7102
Micro-Bath
User’s Guide
Revision 830501-EN
Limited Warranty & Limitation of Liability
Each product from Fluke’s Hart Scientic Division (“Hart”) is warranted to be free from defects in mate rial
and workmanship under normal use and service. The warranty period is one year for the Micro-Bath. The
warranty period begins on the date of the shipment. Parts, product repairs, and services 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 speci cations 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 Micro-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 repair,
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 difculty, 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 prod uct
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 IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE. HART SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL. OR
CONSEQUENTIAL 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
competent jurisdiction, such holding will not affect the validity or enforceability of any other provision.
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@hartscientic.com
www.hartscientific.com
Subject to change without notice. • Copyright © 2008 • Printed in USA
ii
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 .............................................................................7
3 Specications and Environmental Conditions ......................9
3.1 Specifications ........................................................................................... 9
3.2 Environmental Conditions ......................................................................... 9
4 Quick Start .............................................................................. 11
4.1 Unpacking .............................................................................................. 11
4.2 Setup ...................................................................................................... 11
4.3 Power ..................................................................................................... 12
4.4 Setting the Temperature ......................................................................... 12
5 Installation ............................................................................. 13
5.1 Bath Environment ................................................................................... 13
5.2 “Dry-out” Period ..................................................................................... 13
5.3 Bath Preparation and Filling .................................................................. 13
5.4 Power ..................................................................................................... 14
6 Bath Use .................................................................................15
6.1 General .................................................................................................. 15
6.2 Comparison Calibration ......................................................................... 15
6.3 Calibration of Multiple Probes ................................................................. 16
7 Parts and Controls ................................................................17
7.1 Front Panel ............................................................................................. 17
7.2 Back Panel ............................................................................................. 17
7.3 Accessories ........................................................................................... 19
7.3.1 Transport/Pour Access Lid ........................................................................... 19
iii
7.3.2 Access Cover (Optional) ..............................................................................19
7.3.3 Probe Basket ................................................................................................20
7.3.4 Stir Bar ..........................................................................................................20
7.3.5 Well Extender (Optional) ..............................................................................20
8 General Operation ..................................................................21
8.1 Changing Display Units .......................................................................... 21
8.2 Switching to 230V Operation .................................................................. 21
8.3 Bath Fluid ................................................................................................ 21
8.3.1 Temperature Range .......................................................................................21
8.3.2 Viscosity ........................................................................................................22
8.3.3 Specific Heat .................................................................................................22
8.3.4 Thermal Conductivity ....................................................................................22
8.3.5 Thermal Expansion........................................................................................22
8.3.6 Electrical Resistivity .......................................................................................22
8.3.7 Fluid Lifetime ................................................................................................. 23
8.3.8 Safety ............................................................................................................23
8.3.9 Cost ............................................................................................................... 23
8.3.10 Commonly Used Fluids ................................................................................. 23
8.3.10.1 Water (Distilled) ................................................................................................... 24
8.3.10.2 Mineral Oil ............................................................................................................ 24
8.3.10.3 Silicone Oil (Dow Corning 200.05, 200.10, 200.20) ............................................. 24
8.3.11 Fluid Characteristics Charts .......................................................................... 24
8.3.11.1 Limitations and Disclaimer .................................................................................. 25
8.3.11.2 About the Graph .................................................................................................. 26
8.4 Stirring ..................................................................................................... 27
8.5 Power ..................................................................................................... 28
8.6 Thermal Electric Devices (TED) ............................................................. 28
8.7 Fluid Drain .............................................................................................. 28
8.8 Temperature Controller .......................................................................... 28
9 Controller Operation .............................................................31
9.1 Well Temperature ................................................................................... 31
9.2 Temperature Set-point ........................................................................... 31
9.2.1 Programmable Set-points ............................................................................31
9.2.2 Set-point Value ............................................................................................. 33
9.2.3 Temperature Scale Units .............................................................................. 33
9.3 Scan ....................................................................................................... 34
9.3.1 Scan Control .................................................................................................34
9.3.2 Scan Rate .....................................................................................................34
iv
9.4 Temperature Display Hold ..................................................................... 35
9.4.1 Hold Temperature Display ............................................................................35
9.4.2 Mode Setting ................................................................................................ 35
9.4.3 Switch Wiring ................................................................................................36
9.4.4 Switch Test Example ....................................................................................36
9.5 Secondary Menu .................................................................................... 36
9.6 Thermal Electric Device (TED) ............................................................... 37
9.7 Proportional Band .................................................................................. 37
9.8 Controller Configuration .......................................................................... 38
9.8.1 Operating Parameters ...................................................................................38
9.8.1.1 High Limit ............................................................................................................ 39
9.8.1.2 Stir Speed ............................................................................................................ 39
9.8.2 Serial Interface Parameters ..........................................................................39
9.8.2.1 Baud Rate ............................................................................................................. 40
9.8.2.2 Sample Period ...................................................................................................... 40
9.8.2.3 Duplex Mode ........................................................................................................ 41
9.8.2.4 Linefeed ............................................................................................................... 41
9.8.3 Calibration Parameters ..................................................................................41
9.8.3.1 R0 ........................................................................................................................ 42
9.8.3.2 ALPHA ................................................................................................................. 42
9.8.3.3 DELTA .................................................................................................................. 42
9.8.3.4 C0 and CG ........................................................................................................... 42
9.8.3.5 rCAL ..................................................................................................................... 42
10 Digital Communication Interface ..........................................43
10.1 Serial Communications .......................................................................... 43
10.1.1 Wiring ...........................................................................................................43
10.1.2 Setup ............................................................................................................43
10.1.2.1 Baud Rate ........................................................................................................... 44
10.1.2.2 Sample Period ...................................................................................................... 44
10.1.2.3 Duplex Mode ........................................................................................................ 44
10.1.2.4 Linefeed ................................................................................................................ 44
10.1.3 Serial Operation ............................................................................................44
10.2 Interface Commands .............................................................................. 45
11 Test Probe Calibration ...........................................................47
11.1 Calibrating a Single Probe ..................................................................... 47
11.2 Stabilization and Accuracy .................................................................... 47
12 Calibration Procedure ...........................................................49
v
12.1 Calibration Points ................................................................................... 49
12.2 Calibration Procedure ............................................................................ 49
12.2.1 Compute DELTA ........................................................................................... 50
12.2.2 Compute R0 & ALPHA ..................................................................................50
12.2.3 Accuracy & Repeatability .............................................................................51
13 Maintenance ..........................................................................53
14 Troubleshooting .....................................................................55
14.1 Troubleshooting Problems, Possible Causes, and Solutions ................. 55
14.2 Comments ............................................................................................... 56
14.2.1 EMC Directive ...............................................................................................56
14.2.2 Low Voltage Directive (Safety) ...................................................................... 56
vi
Tables
Table 1 International Electrical Symbols ........................................................... 1
Table 2 Specifications ....................................................................................... 9
Table 3 Table of Various Bath Fluids ............................................................... 25
Table 4 Nominal Stirrer Motor Settings With Different Liquids ........................ 27
Table 5 Controller Communications Commands ............................................. 46
vii
Figures
Figure 1 7102 Front Panel ................................................................................ 17
Figure 2 7102 Back Panel and Bottom ............................................................ 18
Figure 3 Bath Lids and Lid Parts ..................................................................... 19
Figure 4 Probe Basket ..................................................................................... 20
Figure 5 Stir Bar ............................................................................................... 20
Figure 6 Chart of Various Bath Fluids ............................................................. 26
Figure 7 Controller Operation Flowchart ......................................................... 32
Figure 8 Serial Cable Wiring ........................................................................... 43
viii
Before You Start
Symbols Used
Before You Start1
Symbols Used1.1
Table 1 lists the International Electrical Symbols. Some or all of these symbols may be
used on the instrument or in this manual.
Table 1 International Electrical Symbols
Symbol Description
AC (Alternating Current)
AC-DC
Battery
CE Complies with European Union directives
DC
Double Insulated
Electric Shock
Fuse
PE Ground
Hot Surface (Burn Hazard)
Read the User’s Guide (Important Information)
Off
On
Canadian Standards Association
1
7102 Micro-Bath User’s Guide
Safety Information
Symbol Description
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 xed installation.
Examples include household, office, and laboratory appliances.
C-TICK Australian EMC mark
The European Waste Electrical and Electronic Equipment (WEEE) Directive (2002/96/
EC) mark.
Safety Information 1.2
Use this instrument only as specied in this manual. Otherwise, the protection
provided by the instrument may be impaired.
The following denitions apply to the terms “Warning” and “Caution”.
“Warning” identies conditions and actions that may pose hazards to the user.
“Caution” identies conditions and actions that may damage the instru ment
being used.
1.2.1 Warnings
To avoid personal injury, follow these guidelines.
Disclaimer: Hart Scientific manufactures instruments for the purpose of
temperature calibration. Instruments used for applications other than
calibration are used at the discretion and sole responsibility of the customer.
Hart Scientific cannot accept any responsibility for the use of instruments for
any application other than temperature calibration.
GENERAL
DO NOT install an access cover without holes onto a bath that is energized.
Dangerous pressures may result from uids vaporizing.
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.
Completely unattended operation in not recommended.
DO NOT install access cover without holes onto a bath that is energized. Dangerous
pressures may result from uids vaporizing.
Follow all safety guidelines listed in the user’s manual.
2
Before You Start
Safety Information
Calibration Equipment should only be used by Trained Personnel.
