reduced. Therefore, the SYSTEM LEAK CHECK is most effective when the volume of the closed system is minimized.

For molbloc-L operation, the SYSTEM LEAK CHECK also measures flow through the molbloc to help determine whether a leak is present upstream or downstream of the molbloc. Since molbloc-S is not capable of calculating meaningful flow values with the very small differential pressure present during this test, the SYSTEM LEAK CHECK operates differently for molbloc-L and molbloc-S operation, as described in the OPERATION sections immediately below.

The SYSTEM LEAK CHECK function uses molbox RFM’s high precision

pressure and flow measurement capabilities to help determine whether a leak exists in the system to which the molbloc is connected. This feature is to assist the operator in flow measurement and calibration. The system to which the molbloc is connected is the responsibility of the user. Failures in the system leak check do not normally indicate defects in the molbox RFM or molbloc itself. The molbox leak check is used to identify molbox RFM failures.

 OPERATION – molbloc-L Operation

To access the system leak check press [TARE] and select <3leak check>, <2system>. The display is:

1. The pressure read by the upstream RPT

(left), the downstream RPT (right) and the pressure unit of measure (middle).

347.589 kPaa 347.580

This display is intended to assist the operator in setting the leak check pressure. molbox RFM has actuated internal valves to connect the upstream and dow ns tr eam RPTs together, so they are both measuring an equal system pressure. (see Figure 9).

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Figure 9. molbox RFM

Internal Pneumatic Schematic

– SYSTEM LEAK CHECK – CHECKING OFFSET AND STABILITY

molbloc-L operation

1. Channel A High Isolation: Open

2. Channel A Low Isolation: Open

3. Bypass: Open

4. Microrange Bypass: Open

Close an isolation valve downstream or plug the exhaust of the flow system that is being tested (downstream of the molbloc and the DUT if the molbloc/molbox is being used to test another device).

Using the molbox RFM display to read the pressure set the pressure to the normal operating pressure.

FOR SYSTEMS WITH MASS FLOW CONTROLLERS (MFCs):

Keep in mind that the valves in most MFCs are not intended to provide a

complete gas shutoff and so they may not be suitable to close off the test system. If an MFC is downstream of the molbloc and its downstream port is open to atmosphere, it is best to close the system by connecting a cap to the MFC outlet fitting or by connecting a shutoff valve downstream. If the MFC valve is closed (most MFCs have normally closed valves) when the operating pressure is applied from the upstream side, most of the gas will be stopped by the MFC valve and will not immediately fill the volume between the MFC valve and the downstream cap or valve. If this happens, the gas may leak by the MFC valve to fill this volume during the test and cause a pressure decay and an apparent system leak. The solution is to send a setpoint signal to the MFC to open the MFC valve while pressurizing the system. Then close the MFC valve (remove the setpoint signal) after the system is pressurized to avoid heating of the test gas by the energized valve.

Next, close an isolation valve upstream of the molbloc so the gas supply is no longer open to the system being checked. Once the pressure has stabilized, press [ENTER]. The display is:

The molbox RFM is checking:

• For pressure and temperature stability before running the system leak test

• That the disagreement between the two RPTs is not excessive

347.587 kPaa 347.583 WAIT: 30

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3. OPERATION

After 30 seconds, if the stability check is not passed, molbox RFM displays:

• If the pressure was not stable:

• If the molbloc temperature change

was too great:

• If the offset between the RPTs was too great:

Leak is too large to continue

Temp change was too great to find leaks

Offset excessive check tare

If any of the above three prompts occurs, check the external system for leaks and/or run the molbox RFM leak check before proceeding. If the tare was excessive, tare the molbox RPTs before running the leak check again (see Section

3.4.4.1). Once the 30 second pressure stability/offset

check has been successfully completed, molbox RFM displays:

347.592 kPaa 347.583

0.101 sccm [ENT]

When [ENTER] is pressed, molbox RFM’s valves actuate to set up the system leak check configuration which is identical to the normal operating configuration (see Figure 3). The display becomes:

1. Pressure read by the upstream RPT (left), the downstream RPT (right) and the pressure unit of measure (middle).

2. Current measured flow.

3. Time remaining in the leak check in seconds.

347.592 kPaa 347.583

0.101 sccm 30

possible system upstream leak

molbox RFM measures pressure and flow for a 40 second countdown. After the countdown has elapsed, molbox RFM displays its conclusion from the measurements. The display will be either:

possible system

downstream leak

System passed system

leak check

Upstream and downstream refer to the possible location of the leak relative to the position of the molbloc and the normal flow direction in the system. If you are unable to locate a leak in the flow path components, check or replace the upstream and downstream molbloc to molbox pressure tubes and their connectors and retry the test. They are a critical part of the pneumatic system and if a significant leak is present in these tubes, it will cause an error in flow measurement.

 OPERATION – molbloc-S Operation

In molbloc-S operation, SYSTEM LEAK CHECK is a one-part test which tests for pressure decay in the closed system.

To access the system leak check press [TARE] and select <3leak check>, <2system>.

The display is:

Leak check: 1run 2view

If <2view> is selected the test results screen (see below) is displayed with the results from the most recent leak test.

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To run the leak test, select <1run>. molbox RFM actuates internal valves to connect the upstream and downstream

RPTs together, so they are both measuring an equal system pressure. (see Figure 10).

1. High Isolation: Open

2. Low Isolation: Open

3. Bypass: Open

4. Mirorange Bypass: Open

Figure 10. molbox RFM

Internal Pneumatic Schematic

– SYSTEM LEAK CHECK – CHECKING OFFSET AND STABILITY

molbloc-S operation

Close an isolation valve downstream or plug the exhaust of the flow system that is being tested (downstream of the molbloc and the DUT if the molbloc/molbox is being used to test another device).

Open an isolation valve upstream of the molbloc to allow the working pressure to pressurize the system.

FOR SYSTEMS WITH MASS FLOW CONTROLLERS (MFCS)

Keep in mind that the valves in most MFCs are not intended to provide a

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Next, close the isolation valve upstream of the molbloc so the gas supply is no longer open to the system being checked. Once the pressure has had time to stabilize, press [ENTER].

The next display is:

ENTER to start 60 s leak check

Press [ENTER] to begin the test The next display is:

1. The average pressure from the two molbox RFM absolute RPTs.

2. Current absolute pressure measurement in active pressure unit of measure.

3. SYSTEM LEAK CHECK count down in seconds.

199.16 kPa a leak testing 60s

Press [ESCAPE] to abort the leak test. Pressing [ENTER] while the test is in progress restarts the test and reset the leak

test timer. When the test is complete, a test results screen is displayed:

1. The total change in average pressure over the test interval.

2. The currently selected pressure unit of measure.

3. Average rate of pressure change, per second, during the test.

ΔP –0.0720 kPa Rate –0.0012 kPa/s

Since flow systems using molbloc-S will may use widely varying flow rates and tubing sizes, and test volumes may be quite large, it is difficult to predict what size pressure rate of change is acceptable to avoid significant flow errors. Your best guide may be to run the SYSTEM LEAK CHECK often with your hardware, find a typical rate of change which represents a sound setup, and attempt to match that rate each time. In any case, you should be able to achieve a rate of change smaller than 0.01 % / second of the absolute line pressure.

If you observe a relatively large leak rate and are unable to locate a leak in the flowpath components, check or replace the upstream and downstream molbloc to molbox pressure tubes and their connectors and retry the test. They are a critical part of the pneumatic system and if a significant leak is present in these tubes, it will cause an error in flow measurement.

3.4.4.4 <4AutoZ>

 PURPOSE

To offset the molbox RFM absolute reference pressure transducers (RPTs) relative to a reference value in order to compensate for possible changes in RPT zero between full recalibrations.

Improper use of the AutoZ function can cause out of tolerance pressure

measurements. AutoZ should be used only by qualified personnel for the purpose of rezeroing the molbox RFM reference pressure transducer absolute pressure measurement function.

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The AutoZ function has no effect on the microrange (differential) RPT

measurement (if present).

 PRINCIPAL AutoZ Purpose and Principle

The main component of the change over time of the molbox RFM RPTs is change in zero or offset, independent of span. Offsetting or “rezeroing” molbox RFM RPTs relative to a reference between recalibrations allows measurement uncertainty specifications to be maintained with less frequent full calibrations. The molbox RFM AutoZero function (AutoZ) provides full on-board support for the rezeroing process to simplify its application by the user.

The AutoZero function uses three values:

1. P

: The absolute pressure value indicated by the AutoZ reference, the

std,0

device that is acting as the reference relative to which to offset the RPT.

The pressure at which AutoZ is performed is normally atmospheric pressure

and the P

value can be supplied a) by manual entry, or b) automatically

std,0

from a DHI RPMx Reference Pressure Monitor.

2. P

: The absolute pressure reading of the RPT, with no AutoZ offset, at the

u,0

time AutoZ is performed.

3. P

offset

std,0

The AutoZ function manages the determination, storage and application of P

: The difference between the absolute pressure reading of the RPT

offset

with no AutoZ offset (P

) and the indication of the AutoZ reference (P

u,0

offset

= P

u,0

- P

std,0

represents the change in zero of the RPT relative to the AutoZ standard

offset

for both molbox RFM RPTs in absolute mode. The AutoZ handles both molbox RFM RPTs simultaneously as they are of the same range and always used together.

The source of P

must be an absolute pressure, nominally atmospheric

std,0

pressure, with uncertainty significantly better than that of the RPT that is being AutoZeroed (see Section 1.2.2). This can be accomplished with a variety of digital barometers or with a piston gauge able to set absolute pressure.

When the RPTs are used with AutoZ ON, absolute pressure is calculated as:

= P

u,0

offset

- P

abs

When RPTs are used with AutoZ OFF, P When the RPT is calibrated, P

is set to zero. P

offset

regular intervals using the AutoZ function. The most recent value of P

offset

is ignored.

offset

is then redetermined at

offset

applied to the RPT reading to correct for change in zero over time.

Recommendations for the Use of the AutoZ Function

The AutoZ function provides a powerful and easy to use tool for improving the stability over time of molbox RFM RPTs and maximizing the recalibration interval by compensating for change in zero between full recalibrations. The following simple recommendations will help assure that you use this feature to best advantage.

• Always leave AutoZ ON when operating if the AutoZ routine has been run regularly using a valid atmospheric reference.

• Run AutoZ to update P

only when a reference whose measurement

offset

uncertainty is known to be significantly better than that of the molbox RFM

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3. OPERATION

RPTs is available. Though it may not be practical and generally is not necessary, the best possible reference with which to run AutoZ in absolute measurement mode is a gas operated piston gauge (such as a DHI PG7601) applying an absolute pressure near atmospheric pressure to the molbox RFM test port. The best day to day reference is a properly calibrated DHI RPM4 with a BA100K RPT interfaced directly as an external device to the molbox RFM COM2 port.

