ASTM E230-98

Standard Specification and Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples

SCOPE
1.1 This specification contains reference tables (Tables 8-23) that give temperature-electromotive force (emf) relationships for Types B, E, J, K, N, R, S, and T thermocouples. These are the thermocouple types most commonly used in industry.
1.2 Also included are lists of standard and special tolerances on initial values of emf versus temperature for thermocouples (Table 1), thermocouple extension wires (Table 2), and compensating extension wires for thermocouples (Table 3).
1.3 Tables 4-5, included herein, give data on insulation color coding for thermocouple and thermocouple extension wires as customarily used in the United States.
1.4 Recommendations regarding upper temperature limits for the thermocouple types referred to in 1.1 are given in Table 6.
1.5 Tables 24-43 give temperature-emf data for single-leg thermoelements referenced to platinum (NIST Pt 67). The tables include values for Types BP, BN, JP, JN, KP (same as EP), KN, NP, NN, TP, and TN (same as EN).
1.6 Tables for Types RP, RN, SP, and SN thermoelements are not included since, nominally, Tables 18-21 represent the thermoelectric properties of Type RP and SP thermoelements referenced to pure platinum.
1.7 Polynomial coefficients that may be used for computation of thermocouple emf as a function of temperature are given in Table 7. Coefficients for the emf of each thermocouple pair as well as for the emf of individual thermoelements versus platinum are included.
1.8 Coefficients for sets of inverse polynomials are given in Table 44. These may be used for computing a close approximation of temperature (oC) as a function of thermocouple emf. Inverse functions are provided only for thermocouple pairs and are valid only over the emf ranges specified.
1.9 This specification is intended to define the thermoelectric properties of materials that conform to the relationships presented in the tables of this standard and bear the letter designations contained herein. Topics such as ordering information, physical and mechanical properties, workmanship, testing, and marking are not addressed in this specification. The user is referred to specific standards such as Specifications E235, E574, E585, E608, E1159, or E1223, as appropriate, for guidance in these areas.
1.10 The temperature-emf data in this specification are intended for industrial and laboratory use.

General Information

• Status: Historical
• Publication Date: 09-Jun-1998
• Technical Committee: E20 - Temperature Measurement

Relations

• Referred By: ASTM E839-11(2016)e1 - Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
• Effective Date: 10-Jun-1998
• Referred By: ASTM E3250-21 - Standard Practice for Product Temperature and Equipment Pressure Instrumentation in Pharmaceutical Freeze Drying
• Effective Date: 10-Jun-1998
• Referred By: ASTM A991/A991M-22 - Standard Test Method for Conducting Temperature Uniformity Surveys of Furnaces Used to Heat Treat Steel Products
• Effective Date: 10-Jun-1998
• Referred By: ASTM D7646-23 - Standard Test Method for Determination of Cooling Characteristics of Aqueous Polymer Quenchants for Aluminum Alloys by Cooling Curve Analysis
• Effective Date: 10-Jun-1998
• Referred By: ASTM C335/C335M-23 - Standard Test Method for Steady-State Heat Transfer Properties of Pipe Insulation
• Effective Date: 10-Jun-1998
• Referred By: ASTM C1834-16 - Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress Flexural Testing (Stress Rupture) at Elevated Temperatures
• Effective Date: 10-Jun-1998
• Referred By: ASTM D2879-18 - Standard Test Method for Vapor Pressure-Temperature Relationship and Initial Decomposition Temperature of Liquids by Isoteniscope
• Effective Date: 10-Jun-1998
• Referred By: ASTM E2584-20 - Standard Practice for Thermal Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter
• Effective Date: 10-Jun-1998
• Referred By: ASTM E2536-21 - Standard Guide for Assessment of Measurement Uncertainty in Fire Tests
• Effective Date: 10-Jun-1998
• Referred By: ASTM D8040-18(2023) - Standard Test Method for Corrosion Test for Heat Transfer Fluids in Glassware
• Effective Date: 10-Jun-1998
• Referred By: ASTM F526-21 - Standard Test Method for Using Calorimeters for Total Dose Measurements in Pulsed Linear Accelerator or Flash X-ray Machines
• Effective Date: 10-Jun-1998
• Referred By: ASTM D4693-07(2021) - Standard Test Method for Low-Temperature Torque of Grease-Lubricated Wheel Bearings
• Effective Date: 10-Jun-1998
• Referred By: ASTM C1363-19 - Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
• Effective Date: 10-Jun-1998
• Referred By: ASTM D6200-21 - Standard Test Method for Determination of Cooling Characteristics of Quench Oils by Cooling Curve Analysis
• Effective Date: 10-Jun-1998
• Referred By: ASTM E1232-07(2019) - Standard Test Method for Temperature Limit of Flammability of Chemicals
• Effective Date: 10-Jun-1998

