Fluke 7012 User Manual

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7012

Calibration Bath

User Manual

Rev. 992802

Hart Scientific

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Limited Warranty & Limitation of Liability

Each product from Fluke Corporation, Hart Scientific Division ("Hart") is warranted to be free from de

fects in material and workmanship under normal use and service. The warranty period is one year for the Calibration Bath. The warranty period begins on the date of the shipment. Parts, product repairs, and ser

vices are warranted for 90 days. The warranty extends only to the original buyer or end-user customer of a Hart authorized reseller, and does not apply to fuses, disposable batteries or to any other product, which in Hart's opinion, has been misused, altered, neglected, or damaged by accident or abnormal conditions of operation or handling. Hart warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non-defective media. Hart does not warrant that software will be error free or operate without interruption. Hart does not warrant calibrations on the Calibration Bath.

Hart authorized resellers shall extend this warranty on new and unused products to end-user customers only but have no authority to extend a greater or different warranty on behalf of Hart. Warranty support is available if product is purchased through a Hart authorized sales outlet or Buyer has paid the applicable international price. Hart reserves the right to invoice Buyer for importation costs of repairs/replacement parts when product purchased in one country is submitted for repair in another country.

Hart's warranty obligation is limited, at Hart's option, to refund of the purchase price, free of charge re

pair, or replacement of a defective product which is returned to a Hart authorized service center within the warranty period.

To obtain warranty service, contact your nearest Hart authorized service center or send the product, with a description of the difficulty, postage, and insurance prepaid (FOB Destination), to the nearest Hart authorized service center. Hart assumes no risk for damage in transit. Following warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Hart determines that the failure was caused by misuse, alteration, accident or abnormal condition or operation or handling, Hart will provide an estimate or repair costs and obtain authorization before commencing the work. Following repair, the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges (FOB Shipping Point).

THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IM

PLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. HART SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL. OR CONSE

QUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT, RELIANCE OR ANY OTHER THEORY.

Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court of com

petent jurisdiction, such holding will not affect the validity or enforceability of any other provision.

Rev. 992802

Fluke Corporation, Hart Scientific Division

799 E. Utah Valley Drive • American Fork, UT 84003-9775 • USA Phone: +1.801.763.1600 • Telefax: +1.801.763.1010 E-mail: support@hartscientific.com

www.hartscientific.com

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Table of Contents

1 Before You Start . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.1 WARNINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2.2 CAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.3 Authorized Service Centers. . . . . . . . . . . . . . . . . . . . . . 5

2 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Specifications and Environmental Conditions . . . . . . . . . 11

3.1 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

3.2 Environmental Conditions. . . . . . . . . . . . . . . . . . . . . . 12

4 Quick Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.1 Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.2 Set Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4.3 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4.4 Setting the Temperature . . . . . . . . . . . . . . . . . . . . . . . 14

5 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.1 Bath Environment . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.2 “Dry-out” Period . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.3 Bath Preparation and Filling . . . . . . . . . . . . . . . . . . . . 17

5.4 Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5.5 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

6 Bath Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

6.2 Comparison Calibration . . . . . . . . . . . . . . . . . . . . . . . 19

6.3 Calibration of Multiple Probes . . . . . . . . . . . . . . . . . . . 20

7 Parts and Controls . . . . . . . . . . . . . . . . . . . . . . . . 21

7.1 Front Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . 21

7.2 Side Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

7.3 Back Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7.4 Bath Tank and Lid . . . . . . . . . . . . . . . . . . . . . . . . . . 24

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8 General Operation . . . . . . . . . . . . . . . . . . . . . . . . 27

8.1 Heat Transfer Fluid . . . . . . . . . . . . . . . . . . . . . . . . . 27

8.1.1 Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

8.1.2 Viscosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

8.1.3 Specific Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.4 Thermal Conductivity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.5 Thermal Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.6 Electrical Resistivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.7 Fluid Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.8 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

8.1.9 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8.1.10 Commonly Used Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8.1.10.1 Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8.1.10.2 Ethylene Glycol. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8.1.10.3 Methanol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

8.1.10.4 Mineral Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8.1.10.5 Silicone Oils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8.1.11 Fluid Characteristics Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8.1.11.1 Limitations and Disclaimer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

8.1.11.2 About the Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

8.2 Stirring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

8.3 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

8.4 Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

8.5 Cooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

8.6 Fluid Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

8.7 Temperature Controller . . . . . . . . . . . . . . . . . . . . . . . 34

9 Controller Operation . . . . . . . . . . . . . . . . . . . . . . . 37

9.1 Bath Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . 37

9.2 Reset Cutout . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

9.3 Temperature Set-point . . . . . . . . . . . . . . . . . . . . . . . . 39

9.3.1 Programmable Set-points . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

9.3.2 Set-point Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

9.3.3 Set-point Vernier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

9.4 Temperature Scale Units . . . . . . . . . . . . . . . . . . . . . . 41

9.5 Secondary Menu. . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.6 Heater Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.7 Proportional Band . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.8 Cutout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

9.9 Controller Configuration . . . . . . . . . . . . . . . . . . . . . . 45

9.10 Probe Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.10.1 D0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.10.2 Dg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9.11 Operating Parameters . . . . . . . . . . . . . . . . . . . . . . . . 46

9.11.1 Cutout Reset Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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9.12 Serial Interface Parameters . . . . . . . . . . . . . . . . . . . . . 47

9.12.1 Baud Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

9.12.2 Sample Period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

9.12.3 Duplex Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

9.12.4 Linefeed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

9.13 IEEE-488 Parameters . . . . . . . . . . . . . . . . . . . . . . . . 49

9.13.1 IEEE-488 Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

9.14 Calibration Parameters . . . . . . . . . . . . . . . . . . . . . . . 49

9.14.1 CTO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

9.14.2 H and L . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

10 Digital Communication Interface . . . . . . . . . . . . . . . . 51

10.1 Serial Communications . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.1 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.2 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

10.1.2.1 Baud rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

10.1.2.2 Sample Period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

10.1.2.3 Duplex Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

10.1.2.4 Linefeed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

10.1.3 Serial Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2 IEEE-488 Communication . . . . . . . . . . . . . . . . . . . . . 53

10.2.1 Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.1.1 IEEE-488 Interface Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.2.2 IEEE-488 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

10.3 Interface Commands . . . . . . . . . . . . . . . . . . . . . . . . 53

10.4 Power Control Functions . . . . . . . . . . . . . . . . . . . . . . 56

10.4.1 Heater Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10.4.2 Cooling Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

11 Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . 59

11.1 Calibration Points . . . . . . . . . . . . . . . . . . . . . . . . . . 59

11.2 Measuring the Set-point Error . . . . . . . . . . . . . . . . . . . . 59

11.3 Computing D0 and DG . . . . . . . . . . . . . . . . . . . . . . . 60

11.4 Calibration Example. . . . . . . . . . . . . . . . . . . . . . . . . 60

12 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

12.1 Draining the Bath . . . . . . . . . . . . . . . . . . . . . . . . . . 64

13 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . 67

13.1 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

13.2 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

13.2.1 EMC Directive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

13.2.2 Low Voltage Directive (Safety) . . . . . . . . . . . . . . . . . . . . . . . . . 70

iii

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Figures and Tables

Figure 1 Bath Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 2 Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 3 Refrigeration Controls - Side Panel . . . . . . . . . . . . . . . . . . . 22

Figure 4 Back Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure 5 Drain Location and Lid Options . . . . . . . . . . . . . . . . . . . . . 25

Figure 6 Chart of various bath fluids and their properties . . . . . . . . . . . . . 31

Table 2 Table of various bath fluids and their properties . . . . . . . . . . . . . 32

Figure 7 Controller Operation Flowchart . . . . . . . . . . . . . . . . . . . . . 38

Table 3 Proportional Band — Fluid Table . . . . . . . . . . . . . . . . . . . . 43

Figure 8 Bath temperature fluctuation at various proportional band settings . . . 43

Figure 9 Serial Communications Cable Wiring . . . . . . . . . . . . . . . . . . 51

Table 4 Interface Command Summary.. . . . . . . . . . . . . . . . . . . . . . 54

Table 4 Digital Communications Commands continued . . . . . . . . . . . . . 55

Table 5 Serial Power Control Functions . . . . . . . . . . . . . . . . . . . . . 57

Table 6 Temperature Range Control Functions . . . . . . . . . . . . . . . . . . 57

Figure 10 Sample calibration computations . . . . . . . . . . . . . . . . . . . . 61

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1 Before You Start

1.1 Symbols Used

Table 1 lists the International Electrical Symbols. Some or all of these symbols may be used on the instrument or in this manual.

Symbol Description

AC (Alternating Current)

AC-DC

Battery

CE Complies with European Union Directives

Double Insulated

Electric Shock

Fuse

PE Ground

Hot Surface (Burn Hazard)

Read the User’s Manual (Important Information)

Off

1 Before You Start

Symbols Used

Table 1 International Electrical Symbols

Page 8

Symbol Description

Canadian Standards Association

OVERVOLTAGE (Installation) CATEGORY II, Pollution Degree 2 per IEC1010-1 re

fers to the level of Impulse Withstand Voltage protection provided. Equipment of OVERVOLTAGE CATEGORY II is energy-consuming equipment to be supplied from the fixed installation. Examples include household, office, and laboratory appliances.

C-TIC Australian EMC Mark

The European Waste Electrical and Electronic Equipment (WEEE) Directive (2002/96/EC) mark.

1.2 Safety Information

Use this instrument only as specified in this manual. Otherwise, the protection provided by the instrument may be impaired.

The following definitions apply to the terms “Warning” and “Caution”.

• “WARNING” identifies conditions and actions that may pose hazards to

the user.

• “CAUTION” identifies conditions and actions that may damage the in-

strument being used.

1.2.1

WARNINGS

To avoid possible electric shock or personal injury, follow these guidelines.

GENERAL

•

DO NOT use the instrument for any application other than calibration work. The instrument was designed for temperature calibration. Any other use of the unit may cause unknown hazards to the user.

•

DO NOT use the unit in environments other than those listed in the user’s guide.

•

DO NOT overfill the bath. Overflowing extremely cold or hot fluid may be harmful to the operator. See Section 5.3, Bath Preparation and Filling, for specific instructions.

•

Follow all safety guidelines listed in the user’s manual.

•

Calibration Equipment should only be used by Trained Personnel.

•

If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be impaired.

•

Before initial use, or after transport, or after storage in humid or semi-hu

mid environments, or anytime the instrument has not been energized for more than 10 days, the instrument needs to be energized for a "dry-out"

7012 Calibration Bath

User’s Guide

Page 9

period of 2 hours before it can be assumed to meet all of the safety re

quirements of the IEC 1010-1. If the product is wet or has been in a wet environment, take necessary measures to remove moisture prior to apply

ing power such as storage in a low humidity temperature chamber operat

ing at 50 degree centigrade for 4 hours or more.

•

DO NOT operate high temperature baths (500°C) near flammable materi

als. Extreme temperatures could ignite the flammable material.

•

Overhead clearance is required. Do not place the instrument under a cabi

net or other structure. Always leave enough clearance to allow for safe and easy insertion and removal of probes.

•

The instrument is intended for indoor use only.

BURN HAZARD

•

Extremely cold temperatures may be present in this equipment. Freezer burns and frostbite may result if personnel fail to observe safety precau

tions.

• High temperatures may be present in this equipment. Fires and severe

burns may result if personnel fail to observe safety precautions.

ELECTRICAL HAZARD

• These guidelines must be followed to ensure that the safety mechanisms

in this instrument will operate properly. This mains supply for the instrument must be capable of supplying power to the instrument as listed in Section 3.1, Specifications. The power cord of the instrument is equipped with a three-pronged grounding plug for your protection against electrical shock hazards. It must be plugged directly into a properly grounded three-prong receptacle. The receptacle must be installed in accordance with local codes and ordinances. Consult a qualified electrician. DO NOT use an extension cord or adapter plug.

•

DO use a ground fault interrupt device. This unit contains a liquid. A ground fault device is advised in case liquid is present in the electrical system and could cause an electrical shock.

•

Always replace the power cord with an approved cord of the correct rat

ing and type. If you have questions, contact an Authorized Service Center (see Section 1.3).

•

High voltage is used in the operation of this equipment. Severe injury or death may result if personnel fail to observe the safety precautions. Before working inside the equipment, turn off the power and disconnect the power cord.

BATH FLUIDS

•

Fluids used in this unit may produce noxious or toxic fumes under certain circumstances. Consult the fluid manufacturer’s MSDS (Material Safety Data Sheet). Proper ventilation and safety precautions must be observed.

1 Before You Start

Safety Information

Page 10

•

The instrument is equipped with a soft cutout (user settable firmware) and a hard cutout (set at the factory). Check the flash point, boiling point, or other fluid characteristic applicable to the circumstances of the unit opera

tion. Ensure that the soft cutout is adjusted to the fluid characteristics of the application. As a guideline, the soft cutout should be set 10°C to 15°C below the flash point of the bath fluid. See Section 8.1, Heat Transfer Fluid, for specific information on bath fluids and Section 9.8, Cutout.