• Allow the molbox RFM to stabilize at atmospheric pressure and ambient temperature for 10 to 15 minutes before running AutoZ.

If AutoZ is on, the AutoZ value will be applied while running the calibration of

molbox RPTs and an AutoZ indication is included in the run calibration screen (See Section 5.2.4.1).

 OPERATION

To access the molbox RFM AutoZ function press [TARE], <4AutoZ>. The display is:

1. Active RPT designator.

2. Indication of whether AutoZ is currently ON or OFF for this RPT and measurement mode.

1off 2view 3edit 4run ON

• Select <1off> (or <1on>) to change the AutoZ status.

• Select <2view> to view the current values of P

should be zero when the molbox RFM is new or has just been calibrated.

offset

for the two RPTs.

offset

• Select <3edit> to edit the values of Poffset.

The value of P

• Select <4run> to run the AutoZ routine which determines and activates P values by measurement of P

is always displayed and entered in Pascal (Pa).

offset

(see Section 3.4.4.4.2).

std,0

offset

3.4.4.4.1 Edit AutoZ

The edit AutoZ function should be used with great caution as entering

inappropriate values and turning ON AutoZ may result in out of tolerance measurements. In normal operation, the value of the AutoZ offset, P

offset

should be changed using the run AutoZ function (see Section 3.4.4.4.2). Before editing P

, (see Section 3.4.4.4, PRINCIPLE).

offset

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To edit the current P

1. Edit field for the value of P (1, Hi) RPT.

2. Edit field for the value of P (1, Hi) RPT.

values, press [TARE], <4AutoZ>, <3edit>. The display is:

offset

of the upstream

offset

Poffset:18.7 Pa UP1

of the upstream

offset

Poffset:-3.5 Pa DN2

Edit the P

value(s) as desired and press [ENT] to activate the new value(s).

offset

Press [ESC] to abandon changes.

The value of P

is always displayed and entered in Pascal (Pa).

offset

3.4.4.4.2 Run AutoZ

Run AutoZ is the function by which the current RPT reading is compared to a reference, P The value of P

, at atmospheric pressure to determine a new value of P

std,0

is then used by AutoZ to automatically correct the RPT for

offset

possible change in zero over time (see Section 3.4.4.4, PRINCIPLE). To access run AutoZ, press [TARE], <4AutoZ>, <4run>. The display is:

offset

AutoZ by:

1. Selection of source of P to AutoZ.

Selecting <1Entry> allows the value of P

reference to which

std,0

Selecting <2COM> allows the value of P

to be entered from the front panel keypad.

std,0

1Entry 2COM2

to be read automatically from a DHI

RPMx connected to molbox RFM’s COM2 communications port. When AutoZ is run, the molbox RFM internal valves are actuated to connect both

molbox RPTs to the Hi port on the molbox RFM rear panel (see Figure 21 in Section 5.2.4.1). Be sure the Hi port is fully open to atmosphere when running AutoZ. Note that the molbox RFM quick connectors and molbox to molbloc pressure lines are self sealing and therefore DO NOT open to atmosphere unle ss a quick connector stem is inserted. Use a quick connector stem (DHI P/N 101889, equivalent to Swagelok SS-QM2-S-200) supplied with the molbox RFM accessories to open the port to atmosphere.

Allow the molbox RFM to stabilize at atmospheric pressure and ambient

temperature for 10 to 15 minutes before running AutoZ.

If running AutoZ results in a value of P

that is greater than ± 0.025 % FS of

offset

the span of the RPT that is being AutoZeroed, the RPT and/or the reference used as the source of Pstd,0 may be out of tolerance or the AutoZ process may have been faulty. Before activating a new P

greater than ± 0.025 % FS of

offset

the active RPT, check to be sure that both the RPT and the reference were in good working order, properly vented to stable atmospheric pressure, at the same height, and reading in the same pressure units when AutoZ was run.

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3. OPERATION

When the run AutoZ selection is made, if a HEAD correction is currently active

(see Section 3.6.8) the head correction is momentarily disabled while running AutoZ to avoid “zeroing out” the head value.

The value of P

is always displayed and entered in Pascal (Pa).

offset

Run AutoZ by Entry

AutoZ by entry allows the value of P

(see Section 3.4.4.4, PRINCIPLE) to be

std,0

entered directly from the molbox RFM front panel. This provides a simple way of AutoZeroing relative to an independent reference device such as a house barometer that does not interface directly with molbox RFM.

To access run AutoZ by entry press [TARE], <4AutoZ>, <4run>, <1Entry>. The display is:

1. Real time reading (without head correction) of upstream (1, Hi) RPT in unit of measure on line 2.

2. Real time reading (without head correction) of downstream (2, Lo) RPT in unit of measure on line 2.

3. Entry field for the value of P pressure unit of measure.

. in the current

std,0

Enter the value of the AutoZ reference (P

96.772 kPaa 96.778 Pstd,0:96.7752

) in the same unit of measure as the

std,0

display and press [ENT]. molbox RFM logs the readings and calculates a new AutoZ offset value. The next display is:

1. Current/previous value of P upstream (1, Hi) RPT.

2. Current/previous value of P downstream (2, Lo) RPT.

3. New value of P RPT for the AutoZ that was just run.

4. New value of P RPT for the AutoZ that was just run.

for the upstream (1, Hi)

offset

for the downstream (2, Lo)

offset

Press [ENT] to activate the new values of P of a new AutoZ reference (P

offset

std,0

for the

) value.

Old: 0.0 Pa 0.0 New: 3.7 Pa 2.6

or [ESC] to start over with entry

offset

The value of P

is always in Pascal (Pa). The value of P

offset

is entered in

std,0

the current pressure unit of measure.

Run AutoZ by COM2

AutoZ by COM2 allows a DHI RPMx Reference Pressure monitor connected to the molbox RFM COM2 to act as the AutoZ reference (source of Pstd,0) (see Section

3.4.4.4, PRINCIPLE). The RPMx is read and the new P

is calculated automatically.

offset

To access run AutoZ by COM2 press [TARE], <4AutoZ>, <4run>, <2COM2>.

For molbox RFM to communicate with an RPMx connected to its COM2 port,

the molbox RFM and the RPMx RS-232 interfaces must be set up properly (see Section 3.6.6.1). If, the molbox RFM is unable to locate an RPM ON COM2 when running AutoZ by COM2, it times out after 6 seconds and displays an error message.

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If molbox RFM is able to communicate with an RPMx on its COM2 port, the display is:

1. Real time reading (without head correction) of upstream (1, Hi) RPT in unit of measure on line 2.

2. Real time reading (without head correction) of downstream (2, Lo) RPT in unit of measure on line 2.

3. Real time reading of the RPMx connected to molbox RFM COM2 to provide the value of AutoZ P

offset

Observe the pressure outputs verify that they are stable. A 10 to 15 minute wait, after venting, is recommended before running AutoZ. When ready, press [ENT] to cause AutoZ to run. molbox RFM logs both RPT readings and calculates a new AutoZ offset value. The display is:

1. Current/previous value of P upstream (1, Hi) RPT.

2. Current/previous value of P downstream (2, Lo) RPT.

3. New value of P for the AutoZ that was just run.

4. New value of P RPT for the AutoZ that was just run.

for the upstream (1, Hi) RPT

offset

for the downstream (2, Lo)

offset

Press [ENT] to activate the new values of P

for the

96.772 kPaa 96.778 Pstd,0:96.7752

Old: 0.0 Pa 0.0 New: 3.7 Pa 2.6

or [ESC] to start over.

offset

The value of P

is always displayed and entered in Pascal (Pa).

offset

3.4.4.5 <5BPR> (molbloc-S OPERATION ONLY)

 PURPOSE

To quickly measure the molbloc-S upstream and downstream pressure and calculate and display the BPR (back pressure ratio) when molbox RFM is in a molbloc-S BPR mode which would not otherwise measure the BPR.

The <5BPR> menu selection is only present during molbloc-S operation.

 PRINCIPAL

molbox RFM uses the back pressure ratio, or BPR (the ratio of the molbloc-S downstream absolute pressure to the upstream absolute pressure) to determine whether the flow through the throat of the molbloc-S venturi nozzle is critical and flow measurements within predictable uncertainty limits can be made with molbloc-S (see Section 3.1.2). When operating molbox RFM with molbloc-S, the user may select different BPR monitoring modes (see Section 3.6.9). The BPR function allows the user to measure and display BPR directly at any time regardless of the current BPR mode.

Page 69

 OPERATION

Select [TARE], <5BPR>. The display is:

3. OPERATION

1. The current pressure read by the upstream (left) and downstream (right) RPTs without taking into account the current tare value. These are untared readings in the current pressure unit of measure.

2. The current BPR (ratio of downstream to upstream absolute pressure).

259.312 kPa ↓99.5769 BPR 0.38

Press [ENTER] or [ESCAPE] to exit the BPR function and return to the previous RUN screen and BPR mode.

3.4.5 [P&T] (PRESSURE AND TEMPERATURE)

 PURPOSE

To provide continuous display of the pressures measured by molbox RFM, the Reynolds number of the flow through the molbloc, the temperature of the molbloc and other pressure measurement information depending on whether a molbloc-L or molbloc-S is connected to molbox RFM.

 PRINCIPLE

molbox RFM continuously measures pressures and molbloc temperature and uses these measurements to calculate flow.

The pressure at the molbloc upstream and downstream ports is read by two absolute Reference Pressure Transducers (RPTs). In molbloc-L operation, the flow is calculated from the differential pressure across the molbloc. The differential pressure is calculated as the difference between the two absolute RPT measurements (upstream - downstream) and is displayed in the pressure screen. If the molbox RFM is equipped with the microrange option, differential pressure below 12.5 kPa (1.8 psi) is measured by the microrange option’s low differential pressure RPT.

In molbloc-S operation, the flow is calculated from the molbloc-S upstream pressure. The upstream pressure may be read by either one or both of the RPTs, depending on which BPR mode is used (see Section 3.6.9). When molbox RFM is in a valve state called BPR OFF, the molbloc-S downstream pressure is not measured and both RPTs are used to measure the molbloc-S upstream pressure. Their readings are averaged to reduce the uncertainty of the molbloc-S upstream pressure measurement. An indicator is used next to the “downstream” RPT value to show whether the RPT is currently measuring the molbloc downstream or upstream pressure. Whenever the molbloc-S downstream pressure is measured, the BPR is calculated and shown in the P&T pressure screen. When both RPTs measure the upstream pressure (BPR OFF mode), the indicated pressure for both RPTs is adjusted to equal the average of the two using the dynamic tare and BPR is no longer displayed.

Since the displays and operation of the P&T pressure screen are different for molbloc-L and molbloc-S operation, they are described separately in the  OPERATION sections below.