If this equipment is used in a manner not specied by the manufacturer, the protection
provided by the equipment may be impaired or safety hazards may arise.
Inspect the instrument for damage before each use. DO NOT use the instru ment if it
appears damaged or operates abnormally.
Before initial use, or after transport, or after storage in humid or semi-humid
environments, or anytime the instrument has not been energized for more than 10
days, the instrument needs to be energized for a “dry-out” period of 2 hours before
it can be assumed to meet all of the safety requirements of the IEC 61010-1. If the
product is wet or has been in a wet environment, take necessary measures to remove
moisture prior to applying power such as storage in a low humidity temperature
chamber operating at 50°C for 4 hours or more.
The instrument is intended for indoor use only.
Lift the instrument by the handle provided to move the instrument. DO NOT move
the instrument until the display reads less than 25°C (77°F) and the unit has been
drained or the Transport Lid installed.
BURN HAZARD
ALWAYS ensure the instrument is COOL before closing the instrument for storage.
DO NOT touch the well access surface of the unit.
DO NOT mix water and oil when exceeding temperatures of 90°C (194°F).
DO NOT mix water and oil when exceeding temperatures of 90°C (194°F). The
temperature of the well access is the same as the actual temperature shown on the
display, e.g. if the unit is set at 125°C and the display reads 125°C, the well is at
125°C.
Ensure the power cord is positioned in such a way as it cannot contact hot sur faces
or temperature probes. Always inspect power cord before use for any damage to the
insulation due to contact with hot surfaces, cuts or abrasions.
The top sheet metal of the instrument may exhibit extreme temperatures for ar eas
close to the well access.
DO NOT turn off the unit at temperatures higher than 100°C. This could create a
hazardous situation. Select a set-point less than 100°C and allow the unit to cool
before turning it off.
DO NOT remove the uid at high temperatures. The uid will be the same
temperature as the display temperature.
DO NOT operate near ammable materials. Extreme temperatures could ignite the
ammable material.
Use of this instrument at HIGH TEMPERATURES for extended periods of time
requires caution.
3
7102 Micro-Bath User’s Guide
Safety Information
ELECTRICAL HAZARD
These guidelines must be followed to ensure that the safety mechanisms in this
instrument will operate properly. This instrument must be plugged into an AC only
electric outlet as listed in Section 3.1, Specications. The power cord of the instrument
is equipped with a three-pronged grounding plug for your protection against electrical
shock haz ards. It must be plugged directly into a properly grounded three-prong
recepta cle. The receptacle must be installed in accordance with local codes and
ordinances or adapter plug. DO NOT use an extension cord. Consult a qualied
electrician. Always inspect the power cord before use for any damage to the in sulation
due to contact with hot surfaces, cuts or abrasions.
The instrument is equipped with operator accessible fuses. If a fuse blows, it may
be due to a power surge or failure of a component. Replace the fuse once. If the fuse
blows a second time, it is likely caused by failure of a component part. If this occurs,
contact a Hart Scientic Authorized Service Center. Always replace the fuse with
one of the same rating, voltage, and type. Never replace the fuse with one of a higher
current rating.
Always replace the power cord with an approved cord of the correct rating 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.
1.2.2 Cautions
To avoid possible damage to the intrument, follow these guidelines.
Always operate this instrument at room temperatures listed in Section 3.2,
Environmental Conditions. Allow sufcient air circulation by leaving at least 6 inches
(15 cm) of clearance around the instrument.
Overhead clearance is required. DO NOT place this instrument under a cabinet or
other structure.
Never introduce any foreign material into the well.
DO NOT change the values of the calibration constants from the factory set values.
The correct setting of these parameters is important to the safety and proper operation
of the unit.
DO NOT slam the probe stems into the well. This type of action can cause a shock to
the sensor and affect the calibration.
DO use a ground fault interrupt device.
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 optimum
durability and trouble free operation, it must be handled with care.
4
Before You Start
Authorized Service Centers
Most probes have handle temperature limits. Be sure that the probe handle tem perature
limit is not exceeded in the air above the instrument.
The instrument and any thermometer probes used with it are sensitive instru ments that
can be easily damaged. Always handle these devices with care. Do not allow them to
be dropped, struck, stressed, or overheated.
When calibrating PRTs always follow correct calibration procedure and cali brate
from high temperatures to low temperatures with the appropriate triple point of water
checks.
Components and heater lifetimes can be shortened by continuous high tempera ture
operation.
If a mains supply power uctuation occurs, immediately turn off the bath. Power
bumps from brown-outs and black-outs can damage the instrument. Wait until the
power has stabilized before re-energizing the bath.
Fluids may expand at different rates. Allow for uid expansion inside the well as
the instrument heats. Otherwise, the uid may overow the well and leak into the
instrument.
1.3 Authorized Service Centers
Please contact one of the following authorized Service Centers to coordinate service
on your Hart product:
Fluke Corporation
Hart Scientic Division
5
7102 Micro-Bath User’s Guide
Authorized Service Centers
Fluke Nederland B.V.
Fluke Int’l Corporation
Fluke South East Asia Pte Ltd.
When contacting these Service Centers for support, please have the following
information available:
Model Number
Serial Number
Voltage
Complete description of the problem
6
Introduction
Introduction 2
The Hart Scientic 7102 Micro-Bath may be used as a portable instrument or bench
top temperature calibrator for calibrating thermocouple and RTD temper ature probes.
The 7102 is small enough to use in the eld, and accurate enough to use in the lab.
With an ambient temperature of 23°C (74°F), calibrations may be done over a range of
–5°C to 126°C (23°F to 259°F). The resolution of the 7102 temperature display is 0.01
degrees.
The Micro-Bath calibrator features:
Convenient handle
RS-232 interface
Switchable AC Input (115 VAC or 230 VAC)
Optional well extender to extend well depth
Built in programmable features include:
Temperature scan rate control
Temperature switch hold
Eight Set-point memory
Adjustable readout in °C or °F
The temperature is accurately controlled by Hart’s hybrid analog/digital con troller. The
controller uses a precision platinum RTD as a sensor and controls the well temperature
with a solid state relay (triac) driven heater.
The LED front panel continuously shows the current well temperature. The
temperature may be easily set with the control buttons to any desired tempera ture
within the specied range. The calibrator’s multiple fault protection de vices insure
user and instrument safety and protection.
The 7102 Micro-Bath was designed for portability, low cost, and ease of opera tion.
Through proper use, the instrument will continuously provide accurate calibration
of temperature sensors and devices. The user should be familiar with the safety
guidelines and operating procedures of the calibrator as de scribed in the instruction
manual.
7
Specications and Environmental Conditions3
3.1 Specications
Specifications Table 2
Range -5 to 125°C (23 to 257°F)
Accuracy ±0.25°C
Stability ±0.015°C at -5°C (oil, 5010)
Uniformity ±0.02°C
Resolution 0.01°C/F
Operating Temperature 5 to 45°C (41 to 113°F)
Heating Time 25°C to 100°C (77°F to 212°F): 30 minutes
Cooling Time 25°C to 0°C (77°F to 32°F): 30 minutes
Well Size 2.5" dia. x 5.5" deep (64 x 139 mm)
Exterior Dimension 12" H x 7.2" W x 9.5" D (31 cm x 18 cm x 24 cm)
Weight 15 lb. (6.8 kg) with uid
Power 115 VAC (±10%), 1.8 A, or 230 VAC (±10%), 0.9 A, switchable, 50/60 Hz, 200 W
Readout Switchable °C or °F
Controller Digital controller with data retention
Thermal Electric Devices
(TED)
Cooling Fan and Thermal Electric Devices (TED)
Fault Protection Sensor burnout and short protection
Safety Overvoltage (Installation) Category II, Pollution Degree 2 per IEC 61010-01
Fuse Rating 115 V: 250 V 3A SB (slow blow)
Specications and Environmental Conditions
Specications
±0.03°C at 121°C (oil, 5010)
(access opening is 1.9" [48 mm] in diameter)
150 W
230 V: 250 V 1.6 A T (time delay)
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 – 45°C (41 – 113°F)
ambient relative humidity: maximum 80% for temperature <31°C, de creasing
linearly to 50% at 40°C
mains voltage within ± 10% of nominal
vibrations in the calibration environment should be minimized
altitudes less than 2,000 meters
9
Quick Start4
Caution: READ SECTION 6 ENTITLED BATH USE before placing the bath in
service. Incorrect handling can damage the bath and void the war ranty.
4.1 Unpacking
Unpack the Micro-Bath carefully and inspect it for any damage that may have
occurred during shipment. If there is shipping damage, notify the carrier immediately.
Verify that the following components are present:
7102 Micro-Bath
Transport/Pour Access Lid
Probe Basket
Stir Bar
Power Cord
User’s Guide
Report of Calibration
Calibration Label
Access Cover, optional
Well Extender, optional
Quick Start
Unpacking
Setup 4.2
Caution: DO NOT operate this instrument without fluid.
Place the calibrator on a at surface with at least 6 inches of free space around the
instrument. Plug the power cord into a grounded mains outlet. Observe that the
nominal voltage corresponds to that indicated on the back of the calibrator.
Carefully insert the probe basket into the well. Fill the well with the appropriate uid.
The set-point temperature and the number of and size of probes deter mine the uid
level. Be sure to keep the uid level an adequate distance below the top of the well
to prevent overowing the uid when the probes are in serted. For example, placing
200.05 oil at room temperature (25°C) into the bath and heating the unit to 125°C,
causes a 1-inch (2.54 cm) expansion of the uid inside the well.