1.2.2

CAUTIONS

To avoid possible damage to the instrument, follow these guidelines.

•

Always operate the instrument in room temperatures listed in Section 3.2, Environmental Conditions. Allow sufficient air circulation by leaving at least 15 cm (6 inches) of clearance around the instrument.

•

DO NOT overfill the bath. Overflowing liquid may damage the electrical system. Be sure to allow for thermal expansion of the fluid as the bath temperature increases. See Section 5.3, Bath Preparation and Filling, for specific instructions.

• Read Section 6, Bath Use, before placing the unit into service.

• DO NOT change the values of the bath calibration constants from the fac-

tory set values. The correct setting of these parameters is important to the safety and proper operation of the unit.

• The refrigeration may be damaged or the lifetime shortened if the

set-point temperature is set above 60°C for more than one hour with the refrigeration manually on. Ensure that the refrigeration is off when the unit is used above 60°C.

• The Factory Reset Sequence should be performed only by authorized

personnel if no other action is successful in correcting a malfunction. You must have a copy of the most recent Report of Test to restore the test pa

rameters.

•

DO NOT operate this instrument in an excessively wet, oily, dusty, or dirty environment.

•

The unit is a precision instrument. Although it has been designed for opti

mum durability and trouble free operation, it must be handled with care. Position the unit before the tank is filled with fluid. Use the handles pro

vided to move the unit. Due to the weight of the compressor, it may re

quire two people to safely move the bath. If two people are used, place one person in the front and one person in the back of the unit, carefully slide hands under the unit and lift in unison. The area containing the com

pressor will be heavier than the rest of the unit. Do not move a unit filled

with fluid.

•

Most probes have handle temperature limits. Be sure that the probe handle temperature limit is not exceeded in the air above the instrument.

7012 Calibration Bath

User’s Guide

Page 11

•

The instrument and any thermometer probes used with it are sensitive in

struments that can be easily damaged. Always handle these devices with care. Do not allow them to be dropped, struck, stressed, or overheated.

COLD BATHS

•

Refrigerated baths require that the condensing coil be cleaned periodi

cally. Accumulation of dust and dirt on the condenser will result in pre

mature failure of the compressor.

•

This bath has been equipped with a brownout and over voltage protection device as a safety feature to protect the system components.

•

Mode of Operation: This bath needs to be plugged into the line voltage for at least two minutes before operation. This is only necessary for the first time that the bath is energized or when it is moved from one location to another. Turning the bath ON or OFF does not trigger the delay.

•

If a High/Low voltage condition exists for longer than 5 seconds, the bath will be de-energized. The “Mains Out of Range” light on the back of the bath will be lit indicating a fault condition. Re-energization is automatic upon correction of the fault condition and after a delay cycle of about two minutes. If a fault condition exists upon application of power, the bath will not energize.

Under and Over Voltage Protection at 115 VAC Voltage Cutout: ±12.5 % (101 - 129 VAC) Voltage Cut In: ±7.5 % (106 - 124 VAC)

Under and Over Voltage Protection at 230 VAC Voltage Cutout: ±12.5 % (203 - 257 VAC) Voltage Cut In: ±7.5 % (213 - 247 VAC)

1.3 Authorized Service Centers

Please contact one of the following authorized Service Centers to coordinate service on your Hart product:

Fluke Corporation, Hart Scientific Division

799 E. Utah Valley Drive

American Fork, UT 84003-9775

USA

Phone: +1.801.763.1600

Telefax: +1.801.763.1010

E-mail: support@hartscientific.com

1 Before You Start

Authorized Service Centers

Page 12

Fluke Nederland B.V.

Customer Support Services

Science Park Eindhoven 5108

5692 EC Son

NETHERLANDS

Phone: +31-402-675300

Telefax: +31-402-675321

E-mail: ServiceDesk@fluke.nl

Fluke Int'l Corporation

Service Center - Instrimpex

Room 2301 Sciteck Tower

22 Jianguomenwai Dajie

Chao Yang District

Beijing 100004, PRC

CHINA

Phone: +86-10-6-512-3436

Telefax: +86-10-6-512-3437

E-mail: xingye.han@fluke.com.cn

Fluke South East Asia Pte Ltd.

Fluke ASEAN Regional Office

Service Center

60 Alexandra Terrace #03-16

The Comtech (Lobby D)

118502

SINGAPORE

Phone: +65 6799-5588

Telefax: +65 6799-5588

E-mail: antng@singa.fluke.com

When contacting these Service Centers for support, please have the following information available:

•

Model Number

•

Serial Number

7012 Calibration Bath

User’s Guide

Page 13

•

Voltage

•

Complete description of the problem

1 Before You Start

Authorized Service Centers

Page 14

2 Introduction

The Hart Scientific 7012 bath is a very precise constant temperature bath. An innovative state of the art solid-state temperature controller has been incorpo

rated which maintains the bath temperature with extreme stability. The control

ler uses a microcontroller to execute the many operating functions.

User interface is provided by the 8-digit LED display and four key-switches. Digital remote communications is optionally available with a RS-232 or IEEE-488 interface.

The tank for the 7012 is stainless steel and holds 36 liters. There are two lids available; the standard lid with a rectangular access hole and an optional lid with a recirculating pump (see Figure 5).

2 Introduction

Figure 1 Bath Assembly

Page 15

3 Specifications and Environmental

Conditions

3.1 Specifications

Range

–10°C to 110°C (14°F to 230°F)

Stability

±0.0008°C at 0°C (ethanol) ±0.0008°C at 25°C (water) ±0.003°C at 100°C (oil 5012)

Uniformity

±0.003°C at 0°C (ethanol) ±0.002°C at 25°C (water) ±0.004°C at 100°C (oil 5012)

Temperature Setting

Digital display with push-button data entry

Set-point Resolution

0.002°C; high-resolution mode, 0.00003°C

Display Resolution

0.01°C

Digital Setting Accuracy

±1°C

Digital Setting Repeatability

±0.005°C

Heaters

500 and 1000 Watts

Safety Cutout

Factory-set high temperature

Temperature Drift per ±°C Ambient or ±10 VAC line

±0.2m°C

Pump Recirculation (optional)

15 L/min

Access Opening

162 mm X 292 mm (6.38” X 11.5”)

Depth

457 mm (18”)

Wetted Parts

304 stainless steel

Volume

42 liters (11.2 gallons)

Weight

68 kg (150 lb.)

Size

762 mm H X 686 mm W X 401 mm D (30” X 27” X 15.8”)

Power

115 VAC (±10%), 60 Hz, 1570 W 230 VAC (±10%), 60 Hz, 1570 W (50 Hz Optional)

NOTE: If voltage is outside ±10% VAC, the compressor may be damaged.

Check the back panel label for the correct voltage and frequency prior to energiz

ing the instrument.

System Fuse

115 VAC: 15 A 250 V slow blow 230 VAC: 8 A 250 V slow blow

3 Specifications and Environmental Conditions

Specifications

Page 16

Heater Fuse

115 VAC: 10 A 250 V fast blow 230 VAC: 6 A 250 V fast blow

Safety

OVERVOLTAGE (Installation) CATEGORY II, Pollution Degree 2 per IEC 61010-1

3.2 Environmental Conditions

Although the instrument has been designed for optimum durability and trou

ble-free operation, it must be handled with care. The instrument should not be operated in an excessively dusty or dirty environment. Maintenance and clean

ing recommendations can be found in the Maintenance Section of this manual.

The instrument operates safely under the following conditions:

•

ambient temperature range: 5–50°C (41–122°F)

•

ambient relative humidity: maximum 80% for temperature <31°C, de

creasing linearly to 50% at 40°C

• pressure: 75kPa–106kPa

• mains voltage within ±10% of nominal

• vibrations in the calibration environment should be minimized

• altitude does not effect the performance or safety of the unit

• indoor use only

7012 Calibration Bath

User’s Guide

Page 17

4 Quick Start

CAUTION: READ SECTION 6 ENTITLED “BATH USE” before placing the bath in service. Incorrect handling can damage the bath and void the warranty.

This section gives a brief summary of the steps required to set up and operate the 7012 bath. This should be used as a general overview and reference and not as a substitute for the remainder of the manual. Please read Section 5 through 7 carefully before operating the bath.

4.1 Unpacking

Unpack the bath carefully and inspect it for any damage that may have oc

curred during shipment. If there is shipping damage, notify the carrier immediately.

Verify that all components are present:

• 7012 Bath

• Controller Probe

• Access Hole Cover

• User’s Guide

• Report of TEst

• Fill Hole Cover

• Drain Elbow

If you are missing any item, please contact an Authorized Service Center.

4.2 Set Up

Set up of the bath requires careful unpacking and placement of the bath, filling the bath with fluid, installing the probe and connecting power. Consult Section 5 for detailed instructions for proper installation of the bath. Be sure to place the bath in a safe, clean and level location.

Fill the bath tank with an appropriate liquid. For operation at moderate bath temperatures, clean distilled water works well. Carefully pour the fluid into the bath tank through the large rectangular access hole above the tank avoiding spilling any fluid. The fluid must not exceed a height of 1/2 inch below the bath lid.

The control probe must be inserted through the lid into the bath and plugged into the socket at the back of the bath.

4 Quick Start

Unpacking

Page 18

4.3 Power

Plug the bath power cord into a mains outlet of the proper voltage, frequency, and current capability. Refer to Section 3.1, Specifications, for power require

ment details. Refer to and read the WARNING at the front of this manual con

cerning brownout and over voltage protection.

Set the “HEATER” switch on the front panel to position “LOW” and turn the bath on using the front panel “POWER” switch. The bath will turn on and be

gin to heat or cool to reach the previously programmed temperature set-point. The front panel LED display will indicate the actual bath temperature.

4.4 Setting the Temperature

In the following discussion a solid box around the word SET, UP, EXIT or DOWN indicates the panel button while the dotted box indicates the display reading. Explanation of the button or display reading are to the right of each button or display value.

To view or set the bath temperature set-point proceed as follows. The front panel LED display normally shows the actual bath temperature.

24.68 C

Bath temperature display

When “SET” is pressed the display shows the set-point memory that is currently being used and its value. Eight set-point memories are available.

Access set-point selection

1. 25.0

Set-point 1, 25.0°C currently used

Press “SET” to select this memory and access the set-point value.

Access set-point value

C 25.00

Current value of set-point 1, 25.00°C

Press “UP” or “DOWN” to change the set-point value.

Increment display

C 30.00

New set-point value

Press “SET” to accept the new value and display the vernier value. The bath be

gins heating or cooling to the new set-point.

7012 Calibration Bath

User’s Guide

Page 19

Store new set-point, access vernier

0.00000

Current vernier value

Press “EXIT” and the bath temperature is displayed again.

Return to the temperature display

24.73 C

Bath temperature display

The bath heats or cools until it reaches the new set-point temperature. Set the heater switch to position “HIGH” to allow the bath to more quickly reach a higher temperature. The “HIGH” setting may be necessary to reach higher tem

peratures and control at high temperatures.

When setting the set-point temperature be careful not to exceed the temperature limit of the bath fluid. The over-temperature cut-out should be correctly set to prevent this from happening. See Section 9.8.

If operating the bath below 45 °C set the COOLING power switch to ON. The cooling temperature may require adjustment to provide the proper amount of cooling. See Section 8.5.

To obtain optimum control stability adjust the proportional band as discussed in Section 9.7.

4 Quick Start

Setting the Temperature

Page 20

5 Installation

CAUTION: READ SECTION 6 ENTITLED “BATH USE ”before placing the bath in service. Incorrect handling can damage the bath and void the warranty.

This bath is not designed to be portable. Therefore, moving the bath once it has been installed should be kept to a minimum.

CAUTION: Never move a bath that is full of fluid. This action could be extremely dangerous and could result in personal injury to the person moving the bath.

If the bath is going to be placed in an area where it will need to be moved fre

quently, a special cart can be designed to accommodate the bath making the bath much more portable. Hart sells carts designed for these baths. However, even with a cart the bath should not be moved full of fluid. The fluid can splash causing injury or if the bath and cart tip, the fluid could cause damage to the surrounding area and personal injury to personnel.

If the bath must be moved, be sure to drain the fluid to prevent any injury. The side of the bath with the compressor is heavier than the tank side. To safely move the bath, two people are required.

5.1 Bath Environment

The Model 7012 Bath is a precision instrument which should be located in an appropriate environment. The location should be free of drafts, extreme temper

atures and temperature changes, dirt, etc. The surface where the bath is placed must be level.

If used at higher temperatures where fluid vaporization is significant, a fume hood should be used.

5.2 “Dry-out” Period

Before initial use, after transport, and any time the instrument has not been en

ergized for more than 10 days, the bath will need to be energized for a “dry-out” period of 1-2 hours before it can be assumed to meet all of the safety requirements of the IEC 1010-1.

5.3 Bath Preparation and Filling

The 7012 Bath is not provided with a fluid. Various fluids are available from Hart Scientific and other sources. Depending on the desired temperature range, any of the following fluids, as well as others, may be used in the bath:

5 Installation

Bath Environment

Page 21

•

Water

•

Ethylene Glycol/Water

•

Methanol

•

Mineral oil

•

Silicone oil

Fluids are discussed in detail in Section 8.1.