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 230 – 98 An American National Standard
Standard Specification and
Temperature-Electromotive Force (EMF) Tables for
Standardized Thermocouples
This standard is issued under the fixed designation E 230; 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 tric properties of materials that conform to the relationships
presented in the tables of this standard and bear the letter
1.1 This specification contains reference tables (Tables
designations contained herein. Topics such as ordering infor-
8–23) that give temperature-electromotive force (emf) relation-
mation, physical and mechanical properties, workmanship,
ships for Types B, E, J, K, N, R, S, and T thermocouples.
testing, and marking are not addressed in this specification. The
These are the thermocouple types most commonly used in
user is referred to specific standards such as Specifications
industry.
E 235, E 574, E 585, E 608, E 1159, or E 1223, as appropriate,
1.2 Also included are lists of standard and special tolerances
for guidance in these areas.
on initial values of emf versus temperature for thermocouples
1.10 The temperature-emf data in this specification are
(Table 1), thermocouple extension wires (Table 2), and com-
intended for industrial and laboratory use.
pensating extension wires for thermocouples (Table 3).
1.3 Tables 4–5, included herein, give data on insulation
2. Referenced Documents
color coding for thermocouple and thermocouple extension
2.1 ASTM Standards:
wires as customarily used in the United States.
E 235 Specification for Thermocouples, Sheathed, Type K,
1.4 Recommendations regarding upper temperature limits
for Nuclear or for Other High-Reliability Applications
for the thermocouple types referred to in 1.1 are given in Table
E 574 Specification for Duplex, Base-Metal Thermocouple
6.
Wire with Glass Fiber or Silica Fiber Insulation
1.5 Tables 24–43 give temperature-emf data for single-leg
E 585 Specification for Sheathed Base-Metal Thermo-
thermoelements referenced to platinum (NIST Pt 67). The
couple Materials
tables include values for Types BP, BN, JP, JN, KP (same as
E 608 Specification for Metal-Sheathed Base-Metal Ther-
EP), KN, NP, NN, TP, and TN (same as EN).
mocouples
1.6 Tables for Types RP, RN, SP, and SN thermoelements
E 1159 Specification for Thermocouple Materials,
are not included since, nominally, Tables 18–21 represent the
Platinum-Rhodium Alloys, and Platinum
thermoelectric properties of Type RP and SP thermoelements
E 1223 Specification for Type N Thermocouple Wire
referenced to pure platinum.
2.2 NIST Monograph:
1.7 Polynomial coefficients that may be used for computa-
NIST Monograph 175 Temperature-Electromotive Force
tion of thermocouple emf as a function of temperature are
Reference Functions and Tables for the Letter-Designated
given in Table 7. Coefficients for the emf of each thermocouple
Thermocouple Types Based on the ITS-90
pair as well as for the emf of individual thermoelements versus
2.3 IEC Standard:
platinum are included.
IEC 584–3 First edition, 1989
1.8 Coefficients for sets of inverse polynomials are given in
Table 44. These may be used for computing a close approxi-
3. Source of Data
mation of temperature (°C) as a function of thermocouple emf.
3.1 The data in these tables are based upon the SI volt and
Inverse functions are provided only for thermocouple pairs and
the International Temperature Scale of 1990.
are valid only over the emf ranges specified.
3.2 The temperature-emf data in Tables 8–43 and the
1.9 This specification is intended to define the thermoelec-
corresponding equations in Tables 7 and 44 for all of the
These tables are under the jurisdiction of ASTM Committee E-20 on Tempera-
ture Measurement and are the direct responsibility of Subcommittee E20.04 on
Thermocouples.
Current edition approved June 10, 1998. Published March 1999. Originally Annual Book of ASTM Standards, Vol 14.03.
e1 4
published as E 230 – 63. Last previous edition E 230 – 96 . Available from National Institute of Standards and Technology, U.S. Depart-
These temperature-emf relationships have been revised as required by the ment of Commerce, Gaithersburg, MD 20899.
international adoption in 1989 of a revised International Temperature Scale Discussed in NIST Technical Note 1263, Guidelines for Implementing the New
(ITS-90). Representations of the Volt and Ohm Effective January 1, 1990.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 230
thermocouple types have been extracted from NIST Mono- 4.5 An overall suffix letter “X” (for example KX, TX, EPX,
graph 175. JNX) denotes an “extension grade” material whose thermo-
electric properties will match those of the corresponding
NOTE 1—It is beyond the scope of this standard to discuss the origin of