Keep the uid level at least 1.9 cm (0.75 inches) below the top of the well at all
times. With the probe (probes) in the well ll the tank 3/4 full. Heat to the maximum
temperature of the uid. Slowly ll the well to 2.54 cm (1 inch) be low the top of the
basket at the maximum temperature of the uid.
11
7102 Micro-Bath User’s Guide
Power
Turn on the power to the calibrator by toggling the switch on the power entry module.
The fan should begin blowing air through the instrument and the con troller display
should illuminate after 3 seconds. After a brief self test the con troller should begin
normal operation. If the unit fails to operate please check the power connection.
The display shows the well temperature and the well TEDs start operating to bring
the temperature of the well to the set-point temperature. Insure that the uid is being
stirred.
Power 4.3
Plug the Micro-Bath power cord into a mains outlet of the proper voltage, fre quency,
and current capability. Refer to Section 3.1, Specications, for power details. Turn the
bath on using the rear panel “POWER” switch. The Micro-Bath will turn on and begin
to heat to the previously programmed temperature set-point. The front panel LED
display will indicate the actual bath temperature.
Setting the Temperature 4.4
Section 9.2 explains in detail how to set the temperature set-point on the cali brator
using the front panel keys. The procedure is summarized here.
Press “SET” twice to access the set-point value. 1.
Press “UP” or “DOWN” to change the set-point value. 2.
Press “SET” to store the new set-point. 3.
Press “EXIT” to return to the temperature display. 4.
When the set-point temperature is changed the controller switches the heater on or off
to raise or lower the temperature. The displayed well tempera ture gradually changes
until it reaches the set-point temperature. The well may require 25 minutes to reach
the set-point depending on the span. Another 10 to 15 minutes is required to stabilize
within ±0.03°C of the set-point. Ultimate sta bility may take 20 to 30 minutes more of
stabilization time.
12
Installation
Bath Environment
Installation 5
Caution: READ SECTION 6 ENTITLED BATH USE before placing the bath in
service. Incorrect handling can damage the bath and void the war ranty.
Bath Environment 5.1
The 7102 Micro Bath is a precision instrument which should be located in an
appropriate environment. The location should be free of drafts, extreme temperatures
and temperature changes, dirt, etc. The surface where the bath is placed must be level.
Because the bath is designed for operation at high temperatures, keep all am mable
and meltable materials away from the bath. Although the bath is well in sulated, top
surfaces do become hot. Beware of the danger of accidental uid spills. The bath
should be placed on a heat-proof surface such as concrete with plenty of clear space
around the bath.
If the bath is operated at high temperatures, a fume hood should be used to re move any
vapors given off by hot bath uid.
“Dry-out” Period 5.2
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 61010-1.
Bath Preparation and Filling 5.3
The 7102 Micro Bath is not provided with a uid. Various uids are available from
Hart Scientic and other sources. Depending on the desired temperature range, any of
the following uids, as well as others, may be used in the bath:
Water (distilled)
Ethylene glycol/water
Mineral oil
Silicone oil
Fluids are discussed in detail in Section 8.3, Bath Fluid on page 21.
Remove the access lid from the bath and check the tank for foreign matter (dirt,
remnant packing material, etc.). Thoroughly dry the inside of the well with pa per
towels before lling.
Fill the bath with clean unpolluted uid. Under-lling may reduce bath performance.
The uid should never exceed a height of 1.9 cm (0.75 inches) below the top of the
bas ket. Carefully monitor the bath uid level as the bath temperature rises to pre vent
overow or splashing. Remove excess hot uid if necessary with caution.
13
7102 Micro-Bath User’s Guide
Power
Note: 200.05 Silicon Oil expands 2.54 cm (1 inch) for a 100°C increase in
temperature.
Power 5.4
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,
Specications, for power details.
14
6 Bath Use
Caution: 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 specic procedures.
General 6.1
Be sure to select the correct uid for the temperature range of the calibration. Bath
uids should be selected to operate safely with adequate thermal proper ties to meet the
application requirements. Also, be aware that some uids ex pand and could overow
the bath if not watched. Refer to Section 8.3, Bath Fluid, and subsequent subsections
for information specic to uid selection and to the MSDS sheet specic to the uid
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 uid 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 in jury. 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 uids 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 uid. Always be sure that the probe
is completely dry before inserting it into a hot uid. Be aware that cleaning the probe
can be dangerous if the probe has not cooled to room temperature. Additionally, high
temperature uids may ignite the paper towels if the probe has not been cooled.
Bath Use
General
Warning: Some of the high temperature fluids react violently to water or other
liquid mediums.
For optimum accuracy and stability, allow the bath adequate stabilization time after
reaching the set-point temperature.
Comparison Calibration 6.2
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
sufcient time for the probes to settle and the temperature of the bath to stabilize.
One of the signicant 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 uid
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, these gradients are minimized inside the
15
7102 Micro-Bath User’s Guide
Calibration of Multiple Probes
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 tic, 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 reective 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 xtures 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.
16
Calibration of Multiple Probes6.3
Fully loading the bath with probes increases the time required for the tempera ture to
stabilize after inserting the probes. Using the reference probe as the guide, be sure that
the temperature has stabilized before starting the calibration.
SET
UP
DOWN
EXIT
7102
MICRO-BATH –5°C to 125°C
Parts and Controls
Front Panel
Parts and Controls 7
The user should become familiar with the bath and its parts:
Front Panel 7.1
Figure 1 on this page.
7102 Front PanelFigure 1
Controller Display – The digital display is an important part of the temperature
controller because it not only displays set and actual temperatures but also dis plays
various calibrator functions, settings, and constants. The display shows temperatures
in units according to the selected scale °C or °F.
Controller Keypad – The four button keypad allows easy setting of the set-point
temperature. The control buttons (SET, DOWN, UP, and EXIT) are used to set the
calibrator temperature set-point, access and set other operating parameters, and access
and set calibration parameters.
Setting the control temperature is done directly in degrees of the current scale. It can
be set to one-hundredth of a degree Celsius or Fahrenheit.
The functions of the buttons are as follows:
SET – Used to display the next parameter in the menu and to store parameters to the
displayed value.
DOWN – Used to decrement the displayed value of parameters.
UP – Used to increment the displayed value.
EXIT – Used to exit a function. Any changes made to the displayed value are ignored.
Holding the EXIT button for approximately 0.5 seconds exits back to the main display.
Back Panel 7.2
Figure 2 on next page.
Power Cord – Underneath the calibrator is the removable power cord inlet that plugs
into an IEC grounded socket.
17
7102 Micro-Bath User’s Guide
115V
115V AC / 3 A
230V AC / 1.6 A
50/60 Hz
115V - 3 250V
230V - 250VAT1.6 AT
POWER
FLUKE CORPORATION
HART SCIENTIFIC DIVISION
www.hartscientific.com
RS-232
DISPLAY
HOLD
Back Panel
18
Figure 2 7102 Back Panel and Bottom
Power Switch – The power switch is located on the power entry module (PEM). The
PEM also houses the fuses and the dual voltage selector. The PEM allows the unit to
be eld switchable for 115 VAC (±10%) or 230 VAC (±10%) operation.
Serial Port – A DB-9 male connector is present for interfacing the calibrator to a
computer or terminal with serial RS-232 communications.
Fan – The fan inside the calibrator runs continuously when the unit is being op erated
to provide cooling for the instrument. Slots at the top and around the two cor ners of
the calibrator are provided for airow. The area around the calibrator must be kept
clear to allow adequate ventilation. The airow is directed out the back.
Parts and Controls
Pour Spout
Pour Spout
Cover
Transport
Plug
Transport/Pour Access Lid Optional Access Cover
Guide Ring
Accessories
Accessories 7.3
Transport/Pour Access Lid 7.3.1
A transport/pour access lid (Figure 3) is provided so the uid being used does not have
to be removed when transporting. The lid doubles as a pour spout.
Figure 3
Bath Lids and Lid Parts
Access Cover (Optional) 7.3.2
An aluminum access cover (Figure 3) is available for optimum stability. Holes should
be drilled in the access cover to allow insertion of the probes into the well. The holes
must be within the guide ring for the probes to t into the probe basket.
Warning: DO NOT install an access cover without holes (like the optional
cover) onto a bath that is energized. Dangerous pressures may result from fluids
vaporizing.
19
7102 Micro-Bath User’s Guide
Accessories
Probe Basket 7.3.3
A probe basket (Figure 4) is provided as a guide for the probes and to prevent bumping
of the stir bar.
20
Figure 4 Probe Basket
Stir Bar 7.3.4
The stir bar (Figure 5) sits in the bottom of the well for mixing the uid provid ing
better accuracy, uniformity, and stability.
Figure 5 Stir Bar
Well Extender (Optional) 7.3.5
An optional well extender is available for increasing the depth of the well. This
extender screws onto the well and is equipped with an O-ring. Thread the extender
down until the O-ring makes a good seal. Some uids may expand up to 6.35 cm (2.5
inches). Therefore, when using the well extender keep in mind how much the uid you
are using will expand. Do not overll the well.
General Operation
Changing Display Units
General Operation8
Changing Display Units8.1
The 7102 can display temperature in Celsius or Fahrenheit. The temperature units are
shipped from the factory set to Celsius. To change to Fahrenheit or back to Celsius
there are two ways:
Press “SET” and “UP” simultaneously. This will change the display units.1.
Press the “SET” key three times from the temperature display to show2.
Un = C
or
Press the “UP” or “DOWN” key to change units.1.
Press “SET” to store changes.2.