Remove any access hole cover from the bath and check the tank for foreign matter (dirt, remnant packing material, etc.). Use clean unpolluted fluid. Care

fully fill the bath through the large square access hole to a level that will allow for stirring and thermal expansion. The fluid should never exceed a height of 1/2" below the top of the tank. Carefully monitor the bath fluid level as the bath temperature rises to prevent overflow or splashing. Remove excess fluid if nec

essary and with caution if the fluid is hot.

Be careful to prevent bath fluid from spilling on the stirring motor while filling.

CAUTION: Under filling may reduce bath performance and may possibly

damage the bath heater.

5.4 Probe

Inspect the bath controller probe. This probe should not be bent or damaged in any way. Reasonable caution should be used in handling this probe as it contains a precision thermistor sensor. If damaged, the probe can be replaced. Contact an Authorized Service Center for assistance.

Insert the probe into the 1/4 inch probe hole at the top left side of the bath lid. The tip of the probe must be well immersed in the fluid. The probe connector is plugged into the rear of the bath into the socket labeled “PROBE”.

5.5 Power

With the bath power switch off, plug the bath into an AC mains outlet of the appropriate voltage, frequency, and current capacity. Refer to Section 3.1, Specifications, for power requirement details. Refer to and read the WARNING at the front of this manual concerning brownout and over voltage protection.

Be sure the stirring motor power cord is plugged into the “STIRRER” socket at the back of the bath.

7012 Calibration Bath

User’s Guide

Page 22

6 Bath Use

READ BEFORE PLACING THE BATH IN SERVICE

The information in this section is for general information only. It is not de

signed to be the basis for calibration laboratory procedures. Each laboratory will need to write their own specific procedures.

6.1 General

Be sure to select the correct fluid for the temperature range of the calibration. Bath fluids should be selected to operate safely with adequate thermal proper

ties to meet the application requirements. Also, be aware that some fluids ex

pand and could overflow the bath if not watched. Refer to General Operation, section 8, for information specific to fluid selection and to the MSDS sheet spe

cific to the fluid selected. Generally, baths are set to one temperature and used to calibrate probes only at that single temperature. This means that the type of bath fluid does not have to change. Additionally, the bath can be left energized reducing the stress on the system.

The bath generates extreme temperatures. Precautions must be taken to prevent personal injury or damage to objects. Probes may be extremely hot or cold when removed from the bath. Cautiously handle probes to prevent personal injury. Carefully place probes on a heat/cold resistant surface or rack until they are at room temperature. It is advisable to wipe the probe with a clean soft cloth or paper towel before inserting it into another bath. This prevents the mixing of fluids from one bath to another. If the probe has been calibrated in liquid salt, carefully wash the probe in warm water and dry completely before transferring it to another fluid. Always be sure that the probe is completely dry before inserting it into a hot fluid. Some of the high temperature fluids react violently to water or other liquid mediums. Be aware that cleaning the probe can be danger

ous if the probe has not cooled to room temperature. Additionally, high temper

ature fluids may ignite the paper towels if the probe has not been cooled.

For optimum accuracy and stability, allow the bath adequate stabilization time after reaching the set-point temperature.

6.2 Comparison Calibration

Comparison calibration involves testing a probe (unit under test, UUT) against a reference probe. After inserting the probes to be calibrated into the bath, al

low sufficient time for the probes to settle and the temperature of the bath to stabilize.

One of the significant dividends of using a bath rather than a dry-well to cali

brate multiple probes is that the probes do not need to be identical in construc

tion. The fluid in the bath allows different types of probes to be calibrated at the same time. However, stem effect from different types of probes is not to

tally eliminated. Even though all baths have horizontal and vertical gradients,

6 Bath Use

General

Page 23

these gradients are minimized inside the bath work area. Nevertheless, probes should be inserted to the same depth in the bath liquid. Be sure that all probes are inserted deep enough to prevent stem effect. From research at Hart Scien

tific, we suggest a general rule-of-thumb for immersion depth to reduce the stem effect to a minimum: 15 x the diameter of the UUT + the sensor length. Do not submerge the probe handles. If the probe handles get too warm dur

ing calibration at high temperatures, a heat shield could be used just below the probe handle. This heat shield could be as simple as aluminum foil slid over the probe before inserting it in the bath or as complicated as a specially designed reflective metal apparatus.

When calibrating over a wide temperature range, better results can generally be achieved by starting at the highest temperature and progressing down to the lowest temperature.

Probes can be held in place in the bath by using probe clamps or drilling holes in the access cover. Other fixtures to hold the probes can be designed. The ob

ject is to keep the reference probe and the probe(s) to be calibrated as closely grouped as possible in the working area of the bath. Bath stability is maximized when the bath working area is kept covered.

In preparing to use the bath for calibration start by:

• Placing the reference probe in the bath working area.

• Placing the probe to be calibrated, the UUT, in the bath working area as

close as feasibly possible to the reference probe.

6.3 Calibration of Multiple Probes

Fully loading the bath with probes increases the time required for the temperature to stabilize after inserting the probes. Using the reference probe as the guide, be sure that the temperature has stabilized before starting the calibration.

7012 Calibration Bath

User’s Guide

Page 24

7 Parts and Controls

7.1 Front Control Panel

The following controls and indicators are present on the controller front panel (see Figure 2 below): (1) the digital LED display, (2) the control buttons, (3) the bath on/off power switch, (4) the control indicator light, (5) the heater power switch, and (6) the cooling power switch.

(1) The digital display is an important part of the temperature controller be

cause it not only displays set and actual temperatures but also displays various bath functions, settings, and constants. The display shows temperatures in val

ues according to the selected scale units °C or °F.

(2) The control buttons (SET, DOWN, UP, and EXIT) are used to set the bath temperature set-point, access and set other operating parameters, and access and set bath calibration parameters.

A brief description of the functions of the buttons follows:

SET – Used to display the next parameter in a menu and to set parameters to the displayed value.

DOWN – Used to decrement the displayed value of settable parameters.

UP –Usedtoincrementthedisplayedvalue.

EXIT – Used to exit from a menu. When “EXIT” is pressed any changes made

to the displayed value are ignored.

(3) The on/off switch controls power to the entire bath assembly. It powers the stirring motor and the bath controller/heater circuit.

(4) The control indicator is a two color light emitting diode. This indicator lets the user visually see the ratio of heating to cooling. When the indicator is red,

7 Parts and Controls

Front Control Panel

Figure 2 Front Panel

Page 25

the heater is ON. When the indicator is green the heater is OFF and the bath is cooling.

(5) The heater power switch is used to select the appropriate heater power lev

els for heating and controlling the bath at various temperatures.

(6) The cooling power switch controls power to the cooling compressor and cooling fan.

7.2 Side Panel

The side panel has three features (see Figure 3): 1) the back pressure valve, 2) the cooling temperature regulating valve, and 3) the cooling temp gauge. With the interface option an extra cooling valve (HIGH) is provided.

1) The back pressure valve adjustment is used to control the amount of cooling supplied to the system. This valve reduces the cooling capacity by restricting the flow of refrigerant to the bath, allowing the adjustment of the heating to cooling percentage. Under normal operation the valve should be fully open (counter clockwise).

7012 Calibration Bath

User’s Guide

Figure 3 Refrigeration Controls - Side Panel

Page 26

2) The cooling temperature regulating valve is used to adjust the tempera

ture at which the refrigerant evaporates, which determines cooling effi

ciency. Refer to the label below the gauge for approximate psi and evaporative temperature settings. The following table is reproduced from the label.

For this bath: Control Temperature

Set the Cooling Temp. Valve to this pressure

°C °F Nominal Cooling PSIG

–10 14 4.7

–5 23 9.2

0 32 14.5

5 41 20.7

10 50 27.9

15 59 36.1

20 68 45.5

25 77 56.2

30 86 68.4

35 95 82.1

37 98.6 86

DO NOT set the Cooling Pressure above 90 PSIG

3) The cooling temp gauge is used to indicate the temperature at which the refrigerant is evaporating. The cooling temp regulating valve is used to set and then control this temperature.

7.3 Back Panel

The back panel has five standard features and two optional features (see Figure

4): 1) the probe connector, 2) the stirrer power outlet, 3) the power cord, 4) the

drain valve, 5) serial number notation, 6) the RS-232 interface connecter (op

tional), and 7) the IEEE-488 interface connector (optional). The system fuses are internal.

1) The probe connector on the back panel is used for the temperature con

troller probe.

2) The stirrer power is provided for the stirring motor.

3) The power cord.

4) A drain valve is provided for ease of removing the fluid media from the

bath. Always use a container of adequate size to hold the FULL LOAD of fluid. Some oils are more easily drained at higher temperatures. (See caution note in next section.)

7 Parts and Controls

Back Panel

Page 27

The serial number is located on the upper right corner of the back panel. When contacting an Authorized Service Center, use the serial number and model number.

6) If the bath is supplied with a serial RS-232 interface, the interface cable attaches to the back of the bath at the connector labeled “RS-232”.

7) If the bath is supplied with a GPIB IEEE-488 interface, the interface ca

ble attaches to the back of the bath at the connector labeled “IEEE-488”.

7.4 Bath Tank and Lid

There are two different types of lids. They both have the same overall dimen

sions but the optional lid (see Figure 5) has a recirculating pump and the stan

dard lid has a stirring motor with rectangular access hole. Their features are described with reference to figure numbers as follows:

7012 Calibration Bath

User’s Guide

Figure 4 Back Panel

Page 28

1) The top half of the latch attaches the lid to the bath. There are two latches; one on the front and one on the back.

2) The thermometer/liquid level is a hole in the lid for filling and removing of liquid, checking liquid level, and for mounting a thermometer. A hole may be drilled in the rubber stopper supplied for inserting a thermometer into the bath.

3) The rectangular access hole, on the standard lid, may be used to insert the users device to be thermostatted. To obtain specified control levels this hole must be covered to prevent thermal disturbance to the bath. Covers may be purchased separately from Hart Scientific.

3) The circulation inlet - outlet on the pump lid is the access area or the in

let and outlet for the circulation pump.

7 Parts and Controls

Bath Tank and Lid

Figure 5 Drain Location and Lid Options

Page 29

4) The stirrer/pump motor drives the stirring propellers to provide mixing of the bath fluid. Proper mixing of the fluid is important for good con

stant temperature stability and uniformity. The stir motor power cord plugs into the back of the bath at the power socket labeled “STIRRER”.

5) The probe hole is for the temperature controller probe. The probe must be in this hole for the bath to operate.

6) A drain valve is provided for ease of removing the fluid media from the bath. Always use a container of adequate size to hold the full load of fluid. Some oils are more easily drained at higher temperatures. (See caution note below.)

WARNING: Extreme caution must be maintained to prevent harm to the

user or the surrounding environment. Do not exceed a 120°C fluid temper

ature for draining. The valve could be damaged if 120°C is exceeded. Insulate the container from the floor or other objects that may be damaged by high temperatures as required.

7012 Calibration Bath

User’s Guide

Page 30

8 General Operation

8.1 Heat Transfer Fluid

Many fluids will work with 7012 bath. Choosing a fluid requires consideration of many important characteristics of the fluid. Among these are temperature range, viscosity, specific heat, thermal conductivity, thermal expansion, electri

cal resistivity, fluid lifetime, safety, and cost.

Use the fluid chart in the manual to choose the type of fluid that is best suited for your intended purpose.

8.1.1 Temperature Range

One of the most important characteristics to consider is the temperature range of the fluid. Few fluids work well throughout the complete temperature range of the bath. The temperature at which the bath is operated must always be within the safe and useful temperature range of the fluid. The lower temperature range of the fluid is determined by the freeze point of the fluid or the temperature at which the viscosity becomes too great. The upper temperature is usually limited by vaporization, flammability, or chemical breakdown of the fluid. Vaporization of the fluid at higher temperatures may affect temperature stability because of cool condensed fluid dripping into the bath from the lid.

The bath temperature should be limited by setting the safety cut-out so that the bath temperature cannot exceed the safe operating temperature limit of the fluid.

8.1.2 Viscosity

Viscosity is a measure of the thickness of a fluid, how easily it can be poured and mixed. Viscosity affects the temperature stability of the bath. With low vis

cosity, fluid mixing is better which creates a more uniform temperature throughout the bath. This improves the bath response time which allows it to maintain a more constant temperature.

For good control the viscosity should be less than 10 centistokes. 50 centistokes is about the upper limit of allowable viscosity. Viscosities greater than this cause very poor control stability and may also overheat or damage the stirring motor. With oils, viscosity may vary greatly with temperature. Viscosity in

creases as temperature decreases. When fluid viscosity increases, stability per

formance of the unit may decrease.

When using fluids with higher viscosities the controller proportional band may need to be increased to compensate for the reduced response time. Otherwise the temperature may begin to oscillate.

Ensure that stirring occurs at all temperatures.

