Rosemount 4081 pH Two-Wire Transmitter Manuals & Guides

Download

Model 4081 pH/ORP

Remote Controlled FOUNDATION



Fieldbus

Two-Wire pH/ORP Transmitter

Instruction Manual

PN 51-4081pH/rev.D August 2002



ESSENTIAL INSTRUCTIONS

READ THIS PAGE BEFORE PROCEEDING!

Rosemount Analytical designs, manufactures, and tests its products to meet many national and international standards. Because these instruments are sophisticated technical products, you must properly install, use, and maintain them to ensure they continue to operate within their normal specifications. The following instructions must be adhered to and integrated into your safety program when installing, using, and maintaining Rosemount Analytical products. Failure to follow the proper instructions may cause any one of the following situations to occur: Loss of life; personal injury; property damage; damage to this instrument; and warranty invalidation.

• Read all instructions prior to installing, operating, and servicing the product. If this Instruction Manual is not the correct manual, telephone 949-757-8500 or (toll free) 800-654-7768 and the requested manual will be provided. Save this Instruction Manual for future reference.

• If you do not understand any of the instructions, contact your Rosemount representative for clarification.

• Follow all warnings, cautions, and instructions marked on and supplied with the product.

• Inform and educate your personnel in the proper installation, operation, and maintenance of the product.

• Install your equipment as specified in the Installation Instructions of the appropriate Instruction Manual and per applicable local and national codes. Connect all products to the proper electrical and pressure sources.

• To ensure proper performance, use qualified personnel to install, operate, update, program, and maintain the product.

• When replacement parts are required, ensure that qualified people use replacement parts specified by Rosemount. Unauthorized parts and procedures can affect the product’s performance and place the safe operation of your process at risk. Look alike substitutions may result in fire, electrical hazards, or improper operation.

• Ensure that all equipment doors are closed and protective covers are in place, except when maintenance is being performed by qualified persons, to prevent electrical shock and personal injury.

Emerson Process Management

Rosemount Analytical Inc.

2400 Barranca Parkway Irvine, CA 92606 USA Tel: (949) 757-8500 Fax: (949) 474-7250

http://www.RAuniloc.com

WHAT YOU NEED TO KNOW

BEFORE INSTALLING AND WIRING A ROSEMOUNT ANALYTICAL

SENSOR TO THE MODEL 4081 pH/ORP TRANSMITTER

1. THE MODEL NUMBER OF THE SENSOR

• Look on the label.

• Also note the model option string.

• If the label is missing or unreadable, see the flowcharts on pages 28 through 30.

Write the sensor model number here

2. THE TYPE OF TEMPERATURE ELEMENT

• Look on the label.

• If the label is missing or unreadable, measure the resistance between the RTD leads.

Write the temperature element RTD here

3. THE LOCATION OF THE PREAMPLIFIER: INSIDE OR OUTSIDE THE TRANSMITTER?

• If the sensor is wired through a junction box, the preamplifier is ALWAYS in the junction box or the sensor.

If resistance is . . . the RTD is . . .

about 110 ohms Pt 100

about 3000 ohms Balco 3K

• If the sensor is wired directly to the transmitter, the preamplifier can be in either the sensor or the transmitter.

• Look at the wires in the sensor cable. A GREEN wire means the preamplifier is in the sensor. An coaxial cable means the preamplifier is in the transmitter. A coaxial cable is an insulated wire surrounded by a braided metal shield. The wire terminates in either a BNC connector or an ORANGE wire with a CLEAR shield.

Write the preamplifier location here

CAN YOU USE THE QUICK START GUIDE

ON THE FOLLOWING PAGE?

Use the Quick Start Guide if . . .

1. you do NOT require an intrinsically safe or explosion-proof installation,

2. you are NOT measuring ORP,

3. you are NOT using a a sensor-mounted junction box or a remote junction box,

4. you are NOT using a sensor made by another manufacturer,

5. you are using one of the following sensors:

Note: Only the model option numbers needed to select the correct wiring diagram in the

Quick Start Guide are shown. Other model option numbers are not shown.

If you cannot use the Quick Start Guide, turn to Section 2.0 of the instruction manual.

Base Model RTD Preamplifier located Model Option (note)

381+ Pt 100 in sensor (green wire) 381+ -55 381+ Pt 100 in transmitter (orange wire) 381+ -52 385+ Pt 100 in sensor (green wire) 385+ -03 385+ Pt 100 in transmitter (orange wire) 385+ -04 396P Pt 100 in transmitter (orange wire) 396P-02-54 396P Pt 100 in sensor (green wire) 396P-01-55 396P Pt 100 in transmitter (orange wire) 396P-02-55 396R Pt 100 in transmitter (orange wire) 396R-54

QUICK START GUIDE FOR MODEL 4081pH/ORP

Before using this Quick Start Guide, please read “WHAT YOU NEED TO KNOW BEFORE INSTALLING AND WIRING A ROSEMOUNT ANALYTICAL SENSOR TO THE MODEL 4081 pH/ORP TRANSMITTER” on the preceding page.

Section 1.1 Setup for the Models 381+-52, 385+-04, 396P-02-54, 396P-02-55 and 396R-54 without a junction box

A. The factory setting of the preamplifier switch is in the appropriate location, so no adjustment is necessary. B. Mount the transmitter in the desired location. Most installations use PN 2002577, pipe mounting bracket. C. Continue the start up with Section 2 Wiring.

Section 1.2 Setup for Sensor Models 381+-55, 385+-03, and 396P-01-55 without a junction box

A. This section shows how to set the preamplifier switch and should be done prior to installation of the transmitter. B. Loosen the cover lock nut on the Model 4081pH/ORP transmitter until the tab disengages from the circuit end cap.

Unscrew and remove the cap. Unscrew the three bolts holding the circuit board stack in the enclosure.

C. Pull up on the display board. Do not disconnect the ribbon cable between it and the CPU board. The CPU and analog

boards are joined by a pin and socket connector along the bottom edge of the boards. Carefully pull the boards apart and remove the CPU board. The analog board is on the bottom and remains in the enclosure. See Figure 1 below.

D. The analog board is shaped like a circle with an arc missing. Directly opposite the straight side is a slide switch. Change

the switch position to the "sensor or j-box" setting by sliding the switch closer to the edge of the board. See Figure 2 below.

E. To reassemble the stack, place the display board on the CPU board. Be sure the display board is properly oriented. The

small square window (the infrared detector for the remote controller) marks the top of the board. Insert the three bolts through the holes. Align the bolts with the standoffs on the analog board and position the display and CPU boards on the analog board. If the boards are properly aligned, the bolts will drop in place. Press along the bottom of the stack to seat the pin and socket connector. Tighten the bolts, replace the cap and cover lock nut.

F. Mount the transmitter in the desired location. Most installations use PN 2002577, pipe mounting bracket.

FIGURE 2

FIGURE 1

Section 2 Wiring

A. Wire sensor Model 381+-55, 385+-03, or 396P-01-55 directly to the transmitter as shown in Figure 3. B. Wire sensor Model 381+-52, 385+-04, 396P-02-55, 396P-02-55, or 396R-54 as shown in Figure 4. C. Wire the 12 - 42.4 Vdc power supply to TB-15 and TB-16.

Section 3 Power up and Calibration

A. Apply dc power to the transmitter. B. Remove the red protective "boot" from the sensor end. Rinse with deionized water and gently pat dry with a tissue (don't

wipe or rub). Place the pH sensor in the first buffer. Install the batteries in the remote controller.

Note: A pH measurement is only as good as the calibration, and the calibration is only as good as the buffers used. A careful buffer calibration is the first step in making an accurate pH measurement. For best results, calibrate with buffers having the same temperature as the process. Allow time for the sensor and buffers to reach the same temperature. If the process temperature is more than 10 C different from the buffer, allow at least 20 minutes. Be careful using buffers at high temperatures because the pH of many buffers is undefined above 60 C. See the main instruction manual for further information.

C. Aim the infrared remote controller (IRC) at the LCD display.

Press CAL. CALIbrAtE will appear. Press ENTER. CAL bF1 will appear.

D. With the sensor in the first buffer, be sure the glass bulb and the temperature element are completely submerged (i.e. 3

inches). Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. Press ENTER. bF1 will flash until reading is stable. The measured pH value will appear in the main display. Press éor êuntil the small number next to bF1 matches the nominal pH buffer value (i.e. 4.01 pH). Press ENTER to save the first calibration point. CAL bF2 will appear.

E. Remove the sensor from the first buffer, rinse, and place in the second buffer.

Press ENTER. bF2 will flash until the reading is stable. The measured pH value will appear in the main display. Press éor êuntil the small number next to bF2 matches the nominal pH buffer value (i.e. 10.00 pH).

Press ENTER to save the second calibration point. F. Press RESET to return to the process display. The calibration is complete. G. Place the sensor in the process. The start up is complete, although the following optional procedure may be useful.

NOTE: Diagnostics is turned OFF. See menu tree, Figure 5-4.

NOTES:

1. INSTRUMENT JUMPER SUPPLIED BY CUSTOMER.

2. DO NOT CONNECT BLUE WIRE INSIDE TRANSMITTER. INSULATE STRIPPED END OF BLUE WIRE.

FIGURE 3 FIGURE 4

-VDC

+VDC

QUICK REFERENCE GUIDE

MODEL 4081PH/ORP

Automatic Buffer Calibration Note: A pH measurement is only as good as the calibration, and the calibration is only as good as the buffers used. For best

results, calibrate with buffers having the same temperature as the process. Allow time for the sensor and buffers to reach the same temperature. If the process temperature is more than 10°C different from the buffer, allow at least 20 minutes. Be careful using buffers at high temperatures. The pH of many buffers is undefined above 60°C. See the main instruction manual for further information.

A. Aim the infrared remote controller (IRC) at the LCD display.

Press HOLD on the IRC. HoLd OFF will appear. Press êto toggle the display to HoLd On. Press ENTER to engage hold mode. The HOLD indicator will appear to the left of the pH value.

B. Press CAL. CALIbrAtE will appear.

Press ENTER. CAL bF1 will appear.

C. With the sensor in the first buffer, be sure the glass bulb and the temperature element are completely submerged (about 3

inches deep). Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. Press ENTER. bF1 will flash until reading is stable. The measured pH value will appear in the main display. Press é or êuntil the small number next to bF1 matches the nominal pH buffer value (i.e., 4.01 pH). Press ENTER to save the first calibration point. CAL bF2 will appear.

D. Remove the sensor from the first buffer, rinse and place in the second buffer.

Press ENTER. bF2 will flash until the reading is stable. Press éor êuntil the small number next to bF2 matches the nominal pH buffer value (i.e., 10.00 pH). Press ENTER to save the second calibration point.

E. The calibration is complete, but the transmitter remains in the CALIbrAtE sub-menu for two minutes after ENTER is

pressed. Press RESET to return to the process display immediately. F. Place sensor in the process. G. (Optional) For maintenance purposes, track the slope of the pH electrode. The slope value of a new electrode is 59mV

per pH unit, and this value falls over time. The sensor should be changed when the slope nears 47.5 mV per pH. To view

the slope value, use the following steps.

Press CAL. CALIbrAtE will appear.

Press NEXT. Std will appear.

Press ENTER. The current pH value will appear next to Std.

Press ENTER. SLOPE and the current slope value will appear. Record this number as your slope value.

Press RESET to return to the process display. H. After calibration, press HOLD. HoLd On will display.

Press êto toggle the display to HoLd Off. Press ENTER to save this into memory.

The HOLD indicator on the display will turn off.

Standardizing to Match a Reference Instrument Note: Standardization does not perform a true calibration. Regular buffer calibrations are still needed to update the sensor

slope value. For best results take your grab sample from a point as close as possible to the pH sensor and measure the sample at the same temperature as the process.

A. Aim the infrared remote controller (IRC) at the LCD display.

Press HOLD on the IRC. HoLd OFF will appear.

Press êto toggle the display to HoLd On.

Press ENTER to engage the hold mode. The HOLD indicator will appear to the left of the pH value. B. Press CAL. CALIbrAtE will appear.

Press NEXT. Std will appear.

Press ENTER. The measured value will appear. C. Take a grab sample of the process and measure it with your reference instrument. Use the editing keys to adjust the value

on the Model 4081pH/ORP to match the reference instrument. Press ENTER to save the corrected pH value. D. If the value is acceptable, the sensor slope is displayed. The slope has not been changed. E. Press RESET to return to the process display. F. After calibration, press HOLD. HoLd On will display.

Press êto toggle the display to HoLd Off. Press ENTER to save this into memory. The HOLD indicator on the display will turn off.

Technical Support Hotline:

For assistance with any technical problems, please contact our Customer Support Center (CSC) The CSC is staffed from 5:00am to 5:00pm PST.

Phone (US only): 800-854-8257 Phone: 949-757-8500

Fax: 949-863-9159 Email: uniloc.csc@frco.com

World Wide Web: www.RAuniloc.com

PROGRAM

CALIBRATE

GIMP 1000 V Er 4081

tEMP 25 C

InPut 58.9 ShoW FLt

nonE

rIMP 10

dIAGnOStIC tEMP

bUFFErdISPLAY ISOPOtntAL

CALIbrAtE

Std

tEMP AdJ

tEMP 25.0

tAUtO On

tMAn 25.0

tC 100-3

tYPE PH

tEMP C

OUtPUt Cur

COdE 000

bAUtO On

bUFFEr Std

tIME 04

PH 00.02

tCOEF 00.00

ISO 07.00

Snr 07.00

rOFFSt 060

dIAG OFF

IMPtC OFF

GWH 1000

GFH 1500

GWL 020

GFL 010

CAL 200

rEF LO

rFH 140

rWH 040

rWL 000

rFL 000

CAL bF1

bF 1

bF1 4.01

CAL bF2

bF 2

bF2 10.01

DIAGNOSE

Std 7.00

SLOPE 59.01

Sub-menu

PROMPT

Diag Message

Menu Tree for pH

MODEL 4081 pH/ORP TABLE OF CONTENTS

MODEL 4081 PH/ORP

MICROPROCESSOR ANALYZER

TABLE OF CONTENTS

Section Title Page

1.0 DESCRIPTION AND SPECIFICATIONS ................................................................ 1

1.1 Features................................................................................................................... 1

1.2 FOUNDATION Fieldbus Technology........................................................................ 2

1.3 Specifications - General for Model 4081 pH/ORP ................................................... 3

1.4 Specifications - pH ................................................................................................... 4

1.5 Specifications - ORP................................................................................................ 4

1.6 Ordering Information ............................................................................................... 4

2.0 INSTALLATION ....................................................................................................... 7

2.1 Unpacking and Inspection........................................................................................ 7

2.2 Pre-Installation Set Up ............................................................................................. 7

2.3 Orienting the Display Board ..................................................................................... 10

2.4 Mechanical Installation............................................................................................. 10

2.5 Power Supply Wiring................................................................................................ 13

3.0 WIRING.................................................................................................................... 14

3.1 General Information ................................................................................................. 14

3.2 Wiring Diagrams ...................................................................................................... 15

4.0 INTRINSICALLY SAFE AND EXPLOSION PROOF ............................................... 31

4.1 Intrinsically Safe and Non-Incendive Installations.................................................... 31

4.2 Explosion Proof Installations.................................................................................... 31

5.0 OPERATION WITH REMOTE CONTROLLER ....................................................... 33

5.1 Overview .................................................................................................................. 33

5.2 Displays ................................................................................................................... 34

5.3 Infrared Remote Controller (IRC)............................................................................. 35

5.4 Menu Tree - pH........................................................................................................ 36

5.5 Diagnostic Messages - pH ....................................................................................... 36

5.6 Menu Tree -ORP...................................................................................................... 37

5.7 Diagnostic Messages - ORP.................................................................................... 37

5.8 Security .................................................................................................................... 38

6.0 CALIBRATION OF pH MEASUREMENTS ............................................................. 39

6.1 General .................................................................................................................... 39

6.2 Entering and Leaving the Calibrate Menu................................................................ 39

6.3 Using the Hold Function........................................................................................... 39

6.4 Temperature Calibration........................................................................................... 40

6.5 Auto Calibration ....................................................................................................... 41

6.6 Manual Calibration ................................................................................................... 43

6.7 Making the Transmitter Reading Match a Second pH Meter (Standardization)....... 45

MODEL 4081 pH/ORP TABLE OF CONTENTS

TABLE OF CONTENTS CONT’D

7.0 PROGRAMMING FOR pH MEASUREMENTS....................................................... 47

7.1 General .................................................................................................................... 47

7.2 Entering and Leaving the Program Menu ................................................................ 47

7.3 Diagnostic Parameters............................................................................................. 49

7.4 Temperature Related Settings ................................................................................. 53

7.5 Display Units ............................................................................................................ 55

7.6 Buffer Calibration Parameters.................................................................................. 56

7.7 Isopotential Parameters ........................................................................................... 58

8.0 CALIBRATION OF ORP MEASUREMENTS .......................................................... 60

8.1 General .................................................................................................................... 60

8.2 Entering and Leaving the Calibrate Menu................................................................ 60

8.3 Using the Hold Function........................................................................................... 60

8.4 Temperature Calibration........................................................................................... 61

8.5 Standardization ........................................................................................................ 62

9.0 PROGRAMMING FOR ORP MEASUREMENTS.................................................... 63

9.1 General .................................................................................................................... 63

9.2 Entering and Leaving the Program Menu ................................................................ 63

9.3 Temperature Element............................................................................................... 64

9.4 Display Units ............................................................................................................ 65

9.5 Diagnostic Parameters............................................................................................. 66

10.0 MAINTENANCE ...................................................................................................... 69

10.1 Overview .................................................................................................................. 69

10.2 Transmitter Maintenance ......................................................................................... 69

10.3 pH Sensor Maintenance .......................................................................................... 70

10.4 ORP Sensor Maintenance ....................................................................................... 72

10.5 Calibration................................................................................................................ 72

11.0 TROUBLESHOOTING ........................................................................................... 73

11.1 Warning and Fault Messages .................................................................................. 73

11.2 Calibration Errors ..................................................................................................... 74

11.3 Troubleshooting - General ....................................................................................... 74

11.4 Troubleshooting When a Diagnostic Message is Showing ...................................... 74

11.5 Troubleshooting When No Diagnostic Message is Showing.................................... 86

11.6 Systematic Troubleshooting..................................................................................... 91

11.7 Displaying Diagnostic Variables............................................................................... 93

11.8 Testing the Transmitter by Simulating pH ................................................................ 93

11.9 Factory Assistance and Repairs .............................................................................. 96

iii

MODEL 4081 pH/ORP TABLE OF CONTENTS

TABLE OF CONTENTS CONT’D

12.0 pH MEASUREMENTS............................................................................................. 97

12.1 General .................................................................................................................... 97

12.2 Measuring Electrode ................................................................................................ 98

12.3 Reference Electrode ................................................................................................ 98

12.4 Liquid Junction Potential .......................................................................................... 99

12.5 Converting Voltage to pH......................................................................................... 99

12.6 Glass Electrode Slope ............................................................................................. 100

12.7 Buffers and Calibration ............................................................................................ 100

12.8 Isopotential pH ......................................................................................................... 101

12.9 Junction Potential Mismatch .................................................................................... 101

12.10 Sensor Diagnostics .................................................................................................. 102

12.11 Shields, Insulation, and Preamplifiers...................................................................... 102

13.0 ORP MEASUREMENTS.......................................................................................... 103

13.1 General .................................................................................................................... 103

13.2 Measuring Electrode ................................................................................................ 104

13.3 Reference Electrode ................................................................................................ 104

13.4 Liquid Junction Potential .......................................................................................... 104

13.5 Relating Cell Voltage to ORP................................................................................... 105

13.6 ORP, Concentration, and pH.................................................................................... 105

13.7 Interpreting ORP Measurements ............................................................................. 106

13.8 Calibration................................................................................................................ 107

14.0 GLOSSARY............................................................................................................. 109

15.0 RETURN OF MATERIAL......................................................................................... 115

INDEX ...................................................................................................................... 116

Appendix Title Page

A 4081 pH RESOURCE AND TRANSDUCER BLOCK PARAMETERS .................. 118

B 4081 ORP RESOURCE AND TRANSDUCER BLOCK PARAMETERS ................ 125

MODEL 4081 pH/ORP TABLE OF CONTENTS

TABLE OF CONTENTS CONT’D

LIST OF FIGURES

Number Title Page

2-1 Model 4081 pH/ORP Transmitter - Exploded Drawing of Circuit Board Stack ......... 8

2-2 Model 4081 pH/ORP Transmitter - Analog Board .................................................... 9

2-3 Model 4081 pH/ORP Transmitter - CPU Board........................................................ 10

2-4 Mounting the Model 4081 pH/ORP Transmitter on a Flat Surface ........................... 11

2-5 Using the Pipe Mounting Kit to Attach the Model 4081 pH/ORP to a pipe ............... 12

2-6 Power Supply Wiring ................................................................................................ 13

2-7 Typical Fieldbus Network Electrical Wiring Configuration ........................................ 13

3-1 Wiring and Preamplifier Configurations for pH and ORP Sensors ........................... 14

3-2 Wire Functions for Models 399-02, 399-09, 381pH-30-41, and 381pHE-31-41 .......

before removing BNC and terminating cable ........................................................... 18

3-3 Wire Functions for Models 399-02, 399-09, 381pH-30-41, and 381pHE-31-41 .......

after removing BNC and terminating cable. Wire Functions for Models ..................