For temperature measurement, two Platinum Resistance Thermometers (PRTs) are embedded in each molbloc. These are connected to the molbox RFM by the molbox to molbloc cable. The molbox RFM ohmic measurement system reads the resistance of the PRTs and calculates molbloc temperature.

molbox RFM continuously calculates the Reynolds number of the flow through the molbloc. molbox RFM’s current pressure and temperature readings as well as the Reynolds number of the current flow can be displayed using the P&T function.

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 OPERATION – molbloc-L Operation Press [P&T] from any run screen. The display is:

1. Pressure read by the upstream RPT (left), the downstream RPT (right) and the pressure unit of measure (middle).

2. The current differential pressure in the current pressure unit of measure. <DP> indicates the value is differential pressure. <mDP> indicates the measurement is from the microrange differential RPT (if present).

3. Current Reynolds number of the flow through the molbloc.

Pressing [P&T] again or the [+/-] key toggles between the pressure screen and the temperature screen:

97.788 kPa 97.783 mDP 0.005 Re 0.02

1. The average molbloc temperature in the current unit of measure (upstream + downstream/2).

2. The temperature measured by the upstream molbloc platinum resistance thermometer in the current unit of measure.

3. The temperature measured by the downstream molbloc platinum resistance thermometer in the current unit of measure.

21.80ºC

21.82ºC 21.78ºC

To leave the P&T function and return to the MAIN run screen, press [ESCAPE].

To change the pressure and/or temperature unit of measure, see Sections 3.5.2 and 3.5.3.

 OPERATION – molbloc-S operation

1. The current pressure read by the upstream (left) and downstream (right) RPTs and the current pressure unit of measure (middle). In BPR OFF or Auto modes, tare is automatically applied to these readings. In BPR ON mode, tare is never applied.

2. Arrow to indicate which pressure is being read by the “downstream” RPT. Down arrow indicates downstream pressure, Up arrow indicates upstream pressure.

3. The current BPR (ratio of downstream to upstream absolute pressure).

4. Current Reynolds number.

259.31 kPa ↓ 99.577 BPR 0.38 Re 11039

Pressing [P&T] again or the [+/-] key toggles between the pressure screen and the temperature screen:

1. The average molbloc temperature in the current unit of measure (upstream + downstream/2).

2. The temperature measured by the upstream molbloc platinum resistance thermometer in the current unit of measure.

3. The temperature measured by the downstream molbloc platinum resistance thermometer in the current unit of measure.

To leave the P&T function and return to the MAIN run screen, press [ESCAPE].

To change the pressure and/or temperature unit of measure, see Sections 3.5.2 and 3.5.3.

21.80ºC

21.82ºC 21.78ºC

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3. OPERATION

3.4.6 [DISPLAY]

 PURPOSE

To select, from a variety of choices, the information that is displayed in the molbox RFM main run display.

 PRINCIPLE

molbox RFM supports a variety of ADVANCED FLOW MEASUREMENT functions that are generally displayed on the second (bottom) line of the molbox RFM display. In summary, the available DISPLAY functions included are:

RATE: Calculates and displays the current rate of change of flow in current flow

units/second (see Section

3.4.6.1). This function is a useful indication of stability of the flow being measured. It is often used as a “go/no go” criterion for when to take data when comparing molbox RFM and a DUT (e.g., in a calibration).

AVERAGE: Calculates the average flow measurement over a user specified period of time

and displays the average, the standard deviation about the mean and a countdown in seconds to the next average (see Section

3.4.6.2). This function is often used to filter out flow noise in an unstable system or to gather a corresponding sample when comparing molbloc/molbox

measurements to another device with a long integration time (e.g., a volumetric flow standard). The magnitude of the noise is quantified by the standard deviation about the mean. A second screen allows the instantaneous flow values to be viewed during an averaging cycle.

the

HI/LO: Records and displays the maximum and minimum flows measured since HI/LO

reset (see Section and maximum

3.4.6.3). This function is used to keep track of the minimum

flow observed over a period of time or to monitor whether a flow

min/max limit has been exceeded.

TOTAL: Totalizes the mass or volume flowed over a period of time (see Section

3.4.6.4). Used to measure total mass or volume over

a period of time. Can be useful in calibrating or verifying a totalizing flow device, when comparing molbloc/molbox to a gravimetric standard or to add or remove a specific quantity of mass or volume to/from a system.

UNIT: Displays the measurement of flow through the molbloc simultaneously in a

second flow unit (see Section working with an unfamiliar flow unit of measure

3.4.6.5). This function is convenient when to simultaneously display a

familiar unit or any time a real time flow unit conversion is desired.

DEVIATION: Continuously calculates and displays the deviation, in % of reading, between

the current flow measured by molbox RFM and a target flow defined by the user (see Section

3.4.6.6). This function is useful in quickly calculating

the error of a DUT’s measurement or control, or the evolution of flow around and/or away from a desired set point.

FREEZE: Captures and displays the instantaneous flow value measured by molbox RFM

when the [ENTER] key is pressed (see Section 3.4.6.7). This function is useful to record the flow present at the time of an operator observed trigger event.

CLEAN: Blanks out the second line of the display (see Section 3.4.6.8). This function is

used when a simple display of

flow measured by the molbox RFM, without

additional information, is desired.

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

 OPERATION

To select a DISPLAY function, press [DISPLAY] from the MAIN run screen.

The display is:

The cursor is on the active DISPLAY function. Selecting a DISPLAY function returns to the MAIN run screen with the selected function active.

See Section 3.4.6, PRINCIPLE for a summary of DISPLAY functions and Sections 3.4.6.1 through 3.4.6.8 for detailed information on each DISPLAY function.

In molbloc-S operation, at times, the back pressure ratio, BPR, will be too high for molbox

RFM to calculate a meaningful flow value. When this occurs, the top line of the run screen display always reads <BPR HI> and the bottom line shows the label <BPR> and the current measured BPR value. This display has priority over the appearance of the display functions described in this section, but the display will return to normal when the BPR returns to a usable level for molbloc-S measurements (see Section 3.1.2).

1avg 2rate 3hi/lo 4total 5unit 6dev ↓

7freeze 8clean

The default DISPLAY function is RATE which causes the second line of the display to

show <R> followed by the current rate of change of flow in current flow unit of measure per second (see Section 3.4.6.1).

3.4.6.1 <1RATE>

 PURPOSE

To activate the RATE DISPLAY.

See Section 3.4.6, PRINCIPLE.

 OPERATION

To activate the RATE DISPLAY press [DISPLAY] and select <1rate>. Selecting <1rate> returns to the MAIN run screen with the RATE DISPLAY active.

With the RATE DISPLAY active, the MAIN run screen is:

1. Standard MAIN run screen top line.

2. Current rate of change of flow in current flow unit of measure per second.

* 101.27 sccm N20 R 0.03/sec

The RATE DISPLAY is different and separate from the stability setting that

is used to set the stability criterion on which the Ready/Not Ready indication is based (see Sections

rate

current

of change to be displayed and has NO affect on the stability

setting or the Ready/Not Ready condition.

3.1.3). The RATE DISPLAY only causes the

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3. OPERATION

To go to a DISPLAY other than RATE, press [DISPLAY] and make a new

DISPLAY choice.

3.4.6.2 <2AVG> (AVERAGE)

 PURPOSE

To activate the AVERAGE DISPLAY and/or adjust the period of time over which averaging occurs.

See Section 3.4.6, PRINCIPLE.

 OPERATION

To access the AVERAGE DISPLAY, press [DISPLAY] and select <2avg>. The display is:

Averaging Period:

1. Edit field for averaging period in seconds. Default is 20. Minimum 3, maximum 999.

20 s

Edit the averaging time period if desired. Pressing [ENTER] returns to the MAIN run screen with the AVERAGE DISPLAY active.

With the AVERAGE DISPLAY active the MAIN run screen is:

1. Average flow measured over last completed averaging period.

2. Standard deviation of last completed averaging period.

3. Countdown in seconds until completion of ongoing averaging period.

* 101.99 sccm N20 δ 0.06 18 sec

The AVERAGE DISPLAY has a second screen that allows the instantaneous flow readings to be viewed while an averaging cycle is running. Pressing [+/-] toggles between the MAIN run AVERAGE screen and the instantaneous values AVERAGE screen. The instantaneous AVERAGE screen is:

1. Instantaneous flow value at molbox RFM’s normal integration rate.

2. Countdown in seconds until completion of ongoing averaging period.

3. Current rate of change of flow in flow unit of measure/second..

* 101.59 sccm N20 R 0.0025 18 sec

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

3.4.6.3 <3 HI/LO>

 PURPOSE

See Section 3.4.6, PRINCIPLE.

 OPERATION

To activate the HI/LO DISPLAY press [DISPLAY] and select <3hi/lo>. Selecting <3hi/lo> resets the HI/LO values and returns to the MAIN run screen with the

HI/LO DISPLAY active. With the HI/LO DISPLAY active, the MAIN run screen is:

To activate the HI/LO DISPLAY.

1. Standard MAIN run screen top line.

2. Highest flow observed since HI/LO reset.

3. Lowest flow observed since HI/LO reset.

* 101.22 sccm N20 H 101.44 L99.113

The HI/LO values change each time a new HI or LO flow value occurs. The HI/LO record can be reset at any time by pressing [ENTER] allowing a HI/LO reset without going back through the DISPLAY menu.

Changing the flow unit of measure, the gas, the K factor or running a TARE

function while in HI/LO resets the HI/LO record.

To go to a DISPLAY other than HI/LO, press [DISPLAY] and make a new

DISPLAY choice.

3.4.6.4 <4TOTAL> (TOTALIZER)

 PURPOSE

To activate the TOTALIZER DISPLAY.

See Section 3.4.6, PRINCIPLE.

 OPERATION

To activate the TOTALIZER DISPLAY, press [DISPLAY] and select <4total>. The display is:

Totalizing period:

1. Edit field for time over which to totalize (hh:mm:ss). Default period is 00:10:00; maximum 99:59:59.

00:10:00

Edit the totalizing period as desired. Pressing [ENTER] returns to the MAIN run screen with the TOTALIZER DISPLAY active. With the TOTALIZER DISPLAY active the MAIN run screen is:

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3. OPERATION

1. Standard MAIN run screen top line.

2. Total mass or volume accumulated over elapsed totalizing run time.

3. Units of measure of mass or volume (derived from the current flow unit) of the totalized value (see Table 12). The units of measure are not shown if the screen space is needed to show a large totalized value.

4. Elapsed totalizing time (hh:mm:ss). Always starts from zero and counts up until totalizing period elapses.

* 101.45 sccm N20 Σ0.00 scc 00:00:00

Press [ENTER] to start totalizing. The elapsed time counter starts and the total mass or volume begins to accumulate. Totalizing continues until the set totalize period is complete. When the totalizing period is complete, molbox RFM sounds three beeps and displays the totalizing complete screen in which the total flow or volume and elapsed totalizing time are frozen with totalizing time NOT flashing.