Switching to 230V Operation8.2
The 7102 is switchable from 115 VAC to 230 VAC 50/60 Hz. Swithcing the voltage
can change the calibration, so the unit should be calibrated after changing the input
voltage.
To change from 115 VAC to 230 VAC:
Unplug the unit.
With a small straight slot screwdriver remove the fuse holder located on the
back of the bath. Replace the two fuses (3 amp 250 V) with 1.6 amp 250 V
fuses.
Replace the fuse holder with the “230V” in the display window.
Note: Use 3 amp fuses for 115 V and 1.6 amp for 230V only. DO NOT PLUG
THE UNIT INTO 230 V IF THE FUSE HOLDER READS 115 V.
8.3 Bath Fluid
Many uids work with the 7102 bath. Choosing a uid requires consideration of many
important characteristics of the uid. Among these are temperature range, viscosity,
specic heat, thermal conductivity, thermal expansion, electri cal resistivity, uid
lifetime, safety, and cost.
Temperature Range8.3.1
One of the most important characteristics to consider is the temperature range of the
uid. Few uids 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 uid. The lower tempera ture range of the uid is
determined by the freeze point of the uid or the tem perature at which the viscosity
becomes too great. The upper temperature is usually limited by vaporization,
21
7102 Micro-Bath User’s Guide
Bath Fluid
ammability, or chemical breakdown of the uid. Vaporization of the uid at higher
temperatures may affect temperature stability because of cool condensed uid dripping
into the bath from the lid.
Viscosity8.3.2
Viscosity is a measure of the thickness of a uid, how easily it can be poured and
mixed. Viscosity affects the temperature stability of the bath. With low vis cosity,
uid 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 ten centistokes. Twenty
centistokes is about the upper limit of allow able 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.
When using uids 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.
Specic Heat8.3.3
Specic heat is the measure of the heat storage ability of the uid. Specic heat, to a
small degree, affects the control stability. It also affects the heating and cooling rates.
Generally, a lower specic heat means quicker heating and cooling. The proportional
band may require some adjustment depending on the specic heat of the uid.
22
Thermal Conductivity8.3.4
Thermal conductivity measures how easily heat ows through the uid. Ther mal
conductivity of the uid 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.
Thermal Expansion8.3.5
Thermal expansion describes how the volume of the uid changes with temper ature.
Thermal expansion of the uid used must be considered since the in crease in uid
volume as the bath temperature changes may cause overow. Excessive thermal
expansion may also be undesirable in applications where constant liquid level is
important. Many uids including oils have signicant thermal expansion.
Electrical Resistivity8.3.6
Electrical resistivity describes how well the uid insulates against the ow 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 oc cur through the uid.
In such conditions choose a uid with very high resistivity.
Fluid Lifetime8.3.7
Many uids degrade over time because of evaporation, water absorption, gel ling,
or chemical breakdown. Often the degradation becomes signicant near the upper
temperature limit of the uid, substantially reducing the uid’s lifetime.
8.3.8 Safety
When choosing a uid always consider the safety issues associated. Obviously
where there are conditions of extreme hot or cold there can be danger to people and
equipment. Fluids may also be hazardous for other reasons. Some uids 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 va pors are produced.
Warning: Fluids at high temperatures may pose danger from BURNS, FIRE,
and TOXIC FUMES. Use appropriate caution and safety equip ment.
Fluids may be ammable and require special re safety equipment and proce dures.
An important characteristic of the uid to consider is the ash point. The ash point
is the temperature at which there is sufcient vapor given off so that when there is
sufcient oxygen present and a ignition source is applied the va por will ignite. This
does not necessarily mean that re will be sustained at the ash point. The ash 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 uids require special disposal according to applica ble
federal or local laws after use.
General Operation
Bath Fluid
Cost8.3.9
Cost of bath uids 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 uid.
Commonly Used Fluids8.3.10
Below is a description of some of the more commonly used uids and their
characteristics.
23
7102 Micro-Bath User’s Guide
Bath Fluid
Water (Distilled) 8.3.10.1
Water is often used because of its very low cost, availability, and excellent tem perature
control characteristics. Water has very low viscosity and good thermal conductivity
and heat capacity which makes it among the best uids 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 signicant. Water used in
the bath should be distilled or softened to prevent mineral deposits. Consider using an
algaecide chemical in the water to prevent contamination.
Mineral Oil8.3.10.2
Mineral oil or parafn 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 signicant. The vapors may be dangerous and use of a fume hood is highly
recommended. As with most oils mineral oil will expand as temperature increases
so be careful not to ll the bath too full that it over ows 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 am mable and may also cause serious injury if inhaled or
ingested.
24
Silicone Oil (Dow Corning 200.05, 200.10, 200.20)8.3.10.3
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 signicantly with temperature
and thermal expansion also occurs. These oils have very high electrical resistivity.
Silicone oils are fairly safe and non-toxic. Silicone oils are fairly expensive.
Fluid Characteristics Charts8.3.11
Table 3 on page 25 and Figure 6 on page 26 have been created to provide help in
selecting a heat exchange uid media for your constant temperature bath. These 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. There may be other useful
uids not shown in this listing.
The charts include information on a variety of uids which are often used as heat
transfer uid in baths. Because of the temperature range some uids may not be useful
with your bath.
General Operation
Bath Fluid
Limitations and Disclaimer 8.3.11.1
The information given in this manual regarding uids is intended only to be used as
a general guide in choosing a uid. Though every effort has been made to provide
correct information we cannot guarantee accuracy of data or assure suitability of a
uid for a particular application. Specications may change and sources sometimes
offer differing information. Hart Scientic cannot be liable for any personal injury or
damage to equipment, product or facilities resulting from the use of these uids. The
user of the bath is responsible for collecting correct information, exercising proper
judgment, and insuring safe operation. Operating near the limits of certain properties
such as the ash point or viscos ity can compromise safety or performance. Your
company’s safety policies re garding ash points, toxicity, and such issues must be
considered. You are responsible for reading the MSDS (material safety data sheets)
and acting accordingly.
Table 3 Table of Various Bath Fluids
Fluid
(# = Hart
Part No.)
Halocarbon
0.8
#5019
Methanol -96°C (fr) 60°C (b) 54°C 1.3 @ -35°C
Water 0°C (fr) 95°C (b) NONE 1 @ 25°C
Ethylene
Glycol-50%
#5020
Mineral Oil 40°C (v) 190°C () 190°C 15 @ 75°C
Dow Corning
200.05 Silicone
Oil
Dow Corning
200.10 #5012
Dow Corning
200.20 #5013
Dow Corning
200.50 Silicone
Oil
Dow Corning
550
#5016
Dow Corning
710
#5017
Dow Corning
210-H Silicone
Oil
Heat Transfer
Salt #5001
*Limiting Factors — b – boiling point e – high evaporation – ash 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.
Lower
Temperature
Limit *
-90°C (v) ** 70°C (e) NONE 5.7 @ -50°C
-35°C (fr) 110°C (b) NONE 7 @ 0°C
-40°C (v) ** 133°C (, cc) 133°C 5 @ 25°C 0.92 @ 25°C 0.4 0.00028 @ 25°C 0.00105 1000 @ 25°C
-35°C (v) ** 165°C (, cc) 165°C 10 @ 25°C
7°C (v) 230°C (, cc) 230°C 20 @ 25°C 0.949 @ 25°C 0.370 @ 40°C
25°C (v) 280°C (, cc) 280°C 50 @ 25°C 0.96 @ 25°C 0.4 0.00037 @ 25°C 0.00104 1000 @ 25°C
70°C (v) 232°C (, cc)
80°C (v) 302°C (, oc) 302°C 50 @ 80°C
66°C (v) 315°C (, oc) 315°C 50 @ 66°C
145°C (fr) 530°C NONE 34 @ 150°C
Upper
Temperature
Limit *
300°C (, oc)
Flash
Viscosity
Point
(centistokes)
0.8 @ 40°C
0.5 @ 70°C
0.66 @ 0°C
0.45 @ 20°C
0.4 @ 75°C
2 @ 50°C
0.7 @ 100°C
5 @ 125°C
3 @ 135°C
232°C 50 @ 70°C
10 @ 104°C
7 @ 204°C
14 @ 204°C
6.5 @ 300°C
2.4 @ 500°C
Specic
Gravity
1.71 @ 40°C 0.2 0.0004 0.0011
0.810 @ 0°C
0.792 @ 20°C
1.00 1.00 0.0014 0.0002 @ 25°C
1.05 0.8 @ 0°C 0.001
0.87 @ 25°C
0.84 @ 75°C
0.81 @ 125°C
0.934 @ 25°C 0.43 @ 40°C
1.07 @ 25°C 0.358 @ 40°C
1.11 @ 25°C 0.363 @ 40°C
0.96 @ 25°C 0.34 @ 100°C 0.0003 0.00095 100 @ 25°C
2.0 @ 150°C
1.9 @ 300°C
1.7 @ 500°C
Specic
Heat
(cal/g/°C)
0.6 0.0005 @ 20°C 0.0014 @ 25°C
0.48 @ 25°C
0.53 @ 75°C
0.57 @ 125°C
0.45 @ 100°C
0.482 @ 200°C
0.393 @ 100°C
0.420 @ 200°C
0.386 @ 100°C
0.433 @ 200°C
0.454 @ 100°C
0.505 @ 200°C
0.33 0.0014 0.00041 1.7 W/cm
Thermal
Conductivity
(cal/s/cm/°C)
0.00025 @ 25°C 0.0007 @ 50°C 5 @ 25°C
0.00032 @ 25°C 0.00108 1000 @ 25°C
0.00034 @ 25°C 0.00107 1000 @ 25°C
0.00035 @ 25°C 0.00075 100 @ 25°C
0.00035 @ 25°C 0.00077 100 @ 25°C
Thermal
Expansion
(cm/cm/°C)
Resistivity
(1012 W-cm )
10 @ 150°C
50 @ 150°C
50 @ 150°C
50 @ 150°C
1 @ 150°C
1 @ 150°C
1 @ 150°C
3
25
7102 Micro-Bath User’s Guide
Bath Fluid
Figure 6 Chart of Various Bath Fluids
About the Graph 8.3.11.2
The uid graph visually illustrates some of the important qualities of the uids shown.
