E 710 86 (1997)

Designation: E 710 – 86 (Reapproved 1997)

Standard Test Method for

Comparing EMF Stabilities of Base-Metal Thermoelements

in Air Using Dual, Simultaneous, Thermal-EMF Indicators1

This standard is issued under the fixed designation E 710; the number immediately following the designation indicates the year of

original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A

superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

1. Scope

1.1 This test method provides tests to compare the emf

stabilities of base-metal thermoelements using dual, simulta￾neous, thermal-emf indicators. The tests are conducted in air at

a specified constant temperature, and the emfs of the base￾metal thermoelements are measured against a platinum ther￾moelement. Thus, the method also yields the time-dependent

change of the emf of a base-metal thermoelement relative to a

platinum thermoelement. The total life (time to open circuit) of

the thermoelement can be determined by the method, if

desired.

1.2 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 appro￾priate safety and health practices and determine the applica￾bility of regulatory limitations prior to use.

2. Referenced Documents

2.1 ASTM Standards:

E 220 Test Method for Calibration of Thermocouples by

Comparison Techniques2

E 230 Specification and Temperature-Electromotive Force

(EMF) Tables for Standardized Thermocouples2

E 344 Terminology Relating to Thermometry and Hydrom￾etry2

E 563 Practice for Preparation and Use of Freezing Point

Reference Baths3

3. Terminology

3.1 Definitions—The definitions given in Terminology

E 344 shall apply.

3.2 Definition of Term Specific to This Standard:

3.2.1 emf stability—The change in output expressed in

millivolts (or in equivalent degrees if the thermoelectric power

is known) occurring over a specified time at a specified

temperature.

4. Summary of Test Method

4.1 In this test method, dual, thermal-emf indicators are

used to measure simultaneously the emf E1 of a thermocouple

used to measure the test temperature and the emf E2 of a

base-metal thermoelement relative to a platinum thermoele￾ment. The test method consists of the measurement of E2 at

specified time intervals and at a specified constant value of E1,

which corresponds to a specified, constant indicated tempera￾ture, until the required time of the test is exceeded or until an

open circuit in the base-metal thermoelement results. Because

all the measurements are made at the same indicated test

temperature (E2 is measured at a specified constant value of

E1), temperature corrections to E2 are not needed.

4.2 This test method is based on Method A of Test Method

E 220, where the standard thermocouple of Test Method E 220

becomes the thermocouple used to measure the test tempera￾ture of this method, and a specified constant temperature

replaces the series of measured temperatures of Test Method

E 220.

4.3 The accuracy of this test method depends on the emf

stability of the platinum thermoelement. If there is concern that

the platinum thermoelement has become unstable, the proce￾dure described in Appendix X1 shall be performed.

5. Significance and Use

5.1 This test method is important because the accuracy of

the temperature measurement is related to the emf stability of

the thermoelements.

5.2 This test method is used primarily by users of thermo￾couples to verify that they meet the intended requirements.

5.3 This test method is useful in comparing the emf stability

of two base metal thermoelements using dual thermal emf

indicators.

5.4 The relative stabilities of base metal thermoelements

determined by this test method are valid only under the

specified test conditions and would be affected by changes in

the following conditions: (1) temperature profile or gradient

along the length of the thermoelements; (2) abundance, veloc￾ity and composition of the air surrounding the test pieces; (3)

relative inhomogeneity of the test thermoelements; (4) purity

level of the platinum thermoelement.

5.5 The test method does not include the determination of

the stabilities of base metal thermoelements following changes

from one constant temperature to another.

1 This test method is under the jurisdiction of ASTM Committee E-20 on

Temperature Measurement and is the direct responsibility of Subcommittee E20.04

on Thermocouples.

Current edition approved March 27, 1986. Published May 1986. Originally

published as E710 - 79. Discontinued January 1995 and reinstated as

E 710 – 86 (1997). 2 Annual Book of ASTM Standards, Vol 14.03. 3 Discontinued; see 1994 Annual Book of ASTM Standards, Vol 14.03.

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