To start a new totalizing run from the totalizing complete screen, press [ENTER]. This clears the previous total, resets to the totalizing timer and starts totalizing.

Certain functions cannot be executed while totalizing. These functions

include change K, change gas, change flow unit of measure, tare. If <Access restricted while totalizing> is displayed when a function key is pressed during totalizing, the function is one that cannot be executed while totalizing. To execute the function, abort the totalizing run or wait until after the run has completed. This feature is to avoid accidentally aborting or corrupting a totalizing run.

To set a new totalizing time without going back through the [DISPLAY]

menu, press [ENTER] and select <2new> from the TOTALIZER screen. To freeze a split total without stopping the totalizing run, press [ENTER] or [ESCAPE] while totalizing.

Table 12. Flow Units and Corresponding Total Mass or Volume Units

FLOW UNIT

mol/s mol

kg/s kg

mg/s mg

slh or slm sl

sccm scc

scfh or scfm scf

Ulm ul

Uccm ucc

ucfm or ucfh ucf

plm or plh pl

pccm pcc

pcfm or pcfh pcf

lm or lh l

ccm cc

m3m or m3h m3

cfm or cfh cf

TOTAL MASS OR

VOLUME UNIT

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

3.4.6.5 <5UNIT>

 PURPOSE

See Section 3.4.6, PRINCIPLE.

To activate the UNIT DISPLAY.

 OPERATION

To activate the UNIT DISPLAY, press [DISPLAY] and select <5unit>. The unit of measure that will be used for the second line of the MAIN run screen display must then be selected. The unit selection process is identical to that of the [UNIT] function key (see Section 3.4.3). Once the unit has been selected operation returns to the MAIN run screen with the UNIT DISPLAY active.

With the UNIT DISPLAY active the MAIN run screen is:

1. Standard MAIN run screen top line.

2. Flow equivalent of the current measured flow in the alternate flow unit of measure.

3. Alternate flow unit of measure selected in UNIT DISPLAY.

* 101.27 sccm N20 = 0.1013 slm

The reference temperature setting for the user units (i.e., uccm and ulm)

(see Section 3.4.3.3) and the temperature and pressure settings for volume units (see Section 3.4.3.4) apply to the units in the main UNIT selections as well as the UNIT DISPLAY selection. Therefore, it

is not possible to simultaneously display user units or volume units with different reference temperatures and/or pressures. When you change the temperature or pressure setting for one type of unit, you change it for that type of unit wherever it is used. It is possible to show the difference between volumetrically based mass flow units at 0 °C and another temperature by choosing the “s” version (e.g., sccm) for 0 °C as the main unit and a user unit with a different reference temperature as the UNIT DISPLAY, or vice-versa.

To go to a DISPLAY other than UNIT, press [DISPLAY] and make a new

DISPLAY choice.

3.4.6.6 <6DEV>

 PURPOSE

To activate the DEVIATION DISPLAY and/or edit the deviation target.

See Section 3.4.6, PRINCIPLE.

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 OPERATION

To activate the DEVIATION DISPLAY, press [DISPLAY] and select <6dev>. The display is:

Target:

1. Edit field to edit the target value from which the deviations is to be measured.

100.00 sccm

Edit the desired target value. Pressing [ENTER] returns to the MAIN run screen with DEVIATION DISPLAY active using the entered target value.

With the DEVIATION DISPLAY active the MAIN run screen is:

1. Standard MAIN run screen top line.

2. Target value in current flow unit of measure.

3. Deviation of current flow from target value in % of reading.

* 100.53 sccm N20 D 0.53 % T 100.00

Pressing [ENTER] from the MAIN run screen when the DEVIATION DISPLAY is

active goes directly to the target editing screen. This allows the target value to be changed without going through the DISPLAY menu.

The DEVIATION DISPLAY target value is the value from which % deviations (D)

are measured by the DEVIATION DISPLAY following:

D = (current flow – target)

target

x 100

To go to a DISPLAY other than DEVIATION, press [DISPLAY] and make a new

DISPLAY choice.

3.4.6.7 <7FREEZE>

 PURPOSE

To activate the FREEZE DISPLAY.

See Section 3.4.6, PRINCIPLE.

 OPERATION

To activate the FREEZE DISPLAY press [DISPLAY] and select <7freeze>. Selecting <7freeze> returns to the MAIN run screen with the FREEZE DISPLAY active.

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With the FREEZE DISPLAY active, the MAIN run screen is:

1. Standard MAIN run screen top line.

2. Flow measured in the current flow units when [ENTER] was pressed (displays 0.00 by default when FREEZE DISPLAY is first activated).

* 101.75 sccm N20 F 99.24

Pressing [ENTER] causes the current flow measured by molbox RFM to be captured and displayed.

If the flow measurement unit is changed while the FREEZE DISPLAY is active,

the FREEZE value defaults back to zero.

To go to a DISPLAY other than FREEZE, press [DISPLAY] and make a new

DISPLAY choice.

3.4.6.8 <8CLEAN>

 PURPOSE

To activate the CLEAN DISPLAY.

See Section 3.4.6, PRINCIPLE.

 OPERATION

To activate the CLEAN DISPLAY press [DISPLAY] and select <8clean>. Selecting <8clean> returns to the MAIN run screen with the CLEAN DISPLAY active.

With the CLEAN DISPLAY active, the MAIN run screen is:

1. Standard MAIN run screen top line.

2. “Clean” second line.

* 101.45 sccm N2O

To go to a DISPLAY other than CLEAN, press [DISPLAY] and make a new

DISPLAY choice.

3.4.7 [MICRO] (OPTIONAL)

 PURPOSE

To turn ON and OFF automatic operation of the optional MICRORANGE FLOW MEASUREMENT function.

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 PRINCIPLE

Use of the microrange feature improves molbox RFM flow measurements while using

molbloc-L only. Microrange has no effect and is disabled during molbloc-S operation.

The molbox RFM microrange option (if present) improves molbox RFM flow measurements when using a molbloc-L element below 10 % FS of its measurement range. Flow measurement resolution and accuracy are enhanced by implementing a low differential pressure RPT which improves the resolution and accuracy of differential pressure measurement when differential pressure is below 12.5 kPa (1.8 psi). See Section 3.1.5 for microrange operational principles and Section 1.2.4.1.1 for microrange specifications.

In automatic microrange mode, use of the microrange option to improve flow measurement is optimized in a manner that is transparent to the user. In particular, the transition between the two different types of differential pressure measurement is smoothed out by weighted averaging of the differential values in a transition zone between 10 and 12.5 kPa differentials (1.5 to 1.8 psi).

The MICRO function turns ON and OFF the microrange option’s automatic mode. With automatic microrange OFF, the microrange option differential pressure RPT measurements are not used at all (unless manual microrange is ON, see Section 3.6.7). With automatic microrange option ON, the differential pressure value used to calculate mass flow can come from the difference between the upstream and downstream RPTs, the microrange differential RPT or a combination of the two during the transition from one method to the other.

The microrange option can also be operated in a manual mode (see Section 3.6.7).

 OPERATION

The MICRO function can be operated at any time from the main run screen. Pressing [MICRO] causes automatic microrange to turn ON if it is OFF and to turn OFF if it is ON. When [MICRO] is pressed, the molbox RFM displays a 3 second message indicating whether it is turning automatic microrange ON or OFF and then returns to the main run screen in the new condition. Automatic microrange ON is indicated by an <m> in the microrange status character of the main run screen. If molbox RFM is not equipped with the microrange option, a 5 second message indicates that the microrange option is not installed. Don’t confuse this message with <Access denied> which displays when the security level setting restricts [MICRO] key access (see Section 3.6.2).

Turning microrange OFF may reduce the accuracy of flow measurements below 10 % of the

molbloc flow measurement range and lead to unexpected results.

Automatic microrange option ON is indicated by an “m” in the microrange option

designator character of the main run screen (top line, 6th character from the right). Microrange option OFF is indicated by a blank designator (see Section3.2).

Use of the MICRO function overrides the current setting of manual microrange option made

by pressing [SPECIAL] and selecting <7micro> (see Section 3.6.7). If manual microrange is ON, pressing [MICRO] turns OFF manual microrange and turns ON automatic microrange.

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3.4.8 [MOLBLOC]

 PURPOSE

To initialize and/or rapidly identify a molbloc that is connected to molbox RFM.

 PRINCIPLE

molblocs carry an EEPROM on which are stored the molbloc identification header, molbloc specific flow calibration coefficients and the zero offset of the molbloc platinum resistance thermometers. molbox RFM must have this information to accurately identify the molbloc to which it is connected and to correctly calculate flow through the molbloc. molbox RFM does not continuously read the information off the molbloc EEPROM. It reads and loads the information on the molbloc EEPROM each time it powers up. However, if the molbloc connected to the molbox is changed without turning the molbox RFM OFF and back ON, the new molbloc and the previous molbloc’s calibration information will continue to be used.

The [molbloc] function key provides a rapid and simple way of causing the molbox RFM to load the molbloc to which it is connected and display a summary of its characteristics. This is useful when changing molblocs or to identify the molbloc that is currently in service.

More complete molbloc information, including a list of gases for which the molbloc has

specific calibration coefficients, can be accessed by pressing [SETUP] and selecting <4molbloc> (see Section 3.5.4).

 OPERATION

Press the [molbloc] function key at any time from the main run screen. molbox RFM will take a moment to read the molbox EEPROM and then display a summary of the molbloc identification header including range designation, serial number and calibration date. This screen is displayed for 5 seconds before operation returns to the main run screen.

If molbox RFM is unable to establish communications with a molbloc, the display is:

molbloc not detected ENTER searches again

Pressing [ESCAPE] returns to the run screen. Pressing [ENTER] repeats the molbloc search just as if [molbloc] had been pressed again.

There is a risk of corrupting the molbloc EEPROM information when molbloc to molbox

RFM electrical connections are made with the molbox RFM power ON. The recommended procedure is to power OFF the molbox RFM when making and breaking molbloc electrical connections. The SOFT POWER OFF does not remove power from the molbloc cable, so the power cord must be disconnected to power OFF the molbox RFM.

3.4.8.1 molbloc-L AND molbloc-S SIZE AND RANGE DESIGNATIONS

Until mid-1999, molbloc-L elements (molbloc-S was not available at the time) were always identified by “Range”. The molbloc-L “Range” is the molbloc’s nominal full scale flow in Nitrogen (N2) at an operating pressure of 250 kPa absolute. Actual molbloc ranges change with the molbloc pressure dependent calibration type and gas (see Section elements have been designated by size with a sizing code (see Table 13).