Temperature Range: The temperature scale is shown in degrees Celsius. The uids’
general range of application is indicated by the shaded bands. Qualities including pour
point, freeze point, important viscosity points, ash point, boil ing point and others
may be shown.
Freezing Point: The freezing point of a uid is an obvious limitation to stir ring. As
the freezing point is approached high viscosity may also limit performance.
26
General Operation
Pour Point: This represents a handling limit for the uid.
Viscosity: Points shown are at 50 and 10 centistokes viscosity. When viscosity is
greater than 50 centistokes stirring is very poor and the uid is unsatisfactory for bath
applications. Optimum stirring generally occurs at 10 centistokes and below.
Fume Point: A fume hood should be used. This point is very subjective in na ture and
is impacted by individual tolerance to different fumes and smells, how well the bath is
covered, the surface area of the uid in the bath, the size and ventilation of the facility
where the bath is located and other conditions. We as sume the bath is well covered at
this point. This is also subject to company policy.
Flash Point: The point at which ignition may occur. The point shown may be either
the open or closed cup ash point. Refer to the ash point discussion in Section 8.3.8.
Boiling Point: At or near the boiling point of the uid, the temperature stabil ity is
difcult to maintain. Fuming or evaporation is excessive. Large amounts of heater
power may be required because of the heat of vaporization.
Decomposition: The temperature may reach a point at which decomposition of the
uid begins. Further increasing the temperature may accelerate decomposi tion to the
point of danger or impracticality.
Stirring8.4
Stirring of the bath uid is very important for stable temperature control. The uid
must be mixed well for good temperature uniformity and fast controller response. The
stirrer is adjusted for optimum performance. Table 4 on page 27 shows nominal stirrer
motor settings for several uids.
If the stirrer does not function properly, the instrument will oscillate and not meet
published specications.
Note: If the bath is used with the probe basket removed, stir motor settings need
to be changed so that a small vortex can be seen in the liquid.
Stirring
Warning: Do not mix water and oil when exceeding temperatures of 90°C
Table 4 Nominal Stirrer Motor Settings With Different Liquids
Liquid Stir Motor Setting Temperature
Distilled Water 15 5°C to 90°C
(41°F to 194°F)
Ethylene Glycol 15 -5°C to 90°C
(25°F to 194°F)
200.05 Oil 15 -5°C to 125°C
(-23°F to 258°F)
200.10 Oil 15 25°C to 125°C
(77°F to 258°F)
27
7102 Micro-Bath User’s Guide
Power
Power 8.5
Power to the bath is provided by an AC mains supply and passes through a l ter to
prevent switching spikes from being transmitted to other equipment. Re fer to Section
3.1, Specications, for power details.
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 will briey show a four digit num ber. This
number indicates the number of times power has been applied to the bath. Also briey
displayed is data which indicates the controller hardware conguration. This data is
used in some circumstances for diagnostic purposes.
Thermal Electric Devices (TED) 8.6
The power to the bath is precisely controlled by the temperature controller to maintain
a constant bath temperature. Power is controlled by periodically switching the TEDs
on for a certain amount of time using power transistors.
Fluid Drain 8.7
The uid may be drained from the 7102 by tightly screwing the transport/pour access
lid onto the top of the bath and pouring the liquid into an appropriate container.
28
Temperature Controller 8.8
The bath temperature is controlled by Hart Scientic’s unique hybrid digi tal/analog
temperature controller. The controller offers the tight control stability of an analog
temperature controller as well as the exibility and programmabil ity of a digital
controller.
The bath temperature is monitored with a platinum resistance sensor in the con trol
probe. The signal is electronically compared with the programmable refer ence signal,
amplied, and then fed to a pulse-width modulator circuit which controls the amount
of power applied to the bath heater.
The bath is operable within the temperature range given in the specications. For
protection against solid-state relay failure or other circuit failure, a bi-me tallic cut-out
automatically turns off the heater anytime the bath temperature exceeds the maximum
temperature.
The controller allows the operator to set the bath temperature with high resolu tion,
adjust the proportional band, monitor the heater output power, and pro gram the
controller conguration and calibration parameters. The controller may be operated
in temperature units of degrees Celsius or Fahrenheit. The controller is operated and
programmed from the front control panel using the four key switches and digital LED
display. The controller is equipped with a serial RS-232 digital interface for remote
operation. Operation using the digital interfaces is discussed in Section 10.
General Operation
Temperature Controller
When the controller is set to a new set-point the bath heats or cools to the new
temperature. Once the new temperature is reached the bath usually takes 15 – 20
minutes for the temperature to settle and stabilize. There may be a small over shoot or
undershoot.
29
Controller Operation
Well Temperature
9 Controller Operation
This chapter 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 well temperature, set the temperature set-point in degrees C or F,
monitor the heater output power, adjust the controller propor tional band, and program
the calibration parameters, operating parameters, and serial interface conguration.
Operation of the functions and parameters are shown in the owchart in Figure 7 on
page 32. This chart may be copied for reference.
In the following discussion a button with the word SET, UP, EXIT or DOWN
inside 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.
Well Temperature 9.1
The digital LED display on the front panel allows direct viewing of the actual well
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,
100.00C
The temperature display function may be accessed from any other function by pressing
the “EXIT” button.
Well temperature in degrees Celsius
9.2 Temperature Set-point
The temperature set-point can be set to any value within the range and resolu tion as
given in the specications. Be careful not to exceed the safe upper tem perature limit of
any device inserted into the well.
Setting the temperature involves selecting the set-point memory and adjusting the setpoint value.
Programmable Set-points 9.2.1
The controller stores 8 set-point temperatures in memory. The set-points can be
quickly recalled to conveniently set the calibrator to a previously programmed
temperature set-point.
To set the temperature one must rst 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.
31
7102 Micro-Bath User’s Guide
UP
UP
DO WN DO WN
SET
Operating
Pa rameter s
Menu
SET
SET
Ca l
Menu
ALPH A
DE LT A
Adj .R0
DO NO T CHANG E THESE VALUES . SEE MANU AL
DO NO T CHANG E THESE VALUES . SEE MANU AL
Adj. ALPH A
Ser ia l
Inter fa ce
Menu
BA UD
Rate
Adjus t
BA UD Rate
Sampl e
Pe ri od
Adj. Sampl e
Pe ri od
Dupl ex
Mode
Adj .Dupl ex
Mode
Linef eed
C0
0
Adjus t
Linef eed
Adjus t
C0
Adjus t
0 ohm
CG
200
Adjus t
CG
Adjus t
200 ohm
EXITEXIT
EXIT
EXIT
EXIT
UP
DO WN
DO WN
SET
SET
SET
UP
+
+
+
Displ ay Po we r
Toggles °C / °F
SET
SET
Select Setpoint
Adjust Setpoint
Units °C/°F
Scan On/Off
Scan Rate
Displ ay
Te mperatur e
Configuration Menu
Secondar y Functions
X5
Sti r
Speed
Adj. Sti r
Speed
HL
Adj.H L
Toggles Displa y of Rs
Switch Hold Displa y Mode
EXIT
Set Propor tional Band
R0
Adj .DEL TA
rCA L
Pres s“SET” to step through the menu and
to store the parameter va lu e.
Pres s“EXIT ”bri efly to skip a parameter
without stor ing the parameter va lu e.
Hold “EXIT” to e xit the menu and displa y
the temperatur e
Menu Legend:
Temperature Set-point
Figure 7
Controller Operation Flowchart
32
Controller Operation
Temperature Set-point
100.00C
Access set-point memory
S
1. 25
To change the set-point memory press “UP” or “DOWN”.
4. 125.
Press “SET” to accept the new selection and access the set-point value.
Accept selected set-point memory
S
Set-point Value 9.2.2
The set-point value may be adjusted after selecting the set-point memory and pressing
“SET”.
4 125.
If the set-point value is correct, hold “EXIT” to resume displaying the well
temperature. Press “UP” or “DOWN” to adjust the set-point value.
Well temperature in degrees Celsius
Set-point memory 1, 25°C currently used
New set-point memory 4, 125°C
Set-point 4 value in °C
125.00
When the desired set-point value is reached press “SET” to accept the new value and
access the temperature scale units selection. If “EXIT” is pressed in stead of “SET”,
any changes made to the set-point are ignored.
Accept new set-point value
S
Temperature Scale Units 9.2.3
The temperature scale units of the controller can be set by the user to degrees Celsius
(°C) or Fahrenheit (°F). The selected units are used in displaying the well temperature,
set-point, and proportional band.
Press “SET” after adjusting the set-point value to change display units.
Un= C
Press “UP” or “DOWN” to change the units.
New set-point value
Scale units currently selected
33
7102 Micro-Bath User’s Guide
Scan
Un= F
Scan 9.3
The scan rate can be set and enabled so that when the set-point is changed the bath
heats or cools at a specied rate (degrees per minute) until it reaches the new set-point.