399-09-10-62, 381pH-30-42, and 381pHE-31-42 as received ................................. 18

3-4 Wiring Diagram for Models 399-02, 399-09, 381pH-30-41, and 381pHE-31-41 ......

after removing BNC and terminating cable. Wiring Diagram for Models 399-09-10-62,

381pH-30-42, and 381pHE-31-42 as received. Wiring directly to the transmitter .... 18

3-5 Wiring Diagram for Models 399-02, 399-09, 381pH-30-41 after removing BNC .....

and terminating cable. Wiring Diagram for Model 399-09-10-62, 381pH-30-42, and 381pH-31-42 as received. Wiring through a remote junction box to the transmitter 18

3-6 Wire Functions for Models 397-50, 397-54, 396-50, 396-54, 396R-50-60, 396R-54-60,

389-02-50, and 389-02-54 before removing BNC and terminating cable................. 19

3-7 Wire Functions for Models 397-50, 397-54, 369-50, 396-54, 396R-50-60, 396R-54-60,

389-02-50, and 389-02-54 after removing BNC and terminating cable. Wire .........

Functions for Models 397-54-62, 396-02-62, and 389-02-54-62 as received .......... 19

3-8 Wiring Diagram for Models 397-50, 397-54, 369-50, 396-54, 389-02-50, and.........

389-02-54 after removing BNC and terminating cable. Wiring Diagram for Models

397-54-62, 396-02-62, and 389-02-54-62 as received. Wiring Directly to the ........

Transmitter .................................................................................................... 19

3-9 Wiring Diagram for Models 397-50, 397-54, 369-50, 396-54, 396R-50-60, 396R-54-60,

389-02-50, and 389-02-54 after removing BNC and terminating cable. Wiring ......

Diagram for Models 397-54-62, 396-02-62, and 389-02-54-62 as received. ..........

Wiring Through a Remote Junction Box to the Transmitter ..................................... 19

3-10 Wire Functions for Models 396R-50, 396R-54, 396R-50-61, 396P-02-50, 396P-02-54,

396P-05-55, 385+-04, and 385+-41-52.................................................................... 20

3-11 Wiring Diagram for Models 396R-50, 396R-54, 396R-50-61, 396P-02-50, 396P-02-54,

396P-05-55, 385+-04, and 385+-41-52. Wiring Directly to the Transmitter ............ 20

3-12 Wiring Diagram for Models 396R-50, 396R-54, 396R-54-61, 396P-02-50, 396P-02-54,

396P-02-55, 385+-04, and 385+-41-52. Wiring Through a Sensor-Mounted ..........

Junction Box to the Transmitter ............................................................................... 20

3-13 Wire Functions for Models 396P-01-55, 385+-03, 381+-40-55, and 381+-43-55 .... 21

3-14 Wiring Diagram for Models 396P-01-55, 385+-03, 381+-40-55, and 381+-43-55.... 21

3-15 Wire Functions for Model 385+-02 ........................................................................... 22

3-16 Wiring Diagram for Model 385+-02 .......................................................................... 22

3-17 Wire Functions for Model 328A-07........................................................................... 23

3-18 Wiring Diagram for Model 328A ............................................................................... 23

3-19 Wiring Diagram for Model 320HP-10-55 .................................................................. 24

3-20 Wiring Diagram for Model 320HP-10-58 .................................................................. 24

3-21 Wire Functions for Model 399-33 ............................................................................. 25

MODEL 4081 pH/ORP TABLE OF CONTENTS

TABLE OF CONTENTS - CONT’D

LIST OF FIGURES - CONT’D

Number Title Page

3-22 Wiring Diagram for Model 399-33 ............................................................................ 25

3-23 Procedure for Removing BNC Connector and Preparing Coaxial Cable for ............

Connection to the Model 4081 pH/ORP Transmitter................................................ 26

3-24 Preparation of Raw Connecting Cable ..................................................................... 27

4-1 CSA I.S. Label .......................................................................................................... 31

4-2 FM Explosion-Proof Installation for Model 4081 pH/ORP Transmitter ..................... 32A

4-3 CSA Intrinsically Safe Installation for Model 4081 pH/ORP Transmitter .................. 32B

4-4 FMRC Intrinsically Safe Installation for Model 4081 pH/ORP Transmitter ............... 32C

5-1 Functional Block Diagram for the Model 4081 pH/ORP Transmitter with.................

FOUNDATION Fieldbus ............................................................................................. 33

5-2 Process Display Screen ........................................................................................... 34

5-3 Program Display Screen .......................................................................................... 34

5-4 Infrared Remote Controller ....................................................................................... 35

5-5 Menu Tree for pH ..................................................................................................... 36

5-6 Menu Tree for ORP ................................................................................................. 37

7-1 Suggested Glass Impedance Warning and Failure Limits ....................................... 49

7-2 Suggested Warning and Failure Limits for Low Impedance Reference Electrodes . 50 7-3 Suggested Warning and Failure Limits for High Impedance Glass Reference Electrodes 50 9-1 Suggested Warning and Failure Limits for Low Impedance Reference Electrodes . 66 9-2 Suggested Glass Impedance Warning and Failure Limits for a Glass Reference ...

Electrode .................................................................................................................. 66

10-1 Exploded View of Model 4081 pH/ORP Transmitter ................................................ 69

10-2 Checking the Potential of the Reference Electrode.................................................. 71

11-1 Warning Annunciation .............................................................................................. 73

11-2 Fault Annunciation.................................................................................................... 73

11-3 Three-Wire RTD .................................................................................................... 80

11-4 Temperature Simulation into the Model 4081 pH/ORP Transmitter ......................... 81

11-5 Troubleshooting Flow Chart/Preamplifier in Sensor-Mounted Junction Box or........

Remote Junction Box ............................................................................................... 91

11-6 Troubleshooting Flow Chart/Preamplifier in Transmitter or Built into Sensor........... 92

11-7 pH Simulation When the Preamplifier is Located in the Transmitter ........................ 94

11-8 pH Simulation When the Preamplifier is Located in a Remote Junction Box or.......

in a Sensor-Mounted Junction Box .......................................................................... 94

11-9 Simulate pH Through Model 381+ Sensor Preamplifier........................................... 95

12-1 pH Measurement Cell............................................................................................... 97

12-2 Measuring Electrode (pH) ........................................................................................ 98

12-3 Cross-Section Through the pH Glass....................................................................... 98

12-4 Reference Electrode................................................................................................. 99

12-5 The Origin of Liquid Junction Potential..................................................................... 99

12-6 Glass Electrode Slope.............................................................................................. 100

12-7 Two-Point Buffer Calibration..................................................................................... 101

12-8 Liquid Junction Potential Mismatch .......................................................................... 102

13-1 ORP Measurement Cell ........................................................................................... 103

13-2 Measuring Electrode (ORP) ..................................................................................... 104

13-3 Reference Electrode................................................................................................. 104

13-4 The Origin of Liquid Junction Potential..................................................................... 105

13-5 Electrode Potential ................................................................................................... 105

13-6 ORP Measurement Interpretation ............................................................................ 106

MODEL 4081 pH/ORP TABLE OF CONTENTS

TABLE OF CONTENTS CONT’D

LIST OF TABLES

Number Title Page

3-1 Wiring Diagrams for Model 399 Sensors.................................................................. 15

3-2 Wiring Diagrams for Model 397 Sensors.................................................................. 15

3-3 Wiring Diagrams for Model 396R Sensors ............................................................... 15

3-4 Wiring Diagrams for Model 396P Sensors ............................................................... 16

3-5 Wiring Diagrams for Model 396 Sensors.................................................................. 16

3-6 Wiring Diagrams for Model 389 Sensors.................................................................. 16

3-7 Wiring Diagrams for Model 385+ Sensors................................................................ 17

3-8 Wiring Diagrams for Model 381+ Sensors................................................................ 17

3-9 Wiring Diagrams for Model 381pHE and 381pH Sensors ........................................ 17

3-10 Wiring Diagrams for Model 328A Sensors ............................................................... 17

3-11 Wiring Diagrams for Model 320HP Sensors............................................................. 17

7-1 pH Settings List ....................................................................................................... 48

7-2 pH Values of Standard Buffer Solutions and the Temperature Range over which ...

pH Values are Defined ............................................................................................. 56

7-3 pH Values of Commercial (technical) Buffers and the Temperature Range over .....

which pH Values are Defined .................................................................................. 57

7-4 Standard and Technical Buffers Recognized by the Model 4081 pH Transmitter ... 57

9-1 ORP Settings List .................................................................................................... 63

10-1 Replacement Parts for Model 4081 pH Transmitter ................................................ 70

11-1 RTD Resistance Values ........................................................................................... 80

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

1.1 Features

1.2

FOUNDATION Fieldbus Technology

1.3 Specifications - General for Model 4081 pH/ORP

1.4 Specifications - pH

1.5 Specifications - ORP

1.6 Ordering Information

• REMOTE COMMUNICATION IS SIMPLE; use the handheld infrared remote controller, DeltaV

, or FOUNDATION2Fieldbus host.

• LARGE TWO LINE DISPLAY shows pH or ORP, temperature, and output signal.

• SIMPLE, INTUITIVE menus make programming and calibrating easy.

• AUTOMATIC TWO-POINT BUFFER CALIBRATION reduces errors.

• SOLUTION TEMPERATURE COMPENSATION converts the pH measured at any temperature to the pH at 25°C.

• CONTINUOUS DIAGNOSTICS monitor sensor performance and warn the user of impending problems.

• ROBUST NEMA 4X and NEMA 7 ENCLOSURE protects the transmitter from harsh plant environments.

• SOLUTION TEMPERATURE COEFFICIENT allows pH adjustment for actual pH changes with temperature.

• NON-VOLATILE EEPROM MEMORY retains program settings and calibration data during power failures.

1.1 FEATURES

APPLICATION: The Model 4081pH/ORP Transmitter

with the appropriate pH or ORP sensor measures pH between 0 and 14 and ORP between -1400 and 1400 millivolts. Converting the transmitter from a pH instrument to an ORP instrument takes only seconds.

REMOTE COMMUNICATIONS: Remote communications with the Model 4081 pH/ORP transmitter is easy. The handheld, push button infrared remote controller works from as far away as six feet. The transmitter also communicates via any FOUNDATION fieldbus host, such as the Fisher Rosemount DeltaV system.

DISPLAY: The 0.8-inch high LCD main display means pH and ORP values are easy to read even at a distance. Temperature reading also appears in a 0.3 inch high display.

MENUS: Menu formats for calibration and programming are simple and intuitive. Prompts guide the user through the basic procedures. Diagnostic and error messages appear in plain language. There are no annoying error codes to look up.

1. DeltaV is a trademark of Fisher-Rosemount.

2. FOUNDATION is a registered trademark of Fieldbus Foundation.

CALIBRATION: Two-point, temperature-corrected buffer

calibration is standard. To reduce errors caused by impatient operators, the Model 4081 transmitter does not accept calibration data until programmed stability limits have been met. If data are not acceptable, the transmitter displays an error message and does not update the calibration. The transmitter recognizes buffer values commonly used in the world today. Manual two-point and one-point calibration is also available.

AUTOMATIC TEMPERATURE COMPENSATION:

External 3 or 4 wire PT100 RTD, PT1000 RTD, or 3K Balco thermistor located in the sensor compensates the pH reading for temperature fluctuations. Compensation covers the range -15 to 130°C (5 to 270°F). Manual temperature compensation is program selectable.

SOLUTION TEMPERATURE COMPENSATION: The Model 4081 pH transmitter features solution temperature compensation. The transmitter calculates and displays the pH at 25°C from the pH measured at any temperature. The temperature coefficient of the liquid being measured must be known.

SENSOR DIAGNOSTICS: Continuous diagnostics alert the user to impending or existing sensor failure. Diagnostic messages in plain language aid in troubleshooting. The manual contains a thorough, step-by-step troubleshooting guide.

HOUSING: The Model 4081 pH/ORP transmitter housing meets NEMA 4X standards. The transmitter tolerates outdoor and harsh plant environments. The housing also meets NEMA 7B explosion-proof standards.

HAZARDOUS AREA INSTALLATION: Circuits in the Model 4081 pH/ORP transmitter are designed and built to be intrinsically safe when used with the appropriate safety barrier.

OUTPUT: The digital FOUNDATION fieldbus output signal is fully adjustable between 0 and 14 pH and between 1400 and 1400 mV.

1.2 FOUNDATION FIELDBUS TECHNOLOGY

OUNDATION fieldbus is an all digital, serial, two-way communication system that interconnects field equipment such as sensors, actuators, and controllers. Fieldbus is a Local Area Network (LAN) for instruments used in both process and manufacturing automation with built-in capability to distribute the control application across the network. The fieldbus environment is the base level group of digital networks in the hierarchy of plant networks.

The fieldbus retains the desirable features of the 4 - 20 mA analog system, but uses a digital signal. Fieldbus transmitters include a standardized physical interface to the wire, bus powered devices on a single pair of wires, and intrinsic safety options, and enables additional capabilities, such as:

* increased capabilities due to full digital communica-

tions,

* reduced wiring and wire terminations due to multiple

devices on one pair of wires,

* increased selection of suppliers due to interoperability,

* reduced loading on control room equipment with the

distribution of some control and input/output functions to field devices.

* speed options for process control and manufacturing

applications.

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

1.3 SPECIFICATIONS -GENERAL FOR MODEL 4081 pH/ORP

Case: Cast aluminum containing less than 6% magnesium.

NEMA 4X (IP65), NEMA 7 (explosion-proof)

Epoxy-polyester painted over low-copper aluminum. Neoprene O-rings on cover.

Dimensions: 6.3 in. x 6.9 in. x 6.4 in. (160 mm x 175 mm x

161 mm); diameter 6.1 in (155 mm)

Conduit Openings: 2 X 3/4 in. FNPT

Reference Impedance: Transmitter accepts high impedance

(i.e. glass) reference electrodes as well as low impedance (i.e. silver-silver chloride) reference electrodes.

Output: Digital FOUNDATION fieldbus

Response Time: Display reaches 95% of final reading within

10 seconds.

Temperature Sensors: The following RTDs can be used with

the Model 4081 pH/ORP transmitter:

3 and 4 wire Pt 100 RTDs

3 and 4 wire Pt 1000 RTDs

3000 ohm Balco RTD

Transmitter can also be used with two-wire RTDs.

Temperature Range: 5°F to 248°F (-15°C to 120°C)

Local Display: Two line LCD; first line shows process vari-

able (pH or ORP), second line shows temperature and output signal. When triggered, fault and warning messages alternate with temperature and output readings.

Process variable: 7 segment LCD, 0.8 in. (20 mm) high

Temperature/output: 7 segment LCD, 0.3 in. (7 mm) high

Display board can be rotated 90 degrees clockwise or counterclockwise.

During calibration and programming, messages and prompts appear in the temperature/output area.

Power Supply and Load Requirements: A minimum power

supply voltage of 9 Vdc to 32 Vdc is required; Intrinsically Safe installations may be limited to a maximum of 2-3 transmitters per node, depending on the barrier used.

Security: User selected security code prevents

accidental changes to program settings.

Ambient Temperature: -4 to 149°F (-20 to 65°C)

Relative Humidity: 0 to 95% (with covers sealed)

Storage Temperature: -22 to 176°F (-30 to 80°C)

OUNDATION

Fieldbus:

Two AI Function Blocks: pH and temperature Execution time: 75 milliseconds

Hazardous Area Protection: The Model 4081 pH/ORP is

certified to the following: NEMA 7B: Explosion proof housing

CE: EMI/RFI Certification

EN50081-1

EN50082-2

Hazardous Area Classification:

Explosion Proof:

FM: Class I, Div. 1, Groups B, C & D

Class II, Div. 1, Groups E, F, & G Class III, Div. 1

CSA: Class I, Div. 1, Groups C& D

Class I, Div. 2, Groups A, B, C & D Class II, Div. 2, Groups E, F & G Class III, Div. 1

Intrinsic Safety:

FM: Class I, II & III, Div. 1

T4 T AMB= 40°C; T3AT AMB= 70°C

CSA: Class I, Div. 1

T 3C T AMB=40°C; T3 T AMB=80°C

CENELEC: EEx ia IIC

T5 Tamb=40°C; T4 Tamb=60°C

Non-Incendive:

FM: Class I, Div. 2, Groups A, B, C & D

CSA: Class I, Div. 2, Groups A, B, C & D T5

(Tamb=40°C)

Weight/Shipping Weight: 10 lb/10 lb (4.5 kg/4.5 kg).

Weights and shipping weights are rounded to the nearest whole pound.

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

1.6 ORDERING INFORMATION

The Model 4081 pH/ORP two-wire microprocessor transmitter is housed in a NEMA 4X and NEMA 7 case. Communication with the transmitter is through a hand-held infrared remote controller, DeltaV, or FOUNDATION fieldbus host. Automatic temperature compensation is standard, and the transmitter can be programmed to convert measured pH to pH at 25°C. Continuous sensor diagnostics are standard.

MODEL

4081pH/ORP FOUNDATION FIELDBUS TWO-WIRE MICROPROCESSOR TRANSMITTER

Code REQUIRED SELECTION 01-20 LCD (Infrared Remote Control - included), 9.4 lb/4.3 kg 01-21 LCD (Infrared Remote Control - not included)

1.4 SPECIFICATIONS - pH

pH Input Range: 0 to 14 pH

Temperature Input Range: 5°F to 248°F (-15°C to 120°C)

Output Scale Expansion: Continuously expandable

between pH 0 and 14

Accuracy at 25°C: ±0.01 pH

Repeatability at 25°C: ±0.01 pH

Resolution: 0.01 pH and 0.1°C or °F

Stability at 25°C: 0.25% per year

Temperature Compensation: Automatic or manual

between 5°F to 248°F (-15°C to 120°C)

Solution Temperature Compensation: Transmitter will

convert pH measured at any temperature to the pH at 25°C. Temperature coefficient is programmable between -0.044 pH/°C and 0.028 pH/°C

Calibration: Automatic two-point and manual two-point

buffer calibration. For automatic calibration, the transmitter recognizes NIST, DIN 19266 and 19267, JIS 8802, BSM, Merck, and Ingold buffers.

1.5 SPECIFICATIONS - ORP

ORP Input Range: -1400 to 1400 mV

Temperature Input Range: 5°F to 248°F (-15°C to 120°C)

Accuracy at 25°C: ±1 mV

Repeatability at 25°C: ±1 mV

Resolution: 1 mV and 0.1°C or °F

Stability at 25°C: 0.25% per year

Code AGENCY APPROVALS (no selection required)

67 FM approved, Intrinsically Safe (when used with approved sensor and safety barrier) and Explosion Proof 69 CSA approved, Intrinsically Safe (when used with approved sensor and safety barrier) and Explosion Proof 73 CENELEC approved, Intrinsically Safe (safety barrier required)

4081pH - 01 - 20 - 67 EXAMPLE

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

MODEL 4081 pH/ORP TRANSMITTER-SENSOR COMPATIBILITY CHART

PREAMPLIFIER LOCATION

Sensor-mounted Remote

MODEL pH ORP Sensor junction box junction box Transmitter

320B x see note

320HP x see note x

330B x see note 328A x x x

370 x x x x 371 x x x x

381pH x x x x

381pHE x x x x

381 x x x

381+ x x x x

385 x x x x

385+ x x x x x x

389 x x x x

396 x x x 396P x x x x x 396R x x x x x

397 x x x

398 x x x x 398R x x x x x

399 x x x x

399-33 x x

GP1 x x x x

NOTE: Preamplifier installed in junction box attached to sensor mounting plate.

Notes: 1. Special Quotation No. SQ5856 2. Remote J-box/Preamplifier assembly PN 23555-00 3. Sensor Head J-box PN 23709-00

pH SENSOR PREAMP LOCATION DIAGNOSTIC CAPABILITY

320B-99

Sensor junction box only Glass only

320HP-55

Transmitter only or remote junction box Glass only

328A Transmitter or remote junction box

Glass only

381 pHE-31-41-52 Transmitter or remote junction box

Glass only 381+ Transmitter, sensor or remote junction box Glass and Reference 385-53 Transmitter or remote junction box

Glass only 385+ Transmitter, Sensor or remote junction box

Glass and Reference 389-02-54 Transmitter or remote junction box

Glass only 396 TUpH Transmitter, Sensor or remote junction box

Glass only 396P TUpH Transmitter, Sensor or remote junction box

Glass and Reference 399-09 Transmitter or remote junction box

Glass only 396R Transmitter or remote j-box

sensor head

Glass and Reference

ORP SENSOR PREAMP LOCATION DIAGNOSTIC CAPABILITY

330B-99

Sensor None

381pHE-31-41-52 Transmitter or remote junction box

None 381+ Transmitter, sensor or remote junction box Reference only 385-53 Transmitter or remote junction box

None 385+ Transmitter Sensor or remote junction box

Reference only 389-02-12-54 Transmitter or remote junction box

None 396P Transmitter Sensor or remote junction box

Reference only 396R Transmitter or remote junction box

sensor head

Reference only 399-33 Transmitter or remote junction box None

MODEL 4081 pH/ORP SECTION 1.0

DESCRIPTION AND SPECIFICATIONS

MODEL/PN DESCRIPTION SHIPPING WEIGHT

23572-00 Infrared remote controller, includes two 1.5 V AAA alkaline batteries 1 lb/0.5 kg 23555-00 Remote junction box, includes preamplifier (PN 23557-00), 10 terminals on 2 lb/1.0 kg

sensor side and 12 terminals on transmitter side (additional two terminals

supply power from transmitter to the preamplifier) 23557-00 Preamplifier for remote junction box (PN 23555-00) 1 lb/0.5 kg 23550-00 Remote junction box without preamplifier, 12 terminals on sensor side and 2 lb/1.0 kg

12 terminals on transmitter side 23646-01 Extension cable for connecting transmitter to junction box, 10 conductors with 1 lb per 10 ft

1 internal drain wire, cable is terminated and ready for use, specify length 1.0 kg per 10 m

(in feet) when ordering 9200273 Extension cable for connecting transmitter to junction box, 10 conductors with 1 lb per 10 ft

1 internal drain wire, cable is not terminated, customer must prepare cable 1.0 kg per 10 m

ends, specify length (in feet) when ordering 2002577 Pipe mounting kit for 2-inch pipe, complete, includes mounting bracket, 2 lb/1.0 kg

U bolts, and all necessary fasteners 9241178-00 Stainless steel tag, specify marking, shipped loose 1 lb/0.5 kg 9120531 BNC adapter, BNC female to two leads 1 lb/0.5 kg 9210012 Buffer solution, 4.01 pH at 25°C, potassium hydrogen phthalate solution, NIST 2 lb/1.0 kg

pH scale buffer, 16 oz (473 mL) 9210013 Buffer solution, 6.86 pH at 25°C, potassium dihydrogen phosphate and 2 lb/1.0 kg

sodium hydrogen phosphate solution, NIST pH scale buffer, 16 oz (473 mL) 9210014 Buffer solution, 9.18 pH at 25°C, sodium tetraborate solution, NIST pH scale 2 lb/1.0 kg

buffer, 16 oz (473 mL) R508-16OZ ORP standard, 475 ± 20 mV at 25°C, iron (II) ammonium sulfate and iron (III) 2 lb/1.0 kg

ammonium sulfate in 1 M sulfuric acid, 16 oz (473 mL) 5104081P Instruction manual 1 lb/0.5 kg

ACCESSORIES

* Weights rounded up to nearest pound or nearest 0.5 kg.