1.2.4.1.2). Since mid-1999, in addition to nominal range, molbloc-L

On molbloc-L EEPROMs, the molbloc is still identified by its nominal than by its size. The identification of the molbloc displayed by [SETUP], <4molbloc> identifies molbloc-L by both its nominal range and sizing code. molbloc-L size and range designation correspondence are given in Table 13.

range

rather

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Table 13. molbloc-L Size and Nominal Range Designations

molbloc

“NOMINAL

RANGE”

DESIGNATION

10 sccm

50 sccm 100 sccm 200 sccm 500 sccm

1 slm

5 slm 10 slm 30 slm

100 slm

molbloc-L SIZE

DESIGNATION

1E1 5E1 1E2 2E2 5E2 1E3 5E3 1E4 3E4 1E5

molbloc-S elements are also identified by size designations, each of which relate to a specific molbloc-S K

value. molbloc-S flow ranges depend on calibration

type and the pressure limitations of the application and molbox used. For information on the possible molbloc-S flow ranges with various operating pre s s u re s , se e Section 1.2.4.2.2). molbloc-S size and K

value correspondence are

given in Table 14.

Table 14. molbloc-S Size Designation and Pressure to Flow Conversion Ratio (KF)

(sccm/kPa)

50 100 200 500

1 000 2 000 5 000

10 000

molbloc-S SIZE

DESIGNATION

5E1-S 1E2-S 2E2-S 5E2-S 1E3-S 2E3-S 5E3-S 1E4-S

3.4.9 [RES]

 PURPOSE

To set the resolution of molbox RFM’s display of the flow through the molbloc and other flow display and entry values.

 PRINCIPLE

The resolution with which the flow measured by molbox RFM is displayed can be adjusted. This feature can be used to reduce the resolution when lower precision measurements are being made and additional digits might confuse or distract the operator.

The resolution setting determines the number of digits with which flow is displayed. The desired resolution is calculated based on the nominal nitrogen gas full scale of the molbloc range in the current flow unit of measure and then rounded to the furthest digit to the right (i.e., resolution of 0.01 % on a 100 sccm molbloc is 0.01 sccm).

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The default (and maximum) resolution setting is 0.01 % of the molbloc full scale. The RES

setting does not affect the resolution of flow information transmitted remotely. Remote information is always sent using flow resolution of 0.001% of molbloc full scale (0.0001% when microrange is active).

 OPERATION

To access the resolution function press [RES]. Press the [←] to decrease the resolution and [→] to increase the resolution. Each press

changes the resolution by a factor of 10. Once the desired resolution is displayed, press [ENTER] to set the selected resolution and return to the main run screen.

The resolution setting affects the display of the measured flow as well as other

indications and settings (e.g., quantities shown by the [DISPLAY] functions).

3.5 [SETUP]

 PURPOSE

The [SETUP] key accesses a menu of commonly used molbox RFM functions and features that do NOT have direct function keys. These functions include:

<1flowU> To customize the flow unit choices available under [UNIT] (see Sections 3.5.1 and 3.4.3). <2presU> To

select/change the unit of measure in which molbox RFM displays pressure values

(see Section 3.5.2).

<3temp

U> To select/change the unit of measure in which molbox RFM displays temperature values

(see Section 3.5.3).

molbloc> To initialize a molbloc when it is connected to molbox RFM and/or to identify the molbloc

currently connected to molbox RFM (see Section 3.5.14).

<5stab> To

change the stability limit that serves as the criterion for the flow Ready/Not Ready

indication (see Sections 3.5.5 and 3.1.3).

<6adj> To s

et an adder and multiplier to adjust molbox RFM flow readings (see Section 3.5.6).

 OPERATION

To access the SETUP menu, press [SETUP] from the MAIN screen. The display is:

run

1flowU 2presU 3tempU 4molbloc 5stab 6adj

See Sections 3.5.1 to 3.5.6 for detailed information on each SETUP function.

3.5.1 <1flowU>

 PURPOSE

To customize the selection of flow units of measure that are available for selection from the [UNIT] function key (see Section 3.4.3).

 PRINCIPLE/OPERATION

See Section

3.4.3.5.

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3.5.2 <2presU>

 PURPOSE

To select/change the unit of measure in which molbox RFM displays pressure values.

 OPERATION

To set the unit of measure in which molbox RFM displays pressure values, press [SETUP] and select <2presU>.

The display is:

Pressure unit type: 1SI 2other 3user

Select the unit type desired, then select the unit desired. After the unit selection, operation returns to the previous run screen with the selected pressure unit of measure active.

The pressure units of measure available are listed in Table 15.

Table 15. Pressure Units of Measure Available

<1SI> <2Other> <3User>*

<1Pa>

<2kPa>

<3mPa>

<4mbar>

<5bar>

<6mmHg>

<7mmWa>

*3User: User defined unit.

<1psi> <2psf>

<3inHg> <4inWa> <5kcm2>

<1user>

The “user” unit is defined in terms of user units/Pa when the user unit is selected.

See Section 7.1.1 for definition of the pressure unit conversions used by molbox RFM.

3.5.3 <3tempU>

 PURPOSE

To select the unit of measure in which molbox RFM displays temperature values.

 OPERATION

To set the unit of measure in which molbox RFM displays temperature values, press [SETUP] and select <3tempU>.

The display is:

Select the desired unit. After the unit selection, operation returns to the run screen with the selected temperature unit active.

See Section 7.1.2 for definition of the temperature unit conversions used by molbox RFM.

Temperature unit: 1celcius 2fahrenheit

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3.5.4 <4MOLBLOC>

 PURPOSE

To initialize a molbloc when it is connected to molbox RFM and/or to identify the molbloc currently connected to molbox RFM. To determine the gases with which the molbloc has been calibrated.

 PRINCIPLE

molbox uses molbloc specific calibration information contained in the molbloc's EEPROM to determine whether it should operate in molbloc-L or molbloc-S mode and in its calculation of flow through the molbloc. For the molbox RFM to correctly calculate the flow through the molb l o c , i t must use the specific information for the molbloc that is currently connected. molbloc EEPROM information is r ead and stored by molbox RFM in the molbox power up sequence when it is turned on, or by selecting [SETUP], <4molbloc>.

The <4molbloc> function may be used any time there is a change in the molbloc connected to a channel to assure that molbox RFM uses the correct molbloc information on subsequent measurements. The <4molbloc> function can also be used to display identifying information on the molbloc currently connected to the molbox RFM and to determine the gases with which the molbloc has been calibrated.

 OPERATION

To access the molbloc function, press [SETUP], and <4molbloc>. Operation is similar to operation of the [molbloc] direct function key (see Section 3.4.8).

However, when in the molbloc identification screen, pressing [ENTER] causes a list of the gases for which the molbloc has specific calibration coefficients to be displayed. The gases are listed using their chemical abbreviationsError! Reference source not found.. After viewing, press [ESCAPE] to return to the current run screen.

3.5.5 <5STAB>

 PURPOSE

To change the stability limit that serves as the criterion for the flow Ready/Not Ready indication (see Section 3.1.3).

 PRINCIPLE

molbox RFM continuously monitors the rate of change of connected and compares this rate to the stability limit to make a Ready/Not Ready determination (see Section 3.1.3). The STABILITY function allows the stability limit to be adjusted by the user to increase or decrease the stability required for a Ready (<*>) condition to occur.

The default stability limit is ± 0.5 sccm/second (or its equivalent in another flow unit).

The stability limit value is automatically converted when the flow unit of measure is changed.

flow through the molbloc to which it is

The stability limit is separate and different from the RATE DISPLAY function

(see Section 3.4.6.1) which allows the current rate of change of pressure to be displayed.

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 OPERATION To adjust the stability limit press [SETUP] and select <5stab>. The display is:

Flow stability test:

1. Entry field for setting the desired stability limit in the current flow unit of measure. Recalls the default stability limit or the last stability limit set.

0.5 sccm/s

Edit the stability limit setting as desired. Pressing [ENTER] activates the new stability limit and returns to the current run screen.

The stability limit value is automatically converted when flow units of measure

are changed.

The [RES] setting affects the resolution of the stability limit value. If the stability limit

display does not have enough resolution to set the desired value, use [RES] to adjust the resolution (see Section 3.4.9).

3.5.6 <6ADJ>

 PURPOSE

To apply adder (FA) and multiplier (FM) coefficients to the flow measured by molbox RFM.

PRINCIPLE

The ADJ function gives the user the capability to adjust mass flow readings made by molbox RFM. This is accomplished by setting an adder and a multiplier.

The adder (FA) and multiplier (FM) adjust the displayed value of the flow through the molbloc as calculated by the molbox RFM following:

corrected flow = (calculated flow * FM) + FA

If a K factor is active (see Section 3.4.1), the adder and multiplier are applied to the calculated flow before the K factor is applied.

Using the Flow ADJ Function with molbloc-L to Handle a Gas Mixture

Use of ADJ to handle gas mixtures as described below is NOT valid with molbloc-S.

The flow ADJ function can be used to adjust flow readings to measure a gas mixture if the molecular weight and relative content of each component gas is known. Note that this method does not take into account the actual viscosity or compressibility factor of the gas mixture. The thermodynamic properties of the highest concentration gas are used. Therefore, the uncertainty in the measured flow is increased and the method is best when the highest concentration gas is greater than 90% of the mixture.

To use this feature, set the molbox RFM [GAS] (see Section 3.4.2) to the highest concentration gas, then adjust the flow multiplier by:

molecular weight of the mix

molecular weight of the gas selected on the molbox

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For example, to adjust a gas mix that is 95 % Nitrogen (N2) and 5 % Oxygen (O2): n Calculate the molecular weight of the mix.

molecular weight = 28.016

molecular weight = 31.999

Mix molecular weight = (28.016 x 0.95) + (31.999 x 0.05) = 28.215

o Select N p Calculate:

, the highest concentration gas, as the molbox RFM gas.

molecular weight of the mix

molecular weight of the gas selecton on the molbox

28.215

28.016

1.0071

q Set flow multiplier in ADJ function to 1.0071.  OPERATION

To access the ADJ function press [SETUP] and select <6adj>. The display is:

Adder: 0 sccm Mult: 1.00000

Edit the values as desired. Pressing [ENTER] returns you to the MAIN run screen with the edited adder and multiplier values applied.

When the <6adj> function is active (an adder or multiplier other than 0 and 1 is entered), there is an indicator on the top line of the main run screen. The indicator is an “A” in the character to the right of the molbox flow units. The indicator uses the same position as the “K” indicator (see section 3.2). If there is an ADJ and K active at the same time, the indicators will alternate, appearing every other update of the flow value (about once each second).