With the scan disabled the bath heats or cools at the maximum possible rate.
9.3.1 Scan Control
The scan is controlled with the scan on/off function that appears in the main menu
after the set-point function.
Sc=OFF
Press “UP” or “DOWN” to toggle the scan on or off.
Sc=On
Press “SET” to accept the present setting and continue.
Accept scan setting
S
9.3.2 Scan Rate
The next function in the main menu is the scan rate. The scan rate can be set from
.1 to 99.9°C/min. The maximum scan rate however is actually limited by the natural
heating or cooling rate of the instrument. This is often less than 100°C/min, especially
when cooling.
The scan rate function appears in the main menu after the scan control function. The
scan rate units are in degrees C per minute.
New units selected
Scan function off
Scan function on
34
Sr= 10.0
Press “UP” or “DOWN” to change the scan rate.
Sr= 2.0
Press “SET” to accept the new scan rate and continue.
Accept scan rate
S
Scan rate in°C/min
New scan rate
Controller Operation
Temperature Display Hold
Temperature Display Hold 9.4
The 7102 has a display hold function which allows action of an external switch to
freeze the displayed temperature and stop the set-point from scanning. This is useful
for testing thermal switches and cut-outs. The instrument must be powered off before
attaching thermal switches or cut-outs. This section ex plains the functions available
for operating the temperature hold feature. An ex ample follows showing how to set up
and use the hold feature to test a switch.
Hold Temperature Display 9.4.1
The hold feature is enabled by simply pressing the “UP” button when the tem perature
is displayed. The hold temperature display shows the hold temperature on the right
and the switch status on the left. For the status “c” means the switch is closed and “o”
means the switch is open. The status ashes when the switch is in its active position
(opposite the normal position). The hold temper ature shows what the temperature of
the well was when the switch changed from its normal position to its active position.
While the switch is in the normal position the hold temperature will follow the well
temperature.
If the Scan Control is “OFF” and the Hold Temperature Display is being used, the
temperature at which the switch is activated does not affect the set-point temperature.
However, if the Scan Control is “ON” and the Hold Temperature Display is being
used, the temperature at which the switch is activated is stored as the new set-point
temperature.
Operation of the hold temperature display is outlined below.
143.50C
Access hold display
U
c 144.8
To return to the normal well temperature display press “DOWN”.
Mode Setting 9.4.2
The Hold Function is always in the automatic mode. In this mode the normal position
is set to whatever the switch position is when the set-point is changed. For example,
if the switch is currently open when the set-point is changed, the closed position
then becomes the new active position. The normal position will be set automatically
under any of the following conditions, (1) a new set-point number is selected, (2)
the set-point value is changed, (3) a new set-point is set through the communications
channels.
Well temperature display
Switch status and hold temperature
35
7102 Micro-Bath User’s Guide
Secondary Menu
Switch Wiring 9.4.3
The thermal switch or cut-out is wired to the calibrator at the two terminals on
the back of the Micro-Bath labeled “DISPLAY HOLD”. The switch wires may be
connected to the terminals either way. Internally the black terminal connects to
ground. The red terminal connects to +5V through a 100 kW resistor. The calibrator
measures the voltage at the red terminal and interprets +5V as open and 0V as closed.
Switch Test Example 9.4.4
This section describes a possible application for the temperature hold feature and how
the instrument is set up and operated.
Suppose you have a thermal switch which is supposed to open at about 75°C and close
at about 50°C and you want to test the switch to see how accurate and repeatable it
is. You can use the temperature hold feature and the scan function to test the switch.
Measurements can be made by observing the display or, pref erably, by collecting data
using a computer connected to the RS-232 port. To set up the test do the following
steps.
Connect the switch wires to the terminals on the back of the Micro-Bath and 1.
place the switch in the well.
Enable set-point scanning by setting the scan to “ON” in the primary menu (2. see
Section 9.3.1).
Set the scan rate to a low value, say 1.0°C/min. (3. see Section 9.3.2). If the
scan rate is too high you may lose accuracy because of transient temperature
gradients. If the scan rate is too low the duration of the test may be longer than
is necessary. You may need to experiment to find the best scan rate.
Set the first program set-point to a value above the expected upper switch 4.
temperature, say 90°C.
Set the second program set-point to a value below the expected lower switch 5.
temperature, say 40°C, in the program menu.
Collect data on a computer connected to the RS-232 port. Refer to 6. Section
9.8.2, Serial Interface Parameters, for instructions on configuring the RS-232
communications interface.
36
Secondary Menu 9.5
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 rst function in the secondary menu is the heater power display. (See
Figure 7 on page 32.)
Controller Operation
Thermal Electric Device (TED)
Thermal Electric Device (TED) 9.6
The temperature controller controls the temperature of the well by pulsing the TED on
and off. The total power being applied to the TED is determined by the duty cycle or
the ratio of TED on time to the pulse cycle time. By knowing the amount of heating
the user can tell if the calibrator is heating up to the set-point, cooling down, or
controlling at a constant temperature. Monitoring the percent heater power will let the
user know how stable the well temperature is. With good control stability the percent
heating power should not uctuate more than ±5% 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.
100.00C
+
S
To exit out of the secondary menu hold “EXIT”. To continue on to the propor tional
band setting function press “EXIT” momentarily or “SET”.
E
SEC
12.0 P
Well temperature
Access heater power in secondary menu
Flashes
Heater power in percent
Proportional Band 9.7
In a proportional controller such as this the heater output power is proportional to the
well 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 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 well and response time depend on the width of
the proportional band. If the band is too wide the well temperature will deviate
excessively from the set-point due to varying external conditions. This is be cause 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 proportional band is too
narrow the temperature may swing back and forth be cause the controller overreacts to
temperature variations. For best control stabil ity the proportional band must be set for
the optimum width.
37
7102 Micro-Bath User’s Guide
Controller Conguration
The proportional band width is set at the factory to about 5.0°C. The propor tional band
width may be altered by the user if he desires to optimize the con trol characteristics
for a particular application.
The proportional band width is easily adjusted from the front panel. The width may
be set to discrete values in degrees C or F depending on the selected units. The
proportional band adjustment is 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
12.0 P
Access proportional band
S
To change the proportional band press “UP” or “DOWN”.
To store the new setting press “SET”. Press “EXIT” to continue without storing the
new value.
Accept the new proportional band setting
S
Access heater power in secondary menu
E
Heater power in percent
ProP
5.0
4.0
Flashes “ProP” and the setting
Proportional band setting
New proportional band setting
Controller Conguration9.8
The controller has a number of conguration and operating options and calibra tion
parameters which are programmable via the front panel. These are ac cessed from the
secondary menu after the proportional band function by pressing “SET”. Pressing
“SET” again enters the rst of three sets of congu ration parameters: operating
parameters, serial interface parameters, and cali bration parameters. The menus are
selected using the “UP” and “DOWN” keys and then pressing “SET”. (See Figure 7
on page 32.)
38
Operating Parameters9.8.1
The operating parameters menu is indicated by,
PAr
Operating parameters menu
Controller Operation
Controller Conguration
The operating parameters menu contains the High Limit and Stir Speed parameters.
High Limit 9.8.1.1
The High Limit Parameter adjusts the upper set-point temperature. The factory default
and maximum temperature are set to 126°C. For safety, a user can ad just the HL down
so the maximum temperature set-point is restricted.
HL
High Limit parameter
Press “SET” to enable adjustment of HL
HL
H=126
Flashes “HL” and then displays the setting
Current HL setting
Adjust the HL parameter using “UP” or “DOWN”
H=90
New HL setting
Press “SET” to accept the new temperature limit.
Stir Speed 9.8.1.2
The Stir Speed parameter adjusts stirrer motor speed. The factory default is 20.
Str SP
0
Flashes “Str Sp” and then displays the setting
Current Stir Speed setting
To change the stir speed press “UP” or “DOWN”.
16
New Stir Speed setting
Press “SET” to accept the new Stir Speed.
The stir motor speed needs to be varied for best stability. Table 3 on page 25 shows
nominal settings for several uids.
9.8.2 Serial Interface Parameters
The serial RS-232 interface parameters menu is indicated by,
SErIAL
Serial RS-232 interface parameters menu
39
7102 Micro-Bath User’s Guide
Controller Conguration
The serial interface parameters menu contains parameters which determine the
operation of the serial interface. These controls only apply to instruments tted with
the serial interface. The parameters in the menu are — baud rate, sample period,
duplex mode, and linefeed. Press “UP” to enter the menu.
Baud Rate9.8.2.1
The baud rate is the rst parameter in the menu. The baud rate setting deter mines the
serial communications transmission rate.
The baud rate parameter is indicated by,
bAUd
2400 b
Flashes “bAUd” and then displays the setting
Current baud rate
The baud rate of the serial communications may be programmed to 300, 600, 1200,
2400, 4800, or 9600 baud. Use “UP” or “DOWN” to change the baud rate value.
4800 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.
Sample Period9.8.2.2
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 in strument
transmits the current measurement over the serial interface approximately every ve
seconds. The automatic sampling is disabled with a sample period of 0. The sample
period is indicated by,
SPer
SP= 1
Flashes “SPEr” and then displays the setting
Current sample period (seconds)
40
Adjust the value with “UP” or “DOWN” and then use “SET” to store the sam ple rate
to the displayed value. “EXIT” does not store the new value.