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

SECTION 2.0

INSTALLATION

2.1 Unpacking and Inspection

2.2 Pre-Installation Set Up

2.3 Orienting the Display Board

2.4 Mechanical Installation

2.5 Power Supply Wiring

2.1 UNPACKING AND INSPECTION

Inspect the shipping container. If it is damaged, contact the shipper immediately for instructions. Save the box. If there is no apparent damage, remove the transmitter. Be sure all items shown on the packing list are present. If items are missing, immediately notify Rosemount Analytical.

Save the shipping container and packaging. They can be reused if it is later necessary to return the transmitter to the factory.

2.2 PRE-INSTALLATION SETUP

2.2.1 Transmitter Default Settings

Two jumpers and a switch may need to be changed from the factory default settings before installing the transmitter. The settings tell the transmitter the type of temperature element in the sensor, whether the reference electrode is high or low impedance, and the location of the preamplifier. The factory default settings are given below.

default setting temperature element Pt 100 RTD reference impedance low preamplifier location in transmitter

If your sensor or system is different, the transmitter settings must be changed. If you do not know the type of temperature element in the sensor, whether the reference electrode impedance is high or low, or the location of the preamplifier, refer to Sections 2.2.2, 2.2.3, and 2.2.4.

2.2.2 Temperature Element

The Model 4081 pH/ORP transmitter is compatible with sensors having Pt 100, Pt 1000, or 3K Balco RTDs. pH and ORP sensors manufactured by Rosemount Analytical contain either a Pt 100 or a 3K Balco RTD. Sensors from other manufacturers may have a Pt 1000 RTD. For Rosemount Analytical sensors, the type of temperature element in the sensor is printed on the metalized tag attached to the sensor cable. If the label is missing or unreadable, determine the type of RTD by measuring the resistance across the RTD IN and RTD RTN leads. For the majority of sensors manufactured by Rosemount Analytical, the RTD IN lead is red and the RTD RTN lead is white. For the Model 399-33 ORP sensor, the leads are black and white. The Model 328A sensor has no RTD. The Model 320HP system has a readily identifiable separate temperature element. Resistance at room temperature for common RTDs is given in the table.

If the resistance is... the temperature element is a about 110 ohms Pt 100 RTD about 1100 ohms Pt 1000 RTD about 3000 ohms 3K Balco RTD

2.2.3 Reference Electrode Impedance

The standard silver-silver chloride reference electrode used in most industrial and laboratory pH electrodes is low impedance. EVERY pH and ORP sensor manufactured by Rosemount Analytical has a low impedance reference. Certain specialized applications require a high impedance reference electrode. The transmitter must be programmed to recognize the high impedance reference.

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

FIGURE 2-1. Model 4081 pH/ORP Transmitter - Exploded Drawing of Circuit Board Stack

2.2.4 Preamplifier Location

pH sensors produce a high impedance voltage signal that must be preamplified before use. The signal can be preamplified before it reaches the transmitter or it can be preamplified in the transmitter. To work properly, the transmitter must know where preamplification occurs. Although ORP sensors produce a low impedance signal, the voltage from an ORP sensor is amplified the same way as a pH signal.

If the sensor is wired to the transmitter through a junction box, the preamplifier is ALWAYS in either the junction box or the sensor. Junction boxes can be attached to the sensor or installed some distance away. If the junction box is not attached to the sensor, it is called a remote junction box. In most junction boxes used with the Model 4081 pH/ORP, a flat, black plastic box attached to the same circuit board as the terminal strips houses the preamplifier. The preamplifier housing in the 381+ sensor is crescent shaped.

If the sensor is wired directly to the transmitter, the preamplifier can be in the sensor or in the transmitter. If the sensor cable has a GREEN wire, the preamplifier is in the sensor. If there is no green wire, the sensor cable will contain a coaxial cable. A coaxial cable is an insulated wire surrounded by a braided metal shield. Depending on the sensor model, the coaxial cable terminates in either a BNC connector or in a separate ORANGE wire and CLEAR shield.

2.2.5 Changing Switch and Jumper Positions

If the sensor and installation does not match the transmitter default settings in Section 2.2.1, change the settings to the correct values.

1. Refer to Figure 2-1.

2. Loosen the cover lock nut until the tab disengages from the front cover. Unscrew the cover.

3. Remove the three bolts holding the circuit board stack.

4. Lift out the display board. Do not disconnect the ribbon cable between it and the CPU board. The CPU and analog boards are joined by a pin and socket connector along the bottom edge of the boards. Carefully disengage the CPU board from the analog board. The analog board will remain attached to the transmitter body.

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

5. Set the jumpers and the slide switch on the analog board. Refer to Figure 2-2. a. Temperature element jumper.

Jumper position Temperature element

JP-1 Pt 1000 RTD

JP-2 Pt 100 RTD

JP-3 3K Balco RTD

b. Reference impedance jumper.

Jumper position Reference impedance

JP-6 low

JP-7 high

c. Preamplifier location selection switch.

Move slider toward Preamplifier location

edge of board sensor or junction box

center of board transmitter

FIGURE 2-2. Model 4081 pH/ORP Transmitter Analog Board

DWG. NO. REV.

40308110 H

The transmitter must also be programmed to recognize the RTD. If pH is being measured, see Section 7.4.3. If ORP is being measured, see Section 9.3.2.

If sensor diagnostics are to be used with a high impedance reference electrode, the high impedance must be identified in the diagnostics setup program. See Section 7.3.3.

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

6. Verify the settings on the CPU board. Refer to Figure 2-3.

Verify that jumpers JP-1, JP-3, and JP-4 on the CPU board are in the positions shown in Figure 2-3. The jumpers are factory set and should not need moving. For installations where 50 Hz ac power is present, closing JP-3 may improve immunity of the transmitter to noise.

7. To reassemble the stack, place the display board on the CPU board. Be sure the display board is properly oriented. The small window (the infrared detector for the remote controller) marks the top of the board. Insert the three bolts through the holes. Align the bolts with the standoffs on the analog board and position the display and CPU boards on the analog board. If the boards are properly aligned, the bolts will drop in place. Press along the bottom of the stack to seat the pin and socket connector. Tighten the bolts.

8. Replace the end cap and lock nut.

2.3 ORIENTING THE DISPLAY BOARD

The display board can be rotated 90 degrees, clockwise or counterclockwise, from the original position. To reposition the display:

1. Loosen the cover lock nut until the tab disengages from the circuit end cap. Unscrew the cap.

2. Remove the three bolts holding the circuit board stack.

3. Lift and rotate the display board 90 degrees, clockwise or counterclockwise, into the desired position.

4. Position the display board on the stand offs. Replace and tighten the bolts.

5. Replace the circuit end cap.

2.4 MECHANICAL INSTALLATION

2.4.1 General information

1. The transmitter tolerates harsh environments. For best results, install the transmitter in an area where temperature extremes, vibrations, and electromagnetic and radio frequency interference are minimized or absent.

2. To prevent unintentional exposure of the transmitter circuitry to the plant environment, keep the security lock in place over the circuit end cap. To remove the circuit end cap, loosen the lock nut until the tab disengages from the end cap, then unscrew the cover.

3. The transmitter has two 3/4-inch conduit openings, one on each side of the housing. Run sensor cable through the left side opening (as viewed from the wiring terminal end of the transmitter) and run power wiring through the right side opening.

FIGURE 2-3. Model 4081 pH/ORP Transmitter CPU Board

DWG. NO. REV.

40008125 A

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

FIGURE 2-4. Mounting the Model 4081 pH/ORP Transmitter on a Flat Surface

MILLIMETER

INCH

4. Use weathertight cable glands to keep moisture out of the transmitter.

5. If conduit is used, plug and seal the connections at the transmitter housing to prevent moisture from getting inside the transmitter.

NOTE

Moisture accumulating in the transmitter housing can affect the performance of the transmitter and may void the warranty.

6. If the transmitter is installed some distance from the sensor, a remote junction box with preamplifier in the junction box or in the sensor may be necessary. Consult the sensor instruction manual for maximum cable lengths.

2.4.2 Mounting on a Flat Surface.

See Figure 2-4.

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

FIGURE 2-5. Using the Pipe Mounting Kit to Attach the Model 4081 pH/ORP Transmitter to a Pipe

MILLIMETER

INCH

2.4.3 Pipe Mounting.

See Figure 2-5. The pipe mounting kit (PN 2002577) accommodates 1-1/2 to 2 in. pipe.

DWG. NO. REV.

40308104 G

DWG. NO. REV.

40308103 C

MODEL 4081 pH/ORP SECTION 2.0

INSTALLATION

2.5 POWER SUPPLY WIRING

2.5.1 Power Supply Wiring. Refer to

Figures 2-6 and 2-7.

Run the power/signal wiring through the opening nearest terminals 15 and 16. Use shielded cable and ground the shield at the power supply. To ground the transmitter, attach the shield to the grounding screw on the inside of the transmitter case. A third wire can also be used to connect the transmitter case to earth ground.

NOTE

For optimum EMI/RFI immunity, the power supply/output cable should be shielded and enclosed in an earth-grounded metal conduit.

Do not run power supply/signal wiring in the same conduit or cable tray with AC power lines or with relay actuated signal cables. Keep power supply/signal wiring at least 6 ft (2 m) away from heavy electrical equipment.

FIGURE 2-6. Power Supply Wiring

DWG. NO. REV.

40408117 A

FIGURE 2-7. Typical Fieldbus Network Electrical Wiring Configuration

4081 pH/ORP

Transmitter

4081 pH/ORP

Transmitter

MODEL 4081 pH/ORP SECTION 3.0

WIRING

SECTION 3.0

WIRING

3.1 GENERAL INFORMATION

pH and ORP sensors manufactured by Rosemount Analytical can be wired to the Model 4081 pH/ORP transmitter in three ways:

1. directly to the transmitter,

2. to a sensor-mounted junction box and then to the transmitter,

3. to a remote junction box and then from the remote junction box to the transmitter.

The pH (or ORP) signal can also be preamplified in one of four places.

1. in the sensor,

2. in a junction box mounted on the sensor,

3. in a remote junction box.

4. at the transmitter.

Figure 3-1 illustrates the various arrangements.

3.1 General Information

3.2 Wiring Diagrams

FIGURE 3-1. Wiring and Preamplifier Configurations for pH and ORP Sensors.

The asterisk identifies the location of the preamplifier. In (a) and (b) the sensor is wired directly to the transmitter. The signal is amplified at the sensor (a) or at the transmitter (b). In (c) the sensor is wired through a sensor-mounted junction box to the transmitter. The preamplifier is in the sensor-mounted junction box. In (d) and (e) the sensor is wired through a remote junction box to the transmitter. The preamplifier is located in the sensor (d) or the junction box (e).

MODEL 4081 pH/ORP SECTION 3.0

WIRING

3.2 WIRING DIAGRAMS

Refer to Tables 3-1 through 3-11 to locate the appropriate wire function and wiring diagram. There is a separate table for each model. The sensor models having the highest number appear first. If you do not know the model number of the sensor, refer to the flow charts on pages 28 through 30. Only the model option numbers needed to select the cor-

rect wiring diagram are shown. Other numbers are not shown. For all other sensors, see sensor manual.

Table 3-1. Wiring Diagrams for Model 399 sensors

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

399-02 none in transmitter 3K Balco** Figure 3-2 Figure 3-4

399-02 remote in remote junction box 3K Balco** Figure 3-2 Figure 3-5

399-09* none in transmitter Pt 100 Figure 3-2 Figure 3-4

399-09* remote in remote junction box Pt 100 Figure 3-2 Figure 3-5

399-09-62 none in transmitter Pt 100 Figure 3-3 Figure 3-4

399-09-62 remote in remote junction box Pt 100 Figure 3-3 Figure 3-5

399-33 (ORP only) none in transmitter Pt 100 Figure 3-21 Figure 3-22

Table 3-2 Wiring Diagrams for Model 397 Sensors

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

397-50 none in transmitter 3K Balco** Figure 3-6 Figure 3-8

397-50 remote in remote junction box 3K Balco** Figure 3-6 Figure 3-9

397-54* none in transmitter Pt 100 Figure 3-6 Figure 3-8

397-54* remote in remote junction box Pt 100 Figure 3-6 Figure 3-9

397-54-62 none in transmitter Pt 100 Figure 3-7 Figure 3-8

397-54-62 remote in remote junction box Pt 100 Figure 3-7 Figure 3-9

Table 3-3 Wiring Diagrams for Model 396R Sensors

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

396R-50 remote in remote junction box 3K Balco** Figure 3-10 Figure 3-12

396R-50 none in transmitter 3K Balco** Figure 3-10 Figure 3-11

396R-50-60 sensor-mounted in sensor-mounted junction box 3K Balco** Figure 3-6 Figure 3-9

396R-54 none in transmitter Pt 100 Figure 3-10 Figure 3-11

396R-54 remote in remote junction box Pt 100 Figure 3-10 Figure 3-12

396R-54-60 sensor-mounted in sensor-mounted junction box Pt 100 Figure 3-7 Figure 3-9

396R-54-61 sensor-mounted in sensor-mounted junction box Pt 100 Figure 3-10 Figure 3-12

* Sensors have a BNC connector that the Model 4081 pH/ORP transmitter does not accept. Cut off the BNC and terminate

the coaxial cable as shown in Figure 3-23. Alternatively, use a BNC adapter.

** Set the RTD jumper to the 3K position (see Section 2.2). Also, program the transmitter to recognize the 3K RTD (see

Section 7.4.3 for pH or 9.3.2 for ORP).

MODEL 4081 pH/ORP SECTION 3.0

WIRING

Table 3-4 Wiring Diagrams for Model 396P Sensors

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

396P-01-55 none in sensor Pt 100 Figure 3-13 Figure 3-14

396P-01-55 remote in sensor Pt 100 Figure 3-13 Figure 3-14

396P-02-50 none in transmitter 3K Balco** Figure 3-10 Figure 3-11

396P-02-50 remote in remote junction box 3K Balco** Figure 3-10 Figure 3-12

396P-02-54 none in transmitter Pt 100 Figure 3-10 Figure 3-11

396P-02-54 remote in remote junction box Pt 100 Figure 3-10 Figure 3-12

396P-02-55 none in transmitter Pt 100 Figure 3-10 Figure 3-11

396P-02-55 remote in remote junction box Pt 100 Figure 3-10 Figure 3-12

Table 3-5 Wiring Diagrams for Model 396 Sensor

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

396-50* none in transmitter 3K Balco** Figure 3-6 Figure 3-8

396-50* remote in remote junction box 3K Balco** Figure 3-6 Figure 3-9

396-54* none in transmitter Pt 100 Figure 3-6 Figure 3-8

396-54* remote in remote junction box Pt 100 Figure 3-6 Figure 3-9

396-54-62 none in transmitter Pt 100 Figure 3-7 Figure 3-8

396-54-62 remote in remote junction box Pt 100 Figure 3-7 Figure 3-9

Table 3-6 Wiring Diagrams for Model 389 Sensors

Sensor Junction Box Preamplifier RTD Wire Function Wiring Diagram

389-02-50* none in transmitter 3K Balco** Figure 3-6 Figure 3-8

389-02-50* remote in remote junction box 3K Balco** Figure 3-6 Figure 3-9

389-02-54* none in transmitter Pt 100 Figure 3-6 Figure 3-8

389-02-54* remote in remote junction box Pt 100 Figure 3-6 Figure 3-9

389-02-54-62 none in transmitter Pt 100 Figure 3-7 Figure 3-8

389-02-54-62 remote in remote junction box Pt 100 Figure 3-7 Figure 3-9

* Sensors have a BNC connector that the Model 4081 pH/ORP transmitter does not accept. Cut off the BNC and terminate

the coaxial cable as shown in Figure 3-23. Alternatively, use a BNC adapter (PN 9120531).

** Set the RTD jumper to the 3K position (see Section 2.2). Also, program the transmitter to recognize the 3K RTD (see

Section 7.4.3 for pH or 9.3.2 for ORP).

MODEL 4081 pH/ORP SECTION 3.0

WIRING

Table 3-7 Wiring Diagrams for Model 385+ Sensors

Sensor Junction Box Preamplifier RTD Wire Functions Wiring Diagram

385+ -02 sensor-mounted in sensor-mounted junction box Pt 100 Figure 3-15 Figure 3-16

385+ -03 none in sensor Pt 100 Figure 3-13 Figure 3-14

385+ -03 remote in sensor Pt 100 Figure 3-13 Figure 3-14

385+ -04 none in transmitter Pt 100 Figure 3-10 Figure 3-11

385+ -04 remote in remote junction box Pt 100 Figure 3-10 Figure 3-12

Table 3-8 Wiring Diagrams for Model 381+ Sensors

Sensor Junction Box Preamplifier RTD Wire Functions Wiring Diagram

381+ -40-55 none in sensor Pt 100 Figure 3-13 Figure 3-14

381+ -43-55 none in sensor Pt 100 Figure 3-13 Figure 3-14

381+ -40-55 remote in sensor Pt 100 Figure 3-13 Figure 3-14

381+ -43-55 remote in sensor Pt 100 Figure 3-13 Figure 3-14

381+ -41-52 none in transmitter Pt 100 Figure 3-10 Figure 3-11

381+ -41-52 remote in remote junction box Pt 100 Figure 3-10 Figure 3-12

Table 3-9 Wiring Diagrams for Model 381pHE and 381pH Sensors

Sensor Junction Box Preamplifier RTD Wire Functions Wiring Diagram

381pHE-30-41-52* none in transmitter 3K Balco** Figure 3-2 Figure 3-4

381pHE-30-41-52* remote in remote junction box 3K Balco** Figure 3-2 Figure 3-5

381pHE-30-42-52 none in transmitter 3K Balco** Figure 3-3 Figure 3-4

381pHE-30-42-52 remote in remote junction box 3K Balco** Figure 3-3 Figure 3-5

381pH-31-41-52* none in transmitter Pt 100 Figure 3-2 Figure 3-4

381pH-31-41-52* remote in remote junction box Pt 100 Figure 3-2 Figure 3-5

381pH-31-42-52 none in transmitter Pt 100 Figure 3-3 Figure 3-4

381pH-31-42-52 remote in remote junction box Pt 100 Figure 3-3 Figure 3-5

Table 3-10 Wiring Diagrams for Model 328A Sensor

Sensor Junction Box Preamplifier RTD Wire Functions Wiring Diagram

328A none in transmitter none Figure 3-17 Figure 3-18

Table 3-11 Wiring Diagrams for Model 320HP Sensor

Sensor Junction Box Preamplifier RTD Wiring Diagram

320-10-55 on mounting plate in transmitter Pt 100 Figure 3-19

320-10-58 on mounting plate in junction box attached to mounting plate Pt 100 Figure 3-20

* Sensors have a BNC connector that the Model 4081 pH/ORP transmitter does not accept. Cut off the BNC and terminate the coax-

ial cable as shown in Figure 3-23. Alternatively, use a BNC adapter (PN 9120531).

** Set the RTD jumper to the 3K position (see Section 2.2). Also, program the transmitter to recognize the 3K RTD (see Section 7.4.3

for pH or 9.3.2 for ORP).

MODEL 4081 pH/ORP SECTION 3.0

WIRING

REMOVE BNC AND TERMINATE COAXIAL CABLE BEFORE WIRING SENSOR TO TRANSMITTER. SEE FIGURE 3-23. ALTERNATIVELY, USE A BNC ADAPTER OR ORDER MODEL OPTION -62 (SENSOR WITH BNC REMOVED AND TERMINATIONS COMPATIBLE WITH 4081 pH/ORP). IF USING A BNC ADAPTER, THE RED WIRE IS MV OR pH IN AND THE BLACK WIRE IS REFERENCE IN. TO PREVENT SHORT CIRCUITS TO THE TRANSMITTER HOUSING, INSULATE THE BNC BY WRAPPING IT WITH ELECTRICAL TAPE.

FIGURE 3-2. Wire functions for Models 399-02, 399-09,

381pH-30-41, and 381pHE-31-41 before removing BNC

and terminating cable.