The flow adder and multiplier of the ADJ function, if different from 0 and 1, alter the flow

readings made by the molbox. The ADJ function is always "ON". When using adders and multipliers, great caution should be taken to ensure that they are entered and changed correctly and that they are 0 and 1 if no adder or multiplier effect is desired. The ADJ function is restricted in all User Security Levels except “none” to protect against unintentional flow adjustment (See section 3.6.2).

3.6 [SPECIAL]

 PURPOSE

The [SPECIAL] key accesses a menu of molbox RFM functions and settings that are less commonly or not normally used in regular operation. These functions include:

<1reset> Access and execute various reset options (see Section 3.6.1).

level> Set user protection levels that restrict access to certain functions and to edit the user

password (see Section 3.6.2).

<3ul> <4cal> View and adjust the molbox RFM pressure transducers and reference resistors (see Section 3.6.4). <5prefs> Set display screen saver time, unit ID number and date and time (see Section 3.6.5). <6remote> View and edit molbox RFM COM port (RS232) and IEEE-488 interface settings (see Section 3.6.6). <7log> View and/or clear the molbox RFM event log (see Section 3.6.7).

Set upper pressure limit alarm (see Section 3.6.3).

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<8head> Set the height for the pressure fluid head correction (see Section 3.6.8). <9BPR> Set the back pressure ratio (BPR) mode (for molbloc-S operation only) (see Section 3.6.9).

 OPERATION To access the SPECIAL menu, press [SPECIAL] from the MAIN run screen.

1reset 2level 3ul

The display is:

4cal 5prefs 6remote ↓ 7log 8head 9BPR

Select the desired function. See Sections 3.6.1 to 3.6.9 for detailed SPECIAL function descriptions.

Some screens (e.g., the SPECIAL menu) go beyond the two lines provided by the display. This is

indicated by a flashing down arrow in the second line of the display. Press the [←] and [→] keys to move the cursor to access the lines that are NOT visible or directly enter the number of the hidden menu choice if you know it.

3.6.1 <1RESET>

 PURPOSE

To reset various molbox RFM settings to default or factory values.

 PRINCIPLE

molbox RFM stores its user definable settings in non-volatile memory. The reset menu allows the user to selectively or completely reset these settings to factory defaults. Reset clears settings that the user may have made, and should be used only to restore the molbox RFM to a known state. molbox RFM will go through its reboot routine after any type of reset is executed.

 OPERATION

To access the reset choices press [SPECIAL] and select <1reset>. The display is:

Select the desired reset. After confirmation, the reset occurs. A reset always puts the molbox RFM through its start up routine as if power had been turned OFF and back ON.

See Sections 3.6.1.1 through 3.6.1.5 for detailed information on the specific reset choices.

RESET functions change user settings that affect flow measurement. If not used

properly, resetting can cause out of tolerance measurements. RESET functions should only be used by qualified personnel with reference to this manual for information on the RESET functions.

1sets 2units 3com 4cal 5all

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3.6.1.1 <1SETS>

 PURPOSE/OPERATION

To access Reset - Sets, press [SPECIAL] and select <1reset>, <1sets>. Reset - Sets clears and sets to default the user settings for various measurements.

These include:

• Flow unit of measure to sccm (see Section

• Pressure unit of measure to kPa (see Section

3.4.3).

3.5.2).

• Temperature unit of measure to °C (see Section 3.5.3).

• Gas type to N2 (see Section 3.4.2).

Stability criterion to 0.5 sccm (see Section 3.5.5).

•

• K factor to 1 (see Section 3.4.1).

• DISPLAY function to Rate (see Section

3.4.6.1).

• RPT Tare value to 0 (see Section 3.4.4.1).

• Tare preference to upstream pressure (see Section 3.4.4.1.1).

• Flow adder to 0 and flow mu

ltiplier to 1 (see Section 3.5.6).

• Resolution to 0. 01 % (see Section 3.4.9). BPR mode to Auto (see Section 3.6.9)

•

3.6.1.2 <2UNITS>

 PURPOSE/OPERATION

To access Reset - Units, press [SPECIAL] and select <1reset>, <2units>. Reset - Units clears and sets to default all UNIT OF MEASURE functions. These include:

• Six flow units of measure selectable from [UNIT] to defaults (see Section

• Flow unit

eference temperature for uxxx units of measure to 0 °C (see Section 3.4.3.3).

• R

• Volume flow unit of measure conditions

of measure to sccm (see Section 3.4.3).

to molbloc for temperature and

standard atmospheric pressure for pressure (see Section 3.4.3.4).

• Pressure unit of measure to kPa (see Section 3.5.2).

• User pressure unit coefficient to 1.00/Pa (see Section 3.5.2).

• Temperature unit of measure to °C (see Section 3.5.3).

3.4.3).

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3.6.1.3 <3COM>

 OPERATION/PURPOSE To access Reset - Com, press [SPECIAL] and select <1reset>, <3com>. Reset - Com clears and sets to default the molbox RFM communications ports

(see Section 3.6.6). This includes:

• COM1 and COM2 Baud rate: 2 400

Parity: Even Data bits: 7 Stop bits: 1 Terminating characters: <CR>, <LF>

• IEEE-488 (GPIB) Address: 10

Terminating characters: <CR>, <LF>

3.6.1.4 <4CAL>

Use special caution with this reset as critical calibration data may be altered.

To access Reset - Cal, press [SPECIAL] and select <1reset>, <4cal>. Reset - Cal clears and sets to default the user calibration coefficients for molbox

RFM Reference Pressure Transducers (RPTs) (see Section 5.2). If the molbox RFM has been recalibrated at any time since its original factory calibration, the recalibration adjustment was done using these user calibration coefficients. The RPT cal coefficient defaults are:

• Upstream and downstream absolute RPTs: Adder 0

Multiplier: 1 Calibration Date: 19980101

• Microrange differential RPT: Adder: 0

Multiplier: 1

 PURPOSE/OPERATION

Calibration Date: 19980101

Reset - Cal has NO effect on the reference resistance values used to calibrate

the molbox RFM internal ohmic measurement system (see Section 5.3).

3.6.1.5 <5ALL>

 PURPOSE/OPERATION

To return molbox RFM to the original, as delivered factory condition. Performs the RESET - SETS, UNITS, COM and CAL functions and resets all other settable values to defaults.

To access Reset - All, press [SPECIAL] and select <1reset>, <5all>.

Use special caution with this reset as critical calibration data may be altered.

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3.6.2 <2level>

 PURPOSE

To set user protection levels that restrict access to certain functions and to edit the password required for changing user levels.

 PRINCIPLE

molbox RFM’s front panel user interface provides the means to access all molbox RFM user defined data, settings and functions including calibration data. Inadvertent, uninformed or unauthorized altering or deleting of data, settings and functions could require extensive reconfiguration by the user and might cause invalid readings. For these reasons, depending upon the application in which molbox RFM is being used, it may be desirable to restrict access to certain functions. The USER LEVEL function makes this possible. Four different levels of security are available: none, low, medium and high.

Access to changing security levels can be left open, or be protected by a password so that security levels can be used as a convenient way to avoid accidental changing of data or as a secured means of preventing tampering with molbox RFM settings.

3.6.2.1 SECURITY LEVELS

The security levels are structured to support typical operating environments as follows:

None This level is intended for use only by the system manager and/or

calibration facility. It allows access and editing in all areas including critical metrological information and other settings that affect measurement integrity.

Low Low security is designed to protect the specific metrological information

and SYSTEM DIAGNOSTIC AND MAINTENANCE functions of the system against accidental alteration. It is intended for an advanced operator performing many different tasks. Low security is the default user level setting.

Medium Medium security is designed to protect specific metrological information

in the system and to assure that the molbox RFM is operated using consistent operational parameters.

High High security protects all operating parameters. It is intended to

minimize operator choices (e.g., to perform repeated identical tests under consistent conditions).

molbox RFM is delivered with the security level set to low to avoid

inadvertent altering of critical internal settings but with unrestricted access

to changing security level setting. It is recommended that the low security

level be maintained at all times and password protection be implemented if control over setting of security levels is desired.

If there is a risk of unauthorized changing of the security level, changing

authority should be password protected (see OPERATION of this section).

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3. OPERATION

The High security level disables remote communications and returns an error

message (“ERROR”) to all remote commands. All other security levels have NO effect on remote communications.

The security levels are structured to support typical levels of operation. Specifically, the security levels prevent execution of the functions accessed by the key strokes marked by “•”.

Table 16. Security Levels - Functions NOT Executed Per Function/Level

KEYS LOW MEDIUM HIGH

[K] [GAS] [UNIT] [UNIT] (change temperature/pressure conditions) [TARE] (access menu) [TARE], <1tare>, <select tare pressure> [TARE], <2purge>, (change purge time) [TARE], <4AutoZ>, <1on/off> [TARE], <4AutoZ>, <3edit> [TARE], <4AutoZ>, <4run> [P&T] [DISPLAY] [DISPLAY], (change times/target) [MICRO] [molbloc] [RES] [SETUP], <1flowU> [SETUP], <2presU> [SETUP], <3tempU> [SETUP], <4molbloc> [SETUP], <5stab> [SETUP], <6adj> [SPECIAL], <1reset> [SPECIAL], <1reset>, <3com> [SPECIAL], <1reset>, <4cal> [SPECIAL], <1reset>, <5all> [SPECIAL], <4cal> [SPECIAL], <4cal>, <any 3edit> [SPECIAL], <5prefs> [SPECIAL], <5prefs>, <1ScrSvr> [SPECIAL], <5prefs>, <2sound>

• •

• • •

• •

• • •

• •

• • •

• •

• • •

• •

• • •

• •

•

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Table 17. Security Levels - Functions NOT Executed Per Function/Level

KEYS LOW MEDIUM HIGH

[SPECIAL], <5prefs>, <3time> (make changes)

[SPECIAL], <5prefs>, <4ID>, <2edit> [SPECIAL], <5prefs>, <5log> (clear log)

[SPECIAL], <6remote> [SPECIAL], <6remote> (changes settings)

[SPECIAL], <7micro> [SPECIAL], <8head>

[SPECIAL], <9BPR> (change mode) Remote communications disabled

 OPERATION

molbox RFM is delivered with NO active password so access to the User

Level menu is open. The user level is set to <1Low>. User levels can be changed freely until a password has been created. RESET functions (see Section

3.6.1) do not affect the password setting.

(Continued)

• • •

• •

•

To access the USER LEVEL function, press [SPECIAL], <2level>.

If NO password yet exists or if the correct password has been entered,

the display is: Selecting <1change user level> brings

up the restriction menu:

1change user level 3edit password

Restriction: 1none 2low 3medium 4high

Select the desired restriction level, or press [ESCAPE] to return to the current run screen.

Selecting <2edit passw ord> displays the user password and allows it to be edited. Passwords can be up to six numbers in length and cannot start with a zero.