8 General Operation

Heat Transfer Fluid

Page 31

8.1.3 Specific Heat

Specific heat is the measure of the heat storage ability of the fluid. Specific heat, though to a lesser degree, also affects the control stability and the heating and cooling rates. Generally, a lower specific heat causes slightly better control stability and quicker heating and cooling. With fluids with higher specific heat the controller may require a decreased proportional band to compensate for the decrease in sensitivity of the bath temperature to heat input.

8.1.4 Thermal Conductivity

Thermal conductivity measures how easily heat flows through the fluid. Ther

mal conductivity of the fluid affects the control stability, temperature unifor

mity, and probe temperature settling time. Fluids with higher conductivity distribute heat more quickly and evenly improving bath performance.

8.1.5 Thermal Expansion

Thermal expansion describes how the volume of the fluid changes with temperature. Thermal expansion of the fluid used must be considered since the increase in fluid volume as the bath temperature changes may cause overflow. Excessive thermal expansion may also be undesirable in applications where constant liquid level is important. Oils typically have significant thermal expansion.

8.1.6 Electrical Resistivity

Electrical resistivity describes how well the fluid insulates against the flow of electric current. In some applications, such as measuring the resistance of bare temperature sensors, it may be important that little or no electrical leakage occur through the fluid. In this case consider a fluid with very high resistivity.

8.1.7 Fluid Lifetime

Many fluids degrade over time because of evaporization, water absorption, gel

ling, or chemical breakdown. Often the degradation becomes significant near the upper temperature limit of the fluid.

8.1.8 Safety

When choosing a fluid always consider the safety issues associated. Obviously, where there are extreme temperatures there can be danger to personnel and equipment. Fluids may also be hazardous for other reasons. Some fluids may be considered toxic. Contact with eyes, skin, or inhalation of vapors may cause injury. A proper fume hood must be used if hazardous or bothersome vapors are produced.

WARNING: Fluids at high temperatures. May pose danger from BURNS,

FIRE, and TOXIC fumes. Use appropriate caution and safety equipment.

7012 Calibration Bath

User’s Guide

Page 32

Fluids may be flammable and require special fire safety equipment and proce

dures. An important characteristic of the fluid to consider is the flash point. The flash point is the temperature at which there is sufficient vapor given off so that when there is sufficient oxygen present and an ignition source is applied the va

por will ignite. This does not necessarily mean that fire will be sustained at the flash point. The flash point may be either of the open cup or closed cup type. Either condition may occur in a bath situation. The closed cup temperature is always the lower of the two. The closed cup represents the contained vapors in

side the tank and the open cup represents the vapors escaping the tank. Oxygen and an ignition source will be less available inside the tank.

Environmentally hazardous fluids require special disposal according to applica

ble federal or local laws after use.

8.1.9 Cost

Cost of bath fluids may vary greatly, from cents per gallon for water to hun

dreds of dollars per gallon for synthetic oils. Cost may be an important consid

eration when choosing a fluid.

8.1.10 Commonly Used Fluids

Below is a description of some of the more commonly used fluids and their characteristics.

8.1.10.1 Water

Water is often used because of its very low cost, availability, and excellent temperature control characteristics. Water has very low viscosity and good thermal conductivity and heat capacity which makes it among the best fluids for control stability at low temperatures. Temperature stability is much poorer at higher temperatures because water condenses on the lid, cools and drips into the bath. Water is safe and relatively inert. The electrical conductivity of water may pre

vent its use in some applications. Water has a limited temperature range, from a few degrees above 0°C to a few degrees below 100°C. At higher temperatures evaporation becomes significant. Water used in the bath should be distilled or softened to prevent mineral deposits. Consider using an algicide chemical in the water to prevent contamination.

8.1.10.2 Ethylene Glycol

The temperature range of water may be extended by using a solution of 1 part water and 1 part ethylene glycol (antifreeze). The characteristics of the ethylene glycol-water solution are similar to water. Use caution with ethylene glycol since the fluid is very toxic. Ethylene glycol must be disposed of properly.

8.1.10.3 Methanol

Methanol or methyl alchohol is often used at low temperatures below 0°C. Methanol is relatively inexpensive, has good control characteristics, and has a

8 General Operation

Heat Transfer Fluid

Page 33

low freeze point. Methanol is very toxic so care must be taken when using and disposing of this fluid.

8.1.10.4 Mineral Oil

Mineral oil or paraffin oil is often used at moderate temperatures above the range of water. Mineral oil is relatively inexpensive. At lower temperatures mineral oil is quite viscous and control may be poor. At higher temperatures vapor emission becomes significant. The vapors may be dangerous and a fume hood should be used. As with most oils mineral oil will expand as temperature increases so be careful not to fill the bath too full that it overflows when heated. The viscosity and thermal characteristics of mineral oil is poorer than water so temperature stability will not be as good. Mineral oil has very low electrical conductivity. Use caution with mineral oil since it is flammable and may also cause serious injury if inhaled or ingested.

8.1.10.5 Silicone Oils

Silicone oils are available which offer a much wider operating temperature range than mineral oil. Like most oils, silicone oils have temperature control characteristics which are somewhat poorer than water. The viscosity changes significantly with temperature and thermal expansion also occurs. These oils have very high electrical resistivity. Silicon oils are fairly safe. These oils are relatively expensive.

8.1.11 Fluid Characteristics Charts

Table 2 and Figure 6 have been created to provide help in selecting a heat ex-

change fluid media for your constant temperature bath. The charts provide both a visual and numerical representation of most of the physical qualities important in making a selection. The list is not all inclusive, many usable fluids may not have been shown in this listing.

8.1.11.1 Limitations and Disclaimer

Every effort has gone into making these charts accurate, however, the data here does not imply any guarantee of fitness of use for a particular application. Working near the limits of a property such as the flash point or viscosity limit can compromise safety or serviceability. Sources of information sometimes vary for particular properties. Your company’s safety policies as well as per

sonal judgment regarding flash points, toxicity, etc. must also be considered. You are responsible for reading the Material Safety Data Sheets and making a judgment here. Cost may require some compromises as well. Hart Scientific cannot be liable for the suitability of application or for any personal injury, damage to equipment, product or facilities in using these fluids.

The charts include information on a variety of fluids which are often used as heat transfer fluid in baths. Because of the temperature range some fluids may not be useful with your bath.

7012 Calibration Bath

User’s Guide

Page 34

8.1.11.2 About the Graph

The fluid graph visually illustrates some of the important qualities of the fluids shown.

Temperature Range: The temperature scale is shown in degrees Celsius. A sense of the fluid’s general range of application is indicated. Qualities including pour point, freeze point, important viscosity points, flash point, boiling point and others may be shown.

8 General Operation

Heat Transfer Fluid

Figure 6 Chart of various bath fluids and their properties

Page 35

Freezing Point: The freezing point of a fluid is an obvious limitation to stir

ring. As the freezing point is approached high viscosity may also limit good stirring.

Pour Point: This represents a handling limit for the fluid.

Viscosity: Points shown are at 50 and 10 centistokes. Greater than 50 centi

stokes stirring is very poor and unsatisfactory for bath applications. At 10 centistokes and below optimum stirring can occur. These are rules of thumb which have been useful for most applications.

7012 Calibration Bath

User’s Guide

Fluid (# = Hart Part No.)

Lower Temperature Limit*

Upper Temperature Limit*

Flash Point

Viscosity (centistokes)

Specific Gravity

Specific Heat (cal/g/°C)

Thermal Conductivity (cal/s/cm/°C)

Thermal Expansion (cm/cm/°C)

Resistivity (10

-cm )

Halocarbon 0.8 #5019

–90°C (v)** 70°C (e) NONE 5.7 @ –50°C

0.8 @ 40°C

0.5 @ 70°C

1.71 @ 40°C 0.2 0.0004 0.0011

Methanol –96°C (fr) 60°C (b) 54°C 1.3 @ –35°C

0.66 @ 0°C

0.45 @ 20°C

0.810 @ 0°C

0.792 @ 20°C

0.6 0.0005 @ 20°C 0.0014 @ 25°C

Water 0°C (fr) 95°C (b) NONE 1 @ 25°C

0.4 @ 75°C

1.00 1.00 0.0014 0.0002 @ 25°C

Ethylene Glycol—50% #5020

–35°C (fr) 110°C (b) NONE 7 @ 0°C

2 @ 50°C

0.7 @ 100°C

1.05 0.8 @ 0°C 0.001

Mineral Oil 40°C (v) 190°C (fl) 190°C 15 @ 75°C

5 @ 125°C

0.87 @ 25°C

0.84 @ 75°C

0.81 @ 125°C

0.48 @ 25°C

0.53 @ 75°C

0.57 @ 125°C

0.00025 @ 25°C 0.0007 @ 50°C 5 @ 25°C

Dow Corning

200.5 Silicone Oil

–40°C (v)** 133°C (fl, cc) 133°C 5 @ 25°C 0.92 @ 25°C 0.4 0.00028 @ 25°C 0.00105 1000 @ 25°C

10 @ 150°C

Dow Corning

200.10 #5012

–35°C (v)** 165°C (fl, cc) 165°C 10 @ 25°C

3 @ 135°C

0.934 @ 25°C 0.43 @ 40°C

0.45 @ 100°C

0.482 @ 200°C

0.00032 @ 25°C 0.00108 1000 @ 25°C 50 @ 150°C

Dow Corning

200.20 #5013

7°C (v) 230°C (fl, cc) 230°C 20 @ 25°C 0.949 @ 25°C 0.370 @ 40°C

0.393 @ 100°C

0.420 @ 200°C

0.00034 @ 25°C 0.00107 1000 @ 25°C 50 @ 150°C

Dow Corning

200.50 Silicone Oil

25°C (v) 280°C (fl, cc) 280°C 20 @ 25°C 0.96 @ 25°C 0.4 0.00037 @ 25°C 0.00104 1000 @ 25°C

50 @ 150°C

Dow Corning 550 #5016

70°C (v) 232°C (fl, cc)

300°C (fl, oc)

232°C 50 @ 70°C

10 @ 104°C

1.07 @ 25°C 0.358 @ 40°C

0.386 @ 100°C

0.433 @ 200°C

0.00035 @ 25°C 0.00075 100 @ 25°C 1 @ 150°C

Dow Corning 710

#5017

80°C (v) 302°C (fl, oc) 302°C 50 @ 80°C

7 @ 204°C

1.11 @ 25°C 0.363 @ 40°C

0.454 @ 100°C

0.505 @ 200°C

0.00035 @ 25°C 0.00077 100 @ 25°C 1 @ 150°C

Dow Corning 210-H Silicone Oil

66°C (v) 315°C (fl, oc) 315°C 50 @ 66°C

14 @ 204°C

0.96 @ 25°C 0.34 @ 100°C 0.0003 0.00095 100 @ 25°C 1 @ 150°C

Heat Transfer Salt #5001

145°C (fr) 530°C NONE 34 @ 150°C

6.5 @ 300°C

2.4 @ 500°C

2.0 @ 150°C

1.9 @ 300°C

1.7 @ 500°C

0.33 0.0014 0.00041

1.7

/cm

*Limiting Factors — b - boiling point e - high evaporation fl - flash point fr - freeze point v - viscosity — Flash point test oc = open cup cc = closed cup **Very low water solubility, ice will form as a slush from condensation below freezing.

Table 2 Table of various bath fluids and their properties

Page 36

Fume Point: The point at which a fume hood should be used. This point is very subjective in nature and is impacted by individual tolerance to different fumes and smells, how well the bath is covered, the surface area of the fluid in the bath, the size and ventilation of the facility where the bath is located and others. We assume the bath is well covered at this point. This is also subject to company policy.

Flash Point: The point at which ignition may occur. See flash point discussion in Section 8.1.8. The point shown may be either the open or closed cup flash point.

Boiling Point: At the boiling point of the fluid the temperature stability is diffi

cult to maintain. Fuming is excessive. Excessive amounts of heater power may be required because of the heat of vaporization.

Decomposition: All high temperature fluids may be reach a temperature point at which decomposition of some form will begin. While it always begins slowly at some lower temperature, the rate can increase to the point of danger or im

practicality at a higher temperature.

8.2 Stirring

Stirring of the bath fluid is very important for stable temperature control. The fluid must be mixed well for good temperature uniformity and fast controller response. The stirrer is precisely adjusted for optimum performance.

8.3 Power

Power to the bath is provided by an AC mains supply. Refer to Section 3.1, Specifications, for power requirement details. Power to the bath passes through a filter to prevent switching spikes from being transmitted to other equipment. Refer to and read the WARNING at the front of this manual concerning brown

out and over voltage protection.

To turn on the bath switch the control panel power switch to the ON position. The stir motor will turn on, the LED display will begin to show the bath tem

perature, and the heater will turn on or off until the bath temperature reaches the programmed set-point.

When powered on the control panel display briefly shows a four digit number. This number indicates the number of times power has been applied to the bath. Also briefly displayed is data which indicates the controller hardware configu

ration. This data is used in some circumstances for diagnostic purposes.