IF USING A BNC ADAPTER, THE ORANGE WIRE IS MV OR pH IN AND THE CLEAR WIRE IS REFERENCE IN. TO PREVENT SHORT CIRCUITS TO THE TRANSMITTER HOUSING, INSULATE THE BNC WITH BY WRAPPING IT WITH ELECTRICAL TAPE.

FIGURE 3-3. Wire functions for Models 399-02, 399-09,

381pH-30-41, and 381pHE-31-41 after removing BNC and

terminating cable. Wire functions for Models 399-09-10-62,

381pH-30-42 and 381pHE-31-42 as received.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4-pH OR 9.3-ORP)

3. JUMPERS SUPPLIED BY CUSTOMER.

FIGURE 3-4. Wiring diagram for Models 399-02, 399-09,

381pHE-30-41, and 381pHE-31-41 after removing BNC and

terminating cable. Wiring Diagram for 399-09-62, 381pHE-30-42,

and 381pHE-31-42 as received. Wiring directly to the transmitter.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4-pH OR 9.3-ORP)

3. JUMPERS SUPPLIED BY CUSTOMER.

FIGURE 3-5. Wiring diagram for Models 399-02,

399-09, 381pH-30-41, and 381pHE-31-41 after removing BNC and terminating cable. Wiring

Diagram for 399-09-62, 381pH-30-42, and

381pH-31-42 as received. Wiring through a

remote junction box to the transmitter.

-VDC

+VDC

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-6. Wire functions for Models 397-50, 397-54, 396-50,

396-54, 396R-50-60, 396R-54-60, 389-02-50, and 389-02-54

before removing BNC and terminating cable.

IF USING A BNC ADAPTER, THE ORANGE WIRE IS MV OR pH IN AND THE CLEAR WIRE IS REFERENCE IN. TO PREVENT SHORT CIRCUITS TO THE TRANSMITTER HOUSING, INSULATE THE BNC BY WRAPPING IT WITH ELECTRICAL TAPE.

FIGURE 3-7. Wire functions for Models 397-50, 397-54, 396-50,

396-54, 396R-50-60, 396R-54-60, 389-02-50, and 389-02-54 after

removing BNC and terminating cable. Wire functions for

Models 397-54-62, 396-02-62, and 389-02-54-62 as received.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4-pH OR 9.3-ORP)

3. JUMPERS SUPPLIED BY CUSTOMER.

FIGURE 3-8. Wiring diagram for Models 397-50, 397-54, 396-50,

396-54, 389-02-50, and 389-02-54 after removing BNC and termi-

nating cable. Wiring diagram for Models 397-54-62, 396-02-62, and

389-02-54-62 as received. Wiring directly to the transmitter.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION

2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4-pH OR 9.3-ORP)

3. JUMPERS SUPPLIED BY CUSTOMER.

FIGURE 3-9. Wiring diagram for Models 397-50, 397-54, 396-50, 396R-50-60, 396R-54-60, 396-54,

389-02-50, and 389-02-54 after removing BNC

and terminating cable. Wiring diagram for Models 397-54-62, 396-02-62, and 389-02-54-62 as received. Wiring through a remote junction

box to the transmitter.

-VDC

+VDC

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-10. Wire functions for Models 396R-50,

396R-54, 396R-54-61, 396P-02-50, 396P-02-54,

396P-02-55, 385+ -04, and 385+ -41-52.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4-pH OR 9.3-ORP)

3. JUMPER SUPPLIED BY CUSTOMER.

4. DO NOT CONNECT BLUE WIRE. INSULATE STRIPPED END OF WIRE TO AVOID ACCIDENTAL CONNECTIONS.

FIGURE 3-11. Wiring diagram for Models 396R-50,

396R-54, 396R-54-61, 396P-02-50, 396P-02-54,

396P-02-55, 385+ -04, and 385+ -41-52. Wiring

directly to the transmitter.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2).

2. IF SENSOR HAS 3K BALCO RTD, SET JUMPER (SECTION 2.2) AND PROGRAM TRANSMITTER TO RECOGNIZE RTD (SECTION 7.4 [pH] OR 9.3 [ORP])

3. JUMPER SUPPLIED BY CUSTOMER.

4. DO NOT CONNECT BLUE WIRE. INSULATE STRIPPED END OF WIRE TO AVOID ACCIDENTAL CONNECTIONS.

FIGURE 3-12. Wiring diagram for Models 396R-50,

396R-54, 396R-54-61, 396P-02-50, 396P-02-54, 396P-02-55, 385+ -04, and 385+ -41-52. Wiring

through a sensor-mounted junction box to the

transmitter.

-VDC

+VDC

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-13. Wire functions for Models 396P-01-55, 385+ -03,

381+ -40-55, and 381+ -43-55.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION (SEE SECTION 2.2).

2. TO EXTEND CABLE LENGTH, USE JUNCTION BOX PN 2355000 WITH EXTENSION CABLE PN 23646-01 (FINISHED) OR PN 9200273 (UNFINISHED). WIRE THROUGH TERMINALS POINT TO POINT. SEE FIGURE 3-24 FOR TERMINATION OF RAW CABLE.

FIGURE 3-14. Wiring diagram for Models 396P-01-55,

385+ -03, 381+ -40-55, and 381+ -43-55.

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-15. Wire functions for Model 385+ -02.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION.

2. SEE FIGURE 3-24 FOR TERMINATION OF RAW INTERCONNECTING CABLE.

3. JUMPER SUPPLIED BY CUSTOMER.

4. DO NOT CONNECT BLUE WIRE. INSULATE STRIPPED END OF WIRE TO AVOID ACCIDENTAL CONNECTIONS.

FIGURE 3-16. Wiring diagram for Model 385+ -02.

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

NOTE: MODEL 328A-08 HAS UNDRESSED COAXIAL CABLE. SEE SENSOR INSTRUCTION

SHEET FOR CABLE PREPARATION PROCEDURE.

FIGURE 3-17. Wire functions for Model 328A-07.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION.

2. JUMPERS SUPPLIED BY CUSTOMER.

3. MODEL 328A-08 HAS UNDRESSED COAXIAL CABLE. CABLE MUST BE TERMINATED BEFORE WIRING SENSOR TO TRANSMITTER. CENTRAL CONDUCTOR IS pH SIGNAL (TB-10) AND SHIELD IS REFERENCE SIGNAL (TB-5). SEE SENSOR INSTRUCTION SHEET FOR DETAILS.

4. AUTOMATIC TEMPERATURE COMPENSATION MUST BE TURNED OFF. SEE SECTION 7.4.

FIGURE 3-18. Wiring diagram for Model 328A.

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "TRANSMITTER" POSITION.

2. TERMINALS IN JUNCTION BOX ARE NOT NUMBERED. COUNT POSITION FROM LEFT TO RIGHT AS SHOWN IN DRAWING.

3. JUMPERS SUPPLIED BY CUSTOMER.

4. CUSTOMER MUST INSTALL AND WIRE pH ELECTRODE AND TEMPERATURE SENSOR.

5. SEE SENSOR MANUAL FOR PREPARATION OF EXTENSION CABLE (PN 661-646983).

6. DISCONNECT WHITE GUARD WIRE FROM TB-7 AND INSULATE STRIPPED END.

FIGURE 3-19. Wiring diagram for Model 320HP-10-55.

NOTES:

1. PLACE PREAMPLIFIER SELECTION SWITCH S1 IN "SENSOR/JUNCTION BOX" POSITION.

2. JUMPERS SUPPLIED BY CUSTOMER.

3. CUSTOMER MUST INSTALL AND WIRE pH ELECTRODE AND TEMPERATURE SENSOR.

4. SEE SENSOR MANUAL FOR PREPARATION OF EXTENSION CABLE (PN 661-646983).

FIGURE 3-20 Wiring diagram for Model 320HP-10-58.

-VDC

+VDC

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-21. Wire Functions for Model 399-33

FIGURE 3-22. Wiring Diagram for Generic Sensor

-VDC

+VDC

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-23. Procedure for Removing BNC Connector and Preparing Coaxial Cable

MODEL 4081 pH/ORP SECTION 3.0

WIRING

FIGURE 3-24. Preparation of Raw Connecting Cable.

MODEL 4081 pH/ORP SECTION 3.0

WIRING

SENSOR FLOW CHART (continued on page 29)

See Flowchart

on page 30

See Flowchart

on page 29

MODEL 4081 pH/ORP SECTION 3.0

WIRING

SENSOR FLOW CHART (continued on page 30)

MODEL 4081 pH/ORP SECTION 3.0

WIRING

SENSOR FLOW CHART

4.1 INTRINSICALLY SAFE AND NON-INCENDIVE INSTALLATIONS

The installation, wiring, and operating parameters for intrinsically safe and non-incendive operation can be found in Figures 4-1, 4-3, and 4-4.

For CSA I.S. Label, see Figure 4-1 (below).

For CSA Instrinsically Safe installation, see Figure 4-3.

For FMRC Intrinsically Safe installation, see Figure 4-4.

4.2 EXPLOSION PROOF INSTALLATIONS

The installation, wiring, and operating parameters for explosion proof operation are given in Figure 4-2.

MODEL 4081 pH/ORP SECTION 4.0

INTRINSICALLY SAFE & EXPLOSION PROOF

SECTION 4.0

INTRINSICALLY SAFE & EXPLOSION PROOF

4.1 Intrinsically Safe and Non-Incendive Installations

4.2 Explosion Proof Installations

FIGURE 4-1. CSA I.S. Label

FIGURE 4-2. FM Explosion-Proof Installation for Model 4081 pH/ORP Transmitter

32A

FIGURE 4-3. CSA Intrinsically Safe Installation for Model 4081 pH/ORP Transmitter

32B

32C

FIGURE 4-4. FMRC Intrinsically Safe Installation for Model 4081 pH/ORP Transmitter

32D

32E

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

5.1 Overview

5.2 Displays

5.3 Infrared Remote Controller (IRC) - Key Functions

5.4 Menu Tree - pH

5.5 Diagnostic Messages - pH

5.6 Menu Tree - ORP

5.7 Diagnostic Messages - ORP

5.8 Security

5.1 OVERVIEW

This section covers basic transmitter operation and software functionality. For detailed descriptions of the function blocks common to all Fieldbus devices, refer to Fisher-Rosemount Fieldbus FOUNDATION Function Blocks manual, publication number 00809-4783.

Figure 5-1 illustrates how the pH/ORP signal is channelled through the transmitter to the control room and the

OUNDATION Fieldbus configuration device.

FIGURE 5-1. Functional Block Diagram for the Model 4081 pH/ORP Transmitter with FOUNDATION

Fieldbus.

SENSOR

Function Blocks

• AI1

• AI2

• Al3

• PID

• sensor type

• engineering units

• reranging

• damping

• temperature compensation

• calibration

• diagnostics

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

CALIBRATE PROGRAM DIAGNOSE

CALIbrAtE

EXIT NEXT ENTER

7.00

F A U L T

H O L D

Appears when transmitter is in hold (see Section 6.3)

Appears when a disabling condition has occurred (see Section 7.3.2)

Active menu: CALIBRATE, PROGRAM, or DIAGNOSE

Sub-menus, prompts, and diagnostic messages appear here

pH or ORP (ORP in mV)

Units of display

Available commands for submenu, prompt, or diagnostic

FIGURE 5-3. Program Display Screen

The program display screen appears when calibrating, programming, or reading diagnostic messages.

FIGURE 5-2. Process Display Screen

The process display screen appears during normal operation.

pH or ORP (ORP in mV)

Temperature in °C or °F

5.2 DISPLAYS

Figure 5-2 shows the process display screen, and Figure 5-3 shows the program display screen.

5.1.1 Software Functionality. The Model 4081 pH/ORP software is designed to permit remote testing and configuration of the transmitter using the Fisher-Rosemount DeltaV Fieldbus Configuration Tool, or other FOUN- DATION fieldbus compliant host.

5.1.2 Transducer Block. The transducer block contains the actual measurement data. It includes information about sensor type, engineering units, reranging, damping, temperature compensation, calibration, and diagnostics.

5.1.3 Resource Block. The resource Block contains physical device information, including available memory, manufacturer identification, type of device, and features.

5.1.4 F

OUNDATION fieldbus Function Blocks. The Model 4081 pH/ORP includes three Analog Input (AI)

function blocks and one Input Selector (ISEL) function block as part of its standard offering.

Analog Input. The Analog Input (AI) block processes the measurement and makes it available to other function blocks. It also allows filtering, alarming, and engineering unit change.

Charaterizer (optional). The characterizer block changes the characteristic of the input signal. Common uses of the characterizer block include converting temperature to density or humidity, and converting millivolts to temperature for an IR sensor.

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

5.3 INFRARED REMOTE CONTROLLER (IRC) - KEY FUNCTIONS

The infrared remote controller is used to calibrate and program the transmitter and to read diagnostic messages. See Figure 5-4 for a description of the function of the keys.

Hold the IRC within 6 feet of the transmitter, and not more than 15 degrees from the center of the display window.

FIGURE 5-4. Infrared Remote Controller.

RESET - Press to end the current oper-

ation and return to the process display. Changes will NOT be saved. RESET does not return the transmitter to factory default settings.

CAL - Press to access the calibrate menu.*

PROG - Press to access the program menu.*

DIAG - Press to view diagnostic messages.*

HOLD - Press to access the prompt that turns on or off the Hold function.

Editing Keys - Use the editing keys to change the value of a flashing display. The left and right arrow keys move the cursor one digit at a time across a number. The up and down arrow keys increase or decrease the value of the selected digit. The up and down arrow keys also scroll the display through the items in a list.

* Pressing CAL, PROG, or DIAG causes the program screen to appear with the selected menu (CALIBRATE, PROGRAM, OR DIAGNOSE) showing. See Figure 5-3. The first sub-menu (or the first diagnostic message) also appears. Figure 5-5 shows the complete menu tree.

ENTER - Press to advance from a submenu to the first prompt under the submenu. Pressing ENTER also stores the selected item or value in memory and advances to the next prompt.

NEXT - Press to advance to the next sub-menu.

EXIT - Press to end the current operation. The transmitter returns to the first prompt in the present sub-menu. Changes will NOT be saved.

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

PROGRAM

CALIBRATE

GIMP 1000 V Er 4081

tEMP 25 C

InPut 58.9 ShoW FLt

nonE

rIMP 10

dIAGnOStIC tEMP

bUFFErdISPLAY ISOPOtntAL

CALIbrAtE

Std

tEMP AdJ

tEMP 25.0

tAUtO On

tMAn 25.0

tC 100-3

tYPE PH

COdE 000

bAUtO On

bUFFEr Std

tIME 04

PH 00.02

tCOEF 00.00

ISO 07.00

Snr 07.00

rOFFSt 060

dIAG OFF

IMPtC OFF

GWH 1000

GFH 1500

GWL 020

GFL 010

CAL 200

rEF LO

rFH 140

rWH 040

rWL 000

rFL 000

CAL bF1

bF 1

bF1 4.01

CAL bF2

bF 2

bF2 10.01

DIAGNOSE

Std 7.00

SLOPE 59.01

Sub-menu

PROMPT

Diag Message

FIGURE 5-5. Menu Tree for pH

5.4 MENU TREE - pH

The Model 4081 pH transmitter has three menus: CALIBRATE, PROGRAM, and DIAGNOSE. Under the Calibrate and Program menus are several sub-menus. For example, under CALIBRATE, the sub-menus are CALIbrAtE, Std (stan- dard), and tEMP AdJ (temperature adjust). Under each sub-menu are prompts. For example, under Std, the prompts are Std xx.xx and slope xx.xx. The DIAGNOSE menu lets the user view diagnostic messages. Figure 5-5 shows the complete menu tree.

5.5 DIAGNOSTIC MESSAGES - pH

Whenever a warning or fault limit has been exceeded, the transmitter displays diagnostic messages to aid in troubleshooting. Diagnostic messages appear in the same area as the temperature/output readings in the process display screen (see Figure 5-2). The display alternates between the regular display and the diagnostic message. Figure 5-5 shows the diagnostic fault messages for pH.

If more than one warning or fault message has been generated, the messages appear alternately. See Section 11.0, Troubleshooting, for the meanings of the fault and warning messages.

5.6 MENU TREE - ORP

The Model 4081 ORP transmitter has three menus: CALIBRATE, PROGRAM, and DIAGNOSE. Under the Calibrate and Program menus are several sub-menus. For example, under CALIBRATE, the sub-menus are Std (standard) and tEMP AdJ (temperature adjust). Under each sub-menu are prompts. For example, the Std sub-menu contains the single prompt Std. Other sub-menus may contain more than one prompt. Figure 5-6 shows the complete menu tree.

5.7 DIAGNOSTIC MESSAGES - ORP

Whenever a warning or fault limit has been exceeded, the transmitter displays diagnostic messages to aid in troubleshooting. Diagnostic messages appear in the same area as the temperature/output readings in the process display (Figure 5-2). The display alternates between the regular display and the diagnostic message. Figure 5-6 shows the diagnostic fault messages for ORP.

If more than one warning or fault message has been generated, the messages appear alternately. See Section 11.0, Troubleshooting, for the meanings of the fault and warning messages.

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

Sub-menu

PROMPT

Diag Message

FIGURE 5-6. Menu Tree for ORP

PROGRAMCALIBRATE

rIMP 10

VEr 4081

ShoW FLt

nonE

dIAGnOStIC tEMP

dISPLAY

Std

tEMP ADj

tEMP 25.0

tC 100-3

tYPE ORP

tEMP C

COdE 000

rOFFSt 060

dIAG OFF

IMPtC OFF

rEF LO

rFH 140

rWH 040

rWL 000

rFL 000

Std 1000

DIAGNOSE

1400

5.8 SECURITY

5.8.1 General. Use the programmable security code to protect program and calibration

settings from accidentally being changed. The transmitter is shipped with the security feature disabled. To program a security code, refer to Section 7.5, Display Units.

5.8.2 Entering the Security Code.

1. If calibration and program settings are protected with a security code, pressing PROG or CAL on the infrared remote controller causes the Id screen to appear.

2. Use the editing keys to enter the security code. Press ENTER .

3. If the security code is correct, the first sub-menu appears. If the security code is incorrect, the process display reappears.

5.8.3 Retrieving a Lost Security Code.

1. If the security code has been forgotten, enter 555 at the Id prompt and press ENTER . The transmitter will display the present code.

2. Press EXIT to return to the process display.

3. Press PROG or CAL . The Id screen appears.

4. Use the editing keys to enter the security code just shown; then press ENTER .

5. The first sub-menu under the selected menu will appear.

MODEL 4081 pH/ORP SECTION 5.0

OPERATION WITH REMOTE CONTROLLER

PROGRAM

II dd

EXIT ENTER

000000

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

6.1 General

6.2 Entering and Leaving the Calibrate Menu

6.3 Using the Hold Function

6.4 Temperature Calibration

6.5 Auto Calibration

6.6 Manual Calibration

6.7 Making the Transmitter Reading Match a Second pH Meter (Standardization)

6.1 GENERAL

The Calibrate menu allows the user to calibrate the pH and temperature response of the sensor.

The transmitter does a two-point pH calibration. Both manual and auto calibration are available. In auto calibration the transmitter automatically stores temperature-corrected calibration data once readings have met programmed stability limits. In manual calibration the user enters buffer values and judges when readings are stable. The transmitter reading can also be made to match the reading of a second pH meter.

Temperature calibration is a one-point standardization against a reference thermometer.

Prompts guide the user through the calibration procedures.

6.2. ENTERING AND LEAVING THE CALIBRATE MENU

Press CAL on the infrared remote controller (IRC) to enter the Calibrate menu. To store new settings in memory, press ENTER . To leave the Calibrate menu without storing new values, press EXIT . Pressing EXIT with a prompt showing returns the display to the first prompt in the sub-menu. Pressing EXIT a second time returns the transmitter to the process display.

If program settings are protected with a security code, pressing PROG or CAL will cause the Id screen to appear. Key in the security code and press ENTER . The first sub-menu will appear. For more information, see Section 5.8, Security.

A transmitter adjacent to the one being calibrated may pick up signals from the IRC. To avoid accidentally changing settings, use a different security code for each nearby transmitter. See Section 5.8, Security, and Section 7.5, Display Units, for details.

6.3 USING THE HOLD FUNCTION

During calibration, the sensor may be exposed to solutions having pH outside the normal range of the process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the transmitter in hold during calibration. Activating hold keeps the transmitter output at the last value or sends the output to a previously determined value.

After calibration, reinstall the sensor in the process stream. Wait until readings have stabilized before deactivating Hold.

To activate or deactivate Hold, do the following:

1. Press HOLD on the IRC.

2. The HoLd prompt appears in the display. Press é or êto toggle the Hold function between On and OFF.

3. Press ENTER to save.

CALIBRATE

ttEEMMPP AAddJJ

EXIT NEXT ENTER

CALIBRATE

ttEEMMPP

EXIT ENTER

002255..00

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

6.4 TEMPERATURE CALIBRATION

6.4.1 Purpose

1. As discussed in Section 12.6, Glass Electrode Slope, measuring temperature is an important part of measuring pH. The accuracy of a new sensor and transmitter loop is about ±1°C, which is adequate for most applications. A new sensor seldom requires temperature calibration.

2. Calibrate the sensor/transmitter loop if . . . a. ±1°C accuracy is NOT acceptable, or b. the temperature measurement is suspected of being in error.

NOTE

6.4.2 Procedure

1. Place the pH sensor and a calibrated reference thermometer in an insulated container of water at ambient temperature. Be sure the temperature element in the sensor is completely submerged by keeping the sensor tip at least three inches below the water level. Do not let the weight of the sensor rest on the glass bulb. Stir continuously. Allow at least 20 minutes for the standard thermometer, sensor, and water to reach constant temperature.