Password: pppppp 0 disables password

If 0 is entered as the password value, then the password is made inactive and a password will NOT be required to access the user level menu. This is the factory default with a security level of <2low>.

Once a password has been entered, the user level cannot be changed without

reentering the password.

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If there is an active password, the molbox RFM password entry screen

appears.

The user must enter the user defined password or the factory secondary password to proceed. When a password is entered correctly, operation proceeds to the <1change user level 2edit password> screen.

The first field, <nnnn>, is the serial number of the molbox RFM, followed by a second field, <xx>, that counts the number of times that a secondary password has been used. The second field increments each time a secondary password is used. The third field, <pppppp>, is for normal password entry.

The factory secondary password is available in case the user password has been misplaced or forgotten. A factory secondary password can be obtained by contacting a DHI Authorized Service Provider (see Section 7.2). The factory secondary password is different for each molbox RFM and changes each time it is used.

3.6.3 <3UL>

 PURPOSE

3. OPERATION

RFM SN nnn-xx Password: pppppp

To set an upper pressure limit above which molbox RFM will produce a warning, interrupt operation and isolate its internal pressure transducers.

 PRINCIPLE

molbox RFM contains two, high precision reference pressure transducers (RPTs). These can be fatally damaged by large overpressures. The UL function uses molbox RFM's internal capabilities to attempt to protect the RPTs against overpressure. molbox RFM continuously monitors the pressure read by the RPTs. When the pressure passes the level set by the UL function, molbox RFM warns the operator by sounding an audible alarm. Beyond the UL limit there is an overpressure limit, which is not user selectable. If the pressure reaches the overpressure limit, molbox RFM uses its internal valves to isolate the RPTs.

 OPERATION

To access the Upper Limit (UL) function, press [SPECIAL], <3ul>. The display is:

The indication is of the current upper limit setting in the current pressure unit of measure. To specify a different pressure unit of measure, use [SETUP], <2presU> (see Section

3.5.2).

Transducer Max Pres:

630.000 kPaa

To change the upper limit, enter the value desired (see max UL limits below) and press [ENTER]. The display returns to the MAIN run screen with the new upper limit in effect.

The maximum upper limit settings, which are also the default values, are 5 % above the molbox maximum operating pressure ranges. For molbox RFM, the max UL value is 630 kPa absolute (91 psia). The overpressure limit, which cannot be edited, is 660 kPa absolute (96 psia)

If the overpressure limit is exceeded, all molbox RFM isolation valves close and normal operation is interrupted. Normal operation can be reestablished by turning molbox RFM's power OFF and back ON or pressing [ENTER]. Be sure to correct the situation that led to the overpressure condition prior to rebooting molbox RFM or pressing [ENTER]. See Sections

3.6.3.1, 3.1.6 for additional details.

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3.6.3.1 UPPER LIMIT ALARM AND SEQUENCE

When the pressure reaches the upper limit, molbox RFM continues normal operation but sounds an audible alarm. The alarm ceases if the pressure is decreased below the upper limit.

When pressure reaches the overpressure limit, molbox RFM valves close, normal operation ceases and the display indicates:

670.250 kPa 651.780 OVERP! CHK & PWR DWN

The top line indicates the current pressure measurement of the upstream (left) and downstream (right) RPTs. The bottom line is the over pressure warning. Pressure indications that are grossly out of scale generally indicate that the RPT(s) have been fatally overpressured.

Other menus can be observed but the MAIN run screen can not be accessed and no molbox RFM internal valves can be operated. To return the molbox RFM to normal operation, it must be turned OFF and back ON or press [ENTER] from the overpressure screen. When molbox normal operation is reestablished, its isolation valves will open. Be sure the situation that led to the overpressure condition is corrected before attempting to reestablish normal operation.

The upper limit and overpressure functions are intended to use molbox RFM's

features to the extent possible to protect the molbox RFM reference pressure transducers (RPTs) against overpressure. The system is not failsafe and an overpressure causing fatal damage to the RPTs can still occur. Ultimately, protection of the RPTs is the responsibility of the user. RPTs damaged by overpressure are not covered under the product warranty.

molbox RFM continuously monitors for maximum pressure. Whenever the

overpressure limit is exceeded, the pressure value reached, time and date are logged to a privileged location. This information can be of use in determining the events that led to an overpressure situation.

3.6.4 <4CAL>

To calibrate and adjust the molbox RFM reference pressure transducers and ohmic measurement system.

The CALIBRATION functions are considered part of molbox RFM maintenance and are therefore covered in the maintenance section of this manual (see Section 5).

3.6.5 <5PREFS>

 PURPOSE

To access a menu of molbox RFM internal operational preferences and functions. These include:

• <scrSvr>: View and change the SCREEN SAVER function (see Section 3.6.5.1).

• <sounds>: View and change valid and invalid keypad entry sound settings

(see Section 3.6.5.2).

• <time>: View and edit the internal time and date settings (see Section 3.6.5.3).

• <ID>: View and edit the molbox RFM user ID (see Section 3.6.5.4).

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 OPERATION

3. OPERATION

To access the PREFS menu press [SPECIAL], and select <5prefs>. The display is:

1ScrSvr 2sound 3time 4ID

See Sections 3.6.5.1 to 3.6.5.4 for detailed information on each PREFS function.

3.6.5.1 <1SCRSVR>

 PURPOSE

To adjust the time setting of molbox RFM’s SCREEN SAVER function.

 PRINCIPLE

molbox RFM has a SCREEN SAVER function which causes the display to dim after a front panel key is NOT pressed for a certain amount of time. The default time activates the screen saver after 10 minutes. The time can be adjusted by the user or screen saving can be completely eliminated.

 OPERATION

To access the SCREEN SAVER function, press [SPECIAL] and select <5prefs>, <1ScrSav>. Edit the time, in minutes, after which the screen saver

will activate to dim the screen. Set zero to eliminate the SCREEN SAVER function.

Setting screen saver time to zero eliminates the SCREEN SAVER function so

that the display remains permanently at full brightness. The display may also be completed suppressed using the SOFT [ON/OFF] key (see Section 3.3.3).

3.6.5.2 <2SOUND>

 PURPOSE

To adjust or suppress the molbox RFM keypad valid and invalid key press sounds.

 PRINCIPLE

molbox RFM provides audible feedback by a brief “beep” when a valid key press is made. Invalid key presses are indicated by a descending two tone “blurp”. The frequency of this valid key press beep may be selected from three choices or all keypress sounds may be suppressed.

 OPERATION

To access the key press SOUND function, press [SPECIAL] and select <5prefs>, <2sound>.

Select <1none> to suppress the valid and invalid key press sounds completely. Select between <2lo>, <3mid> or <4hi> to adjust the valid key press

tone frequency.

The SOUND function only affects the valid key press tone.

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3.6.5.3 <3TIME>

 PURPOSE

To view and edit the molbox RFM internal time and date settings.

 OPERATION

To access the TIME function press

[SPECIAL] and select <5prefs>, <3time>. The display is:

Select <1time> to edit the time. Edit hours, then minutes, then am/pm by pressing [ENTER] at each entry. Seconds go to zero when minutes are entered.

Select <2date> to edit the date. The date must be specified in YYYYMMDD format.

The molbox RFM date and time are set to United States Mountain Standard

Time in the final test and inspection process at the factory. If desired, use the DATE function to set your local time and date.

Edit: 1time 2 date 08:32:11 am 19980101

3.6.5.4 <4ID>

 PURPOSE

To view or edit the molbox RFM user ID and to view the molbox RFM serial number.

 PRINCIPLE

molbox RFM has a factory programmed serial number that is included on the product label on the bottom of the case and can be viewed in the introductory screen.

molbox RFM also allows the user to store a unique, twelve character, alpha numeric ID number. This feature is frequently used to assign an organizational control ID (e.g., an asset number, tool number, standard number, etc.). The ID function allows the ID number to be viewed and edited. It also displays the molbox RFM factory serial number.

 OPERATION

To access the ID function press [SPECIAL] and select <5prefs>, <4ID>. Select <1view>, to view the current ID.

Select <2edit>, to edit the ID. The ID has twelve characters. When the edit screen is opened, the cursor is on

the first character. Numerical values can be entered directly from the keypad. In addition, the [←] and [→] keys can be used to toggle through a list of available alpha numeric characters. Holding the key slews through the characters. Character order going up ([→]) is: blank space, symbols, lower case letters, upper case letters, numbers. Press [ENTER] to select a character and move to the next character.

When a character is selected the cursor moves to the next character. To leave a blank character, press [ENTER] with the field for that character blank. Use this for the trailing characters if the ID being entered is less than twelve characters.

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After the last of the twelve characters has been entered, the <Save ID?> option is offered. Select <1no> to return to the ID edit screen. Select <2yes> to save the edited ID.

The ID can also be set remotely from a computer which is quite a bit more

convenient than entering characters from the keyboard (see Section 4.3.4). The ID cannot be cleared or reset by any RESET functions (see Section 3.6.1).

3.6.5.5 <5LOG>

 PURPOSE

To view and/or clear the molbox RFM event log.

 PRINCIPLE

molbox RFM records to a log each time one of the following events occurs:

• An over-pressure occurs (see Sections 3.1.6, 3.6.3)

• A memory fault occurs

 OPERATION

To view the event log press [SPECIAL] and select <5prefs>, and then <5log>. The oldest logged event appears. Pressing [ENTER] steps through the logged events from the oldest to the most recent and ending with the option to clear the log <Yes> or <No>.

If NO events have been logged: <End of log> displays.

3.6.6 <6REMOTE>

 PURPOSE

To configure the molbox RFM COM1, COM2 and IEEE-488 communication ports. To test COM1 and COM2 communications.

 PRINCIPLE

The molbox RFM has two RS232 communications ports referred to as COM1 and COM2 and a single IEEE-488 port. COM1 and the IEEE-488 port are for communicating with a host computer (see Section (e.g., a multimeter, second molbox, MFC controller, etc.). These ports can be set up from the molbox RFM front panel.

molbox

RFM provides a self-test for its RS232 communication ports. The self-test allows verification that the molbox RFM RS232 ports (COM1 and COM2) are operating properly and that a valid interface cable is being used.

The RS232 test has two steps: n COM1 sends a message to COM2.

4.1). COM2 is reserved for communicating with an external device

o COM2 sends a message to COM1. In each step, molbox RFM checks the message received at the receiving COM port. If the

receiving COM port times out or receives an incorrect message, that step of the test fails.

 OPERATION

To access the port configurations, press [SPECIAL] and select <6remote>. Select <1COM1>, <2COM2>, or <3IEEE-488> to view and/or edit that port’s settings. Press [SPECIAL] and select <6remote>, <4RS232test> to access the RS232 self-test.

