ASTM E230/E230M-23

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Designation: E230/E230M − 23 An American National Standard
Standard Specification for
Temperature-Electromotive Force (emf) Tables for
1
Standardized Thermocouples
This standard is issued under the fixed designation E230/E230M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope elements of Type C are not included because materials for Type
C thermocouples are normally supplied as matched pairs only.
1.1 This specification contains reference tables (Tables 8 to
1.7 Polynomial coefficients which may be used for compu-
25) that give temperature-electromotive force (emf) relation-
2
tation of thermocouple emf as a function of temperature are
ships for Types B, C, E, J, K, N, R, S, and T thermocouples.
given in Table 7. Coefficients for the emf of each thermocouple
These are the thermocouple types most commonly used in
pair as well as for the emf of most individual thermoelements
industry. The tables contain all of the temperature-emf data
versus platinum are included. Coefficients for type RP and SP
currently available for the thermocouple types covered by this
thermoelements are not included since they are nominally the
standard and may include data outside of the recommended
same as for types R and S thermocouples, and coefficients for
upper temperature limit of an included thermocouple type.
type RN or SN relative to the nominally similar Pt-67 would be
1.2 In addition, the specification includes standard and
insignificant. Coefficients for the individual thermoelements of
special tolerances on initial values of emf versus temperature
Type C thermocouples have not been established.
for thermocouples (Table 1), thermocouple extension wires
1.8 Coefficients for sets of inverse polynomials are given in
(Table 2), and compensating extension wires for thermo-
Table 46. These may be used for computing a close approxi-
couples (Table 3). Users should note that the stated tolerances
mation of temperature (°C) as a function of thermocouple emf.
apply only to the temperature ranges specified for the thermo-
Inverse functions are provided only for thermocouple pairs and
couple types as given in Tables 1, 2, and 3, and do not apply to
are valid only over the emf ranges specified.
the temperature ranges covered in Tables 8 to 25.
1.9 This specification is intended to define the thermoelec-
1.3 Tables 4 and 5 provide insulation color coding for
tric properties of materials that conform to the relationships
thermocouple and thermocouple extension wires as customar-
presented in the tables of this standard and bear the letter
ily used in the United States.
designations contained herein. Topics such as ordering
1.4 Recommendations regarding upper temperature limits
information, physical and mechanical properties,
for the thermocouple types referred to in 1.1 are provided in
workmanship, testing, and marking are not addressed in this
Table 6.
specification. The user is referred to specific standards such as
Specifications E235, E574, E585/E585M, E608/E608M,
1.5 Tables 26 to 45 give temperature-emf data for single-leg
E1159, or E2181/E2181M for guidance in these areas.
thermoelements referenced to platinum (NIST Pt-67). The
tables include values for Types BP, BN, JP, JN, KP (same as
1.10 The temperature-emf data in this specification are
EP), KN, NP, NN, TP, and TN (same as EN).
intended for industrial and laboratory use.
1.6 Tables for Types RP, RN, SP, and SN thermoelements
1.11 Thermocouple color codes per IEC 584–3 are given in
are not included since, nominally, Tables 18 to 21 represent the
Appendix X1.
thermoelectric properties of Type RP and SP thermoelements
1.12 The values stated in either SI units or inch-pound units
referenced to pure platinum. Tables for the individual thermo-
are to be regarded separately as standard.
1.12.1 The values stated in brackets are not conversions to
the values they succeed and therefore shall be used indepen-
1
This specification is under the jurisdiction of ASTM Committee E20 on
dently of the preceding values.
Temperature Measurement and are the direct responsibility of Subcommittee E20.11
1.12.2 The values given in parentheses are conversions of
on Thermocouples - Calibration.
the values they succeed.
Current edition approved May 1, 2023. Published January 2024. Originally
1.12.3 Combining values from the two systems may result
approved in 1963. Last previous edition approved in 2017 as E230/E230M – 17.
DOI: 10.1520/E0230_E0230M-23.
in non-conformance with the standard.
2
These temperature-emf relationships have been revised as required by the
1.13 This standard does n
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