2. Enter the CALIBRATE menu by pressing CAL on the IRC. The CALIbrAtE sub-menu appears (pictured above left).

3. At the CALIbrAtE sub-menu, press NEXT twice. The tEMP AdJ sub- menu appears.

4. Press ENTER to display the temperature editing prompt.

5. Compare the temperature displayed by the transmitter with the temperature measured with the reference thermometer. If the readings are different, use the editing keys to change the flashing display to the value determined with the reference thermometer. The reading cannot be changed by more than 15°C.

6. Press ENTER . The value will be saved, and the display will return to the tEMP AdJ sub-menu.

7. To leave the CALIBRATE menu, press EXIT .

8. Check linearity by measuring the temperature of water 10 to 15°C cooler and 10 to 15°C warmer than the water used for calibration. Because of the time required for the temperature element in the sensor to reach constant temperature, a well-insulated container or, better, a constant temperature bath is required for this step.

6.5 AUTO CALIBRATION

6.5.1 Purpose

1. New sensors must be calibrated before use. Regular recalibration is also necessary.

2. The use of auto calibration instead of manual calibration is strongly recommended. Auto calibration avoids common pitfalls and reduces errors.

3. For more information about calibration in pH measurements and the use of buffers, refer to Section 12.7, Buffers and Calibration.

6.5.2 What Happens During Auto Calibration?

1. The transmitter displays prompts that guide the user through a two-point buffer calibration.

2. The transmitter recognizes the buffers and uses the temperature-corrected pH value in the calibration. The transmitter also measures noise and drift and does not accept calibration data until readings are stable. Stability limits are user-programmable. See Section 7.6, Buffer Calibration Parameters.

6.5.3 Use of Calibration Standards (buffers)

1. A pH measurement is only as good as the calibration, and the calibration is only as good as the buffers used. A careful buffer calibration is the first step in making an accurate pH measurement.

2. Calibrate with buffers having pH values that bracket the pH of the process. For example, if the pH is between 8 and 9, calibrate with pH 7 and 10 buffers. Commercial buffers for intermediate range pH are readily available. Buffers outside the range pH 3.0 to pH 10.0 may not be readily available and must be prepared by the user. Tables 7-2 and 7-3 in Section 7.6, Buffer Calibration Parameters, list the buffers that the transmitter recognizes.

3. Allow time for the sensor and buffers to reach the same temperature. If the sensor was just removed from a process having a temperature more than 10°C different from the buffer, allow at least 20 minutes.

4. For best results, calibrate with buffers having the same temperature as the process. If the buffer and process temperature differ by more than about 15°C an error as great as 0.1pH may result.

5. Be careful using buffers at high temperatures. Protect the solution from evaporation. Evaporation changes the concentration of the buffer and its pH. Be sure the pH of the buffer is defined at high temperatures. Finally, no matter what the temperature is, allow the entire measurement cell, sensor and solution, to reach constant temperature before calibrating.

6. The pH of a buffer changes with temperature. Equations relating pH to temperature for common buffers have been programmed into the Model 4081 pH transmitter. During auto calibration, the transmitter calculates the correct buffer value and uses it in the calibration.

7. Buffers have limited shelf lives. Do not use a buffer if the expiration date has passed. Store buffers at controlled room temperature.

8. Do not return used buffer to the stock bottle. Discard it.

9. Protect buffers from excessive exposure to air. Atmospheric carbon dioxide lowers the pH of alkaline buffers. Other trace gases commonly found in industrial environments, for example, ammonia and hydrogen chloride, also affect the pH of buffers. Molds, from airborne spores, grow readily in neutral and slightly acidic buffers. Mold growth can substantially alter the pH of a buffer.

10. Rinse the sensor with deionized water before placing it in a buffer. Remove excess water from the sensor by gently daubing it with a clean tissue. Do not wipe the sensor. Wiping may generate a static charge, leading to noisy readings. The static charge may take hours to dissipate. A few drops of deionized water carried with the sensor into the buffer will not appreciably alter the pH.

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

6.5.4 Procedure

1. Refer to Section 7.6, Buffer Calibration Parameters. Verify that auto calibration is activated. Identify the buffers being used and set the stability limits.

2. Enter the CALIBRATE menu by pressing CAL on the IRC. The CALIbrAtE sub-menu appears (pictured above left).

3. At the CALIbrAtE sub-menu, press ENTER . The CAL bF1 prompt appears.

4. Rinse the sensor and place it in the first buffer. Be sure the glass bulb and the temperature element are completely submerged. Keep the sensor tip at least three inches below the liquid level. Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. The main display will show the measured pH based on the previous calibration.

5. Press ENTER . bF1 flashes until the measured pH meets the programmed stability limits. If the pH reading is not stable after 20 minutes, the transmitter automatically leaves the CALIBRATE menu and returns to the process mode. If this happens, consult Section 11.5.4, Troubleshooting, for assistance. Once the reading is stable, the display changes to look like the figure at the left. The flashing number is the nominal pH, that is, the pH of the buffer at 25°C. If the flashing number does not match the nominal pH, press

é or

until the correct pH appears. Press ENTER to save the first

calibration point.

6. The CAL bF2 prompt appears.

7. At the CAL bF2 prompt, remove the sensor from the first buffer. Rinse the sensor and place it in the second buffer. Be sure the glass bulb and the temperature element are completely submerged. Keep the sensor tip at least three inches below the liquid level. Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. The main display will show the measured pH of the buffer based on the previous calibration.

8. Press ENTER . bF2 flashes until the pH reading is stable. If the pH reading is not stable after 20 minutes, the transmitter automatically leaves the CALIBRATE menu and returns to process mode. If this happens, consult Section 11.5.4, Troubleshooting, for assistance. Once the reading is stable, the display changes to look like the figure at the left. The flashing number is the nominal pH, that is, the pH of the buffer at 25°C. If the flashing number does not match the nominal pH, press

é or

until the correct pH appears. Press ENTER to save the second calibration point.

9. The calibration is complete, but the transmitter remains in the CALIbrAtE sub-menu for two minutes after ENTER is pressed.

10. Remove the sensor from the buffer and return it to the process. If the transmitter was in hold during calibration, wait until readings have stabilized before taking the transmitter out of hold. See Section

6.3, Using the Hold Function.

11. The transmitter uses the calibration data to calculate a new slope. Refer to Section 12.7, Buffers and Calibration, for more details. If the slope is unacceptable, the calibration will not be updated, and the transmitter will display a SLOPE Err HI or SLOPE Err LO error message. Refer to Section

11.6.3, Troubleshooting, for assistance.

12. To leave the CALIBRATE menu, press EXIT .

13. For quality control and troubleshooting, it is helpful to know the electrode slope. To display the slope, press CAL on the IRC. The CALIbrAtE sub-menu will appear. Press NEXT . The Std sub-menu appears. Press ENTER . The Std prompt appears. Press ENTER again and SLOPE xx.xx will appear in the display. The four digit number is the electrode slope. For a good sensor, the slope is between 50 and 60.

CALIBRATE

bbFF 22

EXIT ENTER

1100..0000

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

NOTE

During calibration, the sensor may be exposed to solutions having pH outside the normal range of the process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the analyzer in hold during calibration. See Section 6.3, Using the Hold Function, for details.

CALIBRATE

CCAALL bbFF 11

EXIT NEXT ENTER

CALIBRATE

CCAALL bbFF 22

EXIT ENTER

CALIBRATE

bbFF 11

EXIT ENTER

44..0000

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

6.6.1 Purpose

1. New sensors must be calibrated before use. Regular recalibration is also necessary.

2. Manual calibration is an alternative to auto calibration. Because auto calibration eliminates many common calibration errors, it is strongly recommended.

3. In auto calibration, the transmitter recognizes the buffer and uses the temperature-corrected pH value in the calibration. The transmitter also measures noise and drift and does not accept calibration data until readings meet programmed limits. In manual calibration, however, the user must judge when readings are stable, look up the buffer value at the calibration temperature, and key in the value.

4. Manual calibration is necessary if non-standard buffers are used for calibration. Manual calibration is also useful in troubleshooting.

5. Because temperature readings from the pH sensor are not available during calibration, a reliable thermometer is required to complete the procedure.

6.6.2 Use of calibration standards (buffers)

1. A pH measurement is only as good as the calibration, and the calibration is only as good as the buffers. A careful buffer calibration is the first step in making an accurate pH measurement.

2. Calibrate with buffers having pH values that bracket the pH of the process. For example, if the pH is between 8 and 9, calibrate with pH 7 and 10 buffers. Commercial buffers having intermediate range pH are readily available. Buffers outside the range pH 3.0 to pH 10.0 may not be readily available and must be prepared by the user.

3. Allow time for the sensor and buffers to reach the same temperature. If the process temperature is more than 10°C different from the buffer, allow at least 20 minutes.

4. For best results, calibrate with buffers having the same temperature as the process. If the buffer and process temperature differ by more than about 15°C an error as great as 0.1pH may result.

5. Be careful using buffers at high temperatures. Protect the solution from evaporation. Evaporation changes the concentration of the buffer and its pH. Be sure the pH of the buffer is defined at high temperatures. The pH of many buffers is undefined above 60°C. Finally, no matter what the temperature is, allow the entire measurement cell, sensor and solution, to reach constant temperature before calibrating.

7. Buffers have limited shelf lives. Do not use a buffer if the expiration date has passed. Store buffers at controlled room temperature.

8. Do not return used buffer to the stock bottle. Discard it.

6.6 MANUAL CALIBRATION

6.6.3 Procedure

1. Before starting, refer to Section 7.6, Buffer Calibration Parameters, to deactivate auto calibration.

2. Enter the CALIBRATE menu by pressing CAL on the IRC. The CALIbrAtE sub-menu appears (pictured above left).

3. At the CALIbrAtE sub-menu, press ENTER . The CAL bF1 prompt appears.

4. Rinse the sensor with deionized water and place it in the first buffer along with a calibrated thermometer. Submerge the sensor tip at least three inches below the liquid level. Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. The main display will show the measured pH based on the previous calibration.

5. Once the pH reading and temperature are stable, press ENTER . The display changes to the screen shown at the left. Use the editing keys to change the flashing display to the pH value of the buffer at the measurement temperature. Press ENTER to save the value as buffer bF1. The transmitter expects a reading to be entered within 20 minutes after the CAL bF1 prompt appears. If ENTER is not pressed, the transmitter leaves the CALIBRATE menu and returns to the process mode.

6. At the CAL bF2 prompt, remove the sensor from the first buffer. Rinse the sensor and thermometer with deionized water and place them in the second buffer. Submerge the sensor tip at least three inches below the liquid level. Do not let the weight of the sensor rest on the glass bulb. Swirl the sensor to dislodge trapped bubbles. The main display will show the measured pH based on the previous calibration.

7. Once the pH reading and temperature are stable, press ENTER . The display changes to the screen shown at the left. Use the editing keys to change the flashing display to the pH value of the buffer at the measurement temperature. Press ENTER to save the value as buffer bF

2. The transmitter expects a reading to be entered within 20 minutes after the CAL bF2 prompt appears. If ENTER is not pressed, the transmitter leaves the CALIBRATE menu and returns to the process mode.

8. The calibration is complete, but the transmitter remains in the CALibrATE sub-menu for two minutes after ENTER is pressed.

9. Remove the sensor from the buffer and return it to the process. If the transmitter was in hold during calibration, wait until readings have stabilized before taking the transmitter out of hold.

10. The transmitter uses the calibration data to calculate a new slope. Refer to Section 12.7, Buffers and Calibration, for more details. If the slope is unacceptable, the calibration will not be updated, and the transmitter will display a SLOPE Err HI or SLOPE Err LO error message. Refer to Sections 11.5.3 and 11.5.5, Troubleshooting, for assistance.

11. To leave the CALIBRATE menu, press EXIT .

12. For quality control and troubleshooting, it is helpful to know the electrode slope. To display the slope, press CAL on the IRC. The CALIbrAtE sub-menu will appear. Press NEXT . The Std sub-menu appears. Press ENTER . The Std prompt appears. Press ENTER again and SLOPE xx.xx will appear in the display. The four digit number is the electrode slope. For a good sensor, the slope is between 50 and 60.

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

NOTE

During calibration, the sensor may be exposed to solutions having pH outside the normal range of the process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the analyzer in hold during calibration. See Section 6.3, Using the Hold Function, for details.

CALIBRATE

CCAALL bbFF 11

EXIT NEXT ENTER

CALIBRATE

CCAALL bbFF 22

EXIT NEXT ENTER

CALIBRATE

CCAALL bbFF 22

EXIT ENTER

CALIBRATE

CCAALL bbFF 11

EXIT ENTER

44..0000

1100..0000

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

6.7 MAKING THE TRANSMITTER READING MATCH A SECOND pH METER (STANDARDIZATION).

6.7.1 Purpose

1. This section describes how to make the transmitter reading match the reading from a

second pH meter. The measurement made with the second meter is called the standard pH (pH

std

). The process of making the two readings agree is called standardization.

2. This section also describes how to enter an independently determined slope into the

transmitter.

6.7.2 What Happens During Standardization?

1. The user enters the pH reading from a second meter into the transmitter. The transmitter

changes the displayed pH to the new value.

2. The transmitter converts the difference between the pH readings, ∆pH, into a voltage dif-

ference. The voltage difference, ∆V, is calculated from the equation:

∆V = [0.1984 (t + 273.14)] ∆pH

where t is the temperature in °C. The voltage difference, called the reference offset, is then added to subsequent pH cell voltage measurements before the voltage is converted to pH. See Sections 12.5 through 12.7 for details on how the pH meter converts voltage into pH readings.

3. Before the transmitter accepts the offset, it compares the offset with the value (rOFFSt)

programmed into the transmitter in Section 7.3, Diagnostic Parameters. If the difference exceeds rOFFSt, the transmitter will not accept the data and will not update the display to the corrected pH.

MODEL 4081 pH/ORP SECTION 6.0

CALIBRATION OF pH MEASUREMENTS

CALIBRATE

SSttdd

EXIT NEXT ENTER

CALIBRATE

SSLLOOPPEE

EXIT NEXT ENTER

CALIBRATE

SSttdd

EXIT NEXT ENTER

0088..0000

5599..0000

6.7.3 Procedure

1. Enter the CALIBRATE menu by pressing CAL on the IRC. The CALibrAtE sub-menu appears (pictured above left).

2. At the CALibrAtE sub-menu, press NEXT. The Std sub-menu appears.

3. With the Std sub-menu displayed, press ENTER. The Std prompt appears.

4. Be sure that the process pH and temperature are stable or, at worst, slowly drifting. Take a grab sample from the process stream or sample line at a point as close as possible to the pH sensor. Note the transmitter reading (pH

trans

) at the time the sample was taken.

5. Measure the pH of the sample (pH

std

) using the second pH meter. For best results make

the measurement at the same temperature as the process.

6. Note the current process reading (pH

curr

). Calculate the corrected reading from the equa-

tion:

corr

= pH

curr

+ (pH

std

- pH

trans

)

where, pH

corr

is the corrected pH value, pH

curr

is the current process reading, pH

std

the pH measured using the standard instrument, and pH

trans

is the pH measured by the transmitter when the sample was taken. Use the editing keys to change the flashing display to pH

corr

calculated above. Press ENTER to save the corrected pH.

7. The transmitter converts the difference between pH

corr

and pH

curr

into mV and compares the result with the value programmed for rOFFSt in Section 7.3, Diagnostic Parameters. If the difference exceeds the value for rOFFSt, the transmitter will not accept the data and will not update the display to the corrected pH. The message StD Err will appear.

8. If the corrected pH value is acceptable, the display will change to look like the screen at the left. The slope displayed is the current electrode slope. If the slope is incorrect and the correct value is known, use the editing keys to change the slope to the desired value. Press ENTER to save the value. To leave the slope unchanged, press EXIT .

9. To leave the CALIBRATE menu, press EXIT .

NOTE

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.1 General

7.2 Entering and Leaving the Program Menu

7.3 Diagnostic Parameters

7.4 Temperature Related Settings

7.5 Display Units

7.6 Buffer Calibration Parameters

7.7 Isopotential Parameters

7.1 GENERAL

This section describes how to do the following:

1. change sensor diagnostic limits,

2. enable and disable automatic temperature compensation,

3. change the units of the displayed variables,

4. program a security code,

5. identify buffers for auto calibration,

6. change the transmitter isopotential point,

Factory default settings are given in Table 7-1. If default settings are acceptable, the transmitter is ready for calibration. See Section 6.0, Calibration of pH Measurements. Once a setting has been changed, there is no way to automatically reset the transmitter to factory defaults. Settings must be returned to default values one at a time. Figure 5-5 shows the menu tree.

7.2 ENTERING AND LEAVING THE PROGRAM MENU

Press PROG on the infrared remote controller (IRC) to enter the Program menu. To save new settings, press ENTER . To leave the Program menu without saving new values, press EXIT . Pressing EXIT with a prompt showing returns the display to the first prompt in the sub-menu. Pressing EXIT again returns the transmitter to the process display.

A transmitter adjacent to the one being programmed may pick up signals from the IRC. To avoid accidentally changing settings, use a different security code for each nearby transmitter. See Section 5.8, Security, and Section 7.5, Display Units, for details.

ITEM MNEMONIC DISPLAY LIMITS FACTORY SETTINGS USER SETTINGS

PROGRAM LEVEL (Sections 7.0 - 7.7).

A. Diagnostic (Section 7.3) dIAgnOStIC

1. Reference Cell Offset (Standardize error) rOFFSt 0 to 1000 mV 60 mV (pH on _______ glass electrode)

2. Diagnostics Function dIAg On/Off Off _______

3. Glass Impedance Temperature Correction IMPtC On/Off On _______

4. Glass Electrode High Impedance Fault GFH 0 to 2000 megohms 1500 megohms _______

5. Glass Electrode High Impedance Warning GWH 0 to 2000 megohms 1000 megohms _______

6. Glass Electrode Low Impedance Warning GWL 0 to 900 megohms 20 megohms _______

7. Glass Electrode Low Impedance Fault GFL 0 to 900 megohms 10 megohms _______

8. Glass Impedance Calibration Warning CAL 0 to 500 % 0 % (not Active) _______

9. Reference Cell Impedance Type rEF LO/HI LO _______

10. Reference Cell High Impedance Fault rFH 0 to 2000 megohms (HI) 1500 megohms _______

0 to 2000 kilohms (LO) 140 kilohms

11. Reference Cell High Impedance Warning rWH 0 to 2000 megohms (HI) 1000 megohms _______

0 to 2000 kilohms (LO) 40 kilohms

12. Reference Cell Low Impedance Warning rWL 0 to 900 megohms (HI) 20 megohms _______

Does not apply for low impedance reference cell

13. Reference Cell Low Impedance Fault rFL 0 to 900 megohms (HI) 10 megohms _______

Does not apply for low impedance reference cell

B. Temperature (Section 7.4) tEMP

1. Auto Temperature Compensation tAUtO On/Off On _______

2. Manual Temperature tMAn -15 to 130

C 25 0C _______

5 to 266

3. Temperature Sensor Type tC 100-3; 100-4; 1000-3; 100-3 _______

1000-4: 3000

C. Display (Section 7.5) dISPLAY

1. Measurement type tYPE pH/ORP pH _______

2. Temperature Units tEMP °C/°F °C _______

3. Code COdE 0 to 999 000 _______

D. Buffer (Section 7.6) bUFFEr

1. Auto Calibration Function b AUtO ON/OFF ON _______

2. Buffers Selection List bUFFEr See Tables 8-2 and 8-3 Standard _______

3. Auto Buffer Stabilization Time tIME 0 to 30 seconds 10 seconds _______

4. Auto Stabilization pH Change PH .002 to .5pH .02 pH _______

E. Isopotential (Section 7.7) ISOPOtntAL

1. Temperature Coefficient tCOEF -0.044 to 0.028 pH/

C 0.000 pH/ 0C _______

2. Solution Isopotential pH ISO -1.35 to 20.12 pH 7.00 pH _______

3. Sensor Isopotential pH Snr 0.00 to 14.00 pH 7.00 pH _______

Table 7-1. pH Settings List

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.3 DIAGNOSTIC PARAMETERS

7.3.1 Purpose

This section describes how to do the following:

1. change the standardization or reference offset,

2. enable and disable sensor diagnostics,

3. enable and disable glass impedance temperature compensation,

4. set the high and low warning and failure limits for the glass electrode.

5. set the high and low warning and failure limits for the reference electrode.

7.3.2 Definitions

1. STANDARDIZATION (REFERENCE) OFFSET. The transmitter reading can be changed to match the reading of a second pH meter. If the difference (converted to millivolts) between the transmitter reading and the desired value exceeds the programmed limit, the transmitter will not accept the new reading. To estimate the millivolt difference, multiply the pH difference by 60. Refer to Section 6.6, Manual Calibration, for additional information. The standardization offset is also the absolute value of the actual cell voltage in pH 7 buffer. For certain types of non-glass pH electrodes, the offset in pH 7 buffer may be as great as 800 mV. To accommodate non-glass electrodes, the offset must be changed from the default value of 60 millivolts.

2. GLASS IMPEDANCE TEMPERATURE COMPENSATION. The impedance of the glass electrode changes with temperature. For changes in glass impedance to be a useful indicator of electrode condition, the measurement must be corrected to a reference temperature.

3. WARNING AND FAILURE LIMITS FOR THE GLASS ELECTRODE. Warning tells the user that the glass electrode impedance is approaching the failure limit. Low and high warning and failure limits are programmable. Low impedance means the glass electrode has cracked and is no longer functioning. High impedance often means the electrode is aging and may soon need replacement. High glass impedance may also mean the electrode is not immersed in the liquid stream. Figure 7-1 shows suggested settings for glass impedance warning and failure limits.