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3.6.6.1 COM1 AND COM2

The COMx ports can be set for the specific settings required by the user. The settings are baud rate, parity, data bits and stop bits. The available options are:

Table 18. COM1 and COM2 Available Settings

BAUD RATE PARITY DATA BITS STOP BITS

300, 600, 1 200, 2 400, 4 800, 9 600, 19 200 NONE, ODD or EVEN 7 or 8 1 or 2

The default COMx settings are 2400, E, 7,1 for both COM ports. The molbox RFM appends a carriage return (<CR>) and a line feed (<LF>) to all

messages that are sent out of the COM1 port to the host. It looks for a carriage return to terminate incoming messages and ignores line feeds. The user MUST wait for a reply to each message sent to the molbox RFM before sending another message to it (see Section

4.2.1).

3.6.6.2 IEEE-488

The IEEE-488 port address can be defined from 1 to 31. The default address is 10. The molbox RFM sends a line feed (<LF>) and asserts the EOI line at the end of

all transmitted messages. It looks for a line feed and/or assertion of the EOI line to terminate incoming messages (see Section 4.2.2).

3.6.6.3 RS232 SELF-TEST

The RS232 self-test is provided to check the molbox RFM COM ports and the interface cable independently of an external device or computer.

If you are having difficulty communicating with molbox RFM from a host computer using RS232, the RS232 self test can help establish that the molbox

RFM COM1 port you are trying to communicate with and the interface cable you are using are good.

To run a self test of the RS232 ports (COM1 and COM2), press [SPECIAL] and select <6remote>, <4RS232test>.

The display prompts you to connect COM1 to COM2 using a standard pin-to-pin DB-9F to DB-9M RS232 cable (see Section

4.2.1.1).

Once the cable has been installed, press [ENTER] to run the self-test. The test is first executed in the COM1→COM2 direction and then in the COM2→COM1 direction.

If the COM1→COM2 test

passes: <PASSED> displays briefly and the test

proceeds to COM2→COM1. If COM2→COM1 passes: <PASSED> is displayed briefly followed by the

conclusion, <molbox RFM RS232 test has PASSED>. If a test fails: Execution is suspended until [ENTER] is pressed.

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3. OPERATION

The molbox RFM RS232 test can fail for three reasons:

1. The RS232 cable being used is incorrect (see Section 4.2.1.1 for

information on the correct cable).

2. COM1 and COM2 do NOT have the same serial communications settings

and therefore cannot communicate together (see Section 3.6.6.1 to set the COM ports).

3. COM1 or COM2 is defective.

The reason for failed communications is almost always a cable or incorrect

RS232 interface settings. Be sure that these are correct before concluding that a COM port is defective.

3.6.7 <7MICRO>

 PURPOSE To turn ON and OFF manual operation of the OPTIONAL MICRORANGE FLOW

MEASUREMENT function.

See also Sections 3.1.5 and 3.4.7 for additional information on the optional microrange

measurement option.

Manual microrange is intended for special uses of the microrange option as explained in

PRINCIPLE of this section. Normal use of the microrange is in automatic operation using the MICRO function (see Section 3.4.7).

 PRINCIPLE

The molbox RFM microrange option (if present) improves molbox RFM flow measurements below 10 % FS of the measurement range. See Section 1.2.4.1.1 for a complete description of microrange principles. The differences between automatic microrange and manual microrange are that in manual microrange:

The differential pressure value used to calculate flow is either 100 % difference between the upstream and downstream absolute RPTs (P1 - P2) or 100 % readings from the microrange differential RPT. No special transitioning from one method to the other is applied.

The current source of the differential pressure measurement used to calculate flow is indicated by the microrange option designator character in the main run screen (<d> when the source is the microrange differential RPT; <a> flashing when the source is the difference between the upstream and downstream absolute RPTs).

Pressing [SPECIAL] and selecting <7micro> allows manual microrange to be turned ON and OFF. With manual microrange OFF, the microrange option differential pressure RPT measurements are not used at all (unless automatic microrange is ON, see Section 3.4.7). With manual microrange option ON, the differential pressure value used to calculate mass flow is either the difference between the upstream and downstream RPTs if differential pressure is > 12.5 kPa (1.8 psi) or the microrange differential RPT if differential pressure is <

12.5 kPa (1.8 psi). The microrange option can also be operated in automatic mode (see Section 3.4.7).

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molbox™ RFM™ OPERATION AND MAINTENANCE MANUAL

 OPERATION

To access the MANUAL MICRORANGE function, press [SPECIAL] and select <7micro>.

The display is:

Manual microrange: 1off 2on

If the manual microrange option is not installed, this menu will not appear. An <Option not installed> message appears in its place.

Select <1off> or <2on>. Operation returns to the run screen with the manual microrange in the condition specified.

Turning the microrange option OFF may reduce the accuracy of flow measurements under

10 % of the flow measurement range and may lead to unexpected results.

Manual microrange option ON is indicated by <d> (option ON, using microrange

differential RPT) or <a> flashing (option ON, not currently using microrange differential RPT) in the microrange option designator character of the main run screen (top line,

character from the right). Manual microrange option OFF is indicated by a blank

designator or the <m> that indicates automatic microrange ON.

Turning ON or OFF manual microrange by pressing [SPECIAL] and selecting <7micro>

overrides the current setting of automatic microrange (see Section 3.4.7).

3.6.8 <8HEAD>

 PURPOSE

To cause a pressure fluid head correction to be added or subtracted to the pressure measured by the molbox RFM reference pressure transducers in order to predict the pressure at height the height of the molbloc when the molbloc is at a level other than the molbox RFM’s reference level.

 PRINCIPLE

molbox RFM measures absolute and differential pressure in molbloc flow elements. The molbox RFM reference pressure transducers (RPTs) are calibrated with the height of the rear panel pressure quick connectors as the pressure reference level. Sometimes, when performing a calibration or test, the molbloc is at a different height than the molbox RFM’s pressure reference level. This difference in height, frequently called head, can cause a significant difference between the pressure measured by the molbox RFM at its reference level and the pressure actually present at the molbloc at a different height. In this case, it is useful to make a head correction to the pressure measured by the molbox RFM in order to predict the pressure actually applied at a different height.

molbox RFM can calculate head pressures for all the gases it supports (see Section 3.4.2), over its working pressure range. The HEAD function allows the difference in height between the molbox RFM and the molbloc to be specified and causes the resulting head pressure to be added to the pressure measured at the molbox RFM rear panel quick connectors.

[SPECIAL], <8head>, is used to specify the height difference between the molbox RFM rear panel quick connectors and another height. Entering a height of zero turns the function off.

Fluke MOLBOX RFM User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

TABLE OF CONTENTS

ABOUT THIS MANUAL

1. INTRODUCTION

1.1 PRODUCT OVERVIEW

1.1.1 MOLBLOC FLOW ELEMENTS

1.1.1.1 MOLBLOC-L FLOW ELEMENT

1.1.1.2 MOLBLOC-S FLOW ELEMENT

1.2 SPECIFICATIONS

1.2.1 GENERAL SPECIFICATIONS

1.2.2 REFERENCE PRESSURE TRANSDUCER (RPT) SPECIFICATIONS

1.2.2.1 UPSTREAM AND DOWNSTREAM RPTS

1.2.2.2 DIFFERENTIAL RPT (MICRORANGE OPTION)

1.2.3 TEMPERATURE MEASUREMENT SPECIFICATIONS

1.2.4 FLOW MEASUREMENT SPECIFICATIONS

1.2.4.1 molbloc-L

1.2.4.1.3 molbloc-L Ranges with Low Pressure Calibrations

1.2.4.1.4 molbloc-L Ranges with High Pressure Calibrations

1.2.4.1.5 molbloc-L DIMENSIONS

1.2.4.2 molbloc-S

1.2.4.2.1 molbloc-S RANGES

1.2.5 FRONT AND REAR PANELS

1.2.5.1 FRONT PANEL

1.2.5.2 REAR PANEL

2.1 UNPACKING AND INSPECTION

2.1.1 REMOVING FROM PACKAGING

2.1.2 INSPECTING CONTENTS

2. INSTALLATION

2.2 SITE REQUIREMENTS

2.3 INITIAL SETUP

2.3.1 PREPARING FOR OPERATION

2.3.2 POWER CONNECTION

2.3.3 MOLBOX RFM TO MOLBLOC CONNECTION

2.3.4 GAS SUPPLY AND FLOWPATH CONNECTIONS

2.3.5 VACUUM SUPPLY (molbloc-S ONLY)

2.3.6 COMMUNICATIONS CONNECTIONS

2.4 POWER UP AND VERIFICATION

2.4.1 POWER UP

2.4.2 CHECK PROPER PRESSURE MEASUREMENT OPERATION

2.4.3 CHECK PROPER TEMPERATURE MEASUREMENT OPERATION

2.4.4 LEAK CHECK

2.4.5 CHECK/SET SECURITY LEVEL

2.5 ADDITIONAL PRECAUTIONS TO TAKE BEFORE MAKING FLOW MEASUREMENTS

2.6 SHORT TERM STORAGE

3.1 GENERAL OPERATING PRINCIPLES

3.1.1 molbloc-L AND molbloc-S OPERATION

3. OPERATION

3.1.3 FLOW READY/NOT READY INDICATION

3.1.3.1 molbloc-L OPERATION

3.1.3.2 molbloc-S OPERATION

3.1.4 SOFT [ON/OFF] KEY

3.1.5 MICRORANGE OPTION (OPTIONAL)

3.1.6 REFERENCE PRESSURE TRANSDUCER (RPT) OVERPRESSURE

3.1.6.1 UPSTREAM AND DOWNSTREAM ABSOLUTE RPTS

3.1.6.2 DIFFERENTIAL RPT, MICRORANGE OPTION

3.2 MAIN RUN SCREEN

3.2.1 molbloc-L OPERATION

3.2.2 molbloc-S OPERATION

3.3 MANUAL OPERATION

3.3.1 KEYPAD LAYOUT AND PROTOCOL

3.3.2 SOUNDS

3.3.3 SOFT [ON/OFF] KEY

3.3.4 DIRECT FUNCTION KEYS SUMMARY

3.4 DIRECT FUNCTION KEYS

3.4.1 [K]

3.4.2 [GAS]

3.4.2.2 molbloc-S OPERATION

3.4.3 [UNIT]

3.4.3.1 MASS FLOW VS. VOLUME FLOW

3.4.3.2 VOLUMETRICALLY BASED MASS FLOW UNITS

3.4.3.4 VOLUME FLOW UNITS (VLM)

3.4.3.5 CUSTOMIZING FLOW UNITS AVAILABLE UNDER THE UNIT FUNCTION

3.4.4 [TARE]

3.4.4.1 <1TARE>

3.4.4.1.1 molbloc-L OPERATION

3.4.4.1.2 molbloc-S Operation

3.4.4.2 <2Purge>