8.4 Heater

The power to the bath heater is precisely controlled by the temperature control

ler to maintain a constant bath temperature. Power is controlled by periodically switching the heater on for a certain amount of time using a solid-state relay.

8 General Operation

Stirring

Page 37

The front panel red/green control indicator shows the state of the heater. The control indicator glows red when the heater is on and glows green when the heater is off. The indicator will pulse constantly when the bath is maintaining a stable temperature.

The heater has two power level settings. The “HIGH” heater power setting is used to quickly heat up the bath fluid to the desired operating temperature. The “HIGH” heater power setting may also be required for control at high tempera

tures. The “LOW” setting is used for control at lower temperatures and for scanning at slower rates. When controlling at the “HIGH” heater power setting instead of “LOW” the proportional band may need to be increased (typically by a factor of four) to compensate for the increase in power gain. Otherwise the temperature may oscillate.

8.5 Cooling

The back pressure control valve limits the cooling capacity of the unit. It will normally be open all the way (full CCW) for temperature slewing and opera

tion. If during operation the front panel meter indicates excessive cooling, this valve is closed partially (turn CW) until the percentage of heating to cooling is brought into line. It is necessary to wait a few minutes after each adjustment until the system settles.

Set the COOLING TEMPERATURE according to the cooling label. The cooling temperature should NOT be set above 90 psig. At about 45°C the refrigeration will not be required as there is sufficient cooling to the room. Wait a few minutes after each adjustment until the system establishes itself. Readjust if required after settling for a while.

For maximum cooling for slewing to lower temperatures, the BACK PRESSURE valve should be fully open and the COOLING TEMPERATURE set to 0°C. Readjust higher or lower as required after set temperature is reached.

8.6 Fluid Drain

The drain at the back of the bath (see Figure 4 and Figure 5 on pages 24 and

25) may be used to remove fluid from the bath. During operation of the bath the drain must be closed.

8.7 Temperature Controller

The bath temperature is controlled by Hart Scientific’s unique hybrid digi

tal/analog temperature controller. The controller offers the tight control stability of an analog temperature controller as well as the flexibility and programmabil

ity of a digital controller.

The bath temperature is monitored with a linear thermistor sensor in the control probe. The signal is electronically compared with the programmable reference

7012 Calibration Bath

User’s Guide

Page 38

signal, amplified, and then fed to a pulse-width modulator circuit which con

trols the amount of power applied to the bath heater.

The bath is operable within the temperature range given in the specifications. For protection against solid-state relay failure or other circuit failure, the microcontroller automatically turns off the heater with a second mechanical re

lay anytime the bath temperature is more than a certain amount above the set-point temperature. As a second protection device, the controller is also equipped with a separate thermocouple temperature monitoring circuit which shuts off the heater if the temperature exceeds the cut-out set-point.

The controller allows the operator to set the bath temperature with high resolu

tion, set the cut-out, adjust the proportional band, monitor the heater output power, and program the controller configuration and calibration parameters. The controller may be operated in temperature units of degrees Celsius or Fahr

enheit. The controller is operated and programmed from the front control panel using the four key switches and digital LED display. The controller may also be optionally equipped with a serial RS-232 or IEEE-488 GPIB digital interface for remote operation. Operation of the controller using the front control panel is discussed in Section 9. Operation using the digital interfaces is discussed in Section 10.

When the controller is set to a new set-point the bath heats or cool to the new temperature. Once the new temperature is reached the bath usually takes 10-15 minutes for the temperature to settle and stabilize. There may be a small overshoot or undershoot of about 0.5°C.

8 General Operation

Temperature Controller

Page 39

9 Controller Operation

This section discusses in detail how to operate the bath temperature controller using the front control panel. Using the front panel key switches and LED dis

play the user may monitor the bath temperature, set the temperature set-point in degrees C or F, monitor the heater output power, adjust the controller propor

tional band, set the cutout set-point, and program the probe calibration parame

ters, operating parameters, serial and IEEE-488 interface configuration, and controller calibration parameters. Operation is summarized in Figure 7.

9.1 Bath Temperature

The digital LED display on the front panel allows direct viewing of the actual bath temperature. This temperature value is what is normally shown on the dis

play. The units, C or F, of the temperature value are displayed at the right. For example,

25.00 C

Bath temperature in degrees Celsius

The temperature display function may be accessed from any other function by pressing the “EXIT” button.

9.2 Reset Cutout

If the over-temperature cutout has been triggered then the temperature display will alternately flash,

Cut-out Indicates cutout condition

The message continues to flash until the temperature is reduced and the cutout is reset.

The cutout has two modes — automatic reset and manual reset. The mode de

termines how the cutout is reset which allows the bath to heat up again. When in automatic mode, the cutout resets itself as soon as the temperature is lowered below the cutout set-point. With manual reset mode the cutout must be reset by the operator after the temperature falls below the set-point.

When the cutout is active and the cutout mode is set to manual (“reset”) then the display will flash “cutout” until the user resets the cutout. To access the reset cutout function press the “SET” button.

Access cutout reset function

The display will indicate the reset function.

9 Controller Operation

Bath Temperature

Page 40

7012 Calibration Bath

User’s Guide

Figure 7 Controller Operation Flowchart

Page 41

rESEt ?

Cutout reset function

Press “SET” once more to reset the cutout.

Reset cutout

This switchs the display to the set temperature function. To return to displaying the temperature press the “EXIT” button. If the cutout is still in the over-tem

perature fault condition the display continues to flash “Cut-out”. The bath temperature must drop a few degrees below the cutout set-point before the cut

out can be reset.

9.3 Temperature Set-point

The bath temperature can be set to any value within the range and with resolu

tion as given in the specifications. The temperature range of the particular fluid used in the bath must be known by the operator and the bath should only be op

erated well below the upper temperature limit of the liquid. In addition, the cutout temperature should also be set below the upper limit of the fluid.

Setting the bath temperature involves three steps: (1) select the set-point memory, (2) adjust the set-point value, and (3) adjust the vernier if desired.

9.3.1 Programmable Set-points

The controller stores 8 set-point temperatures in memory. The set-points can be quickly recalled to conveniently set the bath to a previously programmed temperature set-point.

To set the bath temperature one must first select the set-point memory. This function is accessed from the temperature display function by pressing “SET”. The number of the set-point memory currently being used is shown at the left on the display followed by the current set-point value.

25.00 C

Bath temperature in degrees Celsius

Access set-point memory

1. 25.0

Set-point memory 1, 25.0°C currently used

To change the set-point memory press “UP” or “DOWN”.

4. 40.0

New set-point memory 4, 40.0°C

Press “SET” to accept the new selection and access the set-point value.

9 Controller Operation

Temperature Set-point

Page 42

Accept selected set-point memory

9.3.2 Set-point Value

The set-point value may be adjusted after selecting the set-point memory and pressing “SET”. The set-point value is displayed with the units, C or F, at the left.

C 40.00

Set-point 4 value in °C

If the set-point value need not be changed then press “EXIT” to resume dis

playing the bath temperature. Press “UP” or “DOWN” to adjust the set-point value.

C 42.50

New set-point value

When the desired set-point value is reached press “SET” to accept the new value and access the set-point vernier. If “EXIT” is pressed instead then any changes made to the set-point will be ignored.

Accept new set-point value

9.3.3 Set-point Vernier

The set-point value can only be set with a resolution of 0.002°C. The user may want to adjust the set-point slightly to achieve a precise bath temperature. The set-point vernier allows one to adjust the temperature below or above the set-point by a small amount with very high resolution. Each of the 8 stored set-points has an associated vernier setting. The vernier is accessed from the set-point by pressing “SET”. The vernier setting is displayed as a 6 digit num

ber with five digits after the decimal point. This is a temperature offset in de

grees of the selected units, C or F.

0.00000

Current vernier value in °C

To adjust the vernier press “UP” or “DOWN”. Unlike most functions the ver

nier setting has immediate effect as the vernier is adjusted. “SET” need not be pressed. This allows one to continually adjust the bath temperature with the vernierasitisdisplayed.

0.00090

New vernier setting

Next press “EXIT” to return to the temperature display or “SET” to access the temperature scale units selection.

7012 Calibration Bath

User’s Guide

Page 43

Access scale units

9.4 Temperature Scale Units

The temperature scale units of the controller may be set by the user to degrees Celsius (°C) or Fahrenheit (°F). These units are used in displaying the bath temperature, set-point, vernier, proportional band, and cutout set-point.

The temperature scale units selection is accessed after the vernier adjustment function by pressing “SET”. From the temperature display function access the units selection by pressing “SET” 4 times.

25.00 C

Bath temperature

Access set-point memory

1. 25.0

Set-point memory

Access set-point value

C 25.00

Set-point value

Access vernier

0.00000

Vernier setting

Access scale units selection

Un= C

Scale units currently selected

Press “UP” or “DOWN” to change the units.

Un= F

New units selected

Press “SET” to accept the new selection and resume displaying the bath temperature.

Set the new units and resume temperature display

9 Controller Operation

Temperature Scale Units

Page 44

9.5 Secondary Menu

Functions which are used less often are accessed within the secondary menu. The secondary menu is accessed by pressing “SET” and “EXIT” simulta

neously and then releasing. The first function in the secondary menu is the heater power display.

9.6 Heater Power

The temperature controller controls the temperature of the bath by pulsing the heater on and off. The total power being applied to the heater is determined by the duty cycle or the ratio of heater on time to the pulse cycle time. This value may be estimated by watching the red/green control indicator light or read di

rectly from the digital display. By knowing the amount of heating to the bath the user can tell if the bath is heating up to the set-point, cooling down, or con

trolling at a constant temperature. Monitoring the percent heater power will let the user know how stable the bath temperature is. With good control stability

the percent heating power should not fluctuate more than ±1% within one minute.

The heater power display is accessed in the secondary menu. Press “SET” and “EXIT” simultaneously and release. The heater power will be displayed as a percentage of full power.

S+E

Access heater power in secondary menu

12 Pct

Heater power in percent

To exit out of the secondary menu press “EXIT”. To continue on to the propor

tional band setting function press “SET”.

9.7 Proportional Band

In a proportional controller such as this the heater output power is proportional to the bath temperature over a limited range of temperatures around the set-point. This range of temperature is called the proportional band. At the bot

tom of the proportional band the heater output is 100%. At the top of the pro

portional band the heater output is 0. Thus as the bath temperature rises the heater power is reduced, which consequently tends to lower the temperature back down. In this way the temperature is maintained at a fairly constant temperature.

The temperature stability of the bath depends on the width of the proportional band. See Figure 8. If the band is too wide the bath temperature will deviate ex

cessively from the set-point due to varying external conditions. This is because the power output changes very little with temperature and the controller cannot respond very well to changing conditions or noise in the system. If the propor

7012 Calibration Bath

User’s Guide

Page 45

tional band is too narrow the bath temperature may swing back and forth be

cause the controller overreacts to temperature variations. For best control stability the proportional band must be set for the optimum width.

The optimum proportional band width depends on several factors among which are fluid volume, fluid characteristics (viscosity, specific heat, thermal conductivity), heater power setting, operating temperature, and stirring. Thus the proportional band width may require adjustment for best bath stability when any of these conditions change. Of these, the most significant factors affecting the optimum proportional band width are heater power setting and fluid viscosity. The proportional band should be wider when the higher power setting is used so that the change in output power per change in temperature remains the same.

9 Controller Operation

Proportional Band

Fluid Temperature Heater Setting

Proportional Band Stability

Water 30.0°C Low 0.04°C

0.0004°C

Water 60.0°C Low 0.04°C

0.001°C

Eth-Gly 50% 35.0°C Low 0.05°C

0.0005°C

Eth-Gly 50% 60.0°C Low 0.05°C

0.001°C

Eth-Gly 50% 100.0°C High 0.4°C

0.007°C

Oil 35.0°C Low 0.1°C

0.003°C

Oil 60.0°C Low 0.2°C

0.002°C

Oil 100°C Low 0.2°C

0.003°C

Table 3 Proportional Band — Fluid Table

Figure 8 Bath temperature fluctuation at various proportional band settings

Page 46

The proportional band should also be wider when the fluid viscosity is higher because of the increased response time.

The proportional band width is easily adjusted from the bath front panel. The width may be set to discrete values in degrees C or F depending on the selected units. The optimum proportional band width setting may be determined by monitoring the stability with a high resolution thermometer or with the control

ler percent output power display. Narrow the proportional band width to the point at which the bath temperature begins to oscillate and then increase the band width from this point to 3 or 4 times wider. Table 3 lists typical propor

tional band settings for optimum performance with a variety of fluids at se

lected temperatures.

The proportional band adjustment may be accessed within the secondary menu. Press “SET” and “EXIT” to enter the secondary menu and show the heater power. Then press “SET” to access the proportional band.

S+E

Access heater power in secondary menu

12 Pct

Heater power in percent

Access proportional band

Pb=0.101C

Proportional band setting

To change the proportional band press “UP” or “DOWN”.

Pb=0.060C

New proportional band setting

To accept the new setting and access the cutout set-point press “SET”. Pressing “EXIT” will exit the secondary menu ignoring any changes just made to the proportional band value.