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

FIGURE 7-1. Suggested Glass Impedance Warning and Failure Limits

Typical glass impedance is about 100 megohms at 25°C. A broken electrode has an impedance of 10 megohms or less. A glass impedance greater than 1000 megohms suggests the electrode is nearing the end of its service life. High impedance may also mean the electrode is not immersed in the process liquid.

4. REFERENCE IMPEDANCE. The majority of reference electrodes used in industry are low impedance silver-silver chloride electrodes. Every pH and ORP sensor manufactured by Rosemount Analytical has a low impedance reference. However, there are applications that call for either a high impedance sodium or pH glass reference electrode. Both high impedance and low impedance reference electrodes can be used with the Model 4081 pH/ORP transmitter.

5. WARNING AND FAILURE LIMITS FOR THE REFERENCE ELECTRODE. Warning tells the user that the reference electrode impedance is approaching the failure limit. Low and high warning and failure limits are programmable. For conventional low impedance silver-silver chloride reference electrodes only the high limits are useful. For high impedance reference electrodes, both low and high limits are used.

Figure 7-2 shows suggested limits for low impedance reference electrodes.

Figure 7-3 shows suggested limits for high impedance glass reference electrodes.

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

FIGURE 7-2. Suggested Warning and Failure Limits for Low

Impedance Reference Electrodes

The impedance of a typical silver-silver chloride reference electrode is less than 40 kilohms. If the impedance is greater than about 140 kilohms the reference electrode has failed. Failure is usually caused by a plugged or coated reference junction or a depleted electrolyte fill solution (gel). The reference impedance will also be high if the sensor is out of the process liquid.

FIGURE 7-3. Suggested Warning and Failure Limits for High

Impedance Glass Reference Electrodes.

The limits for a high impedance glass reference electrode are the same as the limits for a high impedance glass measuring electrode.

7.3.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the diAGnOStIC sub-menu appear. Press ENTER .

3. The screen displays the rOFFSt prompt. Use the editing keys to change the flashing display to the desired standardization (reference) offset (in millivolts). The range is 0 to 1000 mV. Press ENTER to save.

4. The dIAG prompt appears. Use

é or

to enable (On) or disable (OFF) the sensor

diagnostics. Press ENTER to save.

5. The IMPtC prompt appears. Use

é or

to enable (On) or disable (OFF) glass impedance temperature compensation. Because glass impedance is a strong function of temperature, correcting glass impedance for temperature is recommended. A third setting (SPC) appears in addition to On and OFF. Do not select SPC; the setting is intended for factory use. Press ENTER to save.

6. The GFH prompt appears. Use the editing keys to change the display to the desired glass electrode impedance high fault value. The allowed values are between 0 and 2000 megohms. Entering 0000 disables the feature. When the glass electrode impedance exceeds the fault value, the transmitter displays the diagnostic message GLASS- FAIL and sets a fault condition. Press ENTER to save.

7. The GWH prompt appears. In the transmitter display, WJ is a W. Use the editing keys to change the display to the desired glass electrode impedance high warning value. The allowed values are between 0 and 2000 megohms. Entering 0000 disables the feature. When the glass electrode impedance exceeds the warning value, the transmitter displays the diagnostic message GLASSWArn. Press ENTER to save.

8. The GWL prompt appears. Use the editing keys to change the display to the desired glass electrode impedance low warning value. The allowed values are between 0 and 900 megohms. Entering 0000 disables the feature. When the glass electrode impedance drops below the warning value, the transmitter displays the diagnostic message GLASSWArn. Press ENTER to save.

9. The GFL prompt appears. Use the editing keys to change the display to the desired glass electrode impedance low fault value. The allowed values are between 0 and 900 megohms. Entering 0000 disables the feature. When the glass electrode impedance drops below the fault value, the transmitter displays the diagnostic message GLASS- FAIL and sets a fault condition. Press ENTER to save.

10. The CAL prompt appears. This diagnostic is intended for factory use. The default value 000 should appear. If 000 is not showing, use the editing keys to change the display to

000. Press ENTER to save.

11. The rEF prompt appears. Press

é or

until the desired setting appears. LO identifies a low impedance reference electrode, and HI identifies a high impedance reference electrode. Press ENTER to save. Selecting LO disables the low impedance warning and failure limits for the reference electrode.

NOTE

Be sure the jumpers on the analog board are set to match the reference electrode impedance. See Section 2.2, Pre-Installation Set Up.

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

PROGRAM

II MMPPtt CC

EXIT NEXT ENTER

OONN

PROGRAM

GGFFHH

EXIT ENTER

11 550000

PROGRAM

GGWWJJHH

EXIT ENTER

11 000000

PROGRAM

GGWWJJLL

EXIT ENTER

00002200

PROGRAM

GGFFLL

EXIT ENTER

0000 11 00

PROGRAM

rrOOFFFFSStt

EXIT ENTER

PROGRAM

ddII AAGGnn OO SSTTII CC

EXIT NEXT ENTER

006600

PROGRAM

dd II AA GG

EXIT ENTER

OOFFFF

PROGRAM

rrEEFF

EXIT ENTER

LLOO

PROGRAM

CCAALL

EXIT ENTER

000000

12. The rFH prompt appears. Use the editing keys to change the display to the desired reference electrode high impedance fault value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 11) 0 - 2000 kilohms

High impedance (HI in step 11) 0 - 2000 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes above the fault value, the transmitter displays the diagnostic message rEFFAIL and sets a fault condition. Press ENTER to save.

13. The rWH prompt appears. Use the editing keys to change the display to the desired reference electrode high impedance warning value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 11) 0 - 2000 kilohms

High impedance (HI in step 11) 0 - 2000 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes above the fault value, the transmitter displays the diagnostic message rEFWArn. Press ENTER to save.

14. The rWL prompt appears. Use the editing keys to change the display to the desired reference electrode low impedance warning value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 11) not applicable

High impedance (HI in step 11) 0 - 900 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes below the warning value, the transmitter displays the diagnostic message rEFWArn. Press ENTER to save. The prompt appears but is disabled when LO is selected in step 11.

15. The rFL prompt appears. Use the editing keys to change the display to the desired reference electrode low impedance fault value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 11) not applicable

High impedance (HI in step 11) 0 - 900 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes below the fault value, the transmitter displays the diagnostic message rEFFAIL and sets a fault condition. Press ENTER to save. The prompt appears but is disabled when LO is selected in step 11.

16. Press EXIT to return to the process display.

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

PROGRAM

rrFFHH

EXIT NEXT ENTER

11 440000

PROGRAM

rrWWJJHH

EXIT NEXT ENTER

00004400

PROGRAM

rrWWJJLL

EXIT NEXT ENTER

00000000

PROGRAM

rrFFLL

EXIT NEXT ENTER

00000000

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.4 TEMPERATURE RELATED SETTINGS

7.4.1 Purpose

This section describes how to do the following:

1. activate and deactivate automatic temperature compensation,

2. set a manual temperature compensation value,

3. match the transmitter to the type of temperature element in the pH sensor.

7.4.2 Definitions

1. AUTOMATIC TEMPERATURE COMPENSATION. The transmitter uses a temperaturedependent factor to convert measured cell voltage to pH. In automatic temperature compensation the transmitter measures the temperature of the process and automatically calculates the correct conversion factor. For maximum accuracy, use automatic temperature compensation. See Section 12.6, Glass Electrode Slope, for more information.

2. MANUAL TEMPERATURE COMPENSATION. In manual temperature compensation, the transmitter uses the programmed temperature to convert measured voltage to pH. It does not use the actual process temperature. Do NOT use manual temperature compensation unless the process temperature varies no more than ±2°C or the pH is between 6 and 8. See Section

12.6, Glass Electrode Slope, for more information about errors associated with improper temperature compensation. Manual temperature compensation is useful if the sensor temperature element has failed and a replacement sensor is not available.

3. TEMPERATURE ELEMENT. pH sensors use a variety of temperature elements. The Model 4081 pH transmitter recognizes the following temperature elements and configurations:

a. three and four wire 100 ohm platinum RTDs

b. three and four wire 1000 ohm platinum RTDs

c. 3000 ohm Balco RTD

A 100 ohm platinum RTD has a resistance of 100 ohms at 0°C. A 1000 ohm platinum RTD has a resistance of 1000 ohms at 0°C. A 3000 ohm Balco RTD (Balco is an alloy of 70% nickel and 30% iron) has a resistance of 3000 ohms at 25°C. Although only two lead wires are necessary to connect the RTD to the transmitter, connecting a third (and sometimes fourth) wire allows the transmitter to correct for the resistance of the lead wires and for changes in wire resistance with temperature.

The Model 4081 pH/ORP transmitter can also be used with a two-wire RTD. Select a three-wire configuration and jumper the RTD return and -RTD sense terminals (terminals 3 and 4, respectively).

7.4.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the tEMP sub-menu appears in the display. Press ENTER .

3. The screen displays the tAUTO prompt. Press

é or

to enable (On) or disable

(OFF) automatic temperature compensation. Press ENTER to save.

4. The tMAN prompt appears. Use the editing keys to change the temperature to the desired value. To enter a negative number, press éuntil no digit is flashing. Then pressêto display the negative sign. Permitted values are between -5.0 and

130.0°C. If tAUTO was disabled in step 3, the temperature entered in this step will be used in all subsequent measurements, no matter what the process temperature is. Press ENTER to save.

5. The screen shows the tC prompt. Press

é or

to scroll to the desired tempera-

ture element and wiring configuration. Press ENTER to save.

1000-3 3 wire 1000 ohm RTD

1000-4 4 wire 1000 ohm RTD

100-3 3 wire 100 ohm RTD

100-4 4 wire 100 ohm RTD

3000 3000 ohm Balco RTD

NOTE

A jumper on the analog board must also be set to match RTD. See Section 2.2, Pre-Installation Set Up.

6. Press EXIT to return to the process display.

PROGRAM

ttCC

EXIT ENTER

11 0000--33

PROGRAM

ttAAUUttOO

EXIT ENTER

OONN

PROGRAM

ttMMAAnn

EXIT ENTER

002255..00

PROGRAM

ttEEMMPP

EXIT NEXT ENTER

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.5 DISPLAY UNITS

7.5.1 Purpose

This section describes how to do the following:

1. switch the process display units between pH and ORP (millivolts),

2. select °C or °F for the temperature display,

3. program a security code.

7.5.2 Definitions

1. DISPLAY UNITS. Select pH if the transmitter is being used to measure pH. Select ORP if the transmitter is being used to measure ORP. ORP is oxidation-reduction potential. ORP has units of millivolts and is usually measured with an inert metal electrode, such as a platinum electrode. The units selected are shown in the main display next to the measured value.

2. SECURITY CODE. The security code unlocks the transmitter and allows complete access to all menus. The transmitter is shipped with the security code disabled.

7.5.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the dISPLAY sub-menu appears. Press ENTER .

3. The screen displays the tYPE prompt. Press

é or

to toggle between pH and OrP.

Press ENTER to save.

4. The screen displays the tEMP prompt.Press

é or

to toggle between C and F.

Press ENTER to save.

5. The screen displays the COdE prompt. Use the editing keys to enter a security code between 001 and 999. Entering 000 disables the security feature. Press ENTER to save. The security code does not become effective until about two minutes after the last keystroke. See Section 5.8.3 to retrieve a lost security code.

6. Press EXIT to return to the process display.

PROGRAM

CCOODDEE

EXIT ENTER

000000

PROGRAM

ttYYPPEE

EXIT ENTER

PPHH

PROGRAM

ttEEMMPP

EXIT ENTER

PROGRAM

ddIISSPPLLAA YY

EXIT NEXT ENTER

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.6 BUFFER CALIBRATION PARAMETERS

7.6.1 Purpose

This section describes how to do the following:

1. activate or deactivate auto calibration,

2. identify which buffers will be used during auto calibration,

3. set the stability criteria for auto calibration.

7.6.2 Definitions

1. AUTO CALIBRATION. In auto calibration, screen prompts direct the user through a two point buffer calibration. The transmitter recognizes the buffers and uses temperature-corrected values in the calibration. The transmitter does not accept data until programmed stability limits have been met. If auto calibration is deactivated, the user must perform a manual calibration. In manual calibration, the user judges when readings are stable and manually enters buffer values. The use of auto calibration is strongly recommended.

2. BUFFERS. Buffers are aqueous solutions to which exactly known pH values have been assigned. Assigning a pH value to a buffer involves certain fundamental assumptions. Slightly different assumptions lead to slightly different pH scales. Over the years, various national standards organizations have developed different scales. The Model 4081 pH/ORP transmitter recognizes the common standard scales as well as common commercial buffers. Commercial buffers, which are sometimes called technical buffers, are traceable to standard buffers, but the accuracy of commercial buffers is generally less than standard buffers. Tables 7-2 and 7-3 list the buffers the Model 4081 pH/ORP transmitter recognizes and the temperature range over which the buffer pH is defined.

NOTE: pH 7 buffer is not a standard buffer. Because it is a popular commercial buffer in the United States, it is included

with the standard buffers. The pH of the buffer is defined between 0 and 95°C.

NIST DIN 19266 JIS 8802 BSI

pH temp (°C) pH temp (°C) pH temp (°C) pH temp (°C)

1.68 5 - 95 1.68 5 - 95 1.68 0 - 95 1.68 0 - 60

3.56 25 - 95 3.56 25 - 60

3.78 0 - 95

4.01 0 -95 4.01 0 - 95 4.01 0 - 95 4.01 0 - 60

6.86 0 -95 6.86 0 - 95 6.86 0 - 95 6.86 0 - 60

7.00 see note

7.41 0 - 50

9.18 0 - 95 9.18 0 - 95 9.18 0 - 95 9.18 0 - 60

10.01 0 - 50 10.01 0 - 50 10.01 0 - 50

12.45 0 - 60 12.45 0 - 60

TABLE 7-2. pH values of standard buffer solutions and the temperature range over which pH values are defined

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

3. STABILITY CRITERIA. For the Model 4081 pH/ORP transmitter to accept calibration data, the pH must remain within a specified range for a specified period of time. The default values are 0.02 pH units and 10 seconds. In other words, at the default setting, calibration data will be accepted as soon as the pH reading is constant to within 0.02 units for 10 seconds. The minimum range is 0.01, and the maximum time is 30 seconds.

7.6.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the bUFFEr sub-menu appears. Press ENTER .

3. The screen displays the bAUTO prompt. Press

é or

to activate (On) or deacti-

vate (OFF) auto calibration. Press ENTER to save.

4. The screen displays the bUFFEr prompt. Press

é or

to select the desired buffer or buffers. The buffer values available under each designation are given in Table 7-4. Press ENTER to save.

TABLE 7-4. Standard and Technical Buffers Recognized by the 4081pH Transmitter

Std NIST, DIN 19266, JIS 8802, and BSM standard buffers ErC Merck Buffers (technical buffers) InG Ingold Buffers (technical buffers) din DIN 19267 (technical buffers)

5. The screen changes to display the tIME prompt. Use the editing keys to change the flashing number to the time in seconds the reading must remain stable for calibration data to be accepted. The maximum is 30 seconds. Press ENTER to save.

6. The screen changes to display the pH prompt. Use the editing keys to change the flashing display to the pH range the reading must remain in for calibration data to be accepted. The minimum range is 0.01. Press ENTER to save.

7. Press EXIT twice to return to the process display.

Merck Ingold DIN 19267

pH temp (°C) pH temp (°C) pH temp (°C)

1.09 0 - 90

2.00 0 - 95 2.00 0 - 95

3.06 0 - 90

4.01 0 - 95

4.65 0 - 90

6.79 0 - 90

7.00 0 - 95 7.00 0 - 95

9.00 0 - 95

9.21 0 - 95 9.23 0 - 90

12.00 0 - 95

12.75 0 - 90

TABLE 7-3. pH values of commercial (technical) buffers and the temperature range over which pH values are defined

PROGRAM

bbAAUUttOO

EXIT ENTER

OOnn

PROGRAM

bbUUFFFFEErr

EXIT ENTER

SSttdd

PROGRAM

bbUUFFFFEErr

EXIT NEXT ENTER

PROGRAM

tt II MMEE

EXIT ENTER

11 00

PROGRAM

ppHH

EXIT ENTER

0000..0022

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

7.7 ISOPOTENTIAL PARAMETERS

7.7.1 Purpose

This section describes how to do the following:

1. convert the pH at the measurement temperature to the pH at a reference temperature by entering a solution temperature coefficient,

2. change the transmitter isopotential pH.

NOTE

Do NOT change the isopotential pH of the transmitter unless you are thoroughly familiar with the role of sensor and transmitter isopotential points in pH measurement, OR unless the sensor operating instructions specifically state that the isopotential pH is a value other than pH 7.

7.7.2 Definitions

1. pH AT A REFERENCE TEMPERATURE. Certain industries (for example, power generation) use pH to indirectly measure the concentration of dilute alkaline solutions, typically ammonia. The pH of dilute ammonia solutions is a strong function of temperature. Therefore, to make pH solely a measure of concentration, the pH must be converted to a value at a reference temperature. The correction factor is expressed as the pH change per unit temperature change (in °C). The correction is commonly called the solution temperature coefficient. The almost universal reference temperature is 25°C.

Example: The temperature coefficient of dilute aqueous ammonia solutions (0.1 to 5 ppm) is about -0.032 pH/°C (the minus sign means the pH decreases as temperature increases). If the pH at 31°C is 8.96, the pH at 25°C is 8.96 + (-0.032) (25 - 31) = 9.15.

2. ISOPOTENTIAL pH. The isopotential pH is the pH at which the cell voltage is independent of temperature. The closer the agreement between the transmitter and sensor isopotential pH, the smaller the error when the calibration and measurement temperatures are different. The default isopotential value for the transmitter is pH 7. Most sensors have an isopotential point fairly close to pH 7, so the default value rarely needs changing. For more information, consult Section 12.8, Isopotential pH. Some sensors have an isopotential pH distinctly different from pH 7. For these sensors, the transmitter isopotential pH must be changed to match the sensor.

NOTE

3. OPERATING ISOPOTENTIAL pH. The operating isopotential pH is a mathematical combination of the solution temperature coefficient and the meter isopotential pH. Changing the solution temperature coefficient ALWAYS changes the operating isopotential pH. When programming the transmitter to perform a solution temperature compensation, it is ALWAYS better to enter the solution temperature coefficient and allow the transmitter to calculate the operating isopotential pH.

7.7.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the ISOPOtntAL sub-menu appears. Press ENTER .

3. The screen displays the tCOEFF prompt. Use the editing keys to change the display to the desired solution temperature coefficient. The allowed values are -0.044 to +0.028 pH/°C. To enter a negative coefficient, press

é or

until no digit is flashing.

Then press

é or

to display the negative sign. Press ENTER to save.

4. The screen displays the ISO prompt. The number showing in the display is the operating isopotential pH. The transmitter calculates the operating isopotential pH from the transmitter isopotential pH and the solution temperature coefficient. If the solution temperature coefficient is 0.00, the operating isopotential pH is 7.00. If the solution temperature coefficient is different from 0.00, the operating isopotential pH will be different from 7.00. It is ALWAYS better to enter the solution temperature coefficient as described in step 3 and let the transmitter calculate the operating isopotential pH. To move to the next prompt without changing the value, press NEXT .

5. The screen displays the Snr prompt. The flashing display is the current transmitter isopotential point. Use the editing keys to change the transmitter isopotential pH to match the sensor isopotential pH. The limits are pH 0.00 to pH 14.00. The default is pH 7.00. Press ENTER to save.

NOTE

6. Press EXIT to return to the process display.

PROGRAM

SSnnrr

EXIT NEXT ENTER

0077..0000

PROGRAM

IISSOOPPOOttnnttAALL

EXIT NEXT ENTER

PROGRAM

ttCCOOEEFFFF

EXIT NEXT ENTER

00..000000

PROGRAM

II SS OO

EXIT NEXT ENTER

0077..0000

MODEL 4081 pH/ORP SECTION 7.0

PROGRAMMING FOR pH MEASUREMENTS

MODEL 4081 pH/ORP SECTION 8.0

CALIBRATION OF ORP MEASUREMENTS

SECTION 8.0

CALIBRATION OF ORP MEASUREMENTS

8.1 General

8.2 Entering and Leaving the Calibrate Menu

8.3 Using the Hold Function

8.4 Temperature Calibration

8.5 Standardization

8.1 GENERAL

The Calibrate menu allows the user to calibrate the ORP and temperature response of the sensor.

The ORP calibration is a one-point standardization against an ORP standard. The temperature calibration is a one-point standardization against a reference thermometer. Prompts guide the user through the calibration procedures.

8.2. ENTERING AND LEAVING THE CALIBRATE MENU

Press CAL on the infrared remote controller (IRC) to enter the Calibrate menu. To store new settings in memory, press ENTER . To leave the Calibrate menu without storing new values, press EXIT. Pressing EXIT with a prompt showing returns the display to the first prompt in the sub-menu. Pressing EXIT a second time returns the transmitter to the process display.

If program settings are protected with a security code, pressing PROG or CAL will cause the Id screen to appear. Key in the security code and press ENTER. The first sub-menu will appear. For more information, see Section 5.8, Security.

8.3 USING THE HOLD FUNCTION

During calibration, the sensor may be exposed to solutions having an ORP outside the normal range of the process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the transmitter in hold during calibration. Activating HOLD keeps the transmitter output at the last value or sends the output to a previously determined value.

After calibration, reinstall the sensor in the process stream. Wait until readings have stabilized before deactivating Hold.

To activate or deactivate Hold, do the following:

1. Press HOLD on the IRC.

2. The HoLd prompt appears in the display. Press

é or

to toggle the Hold function between On and OFF.