SP= 60
New sample period
Controller Operation
Controller Conguration
Duplex Mode9.8.2.3
The next parameter is the duplex mode. The duplex mode may be set to full du plex
or half duplex. With full duplex any commands received by the calibrator via the
serial interface will be immediately echoed or transmitted back to the device of origin.
With half duplex the commands will be executed but not ech oed. The duplex mode
parameter is indicated by,
dUPL
d=FULL
Flashes “dUPL” and then displays the setting
Current duplex mode setting
The mode may be changed using “UP” or “DOWN” and pressing “SET”.
d=HALF
Linefeed 9.8.2.4
New duplex mode setting
The nal 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,
LF
LF= On
Flashes “LF” and then displays the setting
Current linefeed setting
The mode may be changed using “UP” or “DOWN” and pressing “SET”.
LF= OFF
New linefeed setting
9.8.3 Calibration Parameters
The operator of the Micro-Bath controller has access to a number of the bath
calibration constants namely R0, ALPHA, DELTA, C0, CG, and rCAL. These values
are set at the factory and should not be altered. The cor rect 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 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 manual.
Caution: DO NOT change the values of the bath calibration constants from the
factory set values. The correct setting of these parameters is im portant to the
safety and proper operation of the bath.
41
7102 Micro-Bath User’s Guide
Controller Conguration
The calibration parameters menu is indicated by:
CAL
Calibration parameters menu
Press “SET” ve times to enter the menu.
The calibration parameters R0, ALPHA, DELTA, C0, CG, and rCAL characterize the
resistance-temperature relationship of the platinum control sensor. These pa rameters
may be adjusted by an experienced user to improve the accuracy of the calibrator.
R0 9.8.3.1
This probe parameter refers to the resistance of the control probe at 0°C. The value of
this parameter is set at the factory for best instrument accuracy.
ALPHA 9.8.3.2
This probe parameter refers to the average sensitivity of the probe between 0 and
100°C. The value of this parameter is set at the factory for best instrument accuracy.
DELTA 9.8.3.3
This probe parameter characterizes the curvature of the resistance-temperature
relationship of the sensor. The value of this parameter is set at the factory for best
instrument accuracy.
C0 and CG9.8.3.4
These parameters calibrate the accuracy of the bath set-point. These are programmed
at the factory when the bath is calibrated. DO NOT alter the value of these parameters.
If the user desires to calibrate the bath for improved accuracy then calibrate R0 and
ALPHA according to the procedure in Section 12.
42
rCAL9.8.3.5
DO NOT adjust this parameter. It is for factory use only.
Digital Communication Interface
Serial Communications
10 Digital Communication Interface
The Micro-Bath calibrator is capable of communicating with and being con trolled by
other equipment through the digital serial interface.
With a digital interface the instrument may be connected to a computer or other
equipment. This allows the user to set the set-point temperature, monitor the
temperature, and access any of the other controller functions, all using remote
communications equipment. Communications commands are summarized in Table 5
on page 46.
Serial Communications 10.1
The calibrator is installed with an RS-232 serial interface that allows serial dig ital
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.
Wiring 10.1.1
The serial communications cable
attaches to the calibrator through the
DB-9 connector at the back of the
instrument. Figure 8 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. If the unit is used in a
heavy industrial setting, the serial cable
must be limited to ONE METER in
length.
Setup 10.1.2
Before operation the serial inter face must
rst be set up by pro gramming the baud
rate and other conguration parameters.
These parameters are programmed
within the serial interface menu. The
serial interface parameters menu is
outlined in Figure 7 on page 32.
Figure 8 Serial Cable Wiring
To enter the serial parameter pro gramming mode rst press “EXIT” while pressing
“SET” and release to enter the secondary menu. Press “SET” re peatedly until
the display reads “PAr”. Press “UP” until the serial interface menu is indicated
with“SErIAL”. Finally press “SET” to enter the serial pa rameter menu. In the serial
43
7102 Micro-Bath User’s Guide
Serial Communications
interface parameters menu are the baud rate, the sample rate, the duplex mode, and the
linefeed parameter.
Baud Rate 10.1.2.1
The baud rate is the rst 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 7102 serial
communications may be programmed to 300, 600, 1200, 2400, 4800, or 9600 baud.
The baud rate is pre-programmed to 2400 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 pa rameter in the menu.
Sample Period10.1.2.2
The sample period is the next parameter in the menu and prompted with “SPEr”.
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 instrument
transmits the current measurement over the serial interface ap proximately every ve
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.
Duplex Mode10.1.2.3
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 will be immediately
echoed or transmitted back to the device of origin. With half duplex the commands
will be executed but not echoed. The default setting is full duplex. The mode may be
changed using “UP” or “DOWN” and pressing “SET”.
Linefeed10.1.2.4
The nal 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”.
Serial Operation10.1.3
Once the cable has been attached and the interface set up properly the control ler will
immediately begin transmitting temperature readings at the pro grammed rate. The
serial communications uses 8 data bits, one stop bit, and no parity. The set-point and
other commands may be sent via the serial interface to set the temperature set-point
and view or program the various parameters. The interface commands are discussed
in Section 10.2. All commands are ASCII character strings terminated with a carriagereturn character (CR, ASCII 13).
44
10.2 Interface Commands
The various commands for accessing the calibrator functions via the digital in terfaces
are listed in this section (see Table 5). These commands are used with the RS-232
serial interface. The commands are terminated with a carriage-re turn character. The
interface makes no distinction between upper and lower case letters, hence either 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=150.0”<CR> will set the set-point to 150.0 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.
Digital Communication Interface
Interface Commands
45
7102 Micro-Bath User’s Guide
Interface Commands
Table 5 Controller Communications Commands
Command Description Command Format Command Example Returned Returned Example Acceptable Values
Display Temperature
Read current set-point s[etpoint] s set: 999.99 {C or F} set: 150.00 C
Set current set-point to n s[etpoint]=n s=200.00 Instrument Range
Read temperature t[emperature] t t: 999.99 {C or F} t: 55.6 C
Read temperature units u[nits] u u: x u: C
Set temperature units: u[nits]=c/f C or F
Set temperature units to Celsius u[nits]=c u=c
Set temperature units to
Fahrenheit
Read scan mode sc[an] sc scan: {ON or OFF} scan:ON
Set scan mode sc[an]=on/off sc=on ON or OFF
Read scan rate sr[ate] sr srat: 99.9 {C or F}/min srat:12.4C/min
Set scan rate sr[ate]=n sr=1.1 .1 to 99.9
Read hold ho[ld] ho hold: open/closed,
Secondary Menu
Read proportional band setting pr[opband] pr pb: 999.9 pb: 15.9
Set proportional band to n pr[opband]=n pr=8.83 Depends on
Read heater power
(duty cycle)
Conguration Menu
Operating Parameters Menu
Read stirrer motor speed mo[tor] mo mo: 99 mo: 15
Set stirrer motor speed to n mo[tor]=n mo=16 0 to 40
Read high limit hl hl hl:999 hl:126
Set high limit hl=n hl=90 0–126
Serial Interface Menu
Read serial sample setting sa[mple] sa sa: 9 sa: 1
Set serial sampling setting to n
seconds
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 R0 calibration parameter r[0] r r0: 999.999 r0: 100.578
Set R0 calibration parameter to n r[0]=n r=100.324 90 to 110
Read ALPHA calibration
parameter
Set ALPHA calibration parameter
to n
Read DELTA calibration
parameter
Set DELTA calibration parameter de[lta]=n de=1.3742 0–3.0
Read C0 calibration parameter *c[0] *c c0:99.9999 c0:-0.297
Set C0 calibration parameter *c[0]=n *c=-5.113
Read CG calibration parameter *cg *cg cg:99.999 cg:-0.555
Set CG calibration parameter *cg=n *cg=-4.115
Functions not on menu
Read rmware version number *ver[sion] *ver ver.9999,9.99 ver.7102,2.00
Read structure of all commands h[elp] h list of commands
Read all operating parameters all all list of parameters
Legend: [] Optional Command data
Note: When DUPLEX is set to FULL and a command is sent to READ, the command is returned followed by a carriage return and
u[nits]=f u=f
99.9 {C or F}
po[wer] po po: 999.9 po: 1.0
sa[mple]=n sa=0 0 to 999
al[pha] al al: 9.9999999 al: 0.0038573
al[pha]=n al=0.0038433 .002 to .005
de[lta] de de:9.99999 de: 1.507
{} Returns either information
n Numeric data supplied by user
9 Numeric data returned to user
x Character data returned to user
linefeed. Then the value is returned as indicated in the RETURNED column.
hold: open, 30.5 C
Conguration
46
Test Probe Calibration
Calibrating a Single Probe
Test Probe Calibration11
Note: This procedure is to be considered a general guideline. Each laboratory
should write their own procedure based on their equipment and their quality
program. Each procedure should be accompanied by an uncertainty analysis
also based on the laboratory’s equipment and environment.
For optimum accuracy and stability, allow the calibrator to warm up for 25 minutes
after power-up and then allow adequate stabilization time after reach ing the set-point
temperature. After completing operation of the calibrator, al low the well to cool by
setting the temperature to 25°C for one-half hour before switching the power off.
Calibrating a Single Probe 11.1
Insert the probe to be calibrated into the well of the bath. Best results are ob tained
with the probe inserted to the full depth of the well. Once the probe is in serted into
the well, allow adequate stabilization time to allow the test probe temperature to settle
as described above. Once the probe has settled to the tem perature of the well, it may
be compared to the calibrator display temperature. The display temperature should be
stable to within 0.1°C degree for best results.