Accept the new proportional band setting

9.8 Cutout

As a protection against software or hardware fault, shorted heater triac, or user error, the bath is equipped with an adjustable heater cutout device that shuts off power to the heater if the bath temperature exceeds a set value. This protects the heater and bath materials from excessive temperatures and, most impor

tantly, protects the bath fluids from being heated beyond the safe operating temperature preventing hazardous vaporization, breakdown, or ignition of the liquid. The cutout temperature is programmable by the operator from the front panel of the controller. It must always be set below the upper temperature limit

7012 Calibration Bath

User’s Guide

Page 47

of the fluid and no more than 10 degrees above the upper temperature limit of the bath.

If the cutout is activated because of excessive bath temperature, power to the heater shuts off and the bath cools. The bath cools until it reaches a few degrees below the cutout set-point temperature. At this point the action of the cutout is determined by the setting of the cutout mode parameter. The cutout has two selectable modes — automatic reset or manual reset. If the mode is set to auto

matic, the cutout automatically resets itself when the bath temperature falls be

low the reset temperature allowing the bath to heat up again. If the mode is set to manual, the heater remains disabled until the user manually resets the cutout.

The cutout set-point may be accessed within the secondary menu. Press “SET” and “EXIT” to enter the secondary menu and show the heater power. Then press “SET” twice to access the cutout set-point.

S+E

Access heater power in secondary menu

12 Pct

Heater power in percent

Access proportional band

Pb=0.101C

Proportional band setting

Access cutout set-point

CO= 110C

cutout set-point

To change the cutout set-point press “UP” or “DOWN”.

CO= 75C

New cutout set-point

To accept the new cutout set-point press “SET”.

Accept cutout set-point

The next function is the configuration menu. Press “EXIT” to resume display

ing the bath temperature.

9.9 Controller Configuration

The controller has a number of configuration and operating options and calibra

tion parameters which are programmable via the front panel. These are ac

cessed from the secondary menu after the cutout set-point function by pressing

9 Controller Operation

Controller Configuration

Page 48

“SET.” There are 5 sets of configuration parameters — probe parameters, oper

ating parameters, serial interface parameters, IEEE-488 interface parameters, and controller calibration parameters. The menus are selected using the “UP” and “DOWN” keys and then pressing “SET”.

9.10 Probe Parameters

The probe parameter menu is indicated by,

PrObE

Probe parameters menu

Press “SET” to enter the menu. The probe parameters menu contains the pa

rameters, D0 and Dg, which characterize the resistance-temperature relation

ship of the thermistor control probe. These parameters may be adjusted to improve the accuracy of the bath. This procedure is explained in detail in Sec

tion 11.

The probe parameters are accessed by pressing “SET” after the name of the pa

rameter is displayed. The value of the parameter may be changed using the “UP” and “DOWN” buttons. After the desired value is reached press “SET” to set the parameter to the new value. Pressing “EXIT” will cause the parameter to be skipped ignoring any changes that may have been made.

9.10.1 D0

This probe parameter refers to the resistance of the control probe at 0°C. Normally this is set for –25.2290 ohms.

9.10.2 Dg

This probe parameter refers to the average sensitivity of the probe between 0 and 100°C. Normally this is set for 186.9740

9.11 Operating Parameters

The operating parameters menu is indicated by,

PAr

Operating parameters menu

Press “SET” to enter the menu. The operating parameters menu contains the cutout reset mode setting.

9.11.1 Cutout Reset Mode

The cutout reset mode determines whether the cutout resets automatically when the bath temperature drops to a safe value or must be manually reset by the operator.

The parameter is indicated by,

7012 Calibration Bath

User’s Guide

Page 49

CtorSt

Cutout reset mode parameter

Press “SET” to access the parameter setting. Normally the cutout is set for manual mode.

Cto=rSt Cutout set for manual reset

To change to automatic reset mode press “UP” and then “SET”.

Cto=Auto Cutout set for automatic reset

9.12 Serial Interface Parameters

The 7012 bath may optionally be fitted with an RS-232 interface. The serial RS-232 interface parameters menu is indicated by,

SErIAL Serial RS-232 interface parameters menu

The serial interface parameters menu contains parameters which determine the operation of the serial interface. These controls only apply to baths fitted with the serial interface. The parameters in the menu are — BAUD rate, sample period, duplex mode, and linefeed.

9.12.1 Baud Rate

The baud rate is the first parameter in the menu. The baud rate setting determines the serial communications transmission rate.

The baud rate parameter is indicated by,

BAUd Serial baud rate parameter

Press “SET” to choose to set the baud rate. The current baud rate value will then be displayed.

1200 b Current baud rate

The baud rate of the bath serial communications may be programmed to 300,600,1200, or 2400 baud. Use “UP” or “DOWN” to change the baud rate value.

2400 b New baud rate

Press “SET” to set the baud rate to the new value or “EXIT” to abort the opera

tion and skip to the next parameter in the menu.

9 Controller Operation

Serial Interface Parameters

Page 50

9.12.2 Sample Period

The sample period is the next parameter in the serial interface parameter menu. The sample period is the time period in seconds between temperature measure

ments transmitted from the serial interface. If the sample rate is set to 5, the bath transmits the current measurement over the serial interface approximately every five seconds. The automatic sampling is disabled with a sample period of

0. The sample period is indicated by,

SAmPLE

Serial sample period parameter

Press “SET” to choose to set the sample period. The current sample period value will be displayed.

SA= 1

Current sample period (seconds)

Adjust the value with “UP” or “DOWN” and then use “SET” to set the sample rate to the displayed value.

SA= 60

New sample period

9.12.3 Duplex Mode

The next parameter is the duplex mode. The duplex mode may be set to full duplex or half duplex. With full duplex any commands received by the bath via the serial interface are immediately echoed or transmitted back to the device of origin. With half duplex the commands are executed but not echoed. The duplex mode parameter is indicated by,

dUPL

Serial duplex mode parameter

Press “SET” to access the mode setting.

dUP=FULL

Current duplex mode setting

The mode may be changed using “UP” or “DOWN” and pressing “SET”.

dUP=HALF

New duplex mode setting

9.12.4 Linefeed

The final parameter in the serial interface menu is the linefeed mode. This pa

rameter enables (on) or disables (off) transmission of a linefeed character (LF, ASCII 10) after transmission of any carriage-return. The linefeed parameter is indicated by,

Serial linefeed parameter

7012 Calibration Bath

User’s Guide

Page 51

Press “SET” to access the linefeed parameter.

LF= On

Current linefeed setting

The mode may be changed using “UP” or “DOWN” and pressing “SET”.

LF= OFF

New linefeed setting

9.13 IEEE-488 Parameters

Baths may optionally be fitted with an IEEE-488 GPIB interface. In this case the user may set the interface address within the IEEE-488 parameter menu. This menu does not appear on baths not fitted with the interface. The menu is indicated by,

IEEE

IEEE-488 parameters menu

Press “SET” to enter the menu.

9.13.1 IEEE-488 Address

The IEEE-488 interface must be configured to use the same address as the external communicating device. The address is indicated by,

AddrESS I

EEE-488 interface address

Press “SET” to access the address setting.

Add= 22

Current IEEE-488 interface address

Adjust the value with “UP” or “DOWN” and then use “SET” to set the address to the displayed value.

Add= 15

New IEEE-488 interface address

9.14 Calibration Parameters

The operator of the bath controller has access to a number of the bath calibra

tion constants namely CTO, H, and L. These values are set at the factory and must not be altered. The correct values are important to the accuracy and proper and safe operation of the bath. Access to these parameters is available to the user only so that in the event that the controller’s memory fails the user may restore these values to the factory settings. The user should have a list of these constants and their settings with the manual.

9 Controller Operation

IEEE-488 Parameters

Page 52

DO NOT change the values of the bath calibration constants from the factory set

values. The correct setting of these parameters is important to the safety and proper operation of the bath.

The calibration parameters menu is indicated by,

CAL

Calibration parameters menu

Press “SET” five times to enter the menu.

9.14.1 CTO

Parameter CTO sets the calibration of the over-temperature cutout. This is not adjustable by software but is adjusted with an internal potentiometer. For the 7012 baths this parameter should read between 120.

9.14.2 H and L

These parameters set the upper and lower set-point limits of the bath. DO NOT change the values of these parameters from the factory set values. To do so may present danger of the bath exceeding its temperature range causing damage or fire.

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10 Digital Communication Interface

If supplied with the option, the 7012 bath is capable of communicating with and being controlled by other equipment through the digital interface. Two types of digital interface are available — the RS-232 serial interface and the IEEE-488 GPIB interface.

With a digital interface the bath may be connected to a computer or other equipment. This allows the user to set the bath temperature, monitor the tem

perature, and access any of the other controller functions, all using remote com

munications equipment. In addition the heater power setting and cooling capacity may be controlled using the interface. To enable the heater to be switched to high using the interface the “HEATER” switch must be set to the “LOW” position. The cooling power switch must be set to OFF to enable re

mote control.

10.1 Serial Communications

The bath may be installed with an RS-232 serial interface that allows serial digital communications over fairly long distances. With the serial interface the user may access any of the functions, parameters and settings discussed in Section 9 with the exception of the BAUD rate setting. The serial interface uses 8 data bits, 1 stop bit, and no parity.

10.1.1 Wiring

The serial communications cable attaches to the bath through the DB-9 connector at the back of the instrument. Figure 9 shows the pin-out of this connector and sug

gested cable wiring. To eliminate noise, the serial cable should be shielded with low resistance be

tween the connector (DB-9) and the shield.

10.1.2 Setup

Before operation the serial inter

face of the bath must first be set

10 Digital Communication Interface

Serial Communications

Figure 9 Serial Communications Cable Wiring

Page 54

up by programming the baud rate and other configuration parameters. These parameters are programmed within the serial interface menu.

To enter the serial parameter programming mode first press “EXIT” while pressing “SET” and release to enter the secondary menu. Press “SET” repeat

edly until the display reads “ ProbE”. This is the menu selection. Press “UP” repeatedly until the serial interface menu is indicated with “SErIAL”. Finally press “SET” to enter the serial parameter menu. In the serial interface parame

ters menu are the baud rate, the sample rate, the duplex mode, and the linefeed parameter.

10.1.2.1 Baud rate

The baud rate is the first parameter in the menu. The display will prompt with the baud rate parameter by showing “BAUd” . Press “SET” to choose to set the baud rate. The current baud rate value will then be displayed. The baud rate of the 7012 serial communications may be programmed to 300,600,1200, or 2400 baud. The baud rate is pre-programmed to 1200 baud. Use “UP” or “DOWN” to change the baud rate value. Press “SET” to set the baud rate to the new value or “EXIT” to abort the operation and skip to the next parameter in the menu.

10.1.2.2 Sample Period

The sample period is the next parameter in the menu and prompted with “SAmPLE”. The sample period is the time period in seconds between temperature

measurements transmitted from the serial interface. If the sample rate is set to 5, the 7012 transmits the current measurement over the serial interface approximately every five seconds. The automatic sampling is disabled with a sample period of 0. Press “SET” to choose to set the sample period. Adjust the period with “UP” or “DOWN” and then use “SET” to set the sample rate to the displayed value.

10.1.2.3 Duplex Mode

The next parameter is the duplex mode indicated with “dUPL”. The duplex mode may be set to half duplex (“HALF”) or full duplex (“FULL”). With full duplex any commands received by the thermometer via the serial interface are immediately echoed or transmitted back to the device of origin. With half du

plex the commands are executed but not echoed. The default setting is full du

plex. The mode may be changed using “UP” or “DOWN” and pressing “SET”.

10.1.2.4 Linefeed

The final parameter in the serial interface menu is the linefeed mode. This pa

rameter enables (“On”) or disables (“OFF”) transmission of a linefeed charac

ter (LF, ASCII 10) after transmission of any carriage-return. The default setting is with linefeed on. The mode may be changed using “UP” or “DOWN” and pressing “SET”.

7012 Calibration Bath

User’s Guide

Page 55

10.1.3 Serial Operation

Once the cable has been attached and the interface set up properly the control

ler immediately begins transmitting temperature readings at the programmed rate. The set-point and other commands may be sent to the bath via the serial interface to set the bath and view or program the various parameters. The inter

face commands are discussed in Section 10.3. All commands are ASCII charac

ter strings terminated with a carriage-return character (CR, ASCII 13).

10.2 IEEE-488 Communication

The IEEE-488 interface is available as an option. Baths supplied with this op

tion may be connected to a GPIB type communication bus which allows many instruments to be connected and controlled simultaneously. To eliminate noise, the GPIB cable should be shielded.

10.2.1 Setup

To use the IEEE-488 interface first connect an IEEE-488 standard cable to the back of the bath. Next set the device address. This parameter is programmed within the IEEE-488 interface menu.

To enter the IEEE-488 parameter programming menu first press “EXIT” while pressing “SET” and release to enter the secondary menu. Press “SET” repeatedly until the display reaches “PrObE”. This is the menu selection. Press “UP” repeatedly until the IEEE-488 interface menu is indicated with “IEEE”.Press “SET” to enter the IEEE-488 parameter menu. The IEEE-488 menu contains the IEEE-488 address parameter.