3. Press ENTER to save the setting.

CALIBRATE

ttEEMMPP AAddJJ

EXIT NEXT ENTER

CALIBRATE

ttEEMMPP

EXIT ENTER

002255..00

MODEL 4081 pH/ORP SECTION 8.0

CALIBRATION OF ORP MEASUREMENTS

8.4 TEMPERATURE CALIBRATION

8.4.1 Purpose

1. As discussed in Section 13.6 (ORP, Concentration, and pH), ORP is a function of temperature. The accuracy of a new sensor/transmitter loop is about ±1°C, which is adequate for most applications. A new sensor seldom requires temperature calibration.

2. Calibrate the sensor/transmitter loop if . . . a. ±1°C accuracy is NOT acceptable, or b. the temperature measurement is suspected of being in error.

NOTE

8.4.2 Procedure

1. Place the transmitter in ORP mode. See Section 9.4.3, steps 1 - 3. After selecting and saving OrP, press EXIT twice to return to the main display.

2. Place the ORP sensor and a calibrated reference thermometer in an insulated container of water at ambient temperature. Be sure the temperature element in the sensor is completely submerged by keeping the sensor tip at least three inches below the water level. Stir continuously. Allow at least 20 minutes for the standard thermometer, sensor, and water to reach constant temperature.

3. Enter the CALIBRATE menu by pressing CAL on the IRC. The Std sub- menu appears (pictured above left).

4. At the Std sub-menu, press NEXT . The tEMP AdJ sub-menu appears.

5. Press ENTER to display the temperature editing prompt.

6. Compare the temperature displayed by the transmitter with the temperature measured with the reference thermometer. If the readings are different, use the editing keys to change the flashing display to the value determined with the reference thermometer. The reading cannot be changed by more than 15°C.

7. Press ENTER . The value will be saved, and the display will return to the tEMP AdJ sub-menu.

8. To leave the CALIBRATE menu, press EXIT .

9. Check linearity by measuring the temperature of water 10 to 15°C cooler and 10 to 15°C warmer than the water used for calibration. Because of the time required for the temperature element in the sensor to reach constant temperature, a well-insulated container or, better, a constant temperature bath is required for this step.

1400

SSttdd

8.5.3 Procedure

1. Place the transmitter in ORP mode. See Section 9.4.3, steps 1 - 3. After selecting and saving OrP, press EXIT twice to return to the main display.

2. Enter the CALIBRATE menu by pressing CAL on the IRC. The Std sub-menu appears.

3. Rinse the sensor with deionized water and place it in the ORP standard along with a thermometer. Submerge the sensor tip at least three inches below the surface of the liquid. Swirl the sensor to dislodge trapped air bubbles. The main display will show the measured ORP based on the previous calibration.

4. Once the temperature and ORP readings are stable, press ENTER. The screen changes to look like the figure to the left.

5. Use the editing keys to change the flashing display to the desired ORP reading. Press ENTER to save.

6. Press EXIT to return to the main display.

NOTE

During calibration, the sensor may be exposed to solutions having ORP outside the normal range of the process. To prevent false alarms and possible undesired operation of chemical dosing pumps, place the analyzer in hold during calibration. See Section 8.3, Using the Hold Function, for details.

CALIBRATE

SSttdd

EXIT NEXT ENTER

CALIBRATE

SSttdd

EXIT NEXT ENTER

00 2255..00

1400

SSttdd

8.5 Standardization

8.5.1 Purpose

This section describes how to prepare ORP standard solutions and how to make the transmitter reading match the ORP of the standard. Procedures for making ORP standards are taken from ASTM Method D1498-93.

8.5.2 Preparation of ORP Standard Solutions

ASTM D 1498-93 gives procedures for making iron (II) - iron (III) and quinhydrone ORP standards. The iron (II) - iron (III) standard is recommended. It is fairly easy to make and has a shelf life of about one year. In contrast, quinhydrone standards contain toxic quinhydrone and have only an 8-hour shelf life.

Iron (II) - iron (III) standard is available from Rosemount Analytical as PN R508-16OZ. The ORP of the standard solution measured against a silver-silver chloride reference electrode is 476±20 mV at 25°C.

MODEL 4081 pH/ORP SECTION 8.0

CALIBRATION OF ORP MEASUREMENTS

ITEM MNEMONIC DISPLAY FACTORY USER

LIMITS SETTINGS SETTINGS

PROGRAM LEVEL

A. Temperature (Section 9.3) tEMP

1. Temperature Sensor Type tC 100-3; 100-4; 1000-3; 100-3 _______ 1000-4: 3000

B. Display (Section 9.4) dISPLAY

1. Measurement type tYPE pH/ORP pH _______

2. Temperature Units tEMP °C/°F °C _______

3. Code COdE 0 to 999 000 _______

TABLE 9-1. ORP Settings LIst

9.1 GENERAL

This section describes how to do the following:

1. change the units of the displayed variables,

2. program a security code,

Factory default settings are given in Table 9-1. If default settings are acceptable, the transmitter is ready for calibration. See Section 8.0, Calibration of ORP Measurements. There is no way to automatically reset the transmitter to factory defaults. Settings must be returned to default values one at a time. Figure 5-6 shows the menu tree.

9.2 ENTERING AND LEAVING THE PROGRAM MENU

Press PROG on the infrared remote controller (IRC) to enter the Program menu. To save new settings, press ENTER. To leave the Program menu without saving new values, press EXIT. Pressing EXIT with a prompt showing returns the display to the first prompt in the sub-menu. Pressing EXIT again returns the transmitter to the process display.

If program settings are protected with a security code, pressing PROG or CAL will cause the Id screen to appear. Key in the security code and press ENTER. The first sub-menu will appear. For more information, see Section 5.8, Security.

9.4, Display Units, for details.

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

9.1 General

9.2 Entering and Leaving the Program Menu

9.3 Temperature Element

9.4 Display Units

9.5 Diagnostic Parameters

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

9.3 TEMPERATURE ELEMENT

9.3.1 Purpose

This section describes how to match the transmitter to the type of temperature element in the ORP sensor.

9.3.2 Definition

TEMPERATURE ELEMENT: ORP sensors use a variety of temperature elements. The Model 4081 ORP transmitter recognizes the following temperature elements and configurations:

a. three and four wire 100 ohm platinum RTDs

b. three and four wire 1000 ohm platinum RTDs

c. 3000 ohm Balco RTD

The Model 4081 transmitter can also be used with a two-wire RTD. Select a threewire configuration and jumper the RTD return and -RTD sense terminals (terminals 3 and 4, respectively).

9.3.2 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the tEMP sub-menu appears in the display. Press ENTER .

3. The screen shows the tC prompt. Press

é or

to scroll to the desired

temperature element and wiring configuration. Press ENTER to save.

1000-3 3 wire 1000 ohm RTD

1000-4 4 wire 1000 ohm RTD

100-3 3 wire 100 ohm RTD

100-4 4 wire 100 ohm RTD

3000 3000 ohm Balco RTD

NOTE

A jumper on the analog board must also be set to the appropriate RTD type. See Section 2.2, Pre-Installation Set Up.

4. Press EXIT to return to the process display.

PROGRAM

ttCC

EXIT ENTER

11 0000--33

PROGRAM

ttEEMMPP

EXIT NEXT ENTER

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

PROGRAM

CCOODDEE

EXIT ENTER

000000

PROGRAM

ttYYPPEE

EXIT ENTER

PPHH

PROGRAM

ttEEMMPP

EXIT ENTER

PROGRAM

ddIISSPPLLAA YY

EXIT NEXT ENTER

9.4 DISPLAY UNITS

9.4.1 Purpose

This section describes how to do the following:

1. switch the process display units between pH and ORP (millivolts),

2. select °C or °F for the temperature display,

3. program a security code.

9.4.2 Definitions

1. DISPLAY UNITS. Select pH if the transmitter is being used to measure pH. Select ORP if the transmitter is being used to measure ORP. The units selected are shown in the main display next to the measured value.

2. SECURITY CODE. The security code unlocks the transmitter and allows complete access to all menus. The transmitter is shipped with security code disabled.

9.4.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the dISPLAY sub-menu appears. Press ENTER .

3. The screen displays the tYPE prompt. Press

é or

to toggle between pH and OrP.

Press ENTER to save.

4. The screen displays the tEMP prompt. Press

é or

to toggle between C and F.

Press ENTER to save.

5. The screen displays the COdE prompt. Use the editing keys to enter a security code between 001 and 999. Entering 000 disables the security feature. Press ENTER to save.

7. Press EXIT to return to the process display.

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

9.5 DIAGNOSTIC PARAMETERS

9.5.1 Purpose

This section describes how to do the following:

1. change the standardization (reference) offset,

2. enable and disable sensor diagnostics,

3. enable and disable glass impedance temperature compensation for a glass reference electrode,

4. set the high and low warning and failure limits for a glass reference electrode.

9.5.2 Definitions

1. STANDARDIZATION OFFSET (REFERENCE OFFSET). During calibration, the transmitter reading is made to match the ORP of a standard solution. If the difference between the transmitter reading and the desired value exceeds the programmed limit, the transmitter will not accept the new reading. The default value is 60 mV.

2. GLASS IMPEDANCE TEMPERATURE COMPENSATION. In certain applications, the use of a glass (i.e., pH) electrode as a reference electrode may be required. The impedance of a glass electrode changes with temperature. For changes in glass impedance to be a useful indicator of electrode condition, the impedance measurement must be corrected to a reference temperature.

3. REFERENCE IMPEDANCE. The majority of reference electrodes used in industry are low impedance silver-silver chloride electrodes. However, there are applications that call for either a high impedance sodium or pH glass reference electrode. Both high impedance and low impedance reference electrodes can be used with the Model 4081 pH/ORP transmitter.

4. WARNING AND FAILURE LIMITS FOR THE REFERENCE ELECTRODE. Warning tells the user that the reference electrode impedance is approaching the failure limit. Low and high warning and failure limits are programmable. For conventional silver-silver chloride reference electrodes only the high limits are useful. For high impedance reference electrodes, both low and high limits are used.

Figure 9-1 shows suggested limits for low impedance reference electrodes.

Figure 9-2 shows suggested limits for high impedance glass reference electrodes.

FIGURE 9-1. Suggested Warning and Failure Limits

for Low Impedance Reference Electrodes

FIGURE 9-2. Suggested Glass Impedance Warning and Failure Limits for a Glass Reference Electrode

Typical glass impedance is about 100 megohms at 25°C. A broken or cracked electrode has an impedance of 10 megohms or less. A glass impedance greater than 1000 megohms suggests the electrode is nearing the end of its service life. High impedance may also mean the electrode is not immersed in the process liquid.

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

PROGRAM

rrEEFF

EXIT ENTER

LLOO

PROGRAM

II MMPPtt CC

EXIT NEXT ENTER

OONN

PROGRAM

rrOOFFFFSStt

EXIT ENTER

PROGRAM

ddII AAGGnn OO SSTTII CC

EXIT NEXT ENTER

006600

PROGRAM

dd II AA GG

EXIT ENTER

OOFFFF

9.5.3 Procedure

1. Press PROG on the infrared remote controller (IRC).

2. Press NEXT until the diAGnOStIC sub-menu appears. Press ENTER.

4. The dIAG prompt appears. Use the

é or

keys to enable (On) or disable (OFF) the

sensor diagnostics. Press ENTER to save.

5. The IMPtC prompt appears. Use the

é or

keys to enable (On) or disable (OFF) glass impedance temperature compensation. Because glass impedance is a strong function of temperature, correcting glass impedance for temperature is recommended. A third setting (SPC) appears in addition to On and OFF. Do not select SPC; the setting is intended for factory use. Press ENTER to save.

6. The rEF prompt appears. Press

é or

NOTE

Be sure the jumpers on the analog board are set to match the reference electrode impedance. See Section 2.2, Pre-Installation Set Up.

7. The rFH prompt appears. Use the editing keys to change the display to the desired reference electrode high impedance fault value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 6) 0 - 2000 kilohms

High impedance (HI in step 6) 0 - 2000 megohms

PROGRAM

rrFFHH

EXIT ENTER

11 440000

MODEL 4081 pH/ORP SECTION 9.0

PROGRAMMING FOR ORP MEASUREMENTS

8. The rWH prompt appears. In the display, W appears as wj. Use the editing keys to change the display to the desired reference electrode high impedance warning value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 6) 0 - 2000 kilohms

High impedance (HI in step 6) 0 - 2000 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes above the fault value, the transmitter displays the diagnostic message rEFWArn. Press ENTER to save.

9. The rWL prompt appears. Use the editing keys to change the display to the desired reference electrode low impedance warning value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 6) not applicable

High impedance (HI in step 6) 0 - 900 megohms

Entering 0000 disables the feature. When the reference electrode impedance goes below the warning value, the transmitter displays the diagnostic message

rEFWArn. Press ENTER to save. The prompt appears but is disabled when LO is selected in step 6.

10. The rFL prompt appears. Use the editing keys to change the display to the desired reference electrode low impedance fault value. The allowed ranges are

Type of reference electrode Allowed range

Low impedance (LO in step 6) not applicable

High impedance (HI in step 6) 0 - 900 megohms

11. Press EXIT to return to the process display.

PROGRAM

rrWWJJLL

EXIT ENTER

00000000

PROGRAM

rrFFLL

EXIT ENTER

00000000

PROGRAM

rrWWJJHH

EXIT ENTER

00004400

MODEL 4081 pH/ORP SECTION 10.0

MAINTENANCE

SECTION 10.0

MAINTENANCE

10.1 OVERVIEW

This section gives general procedures for routine maintenance of the 4081 pH/ORP transmitter and pH and ORP sensors. The transmitter needs almost no routine maintenance. Sensors require periodic inspection and cleaning. The calibration of the transmitter-sensor combination should be checked regularly, and the loop recalibrated if necessary.

10.2 TRANSMITTER MAINTENANCE

Periodically clean the transmitter window with household ammonia or glass cleaner. The detector for the infrared remote controller is located behind the window at the top of the transmitter face. The window in front of the detector must be kept clean.

Most components of the transmitter are replaceable. Refer to Figure 10-1 and Table 10-1 for parts and part numbers.

10.1 Overview

10.2 Transmitter Maintenance

10.3 pH Sensor Maintenance

10.4 ORP Sensor Maintenance

10.5 Calibration

FIGURE 10-1. Exploded View of Model 4081 pH/ORP Transmitter

Three screws (part 13 in the drawing) hold the three circuit boards in place. Removing the screws allows the display board (communication board) and the CPU board stack (part 1) to be easily removed. A ribbon cable connects the boards. The cable plugs into the CPU board and is permanently attached to the display board. Five screws hold the terminal block (part 5) to the center housing (part 7), and the 16 pins on the terminal block mate with 16 sockets on the back side of the analog board. Use caution when separating the terminal block from the analog board. The pin and socket connection is tight.

}

MODEL 4081 pH/ORP SECTION 10.0

MAINTENANCE

TABLE 10-1. Replacement Parts for Model 4081 pH/ORP Transmitter

PROBLEM CLEANING SUGGESTIONS

Loose scale or debris Use a stream of water from a wash bottle to rinse away solids from the tip of the sensor.

If water does not work, gently wipe the glass bulb and liquid junction with a soft cloth,

tissue, cotton-tipped swab, or a soft bristle brush.

Oil and grease Wash the glass bulb with mild detergent solution and rinse thoroughly with water.

Hard scale (carbonate If wiping the sensor tip with a tissue or cotton swab does not remove the scale, soak the sulfate scales and glass bulb ONLY in a solution of 5% hydrochloric acid. To prepare the acid solution, add corrosion products) 15 mL of concentrated hydrochloric acid to 85 mL of water. Keep the acid away from the

liquid junction and from any stainless steel portions of the sensor. Rinse the sensor thoroughly with deionized water. Some scales (for example, calcium sulfate) cannot be removed easily with acid. Soaking the glass bulb in a 2% solution of disodium EDTA may

be helpful.

Location in Shipping Figure 10-1 PN Description Weight

1 23811-00 PCB stack consisting of the CPU, communication, and analog boards; 1 lb/0.5 kg

display board is not included; CPU, communication, and analog boards are factory-calibrated as a unit and cannot be ordered separately

2 23652-01 LCD display PCB 1 lb/0.5 kg

5 33337-02 Terminal block 1 lb/0.5 kg

6 23593-01 Enclosure cover, front with glass window 3 lb/1.5 kg

7 33360-00 Enclosure, center housing 4 lb/1.5 kg

8 33362-00 Enclosure cover, rear 3 lb/1.0 kg

9 6560135 Desiccant in bag, one each 1 lb/0.5 kg

9550187 O-ring (2-252), one, front and rear covers each require an O-ring 1 lb/0.5 kg

12 note Screw, 8-32 x 0.5 inch, for attaching terminal block to center housing *

13 note Screw, 8-32 x 1.75 inch, for attaching circuit board stack to center *

housing

14 33342-00 Cover lock 1 lb/0.5 kg

33343-00 Locking bracket nut 1 lb/0.5 kg

note Screw, 10-24 x 0.38 inch, for attaching cover lock and locking bracket *

nut to center housing

NOTE: For information only. Screws cannot be purchased from Rosemount Analytical. * Weights are rounded up to the nearest whole pound or 0.5 kg.

10.3 pH SENSOR MAINTENANCE

10.3.1 Frequency of Cleaning

The frequency at which a sensor should be inspected and cleaned can be determined only by experience. If the process liquid coats or fouls the sensor, frequent cleaning may be necessary. If the process does not contain a high level of suspended solids, the need for regular cleaning will be less. Often an increase in glass impedance indicates the electrode is becoming fouled and needs cleaning. Refer to Section 7.3 for a description of the glass impedance diagnostic.

10.3.2 Cleaning Procedures

When using acid or alkaline solvents, be careful to keep the solvent away from the liquid junction. If the cleaning solvent contacts the junction, hydrogen ions (acid solvent) or hydroxide ions (alkaline solvent) will diffuse into the junction. Because hydrogen and hydroxide ions have much greater mobility than other ions, they produce a large junction potential. When the electrode goes back in service, the hydrogen or hydroxide ions slowly diffuse out of the junction, causing the liquid junction potential and the pH reading to drift. It may take hours or days for the reading to stabilize. For a discussion of the influence of ion mobility on liquid junction potentials, see Section 12.4.

Consult the sensor instruction manual for additional information.

Always recalibrate the sensor after cleaning. If the sensor was cleaned with detergent or acid, soak the sensor in pH 4 or pH 7 buffer for at least an hour before calibrating.

10.3.3 Checking the Reference Electrode.

Some processes contain substances, for example, sulfides, that poison the reference electrode. Poisoning alters the electrode potential. For example, sulfide poisoning converts the reference electrode from a silver/silver chloride electrode into a silver/silver sulfide electrode, causing a shift in potential of several hundred millivolts.

A good way to check for poisoning is to compare the voltage of the reference electrode with a silver/silver chloride electrode that is known to be good. The reference electrode from a new sensor is the best choice. To check the suspect electrode, place both sensors in a beaker containing buffer or a solution of potassium chloride. Connect the reference leads to a voltmeter and measure the potential difference. If the suspect electrode is good, the difference should be no more than about 20 mV. Refer to Figure 10-2. A poisoned reference electrode usually requires replacement.

A laboratory silver/silver chloride reference electrode can be used in place of the second sensor. All Rosemount Analytical pH sensors have a silver/silver chloride reference, and most sensors use gelled saturated potassium chloride for the fill. The potentials of a good sensor reference electrode and a saturated silver/silver chloride laboratory electrode will agree within about 20 mV.

10.3.4 Rejuvenating Reference Electrodes

Occasionally, a poisoned or plugged reference electrode can be reconditioned. Although the electrode seldom recovers completely, the procedure might extend the life of the sensor by a few weeks.

a. Clean the sensor as thoroughly as possible.

b. Soak the sensor for several hours in a hot (NOT BOILING) 3% potassium chloride solution. Prepare the

solution by dissolving 3 g of potassium chloride in 100 mL of water.

c. Soak the sensor in pH 4 buffer at room temperature overnight.

d. Calibrate the sensor in buffers and retest it in the process liquid.

MODEL 4081 pH/ORP SECTION 10.0

MAINTENANCE

FIGURE 10-2. Checking the Potential of the Reference Electrode.

Refer to the wiring diagram(s) for the sensors to identify the reference leads.

10.4 ORP SENSOR MAINTENANCE

10.4.1 Frequency of Cleaning

The frequency at which an ORP sensor should be inspected and cleaned can be determined only by experience. If the process liquid coats or fouls the sensor, frequent cleaning may be necessary. If the process does not contain a high level of suspended solids, the need for regular cleaning will be less.

10.4.2 Cleaning Procedures

The platinum electrode is easily cleaned by using a tissue to rub the metal surface with a paste of baking soda (sodium bicarbonate). A clean platinum electrode is bright and shiny.

10.4.3 Checking the Reference Electrode

ORP electrodes manufactured by Rosemount Analytical have a silver/silver chloride reference. Section 10.3.3 describes how to check the performance of the reference electrode.

10.5 CALIBRATION

10.5.1 General

Many users regard calibration as a routine part of sensor/transmitter maintenance. Procedures for calibrating pH sensors, ORP sensors, and general information regarding the use of pH calibration buffers and ORP standards are given in Sections 6.0 Calibration of pH Measurements, 8.0 Calibration of ORP Measurements, 12.0 pH Measurements, and 13.0 ORP Measurements.

10.5.2 Calibration Frequency

The frequency at which sensors should be calibrated can be determined only by experience. Many factors influence calibration frequency. Sensors installed in dirty or corrosive process streams usually require more frequent calibration than sensors used in clean water. Sensors measuring extreme pH values, particularly high pH, also require more frequent calibration than sensors measuring mid-range pH. The width of the pH or ORP control range and the consequences of an out-of-limits condition has a major influence on calibration frequency. The narrower the control range and the greater the sensitivity of the process to control excursions, the more often the sensor should be checked. Finally, if monitoring data are reported to regulatory agencies, the agency itself may dictate the calibration frequency.