Caution: Never introduce any foreign material into the well.
Stabilization and Accuracy 11.2
The stabilization time of the Micro-Bath depends on the conditions and temper atures
involved. Typically the test well will be stable to 0.1°C within 10 min utes of reaching
the set-point temperature. Ultimate stability will be achieved 30 minutes after reaching
the set temperature.
Inserting a cold probe into a well requires another period of stabilizing depend ing on
the magnitude of the disturbance and the required accuracy. For exam ple, inserting a
.25 inch diameter room temperature probe at 200°C takes 5 minutes to be within 0.1°C
of its settled point and takes 10 minutes to achieve maximum stability.
Speeding up the calibration process can be accomplished by knowing how soon
to make the measurement. Typical measurements should be made at the desired
temperatures with the desired test probes to establish these times.
47
Calibration Procedure
Calibration Points
12 Calibration Procedure
Note: This procedure is to be considered a general guideline. Each laboratory
should write their own procedure based on their equipment and their quality
program. Each procedure should be accompanied by an uncertainty analysis
also based on the laboratory’s equipment and environment.
Sometimes the user may want to calibrate the bath to improve the temperature
set-point accuracy. Calibration is done by adjusting the controller probe calibra tion
constants R0, ALPHA, and DELTA so that the temperature of the bath as measured
with a standard thermometer agrees more closely with the set-point. The thermometer
used must be able to measure the well temperature with higher accuracy than the
desired accuracy of the bath. By using a good thermometer and following this
procedure the bath can be calibrated to an ac curacy of better than 0.5°C up to 200°C.
Calibration Points 12.1
In calibrating the bath, R0, ALPHA, and DELTA are adjusted to mini mize the setpoint error at each of three different bath temperatures. Any three reasonably separated
temperatures may be used for the calibration. Improved results can be obtained for
shorter ranges when using temperatures that are just within the most useful operating
range of the Micro-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 50°C to 150°C is chosen as the calibration range then
the calibrator may achieve an ac curacy of say ±0.3°C over the range 50 to 150°C.
Choosing a range of 50°C to 90°C may allow the calibrator to have a better accuracy
of maybe ±0.2°C over that range but outside that range the accuracy may be only
±1.5°C.
Calibration Procedure 12.2
Choose three set-points to use in the calibration of the R0, ALPHA, and DELTA 1.
parameters. These set-points are generally 40.0°C, 95°C, and 195.0°C but other
set-points may be used if desired or necessary.
Set the bath to the low set-point. When the bath reaches the set-point and the 2.
display is stable, wait 15 minutes or so and then take a reading from the thermometer. Sample the set-point resistance by holding down the “SET” key and
pressing the “DOWN” key. Write these values down as T1 and R1 respectively.
Repeat step 2 for the other two set-points recording them as T3.
respectively.
Using the recorded data, calculate new values for R0, ALPHA, and DELTA 4.
parameters using the equations given below:
, R2, T3, and R3
2
49
7102 Micro-Bath User’s Guide
AT T=−
32
BT T=−
21
C
TT
TT
=
−
−
−
33
22
100
1
100 100
1
100
D
TTTT
=
−
−
−
2211
100
1
100 100
1
100
ERT=−
32
FRT=−
21
delta
AF BE
DE CF
=
=
−
aTdelta
TT
11
11
100
1
100
=+
−
aTdelta
TT
33
33
100
1
100
=+
−
rzero
Ra Ra
aa
=
=
−
31 13
13
alpha
RR
Ra Ra
=
−
=
13
31 13
Calibration Procedure
Compute DELTA 12.2.1
T
– Measured temperature using thermometer.
1-3
R
– Value of R from display of 7102 (Press SET and DOWN at the same time.)
1-3
where
T1 and R1 are the measured temperature and resistance at 50.0 °C
T2 and R2 are the measured temperature and resistance at 90.0 °C
T3 and R3 are the measured temperature and resistance at 150.0 °C
Compute R0 & ALPHA12.2.2
Where:
delta is the new value of DELTA computed above
Program the new values for DELTA (delta), R0 (rzero), and ALPHA (alpha) into the
Micro-Bath with the following steps.
50
Press “SET” and “EXIT” keys at the same time and then press “UP” until 1.
Calibration Procedure
Calibration Procedure
“CAL” is displayed.
Press “SET” five times until “2. R0” is displayed.
Press “SET” then use the “UP” or “DOWN” keys until the correct nu merical 3.
setting is displayed. Press “SET” to accept the new value.
Repeat step 2 for ALPHA and DELTA. 4.
Accuracy & Repeatability 12.2.3
Check the accuracy of the Micro-Bath at various points over the calibrated range.
If Micro-Bath does not pass specication at all set-points, repeat the Calibration
Procedure.
51
Maintenance
Maintenance 13
The calibration instrument has been designed with the utmost care. Ease of
operation 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 an oily, wet, dirty, or
dusty environment.
If the outside of the instrument becomes soiled, it may be wiped clean with
a damp cloth and mild detergent. Do not use harsh chemicals on the surface
which may damage the paint.
It is important to keep the well of the calibrator clean and clear of any for eign
matter. DO NOT use chemicals to clean the well.
The bath should be handled with care. Avoid knocking or dropping the
instrument.
If a hazardous material is spilt on or inside the equipment, the user is
responsible for taking the appropriate decontamination steps as outlined by the
national safety council with respect to the material.
If the mains supply cord becomes damaged, replace it with a cord with the
appropriate gauge wire for the current of the instrument. If there are any
questions, call an Authorized Service Center for more information.
Before using any cleaning or decontamination method except those
recommended by Hart, users should check with an Authorized Service Center 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 Micro-Bath may be impaired or safety hazards may
arise.
53
Troubleshooting
Troubleshooting Problems, Possible Causes, and Solutions
Troubleshooting14
This section contains information on troubleshooting and CE Comments.
Troubleshooting Problems, Possible Causes, and Solutions 14.1
In the event that the instrument appears to function abnormally, this section may help
to nd 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 problem cannot otherwise be
solved, contact an Authorized Service Center (see Section 1.3). Be sure to have the
model number and serial number of your instrument available.
Problem Possible Causes and Solutions
Incorrect tempera ture
reading
The instrument heats
or cools too quickly or
too slowly
An “o” is displayed at
the left of the display
The display shows
any error
The stirrer is not
stirring
Temperature readout
is not the actual
temperature of the
well
Instrument is unstable Varying line voltage or uid is not stirring. Place the unit on a clean power line. If the
Incorrect R0, ALPHA, and DELTA parameters. Find the value for R0, ALPHA, and
DELTA on the Report of Calibration that was shipped with the instrument. Reprogram
the parameters into the instrument (see Section 9.8.3, Calibration Parameters). Allow the
instrument to stabilize and verify the accuracy of the temperature reading.
Controller locked up. The controller may have locked up due to a power surge or other
aberration. Initialize the system by performing the Factory Reset Sequence.
Factory Reset Sequence. Hold the SET and EXIT buttons down at the same time while
powering up the instrument. The instrument displays shows ‘ -init-’, the model number,
and the rmware version. Each of the controller parameters and cali bration constants
must be reprogrammed. The values can be found on the Report of Calibration that was
shipped with the instrument.
Incorrect scan and scan rate settings. The scan and scan rate settings may be set to
unwanted values. Check the Scan and Scan Rate settings. The scan may be off (if the
unit seems to be responding too quickly). The scan may be on with the Scan Rate set low
(if unit seems to be responding too slowly).
External switch is open. The external switch is open causing the displayed temperature
to be frozen and keeping the set-point from scanning. Turn the switch test off by pressing
the “DOWN” button on the front panel.
Controller problem. The error messages signify the following problems with the
controller.
Err 1 – a RAM error
Err 2 – a NVRAM error
Err 3 – a Structure error
Err 4 – an ADC setup error
Err 5 – an ADC ready error
Err 6 – Defective control sensor. The control sensor may be shorted, open or otherwise
damaged.
Initialize the system by performing the Factory Reset Sequence described above.
Err 7 – Heater control error. Initialize the system by performing the Factory Reset
Sequence described above.
Stirrer speed needs adjusting. In the Operating Parameters menu, adjust the stirrer
speed (“Str Sp”) to 0. Wait for the motor to stop. Adjust the stirrer speed to a setting
greater than 8 but less than or equal to 25.
Possible RF energy emission. With the unit stable, slowly rotate the unit. If no change
occurs, the unit may need to be calibrated. If the display changes more than twice the
normal display deviation, another unit in the area could be emitting RF en ergy. Move the
unit to a different location and rotate the unit again. If the temperature is correct in this
new area or deviates differently than the rst are, RF energy is pres ent in the room. If you
have to perform the test in the effected area, use the compari son test to eliminate any
possible errors.
uid is not stirring, turn the instrument off for one minute.
55
7102 Micro-Bath User’s Guide
Comments
Problem Possible Causes and Solutions
AC voltage present on
the chassis
Comments14.2
EMC Directive14.2.1
Hart Scientics’ 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 specic standards to which the unit was
tested.
Low Voltage Directive (Safety)14.2.2
In order to comply with the European Low Voltage Directive (73/23/EEC), Hart
Scientic equipment has been designed to meet the EN 61010-1 and EN 61010-2-010
standards.
Use a wall plug tester to check the main power plug at the wall. Use an ohmmeter to
check the continuity between the ground prong on the PEM and the chassis. If the
resistance reading is greater than three ohms, there is a problem. Check the power cord
for continuity on the ground prongs. If the resistance is greater than one ohm, re place the
power cord.
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