Fluke 7381 User manual

7381
Calibration Bath
User’s Guide
June 2013, Rev. 1, 5/23 (English)
©2013-2023 Fluke Corporation. All rights reserved.
Specifications are subject to change without notice.
All product names are trademarks of their respective companies.

LIMITED WARRANTY AND LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under normal use and
service. The warranty period is 1 year and begins on the date of shipment. Parts, product repairs, and
services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of
a Fluke authorized reseller, and does not apply to fuses, disposable batteries, or to any product which, in
Fluke's opinion, has been misused, altered, neglected, contaminated, or damaged by accident or abnormal
conditions of operation or handling. Fluke warrants that software will operate substantially in accordance
with its functional specifications for 90 days and that it has been properly recorded on non-defective media.
Fluke does not warrant that software will be error free or operate without interruption.
Fluke 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 Fluke. Warranty support is
available only if product is purchased through a Fluke authorized sales outlet or Buyer has paid the
applicable international price. Fluke reserves the right to invoice Buyer for importation costs of repair/
replacement parts when product purchased in one country is submitted for repair in another country.
Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair,
or replacement of a defective product which is returned to a Fluke authorized service center within the
warranty period.
To obtain warranty service, contact your nearest Fluke authorized service center to obtain return
authorization information, then send the product to that service center, with a description of the difficulty,
postage and insurance prepaid (FOB Destination). Fluke assumes no risk for damage in transit. Following
warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke
determines that failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal
condition of operation or handling, including overvoltage failures caused by use outside the product’s
specified rating, or normal wear and tear of mechanical components, Fluke will provide an estimate of 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. FLUKE SHALL NOT BE LIABLE
FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES,
INCLUDING LOSS OF DATA, ARISING FROM ANY CAUSE OR 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 or other
decision-maker of competent jurisdiction, such holding will not affect the validity or enforceability of any
other provision.
11/99
Fluke Corporation
P.O. Box 9090
Everett WA 98206-9090
U.S.A.
Fluke Europe B.V.
P.O. Box 1186
5602 BD Eindhoven
The Netherlands

i
Table of Contents
Title Page
Introduction................................................................................................ 1
Contact Fluke Calibration .......................................................................... 1
Safety Information ..................................................................................... 1
Specifications and Environmental Conditions ........................................... 3
Installation ................................................................................................. 3
Unpack the Product .............................................................................. 4
Uncrate and Move the Bath .................................................................. 4
Bath Environment ................................................................................. 5
Tipping Prevention Bracket Installation ................................................ 5
Installation On A Wood Floor ........................................................... 5
Installation On A Concrete Floor...................................................... 5
Parts and Controls..................................................................................... 7
Front Panel ........................................................................................... 7
Bath Tank and Lid................................................................................. 8
Rear Panel and the Fluid Expansion Reservoir.................................... 9
Before You Begin ...................................................................................... 10
Power.................................................................................................... 12
Bath Preparation and Filling ................................................................. 12
Set the Temperature............................................................................. 13
Bath Use.................................................................................................... 13
General ................................................................................................. 13
Comparison Calibration ........................................................................ 14
Calibrate Multiple Probes...................................................................... 15
General Operation ..................................................................................... 15
Heat Transfer Fluid ............................................................................... 15
Temperature Range......................................................................... 15
Viscosity........................................................................................... 15
Specific Heat.................................................................................... 15
Thermal Conductivity ....................................................................... 16
Thermal Expansion .......................................................................... 16
Electrical Resistivity ......................................................................... 17
Fluid Lifetime.................................................................................... 17
Safety............................................................................................... 17
Cost.................................................................................................. 17
Commonly Used Fluids......................................................................... 17

7381
User’s Guide
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Water ............................................................................................... 18
Ethylene Glycol ................................................................................ 18
Mineral Oil........................................................................................ 18
Silicone Oil ....................................................................................... 18
Fluid Characteristics Charts............................................................. 19
Stirring .................................................................................................. 23
Heater................................................................................................... 23
Temperature Controller......................................................................... 23
Cutout ................................................................................................... 23
Cooling Control.......................................................................................... 24
Refrigeration.............................................................................................. 24
Controller Operation .................................................................................. 26
Bath Temperature................................................................................. 26
Reset Cutout......................................................................................... 26
Temperature Set-point.......................................................................... 28
Programmable Set-points ................................................................ 28
Set-point Value ................................................................................ 28
Set-point Vernier .............................................................................. 29
Scan ..................................................................................................... 29
Scan Control .................................................................................... 29
Scan Rate ........................................................................................ 29
Temperature Scale Units...................................................................... 30
Program Menu...................................................................................... 30
Number of Program Set-points ........................................................ 30
Set-points......................................................................................... 31
Program Soak Time ......................................................................... 31
Program Function Mode .................................................................. 31
Program Control............................................................................... 32
Secondary Menu .................................................................................. 32
Heater Power ................................................................................... 32
Proportional Band ............................................................................ 33
Cutout Set-point ............................................................................... 34
Controller Configuration ................................................................... 35
Probe Parameters................................................................................. 35
R0...............................................................................................................................35
ALPHA ............................................................................................. 35
Operating Parameters .......................................................................... 36
Cooling Mode................................................................................... 36
Hot Gas Bypass Mode ..................................................................... 36
Serial Interface Parameters.................................................................. 38
BAUD Rate ...................................................................................... 38
Sample Period ................................................................................. 39
Duplex Mode.................................................................................... 39
Linefeed ........................................................................................... 39
IEEE-488 Setup (Optional)........................................................................ 40
IEEE-488 Parameters........................................................................... 40
IEEE-488 Address ........................................................................... 40
Transmission Termination................................................................ 40
Calibration Parameters......................................................................... 41

Calibration Bath
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CTO ................................................................................................. 41
BO and BG....................................................................................... 41
H and L ............................................................................................ 41
HGbt................................................................................................. 41
Digital Communication Interface................................................................ 42
Serial Communications......................................................................... 42
Wiring.................................................................................................... 42
Interface Commands ............................................................................ 43
Calibration Procedure................................................................................ 47
Calibration Points.................................................................................. 47
Measure the Set-point Error ................................................................. 48
Compute R0and ALPHA ...................................................................... 48
Calibration Example.............................................................................. 49
Maintenance .............................................................................................. 50
Troubleshooting......................................................................................... 52