Use the following procedure to determine how often a pH sensor should be calibrated.

1. Calibrate the sensor. Record the date of calibration and the sensor response in buffers. That is, after calibrating, place the sensor back in the buffers and record the pH and temperature reading in each buffer. Also note the value of the reference offset and slope.

2. Install the sensor in the process stream.

3. After the appropriate period—two weeks for a clean process, several days for a dirty or aggressive process—remove the sensor and check its performance in buffers. Record the pH and temperature readings. The performance of the sensor in buffer after it has been in service is called the as-found condition. Keeping a good record of as-found data is an important step in determining the calibration frequency.

4. If the as-found data are acceptable, do not recalibrate the sensor. Return it to the process. Continue checking the calibration at the same interval.

5. If the as-found data are not acceptable, recalibrate the sensor. After calibration, check the sensor response in each buffer and record the results. Also note the reference offset and the slope. Return the sensor to service. Check the sensor again after a period shorter than the one originally selected. For example, if the first interval was two weeks, repeat the check after one week.

6. After a while it will become apparent how long the sensor holds calibration. The minimum calibration frequency can then be determined.

7. Check the calibration of the sensor at least several times during the regular calibration interval. Interim checks verify the sensor is still in calibration and validate the process measurements made since the last calibration or calibration check.

MODEL 4081 pH/ORP SECTION 10.0

MAINTENANCE

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

SECTION 11.0

TROUBLESHOOTING

11.1 WARNING AND FAULT MESSAGES

11.2 CALIBRATION ERRORS

11.3 TROUBLESHOOTING - GENERAL

11.4 TROUBLESHOOTING WHEN A DIAGNOSTIC MESSAGE IS SHOWING

11.5 TROUBLESHOOTING WHEN NO DIAGNOSTIC MESSAGE IS SHOWING

11.6 SYSTEMATIC TROUBLESHOOTING

11.7 DISPLAYING DIAGNOSTIC VARIABLES

11.8 TESTING THE TRANSMITTER BY SIMULATING pH

11.9 FACTORY ASSISTANCE AND REPAIRS

11.1 WARNING AND FAULT MESSAGES

The Model 4081 pH/ORP transmitter continuously monitors the measurement loop (sensor and transmitter) for conditions that cause erroneous measurements. When a problem occurs, the transmitter displays either a warning or fault message. A warning alerts the user that a potentially system disabling condition exists. If the condition causing the problem is not corrected, there is a high probability that the system will soon fail. A fault alerts the user that a system disabling condition exists. If a fault message is showing, all measurements should be regarded as erroneous.

When a WARNING condition exists:

1. The main display remains stable; it does not flash.

2. A warning message appears alternately with the temperature display. See Figure 11-1. See Section 11.4 for an explanation of the different warnings and suggested ways of correcting the problem.

When a FAULT exists:

1. The main display flashes.

2. The words FAULT and HOLD appear in the main display.

3. A fault message appears alternately with the temperature/output display. See Figure 11-2. See Section 11.4 for an explanation of the different fault messages and suggested ways of correcting the problem.

4. If the transmitter is in HOLD when the fault occurs, the output remains at the programmed hold value. To alert the user that a fault exists, the word FAULT appears in the main display, and the display flashes. A fault or diagnostic message also appears.

FIGURE 11-1. Warning

Annunciation

When a non-disabling problem occurs, a warning message appears alternately with the temperature display.

FIGURE 11-2. Fault Annunciation

When a disabling condition, a fault, occurs, the display appears as pictured above. To further alert the user that measurements are in error, the display flashes. Diagnostic messages appear in the temperature/ output area on the screen.

11.2 CALIBRATION ERRORS

If an error occurs during calibration, an error message appears in the main display, and the transmitter does not update the calibration. The calibration errors are Std Err, SLOPE Err LO, and SLOPE Err HI. See Section 11.5 for an explanation of the error messages and suggested ways of correcting the problem.

11.3 TROUBLESHOOTING - GENERAL

Troubleshooting is easy as 1, 2, 3 . . .

Step 1 Look for a diagnostic message on the display to help identify the problem. Refer to Section 11.4 for an explana-

tion of the message and a list of the possible problems that triggered it.

Step 2 Refer to Section 11.5 for common measurement problems and the recommended actions to resolve them.

Step 3 Follow the step by step troubleshooting approach, offered in Section 11.6, to diagnose and correct less common

or more complex problems.

11.4 TROUBLESHOOTING WHEN A DIAGNOSTIC MESSAGE IS SHOWING

The Model 4081 pH/ORP transmitter continuously monitors the measurement loop (sensor and transmitter) for problems. If a problem is detected, the transmitter displays a fault or error message. The message appears in the temperature/output area of the main display. The table lists each diagnostic message and the section to consult for help.

MESSAGE SECTION

GLASSFAIL 11.4.1

GLASSWArn 11.4.2

rEF FAIL 11.4.3

rEF WArn 11.4.4

CALIbrAtE 11.4.5

tEMP HI 11.4.6

tEMP LO 11.4.6

LInE FAIL 11.4.7

InPUt WArn 11.4.8

SLOPE Err LO 11.4.9

SLOPE Err HI 11.4.10

Std Err 11.4.11

rOM FAIL 11.4.12

CPU FAIL 11.4.12

AdC WArn 11.4.13

CyCLE PWr 11.4.13

WrItE Err 11.4.14

FACt FAIL 11.4.15

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

11.4.1 GLASSFAIL

GLASSFAIL is an electrode fault message. It means the glass impedance is outside the programmed Glass Fault High

(GFH) or Glass Fault Low (GFL) limit. Glass Fault High suggests the electrode is aging or the electrode is not immersed in the process liquid. Glass Fault Low implies the pH sensitive glass is cracked. GLASSFAIL also appears if inappropriate limits have been entered into the transmitter.

If the measurement system was previously commissioned and operating correctly, GLASSFAIL likely means a real problem exists. However if the system is being started up or if the advanced diagnostic feature is being used for the first time,

GLASSFAIL could be caused by a miswired sensor or by programmed limits that are not correct for the sensor.

NOTE

GLASSFAIL is a sensor diagnostic message. Sensor diagnostic mes-

sages are optional. They can be turned off. To disable sensor diagnostic messages, refer to Section 7.3.

Troubleshooting Flowchart - GLASSFAIL

A. Be sure the sensor is completely immersed in the process liquid.

If the diagnostic message disappears, the sensor is in good condition.

If the diagnostic message remains, go to step B.

B. Measure the glass impedance. See Section 11.7 for the procedure. Note the reading.

If the glass impedance is low (<40 megohms)...

1. Be sure the position of switch S-1 on the analog board matches the location of the preamplifier. See Section 2.2.

If switch S-1 was correct go to step 2.

If moving the switch to the correct position makes the diagnostic message disappear, the sensor is in good con dition.

If after moving the switch, the glass impedance is still low, go to step 2.

2. Calibrate the sensor. Use the autocalibration procedure in Section 6.5.

If the sensor calibrates properly...

a. The sensor is in good condition, but the Glass Fail Low (GFL) limit is set too high.

b. Lower the GFL limit to about 10 megohms below the glass impedance value (GIMP) measured in step B.

c. If the Glass Warning Low (GWL) message was also flashing, lower the limit from its former value by the

same amount GFL was lowered from its former value.

If the sensor cannot be calibrated...

The pH sensitive glass membrane is likely cracked and the sensor must be replaced. The crack in the glass may not be visible or may be difficult to see.

If the glass impedance is high (>800 megohms)...

1. Check that the sensor is correctly wired to the transmitter. See the appropriate wiring diagram in Section 3.0.

Pay particular attention to the following:

a. For Rosemount Analytical PLUS (+) and TUpH sensors with integral preamplifiers, the blue solution

ground wire must be attached to TB-8 (SOL GND) and the gray reference in wire must be attached to TB-7 (REF IN). (NOTE: TB-8 means terminal 8 on the terminal board.)

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

b. If the sensor was wired with the blue solution ground wire unattached and a jumper between terminals

TB-8 and TB-7, remove the jumper and reattach the blue solution ground wire to TB-8. Keep the gray reference in wire attached to TB-7.

c. For Rosemount Analytical PLUS (+) and TUpH sensors that do not have an integral preamplifier, attach

the blue solution ground wire to TB-8 or, better, leave the blue wire unattached and jumper TB-7 to TB-8.

d. If the sensor does not have a blue solution ground wire, jumper terminals TB-7 and TB-8.

If the wiring was correct and the glass impedance is still high, go on to step 2.

If correcting wiring errors causes the diagnostic message to disappear, the sensor is in good condition.

If after correcting wiring errors, the glass impedance is still high go on to step 2.

2. Inspect and clean the sensor. Refer to Section 10.3. After cleaning the sensor, calibrate it following the autocalibration procedure in Section 6.5. Be sure to note the sensor slope.

If cleaning the sensor lowers the impedance below 800 megohms...

a. The sensor is in good condition.

b. Return the calibrated sensor to service.

If cleaning does not lower the glass impedance and the sensor can be calibrated...

a. The sensor is probably in good condition; however, it may be nearing the end of its life. The electrode

slope is a good indicator of remaining life.

SLOPE CONDITION OF SENSOR

54-60 mV/unit pH Sensor is in good condition.

48-50 mV/unit pH Sensor is nearing the end of its life. Once the slope drops

below 48 mV/unit pH, the sensor can no longer be calibrated.

b. The Glass Fail High (GFH) limit is probably set too low for the sensor. Set the GFH limit to about

150 megohms greater than the measured glass impedance.

c. If the GLASSWArn message was also flashing, raise the GWH limit from its former value by the

same amount GFH was raised from its former value.

If cleaning does not lower the glass impedance and the sensor cannot be calibrated...

The sensor has failed and should be replaced.

If the glass impedance is moderate (between 40 and 800 megohms)...

1. The sensor may be dirty, in which case cleaning it will lower the impedance reading. The sensor may also be in good condition. The warning and fail limits are simply set too low.

2. Inspect and clean the sensor. Refer to Section 10.3. After cleaning the sensor, calibrate it following the autocalibration procedure in Section 6.5. Be sure to note the sensor slope.

If cleaning the sensor reduces the impedance...

a. The sensor is in good condition.

b. Return the calibrated sensor to service.

If cleaning does not lower the glass impedance and the sensor can be calibrated...

a. The sensor is probably in good condition; however it may be nearing the end of its life. The electrode

slope is a good indicator of remaining life.

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

SLOPE STATUS OF SENSOR

54-60 mV/unit pH Sensor is in good condition.

48-50 mV/unit pH Sensor is nearing the end of its life. Once the slope drops

below 48 mV/unit pH, the sensor can no longer be calibrated.

b. The Glass Fail High (GFH) limit is probably set too low for the sensor. Set the GFH limit to about 150

megohms greater than the measured glass impedance.

c. If the GLASSWArn message was also flashing, raise the GWH limit from its former value by the same

amount GFH was raised from its former value.

If cleaning does not lower the glass impedance and the sensor cannot be calibrated...

The sensor has failed and should be replaced.

11.4.2 GLASSWArn

GLASSWArn is an electrode fault message. It means the glass impedance is outside the programmed Glass Warning

High (GWH) or Glass Warning Low (GWL) limit. Ideally, when the measurement system exceeds the glass warning limits, the user will have adequate time to diagnose and correct problems before a failure occurs. High impedance implies the electrode is aging or the sensor is not completely submerged in the process liquid. Low impedance suggests the pH sensitive glass is cracked. The message also appears if inappropriate limits have been entered into the transmitter.

If the measurement system was previously commissioned and operating correctly, GLASSWArn likely means a real problem exists. However, if the system is being started up or if the advanced diagnostic feature is being used for the first time,

GLASSWArn could be caused by a miswired sensor or by programmed limits that are not correct for the sensor.

NOTE

GLASSWArn is a sensor diagnostic message. All sensor diagnostic

messages are optional. They can be turned off. To disable sensor diagnostic messages, refer to Section 7.3.

Troubleshooting Flowchart - GLASSWArn

Troubleshooting GLASSWArn problems is exactly the same steps as troubleshooting GLASSFAIL problems. Refer to Section 11.4.1.

11.4.3 rEF FAIL

rEF FAIL is an electrode fault message. rEF FAIL means that the reference impedance exceeds the programmed

Reference Fault High (RFH) limit. A plugged or dry reference junction is the usual cause of a high reference impedance. High reference impedance also occurs if the sensor is not submerged in the process liquid or if inappropriate limits have been entered into the transmitter.

If the measurement system was previously commissioned and operating correctly, rEF FAIL likely means a real problem exists. However, if the system is being started up or if the advanced diagnostic feature is being used for the first time,

rEFFAIL could be caused by a miswired sensor or by programmed limits that are not correct for the sensor.

NOTE

rEF FAIL is a sensor diagnostic message. All sensor diagnostic mes-

sages are optional. They can be turned off. To disable sensor diagnostic messages, refer to Section 7.3.

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

Troubleshooting Flowchart - rEF FAIL

A. Be sure the sensor is completely immersed in the process liquid.

If the diagnostic message disappears, the sensor is in good condition.

If the diagnostic message remains, go to step B.

B. Check that the sensor is properly wired to the transmitter. See the appropriate wiring diagram in Section 3.0. Be sure

the reference in wire is attached to TB-7 and the solution ground wire is attached to TB-8. (NOTE: TB-8 means

terminal 8 on the terminal board.)

If correcting wiring problems makes the diagnostic message disappear, the sensor is in good condition.

If wiring is correct and the message still remains, go to step C.

C. Measure and make a note of the reference impedance (rIMP). See Section 11.7.

If the reference impedance is low (<70 kilohms)...

a. The reference electrode is in good condition. pH sensors manufactured by Rosemount Analytical use low

impedance silver/silver chloride reference electrodes.

b. The reference failure high (RFH) limit is probably set too low. Change the limit to a value about 50 kilohms

greater than the measured reference impedance. If rEF WARN was also displayed, change the reference warning high (RWH) limit to about 25 kilohms above the measured reference impedance.

If the reference impedance is high (>70 kilohms)...

1. The sensor may be dirty, in which case cleaning it will lower the impedance. If the sensor is rebuildable,

the reference electrolyte may be depleted. Finally, the sensor may be in good condition. The warning and failure limits are simply set too high.

2. Inspect and clean the sensor. Refer to Section 10.3. If the sensor is rebuildable, replace the reference

junction and replenish the electrolyte solution. Refer to the sensor instruction manual for details. Check the reference impedance again.

If cleaning the sensor reduces the impedance...

a. The sensor is in good condition. Calibrate the sensor and return it to the process.

b. Change the reference failure high (RFH) limit to a value about 50 kilohms greater than the

measured reference impedance. If rEF WARN was also displayed, change the reference warning high (RWH) limit to about 25 kilohms above the measured reference impedance.

If cleaning does not reduce the impedance and the sensor is not rebuildable...

a. Try the reference junction rejuvenation procedure described in Section 10.3.

b. The rejuvenation procedure may not work. At best it will get a little more life out of a sensor

with a plugged reference.

c. Whether or not the rejuvenation procedure worked, go on to step 3.

3. Recalibrate the sensor using the autocalibration procedure in Section 6.5.

If the sensor can be calibrated...

a. The sensor is in good condition. Return it to the process.

b. Change the reference failure high (RFH) limit to a value about 50 kilohms greater than the

measured reference impedance. If rEF WARN was also displayed, change the reference warning high (RWH) limit to about 25 kilohms greater than the measured reference impedance.

If the sensor cannot be calibrated...

The sensor has failed and must be replaced.

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

11.4.4 rEFWArn

rEF WArn is an electrode fault message. It means the reference electrode impedance exceeds the programmed

Reference Warning High (RWH) limit. Ideally, when the measurement system exceeds the warning limits, the user will have adequate time to diagnose and correct problems before a failure occurs. A high reference impedance implies that the liquid junction is plugged or the reference electrolyte is depleted. The message also appears if an inappropriate limit has been entered into the transmitter.

If the measurement system was previously commissioned and operating correctly, rEF WArn likely means a real problem exists. However, if the system is being started up or if the advanced diagnostic feature is being used for the first time, rEF

WArn could be caused by a miswired sensor or by programmed limits that are not correct for the sensor.

NOTE

rEF WArn is a sensor diagnostic message. Sensor diagnostic messages

are optional. They can be turned off. To disable sensor diagnostic messages, refer to Section 7.3.

Troubleshooting Flowchart - rEF WArn

Troubleshooting rEF WArn problems is exactly the same as troubleshooting rEF FAIL problems. Refer to Section 11.4.3.

11.4.5 CALIbrAtE

CALIbrAtE is a diagnostic intended for future use. If the CALIbrAtE message is showing go to Section 7.3 and disable CALIbrAte.

11.4.6 tEMP HI and tEMP LO

tEMP HI and tEMP LO mean the transmitter has detected a problem with the temperature measuring circuit. The problem

may lie in the sensor, the cable, or the transmitter. The determination of temperature is an integral part of the pH measurement. Therefore, failure of the temperature measuring circuit is a system disabling condition. However, in an emergency, automatic temperature compensation can be disabled and the transmitter placed in manual temperature compensation. Refer to Section 7.4. For manual temperature compensation, choose a temperature equal to the average temperature of the process. The resulting pH reading will be in error. The more variable the temperature and the further the pH from 7, the greater the error.

Troubleshooting Flowchart- tEMP HI and tEMP LO

A. Check wiring, jumper settings, and software settings.

1. Check the wiring between the sensor and the transmitter. Refer to the appropriate wiring diagram in Section 3.0. Pay particular attention to TB-3 (RTD RTN), TB-4 (RTD SN), and TB-5 (RTD RTN). (NOTE: TB-3 means terminal 3 on the terminal board.)

2. Be sure the position of the RTD jumper on the analog board matches the type of RTD in the sensor. See Section 2.2.

3. Be sure the software settings in Section 7.4 match the type of RTD in the sensor.

If the diagnostic message disappears, the sensor is in good condition.

If the message persists, go to step B.

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

B. Check the sensor.

Refer to the wiring diagrams in Section 3.0 to identify the RTD leads. Disconnect the RTD leads and measure the resistances shown in Figure 11-3. The measured resistance should agree with the value in Table 11-1 to within about 1%. If the measured resistance is appreciably different (between 1 and 5%) from the value shown, the discrepancy can be calibrated out. See Section 7.4.

If a connection is open or shorted and it should not be, the sensor has failed. Replace the sensor.

If the RTD is different from what was expected, for example, the sensor contains a Pt 100, not a Pt 1000 RTD, reset the jumper and reconfigure the software to match the actual RTD.

If the measured resistances are acceptable, go to step C.

FIGURE 11-3. Three-wire RTD

Consult the table for resistance-temperature data. Lead resistance is about

0.05 ohm/ft at 25°C. Therefore, 15 feet of cable increases the resistance by about 1.5 ohm. The resistance between the RTD return and RTD sense leads should be less than 2 ohms.

Temperature Pt-100 Pt-1000 3K Balco

Resistance Resistance Resistance

0°C 100.0 ohms 1000 ohms 2663 ohms 10°C 103.9 ohms 1039 ohms 2798 ohms 20°C 107.8 ohms 1078 ohms 2833 ohms 25°C 109.6 ohms 1096 ohms 3000 ohms 30°C 111.7 ohms 1117 ohms 3067 ohms 40°C 115.5 ohms 1155 ohms 3202 ohms 50°C 119.4 ohms 1194 ohms 3337 ohms 60°C 123.2 ohms 1232 ohms 3472 ohms 70°C 127.1 ohms 1271 ohms 3607 ohms 80°C 130.9 ohms 1309 ohms 3742 ohms 90°C 134.7 ohms 1347 ohms 3877 ohms

100°C 138.5 ohms 1385 ohms 4012 ohms

TABLE 11-1. RTD Resistance Values

MODEL 4081 pH/ORP SECTION 11.0

TROUBLESHOOTING

C. Check the transmitter.

1. Disconnect the RTD sensor leads and wire the circuit shown in Figure 11-4. Set the resistance to the value for 25°C shown in Table 11-1. The measured temperature should equal 25°C to within ±1°C.

If the measured temperature is correct, the transmitter is working properly.

If the measured temperature is incorrect, calibrate the transmitter against the standard resistance equivalent to 25°C. See Section 6.4 for the procedure. Change the resistance and verify that the temperature reading changes to the correct value.

If the transmitter works properly after temperature calibration, the original calibration was in error. Re-attach the RTD wires and check the temperature performance of the sensor.

If the reading is still wrong, the transmitter electronics have failed. Replace the electronic board stack .

11.4.7 LInE FAIL

LInE FAIL almost always means that the transmitter is measuring an incorrect resistance between terminal TB-3 (RTD

RTN) and TB-4 (RTD SNS). These terminals are critical connections for the three-wire RTD measurement. Figure 11-3 shows a three-wire RTD connection.

Troubleshooting Flowchart- LInE FAIL

A. Check for miswires and open connections at TB-3 and TB-4. Open connections can be caused by loose connections,

poor spade crimps, or broken wires. Be sure to check junction boxes for proper pass through of all wires. See Section

3.0 for junction box wiring.

If correcting a wiring problem makes the message disappear, the system is in good condition.

If the message is still showing go to step B.

FIGURE 11-4. Temperature simulation into

the Model 4081 pH/ORP transmitter.

Rosemount 4081 pH Two-Wire Transmitter Manuals & Guides

Specifications and Main Features

Frequently Asked Questions

User Manual