Standard Test Method for Calibration of Thermocouples By Comparison Techniques

SCOPE
1.1 This method describes the principles, apparatus, and procedure for calibrating thermocouples by comparison with a reference thermometer. Calibrations are covered over temperature ranges appropriate to the individual types of thermocouples within an overall range from approximately - 195 to 1700 °C (- 320 to 3100 °F).
1.2 In general, this method is applicable to unused thermocouples. This method does not apply to used thermocouples due to their potential material inhomogeneity-the effects of which cannot be identified or quantified by standard calibration techniques. Thermocouples with large-diameter thermoelements and sheathed thermocouples may require special care to control thermal conduction losses.
1.3 In this method, all values of temperature are based on the International Temperature Scale of 1990. See Guide E 1594.
1.4 This standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory requirements prior to use.

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Publication Date
09-May-2002
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ASTM E220-02 - Standard Test Method for Calibration of Thermocouples By Comparison Techniques
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:E220–02
Standard Test Method for
1
Calibration of Thermocouples By Comparison Techniques
This standard is issued under the fixed designation E220; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope E563 Practice for Preparation and Use of Freezing Point
2
Reference Baths
1.1 This method describes the principles, apparatus, and
E644 Test Methods for Testing Industrial Resistance Ther-
procedure for calibrating thermocouples by comparison with a
2
mometers
referencethermometer.Calibrationsarecoveredovertempera-
E988 Standard Temperature-Electromotive Force (EMF)
ture ranges appropriate to the individual types of thermo-
2
Tables for Tungsten-Rhenium Thermocouples
couples within an overall range from approximately −195 to
2
E1129 Specification for Thermocouple Connectors
1700 °C (−320 to 3100 °F).
2
E1594 Guide for Expression of Temperature
1.2 In general, this method is applicable to unused thermo-
E1684 Specification for Miniature Thermocouple Connec-
couples. This method does not apply to used thermocouples
2
tors
due to their potential material inhomogeneity—the effects of
E1751 Guide for Temperature Electromotive Force (EMF)
whichcannotbeidentifiedorquantifiedbystandardcalibration
Tables for Non-Letter Designated Thermocouple Combi-
techniques. Thermocouples with large-diameter thermoele-
2
nations
ments and sheathed thermocouples may require special care to
control thermal conduction losses.
3. Terminology
1.3 In this method, all values of temperature are based on
3.1 Definitions—The definitions given in Terminology
the International Temperature Scale of 1990. See Guide
E344 shall apply to this test method.
E1594.
3.2 Definitions of Terms Specific to This Standard:
1.4 This standard may involve hazardous materials, opera-
3.2.1 check standard, n—a measurement instrument or
tions and equipment. This standard does not purport to address
standard whose repeated results of measurement are used to
all of the safety concerns, if any, associated with its use. It is
determine the repeatability of a calibration process and to
the responsibility of the user of this standard to establish
verifythattheresultsofacalibrationprocessesarestatistically
appropriate safety and health practices and determine the
consistent with past results.
applicability of regulatory requirements prior to use.
3.2.2 isothermal block, n—a piece of solid material of high
2. Referenced Documents thermal conductivity used to promote thermal equilibrium
between two or more thermometers.
2.1 ASTM Standards:
2
3.2.3 reference junction compensation, n—the adjustment
E1 Specification for ASTM Thermometers
of the indication of a thermocouple such that the adjusted
E77 Test Method for Inspection and Verification of Ther-
2
indication is equivalent to the emf or temperature that the
mometers
thermocouple would indicate if the reference junctions were
E230 Specification for Temperature-Electromotive Force
2
maintained at 0 °C.
(EMF) Tables for Standardized Thermocouples
3.2.3.1 Discussion—In most cases, the thermocouple indi-
E344 Terminology Relating to Thermometry and Hydrom-
2
cation is adjusted by measuring the temperature of a terminal
etry
blockwherethethermocoupleisconnected,andthenaddingto
E452 Test Method for Calibration of Refractory Metal
2
thethermocoupleemfanadditionalemfequaltotheemfofthe
Thermocouples Using a Radiation Thermometer
thermocouple reference function evaluated at the temperature
of the terminal block. Because the emf-temperature relation-
shipofanyactualthermocouplediffersslightlyfromthatofthe
1
ThismethodisunderthejurisdictionofASTMCommitteeE20onTemperature
reference function, reference junction compensation typically
Measurement and is the direct responsibility of Subcommittee E20.04 on Thermo-
couples.
introduces higher uncertainties compared to the use of a
Current edition approved May 10, 2002. Published September 2002. Originally
well-prepared ice bath.
published as E 220 – 63 T. Discontinued January 1995 and reinstated as
e1
3.2.4 reference junction compensator, n—a device that
E220–86(1996) .
2
Annual Book of ASTM Standards, Vol 14.03. implements reference junction compensation.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E220–02
3.2.5 reference thermometer, n—thermometer that estab- 6.3 The method relies on the assumption that test thermo-
lishes the value of temperature in a given system containing elements are homogeneous. If so, their output voltage at a
additional temp
...

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