10.2.1.1 IEEE-488 Interface Address

The IEEE-488 address is prompted with “AddrESS”. Press “SET” to program the address. The default address is 22. Change the device address of the bath if necessary to match the address used by the communication equipment by pressing “UP” or “DOWN” and then “SET”.

10.2.2 IEEE-488 Operation

Commands may now be sent via the IEEE-488 interface to read or set the tem

perature or access other controller functions. All commands are ASCII charac

ter strings and are terminated with a carriage-return (CR, ASCII 13). Interface commands are listed below.

10.3 Interface Commands

The various commands for accessing the bath controller functions via the digi

tal interfaces are listed in this section (see Table 4). These commands are used with both the RS-232 serial interface and the IEEE-488 GPIB interface. In ei

ther case the commands are terminated with a carriage-return character. The in

terface makes no distinction between upper and lower case letters, hence either

10 Digital Communication Interface

IEEE-488 Communication

Page 56

7012 Calibration Bath

User’s Guide

Command Description

Command Format

Command Example Returned

Returned Example

Acceptable Values

Display Temperature

Read current set-point s[etpoint] s set: 9999.99 {C or F} set: 105.00 C

Set current set-point to n s[etpoint]=n s=100 Instrument

Range

Read vernier v[ernier] v v: 9.99999 v: 0.00000

Set vernier to n v[ernier]=n v=.00001 Depends on

Configuration

Read temperature t[emperature] t t: 9999.99 {C or F} t: 55.69 C

Read temperature units u[nits] u u: x u: c

Set temperature units: u[nits]=c/f

CorF

Set temperature units to Celsius u[nits]=c u=c

Set temperature units to Fahrenheit

u[nits]=f u=f

Secondary Menu

Read proportional band setting pr[op-band] pr pr: 999.9 pr: 15.9

Set proportional band to

pr[op-band]=n pr=8.83 Depends on

Configuration

Read cutout setting c[utout] c c: 9999 {x},{xxx} c: 620 C, in

Set cutout setting: c[utout]=n/r[eset]

Set cutout to

degrees c[utout]=n c=500 Temperature

Range

Reset cutout now c[utout]=r[eset] c=r

Read heater power

(duty cycle)

po[wer] po po: 9999 po: 1 ±100

Configuration Menu

Probe Menu

Read D0 calibration parameter *d0 *d0 d0: 999.9999 d0: -25.2290

Set D0 calibration parameter to

*d0=n *d0=-25.2290 -999.9999 to

999.9999

Read DG calibration parameter *dg *dg dg: 999.9999 dg:186.9740

Set DG calibration parameter to

*dg=n *dg=186.9740 -999.9999 to

999.9999

Operating Parameters Menu

Read cutout mode cm[ode] cm cm: {xxxx} cm: AUTO

Set cutout mode: cm[ode]=r[eset]/a[uto]

RESET or AUTO

Set cutout to be reset manually- cm[ode]=r[eset] cm=r

Set cutout to be reset automatically

cm[ode]=a[uto] cm=a

Serial Interface Menu

Read serial sample setting sa[mple] sa sa: 9 sa: 1

Table 4 Interface Command Summary.

Page 57

10 Digital Communication Interface

Interface Commands

Command Description

Command Format

Command Example Returned

Returned Example

Acceptable Values

Set serial sampling setting to

seconds

sa[mple]=n sa=0 0 to 4000

Set serial duplex mode: du[plex]=f[ull]/h[alf]

FULL or HALF

Set serial duplex mode to full du[plex]=f[ull] du=f

Set serial duplex mode to half du[plex]=h[alf] du=h

Set serial linefeed mode: lf[eed]=on/of[f]

ON or OFF

Set serial linefeed mode to on lf[eed]=on lf=on

Set serial linefeed mode to off lf[eed]=of[f] lf=of

Calibration Menu

Read low set-point limit value *tl[ow] *tl tl: 999 tl: –80

Set low set-point limit to

*tl[ow]=n *tl=-80 –999.9 to 999.9

Read high set-point limit value *th[igh] *th th: 999 th: 205

Set high set-point limit to

*th[igh]=n *th=205 –999.9 to 999.9

Miscellaneous (not on menus)

Read firmware version number *ver[sion] *ver ver.9999,9.99 ver.2100,3.56

Read structure of all commands h[elp] h list of commands

Read Heater f1 f1 f1:9 f1:1

Set Heater f1=1/0 0or1

Set heater to low f1=

f1=0

Set heater to high f1=

f1=1

Read Refrigeration f2 f2 f2:9 f2:0

Set Refrigeration f2=1/0 0or1

Set Refrigeration to on f2=

f2=1

Set Refrigeration to off f2=

f2=0

Read Expansion Valve 1 f3 f3 f3:9 f3:1

Set Expansion Valve 1

f3=1/0

0or1

Set Expansion Valve 1 to on f3=

f3=1

Set Expansion Valve 1 to off f3=

f3=0

Read Cooling Power f4 f4 f4:9 f4:1

Set Back Pressure

f4=1/0

0or1

Set back pressure on f4=

f4=1

Set back pressure off f4=

f4=0

Legend: [] Optional Command data

{} Returns either information

n Numeric data supplied by user

9 Numeric data returned to user

x Character data returned to user

Note: When DUPLEX is set to FULL and a command is sent to READ, the command is returned followed by a

carriage return and linefeed. Then the value is returned as indicated in the RETURNED column.

Digital Communications Commands continued

Page 58

may be used. Commands may be abbreviated to the minimum number of letters which determines a unique command. A command may be used to either set a parameter or display a parameter depending on whether or not a value is sent with the command following a “=” character. For example “s”<CR> will return the current set-point and “s=50.00”<CR> will set the set-point to 50.00 degrees.

In the following list of commands, characters or data within brackets, “[” and “]”, are optional for the command. A slash, “/”, denotes alternate characters or data. Numeric data, denoted by “n”, may be entered in decimal or exponential notation. Characters are shown in lower case although upper case may be used. Spaces may be added within command strings and will simply be ignored. Backspace (BS, ASCII 8) may be used to erase the previous character. A termi

nating CR is implied with all commands.

10.4 Power Control Functions

The digital interface is capable of controlling the heating and cooling functions so that the bath can be remotely operated at any temperature within the range of the bath. To allow the interface to control the heating and the cooling, the front panel controls are disabled by 1) switching the heater switch to LOW, and 2) switching the refrigeration switch to OFF. Otherwise, the interface would not be able to switch these functions off. The 7012 bath has four control functions with the digital interface. These are heater power high/low, cooling on/off, expansion valve on/off, and back pressure valve on/off.

10.4.1 Heater Control

To control the heater with the digital interface the front panel heater switch must be set to LOW (500 W). The heater function is controlled with the “F1" command. Setting the “F1" parameter to 0 sets the heater to LOW (500 W) and setting it to 1 sets the heater to HIGH (1000 W). Sending “F1" with no value causes the controller to return a value showing what the heater setting is. When the heater setting is changed a pop is heard as the heater relay opens or closes.

10.4.2 Cooling Control

To control the refrigeration power with the digital interface the front panel re

frigeration switch must be off. The refrigeration power function is controlled with the “F2" command. Setting the “F2" value to 0 turns the refrigeration off and setting it to 1 turns it on. “F2" alone returns 0 or 1 showing the state of the refrigeration power control.

The “F3" command controls the “high” and “low” cooling temperature range or expansion valves. As discussed in Section 7.2 this valve adjusts the cooling temperature which sets the cooling capacity. Setting ”F3" to 1 opens the valve (on or high) and 0 closes the valve (off or low). A command with no value re

turns the current value. With the valve closed the cooling temperature is set with the cooling temperature knob labeled “LOW”. This should be adjusted for approximately 9–14 psi if the bath is to be used as low as –10°C. The knob la

7012 Calibration Bath

User’s Guide

Page 59

beled “HIGH” controls the cooling temperature when the expansion valve is open or on. This should be adjusted for approximately 45–50 psi. These values are typical but may be adjusted as required for specific applications. The low range must be set to a lower pressure (temperature) than the high range valve.

The “F4" command controls the back pressure valve. When the valve is open the cooling capacity is significantly reduced. This valve should normally be left off/closed throughout the operating range of the bath. Table 5 summarizes the control functions for heating and cooling. Table 6 shows the recommended control settings for each operating temperature range. The ranges may need to be adjusted depending on the bath application.

10 Digital Communication Interface

Power Control Functions

Function Command 0 1

Heater F1 low high

Refrigeration F2 off on

Expansion valve F3 open closed

Back pressure F4 open closed

Table 5 Serial Power Control Functions

Range Heater Refr. Exp.

–10 to 15°C low on open

15 to 40°C low on closed

40 to 110°C low/high off open

Table 6 Temperature Range Control Functions

Page 60

11 Calibration Procedure

Note: This procedure is to be considered a general guideline. Each labo

ratory should write their own procedure based on their equipment and their quality program. Each procedure should be accompanied by an un

certainty analysis also based on the laboratory’s equipment and environ

ment.

In some instances the user may want to calibrate the bath to improve the tem

perature set-point accuracy. Calibration is done by adjusting the controller probe calibration constants DO and DG so that the temperature of the bath as measured with a standard thermometer agrees more closely with the bath set-point. The thermometer used must be able to measure the bath fluid temper

ature with higher accuracy than the desired accuracy of the bath. By using a good thermometer and carefully following the procedure the bath can be cali

brated to an accuracy of better than 0.1°C over a range of 50 degrees.

11.1 Calibration Points

In calibrating the bath DO and DG are adjusted to minimize the set-point error at each of two different bath temperatures. Any two reasonably separated bath temperatures may be used for the calibration however best results are obtained when using bath temperatures which are just within the most useful operating range of the bath. The farther apart the calibration temperatures the larger will be the calibrated temperature range but the calibration error will also be greater over the range. If for instance 20°C and 80°C are chosen as the calibration tem-

peratures, the bath may achieve an accuracy of say ±0.2°C over the range 20 to 80°C. Choosing 30°C and 70°C may allow the bath to have a better accuracy of

maybe ±0.05°C over the range 30 to 70°C but outside that range the accuracy may be only ±0.5°C.

11.2 Measuring the Set-point Error

The first step in the calibration procedure is to measure the temperature errors (including sign) at the two calibration temperatures. First set the bath to the lower set-point which we will call t

. Wait for the bath to reach the set-point and allow 15 minutes to stabilize at that temperature. Check the bath stability with the thermometer. When both the bath and the thermometer have stabilized measure the bath temperature with the thermometer and compute the tempera

ture error err

which is the actual bath temperature minus the set-point temper

ature. If for example the bath is set for a lower set-point of t

=20°C and the

bath reaches a measured temperature of 19.7°C then the error is -0.3°C.

Next, set the bath for the upper set-point t

and after stabilizing measure the

bath temperature and compute the error err

. For our example we will suppose

11 Calibration Procedure

Calibration Points

Page 61

the bath was set for 80°C and the thermometer measured 80.1°C giving an error of +0.1°C.

11.3 Computing D0 and DG

Before computing the new values for D0 and DG the current values must be known. The values may be found by either accessing the probe calibration menu from the controller panel or by inquiring through the digital interface. The user should keep a record of these values in case they may need to be re

stored in the future. The new values DO′ and DG′ are computed by entering the old values for DO and DG, the calibration temperature set-points t

and tH,and

the temperature errors err

and errHinto the following equations,

err t D err t D

LH HL

0′=

−− −

−

()()

err err

′=

−

⎡ ⎣

⎢

⎤ ⎦

⎥

If for example D0 and DG were previously set for –25.229 and 186.9740 respectively and the data for t

L,tH

,errL,anderrHwere as given above then the

new values D0′ and DG′ would be computed as –25.831 and 188.220 respectively. Program the new values D0 and DG into the controller. The new constants will be used the next time the bath temperature is set. Check the calibration by setting the temperature to t

and tHand measuring the errors

again. If desired the calibration procedure may be repeated again to further im

prove the accuracy.

11.4 Calibration Example

The bath is to be used between 25 and 75°C and it is desired to calibrate the bath as accurately as possible for operation within this range. The current val

ues for D0 and DG are –25.229 and 186.974 respectively. The calibration points are chosen to be 25.00 and 75.00°C. The measured bath temperatures are

24.869 and 74.901°C respectively. Refer to Figure 10 for applying the equa

tions to the example data and computing the new probe constants.

7012 Calibration Bath

User’s Guide

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11 Calibration Procedure

Calibration Example

D0 = -25.229

DG = 186.974

= 25.00°C

measured t = 24.869°C

= 75.00°C

measured t = 74.901°C

Compute errors,

err

= 24.869 - 25.00°C = -0.131°C

err

= 74.901 - 75.00°C = -0.099°C

Compute D0,

0131 75 0 25 229 0 099 25 0 25 22

′=

−−−−− −−(.)(.( .))(.)(.( .

75 0 25 0

25 229 25 392

))

(.) .

−

+− =−

Compute DG,

DG′=

−−−

−

⎡ ⎣

⎢

⎤ ⎦

⎥

(. )(. )

0 099 0131

75 0 25 0

1 186 974 187 094

Figure 10 Sample calibration computations

Page 63

12 Maintenance

The calibration instrument has been designed with the utmost care. Ease of op

eration and simplicity of maintenance have been a central theme in the product development. Therefore, with proper care the instrument should require very little maintenance. Avoid operating the instrument in dirty or dusty environments.

•

A battery is used to maintain operating parameters in the unit. All operat

ing parameters, including calibration parameters should be checked on a regular basis to insure accuracy and proper operation of the instrument. See the troubleshooting section for the procedure on checking the status of the battery.

•

The bath should be cleaned regularly to prevent a buildup of oil or dust. Use a paint safe cleaning agent on all painted surfaces. Solvents such as Trichloroethylene or Acetone may dull or dissolve the paint. The stainless steel surfaces may be cleaned with solvents as necessary to remove oils.

• The stirring motor should be clean to allow proper cooling. Normally

only the outside surfaces require any attention. If the inside of the motor has become heavily loaded with oily dust, blow it out with compressed air. Follow normal safety procedures when using pressurized gasses.

• Periodically check the fluid level in the bath to ensure that the level has

not dropped. A drop in the fluid level affects the stability of the bath. Changes in fluid level are dependent upon several factors specific to the environment in which the equipment is used. A schedule cannot be outlined to meet each environmental setting. Therefore, the first year the bath should be checked weekly with notes kept as to changes in bath fluid. After the first year, the user can set up a maintenance schedule based on the data specific to the application.

•

Heat transfer medium lifetime is dependent upon the type of medium and the environment. The fluid should be checked at least every month for the first year and regularly thereafter. This fluid check provides a baseline for knowledge of bath operation with clean, usable fluid. Once some fluids have become compromised, the break down can occur rapidly. Particular attention should be paid to the viscosity of the fluid. A significant change in the viscosity can indicate that the fluid is contaminated, being used out

side of its temperature limits, contains ice particles, or is close to a chemi

cal breakdown. Once data has been gathered, a specific maintenance schedule can be outline for the instrument. Refer to the General Operation section (Section 8) for more information about the different types of flu

ids used in calibration baths.

•

If a hazardous material is spilt on or inside the equipment, the user is re

sponsible for taking the appropriate decontamination steps as outlined by the national safety council with respect to the material. MSDS sheets ap

plicable to all fluids used in the baths should be kept in close proximity to the instrument.

12 Maintenance

Page 64

•

If the mains supply cord becomes damaged, replace it with a cord with the appropriate gauge wire for the current of the bath. If there are any questions, contact an Authorized Service Center for more information.

•

Before using any cleaning or decontamination method except those rec

ommended by Hart, users should check with an Authorized Service Cen

ter to be sure that the proposed method will not damage the equipment.

•

If the instrument is used in a manner not in accordance with the equip

ment design, the operation of the bath may be impaired or safety hazards may arise.

WARNING: When checking the over-temperature cutout, be sure that the

temperature limits of the bath fluid are not exceeded. Exceeding the tem

perature limits of the bath fluid could cause harm to the operator, lab, and instrument.

•

The over-temperature cutout should be checked every 6 months to see that it is working properly. In order to check the user selected cutout, follow the controller directions (Section 9.8) for setting the cutout. Both the manual and the auto reset option of the cutout should be checked. Set the bath temperature higher than the cutout. Check to see if the display flashes cutout and the temperature is decreasing.

• The constant temperature bath depends upon the certain qualities of the

fluid medium in order to maintain a uniform and stable temperature environment. Some oils change their characteristics or become dirty after a period of use. Always remove any foreign materials from the bath.

• Silicone oils as well as others may evaporate off their lighter components

over a period of time leaving the very viscous components remaining. In addition, some decomposition occurs which may impair the temperature stability of the bath. When this happens, the fluid is generally very dark to black and viscous. Vegetable oils polymerize (turn plastic like) after they have been used for a time at high temperatures making them very difficult to remove. When the oil has become unusable it should be changed. The instructions for removing the oil is as follows.

12.1 Draining the Bath

The drain is located on the back of the bath. See Figure 4 on page 24. Locate the drain plug on the end of the drain tube. This drain plug is to be fluid tight until the time of draining. The following information is helpful when draining the bath. Always use a container capable of holding the entire load of fluid. Us

ing an adequate size (about 8 gallons or 1 cubic foot), heat proof fluid container is extremely important. Use safety equipment as appropriate.

1. Water and low viscosity fluids - Drain at room temperature. Normal care

must be taken for fluids that may have corrosive or damaging effects on the surrounding facility or equipment.

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2. High viscosity oils - The fluid should be sufficiently low in viscosity to drain efficiently. Some oils such as 710 silicone oil may need to be heated to 80°C to be fluid enough to drain well. The viscosity affects how rapidly it drains as well as how well it flows off of the walls. Heat proof containers and appropriate safety equipment such as face shields, gloves and body covering are recommended.

WARNING: Extreme danger of BURNS and FIRE. Use safety equipment,

use proper equipment and have fire safety equipment standing by.

12 Maintenance

Draining the Bath

Page 66

13 Troubleshooting

This section contains information on troubleshooting and CE Comments. This information pertains to a number of bath models and certain specifics may not pertain to your model.

13.1 Troubleshooting

In the event that the instrument appears to function abnormally, this section may help to find and solve the problem. Several possible problem conditions are described along with likely causes and solutions. If a problem arises, please read this section carefully and attempt to understand and solve the problem. If the probe seems faulty or the problem cannot otherwise be solved, contact an Authorized Service Center (see Section 1.3, on page 5) for assistance. Be sure to have the instrument model number, serial number, voltage, and problem de

scription available.

Problem Causes and Solutions

The heater indicator LED stays red but the temperature does not increase

The display does not show “

Cut-out

” nor displays an incorrect bath temperature, and the controller otherwise appears to operate normally. The problem may be insufficient heating, no heating at all, or too much cooling.

•

The heater power setting being too low, especially at higher operating

•

One or more burned out heaters or blown heater fuses may also cause this problem. If the heaters seem to be burned out, contact an Authorized Service Center (see Section 1.3, on page 5) for assistance.

The controller display flashes “

Cut-out

” and the heater does

not operate

The display flashs “

Cut-out

” alternately with the process

temperature.

•

If the process temperature displayed seems grossly in error, consult the following problem:

‘The display flashes

“

Cut-out

” and an incorrect process temperature’.

•

Normally, the cutout disconnects power to the heater when the bath temperature exceeds the cutout set-point causing the temperature to drop back down to a safe value. If the cutout mode is set to “AUTO”, the heater switches back on when the temperature drops. If the mode is set to “RESET”, the heater only comes on again when the temperature is reduced and the cutout is man

ually reset by the operator, see Section 9.8, Cutout. Check that the cutout set-point is adjusted to 10 or 20°C above the maximum bath operating temperature and that the cutout mode is set as desired.

•

If the cutout activates when the bath temperature is well below the cutout set-point or the cutout does not reset when the bath temperature drops and it is manually re

set, then the cutout circuitry or the cutout thermocouple sensor may be faulty or disconnected. Contact an Autho

rized Service Center (see Section 1.3, on page 5) for as

sistance.

13 Troubleshooting

Troubleshooting

Page 67

Problem Causes and Solutions

The display flashes “cutout” and an incorrect process temperature

The problem may be that the controller’s voltmeter circuit is not func

tioning properly.

•

A problem could exist with the memory back-up battery. If the battery voltage is insufficient to maintain the mem

ory, data may become scrambled causing problems. A nearby large static discharge may also affect data in memory. Verify that the parameters on the Report of Test are accurate. Cycle the power off, disconnect the bath from AC, and then restart the bath.

•

The controller may need to be reset. Perform the follow

ing Factory Reset Sequence. Factory Reset Sequence. Hold the SET and EXIT but

tons down at the same time while powering up the instrument. The instrument display shows '-init-', the model number, and the firmware version. Each of the controller parameters and calibration constants must be reprogrammed. The values can be found on the Report of Test that was shipped with the instrument.

•

If initializing the memory does not remedy the problem, there may be a failed electronic component. Contact an Authorized Service Center (see Section 1.3, on page 5) for assistance.

The displayed process temperature is in error and the controller remains in the cooling or the heating state at any set-point value

Possible causes may be either a faulty control probe or erroneous data in memory.

•

The probe may be disconnected, burned out, or shorted.

•

Check that the probe is connected properly. The probe may be checked with an ohmmeter to see if it is open or shorted. The probe is a thermistor. The resistance should read approximately 3 kohms between pins 3 and 4, 12 kohms between pins 1 and 4, and 9-11 kohms between pins 1 and 3 at room temperature (25°C). If the probe appears to be defective, contact an Authorized Service Center (see Section 1.3, on page 5) for assis

tance.

•

If the problem is not the probe, erroneous data in mem

ory may be the cause. Re-initialize the memory as dis

cussed in the problem

‘The display flashes “cutout” and

an incorrect process temperature’.

If the problem re

mains, the cause may be a defective electronic compo

nent, contact an Authorized Service Center (see Section

1.3, on page 5) for assistance.

7012 Calibration Bath

User’s Guide

Page 68

Problem Causes and Solutions

The controller controls or at

tempts to control at an inaccurate temperature

The controller operates normally except when controlling at a speci

fied set-point. At this set-point, the temperature displayed does not agree with the temperature measured by the user’s reference ther

mometer to within the specified accuracy. This problem may be caused by an actual difference in temperature between the points where the control probe and thermometer probe measure tempera

ture, by erroneous bath calibration parameters, or by a damaged con

trol probe.

•

Check that the bath has an adequate amount of fluid in the tank and that the stirrer is operating properly.

•

Check that the thermometer probe and control probe are both fully inserted into the bath to minimize temperature gradient errors.

•

Check that the calibration parameters are all correct ac

cording to the Report of Test. If not, re-program the con

stants. The memory backup battery may be weak causing errors in data as described in the problem:

‘The

display flashes “cutout” and an incorrect process temper

ature’.

•

Check that the control probe has not been struck, bent, or damaged. If the cause of the problem remains unknown, contact an Authorized Service Center (see Section 1.3, on page 5) for assistance.

The controller shows that the output power is steady but the process temperature is unstable

Possible causes are an improper proportional band setting or the fluid being used.

•

If the bath temperature does not achieve the expected degree of stability when measured using a thermometer, try adjusting the proportional band to a narrower width as discussed in Section 9.7, Proportional Band.

•

Check to ensure the fluid has not deteriorated or is not too thick.

The controller alternately heats for a while then cools

The bath is not stable and the duty cycle is not constant.

•

The proportional band being too narrow typically causes this oscillation. Increase the width of the proportional band until the temperature stabilizes as discussed in Section 9.7, Proportional Band.

The controller erratically heats then cools, control is unstable

If both the bath temperature and output power do not vary periodically but in a very erratic manner, the problem may be excess noise in the system. Noise due to the control sensor should be less than 0.001°C. However, if the probe has been damaged or has developed an inter

mittent short, erratic behavior may exist. The probe is located inside the stirrer motor cover.

•

Check for a damaged probe or poor connection between the probe and bath.

•

Intermittent shorts in the heater or controller electronic circuitry may also be a possible cause. Contact an Au

thorized Service Center (see Section 1.3, on page 5) for assistance.

13 Troubleshooting

Troubleshooting

Page 69

Problem Causes and Solutions

The bath does not achieve low temperatures

Too much heating or not enough cooling can cause this problem.

•

Check that the control indicator glows green showing that the controller is attempting to cool. The heaters may be disabled as a test by temporarily removing the heater fuses.

The controller does not maintain controller parameters or parame

ters are reset each time the power to the unit is removed

Note: Before performing the memory check,you need to record the controller calibration parameters (found in the CAL menu of the instru

ment) and any user-adjusted parameters that you have changed (such as the programmable set points and proportional band).

Memory Check

Doing a memory check is the easiest way to verify the ability of the battery to maintain controller parameters.

1. Power off the instrument.

2. Disconnect the instrument from AC power for 10 seconds.

3. Reconnect the AC power and power on the instrument.

4. If the display shows InIT and/or the cycle count shows a low num

ber such as 0002, the battery is spent and should be replaced. Con

tact an Authorized Service Center for assistance.

5. After replacing the battery, you must reprogram the calibration and user-adjustable parameters into the controller.

13.2 Comments

13.2.1 EMC Directive

Hart Scientifics’ equipment has been tested to meet the European Electromagnetic Compatibility Directive (EMC Directive, 89/336/EEC). The Declaration of Conformity for your instrument lists the specific standards to which the unit was tested.

13.2.2 Low Voltage Directive (Safety)

In order to comply with the European Low Voltage Directive (73/23/EEC), Hart Scientific equipment has been designed to meet the IEC 1010-1 (EN 61010-1) and the IEC 1010-2-010 (EN 61010-2-010) standards.

7012 Calibration Bath

User’s Guide