thermocouple type within the stated extension grade tolerances
these tables, but if further information is desired, the reader should consult
over a limited temperature span. Most base metal extension
the NIST reference noted above.
wires have the same nominal composition as the thermocouple
3.3 These tables give emf values to three decimal
wires with which they are intended to be used, whereas the
places (1 μV) at temperature intervals of one degree. Such
compensating extension wires for noble metal thermocouple
tables are satisfactory for most industrial uses but may not be
types (S, R, or B) are usually of a different, more economical
adequate for computer and similar applications. If greater
composition whose properties nonetheless closely approximate
precision is required, the reader should refer to the NIST
those of the precious metal thermocouples with which they are
reference noted above which includes tables giving emf values
to be used.
to four decimal places (0.1 μV). Equations which permit easy
and unique generation of the temperature-emf relationships
5. Tolerances on Initial Values of EMF versus
will be found in Table 7. For convenience, coefficients of
Temperature
inverse polynomials that may be used to compute approximate
5.1 Thermocouples and matched thermocouple wire pairs
temperature (°C) as a function of thermocouple emf are given
are normally supplied to the tolerances on initial values of emf
in Table 44.
versus temperature listed in Table 1.
5.1.1 Tolerances on initial values of emf versus temperature
4. Thermocouple Types and Letter Designations
for single-leg thermoelements referenced to platinum have
4.1 The letter symbols identifying each reference table are
been established only for Types KP and KN. These are
those which are in common use throughout industry and
supplied, by common practice, to a tolerance equivalent to one
identify the following thermocouple calibrations:
half the millivolt tolerance of the Type K thermocouple.
4.1.1 Type B—Platinum-30% rhodium (+) versus platinum-
5.1.2 For all other thermocouple types, tolerances on initial
6 % rhodium (−).
values of emf versus temperature for single thermoelements,
4.1.2 Type E—Nickel-10 % chromium (+) versus copper-
when required, should be established by agreement between
45% nickel (constantan) (−).
the consumer and the producer.
4.1.3 Type J—Iron (+) versus copper-45% nickel (constan-
5.1.3 In reference Tables 32, 33, 42, and 43, the thermoele-
tan) (−).
ments are identified by two thermoelement symbols indicating
4.1.4 Type K—Nickel-10 % chromium (+) versus nickel-
their applicability to two thermocouple types. This indicates
5 % (aluminum, silicon) (−) (Note 2).
that the temperature-electromotive force relationship of the
NOTE 2—Silicon, or aluminum and silicon, may be present in combi-
table is typical of the referenced thermoelements over the
nation with other elements.
temperature range given in Table 1 for the corresponding
4.1.5 Type N—Nickel-14 % chromium, 1 ⁄2 % silicon ( + ) thermocouple type. It should not be assumed, however, that
1 1
thermoelements used with one thermocouple type are inter-
versus nickel-4 ⁄2 % silicon- ⁄10 % magnesium (−).
4.1.6 Type R—Platinum-13 % rhodium ( + ) versus plati- changeable with those of the other, or that they have the same
millivolt tolerances for the initial values of emf versus tem-
num (−).
perature.
4.1.7 Type S—Platinum-10 % rhodium ( + ) versus platinum
5.2 Thermocouple extension wires and compensating exten-
(−).
sion wires are supplied to the tolerances on initial values of emf
4.1.8 Type T—Copper ( + ) versus copper-45% nickel (con-
versus temperature shown in Tables 2–3.
stantan) (−).
5.2.1 The initial tolerances of extension grade materials and
4.2 Each letter designation of 4.1 identifies a specific
compensating extension materials apply over a more limited
temperature-emf relationship (Tables 8–23) and may be ap-
span of temperature than the corresponding thermocouple
plied to any thermocouple conforming thereto within stated
grade materials. Applicable temperature ranges, consistent with
tolerances on initial values of emf versus temperature, regard-
typical usage, are given in Tables 2–3.
less of its composition.
4.3 The thermoelement identifying symbols in Tables 24 to
6. Color Coding
43 use the suffix letters P and N to denote, respectively, the
6.1 Color codes for insulation on thermocouple grade ma-
positive and negative thermoelement of a given thermocouple
terials, along with corresponding thermocouple and thermoele-
type.
ment letter designations, are given in Table 4.
4.4 Tables 24 to 43 identify specific temperature-emf rela-
6.2 Extension wires for thermocouples are distinguished by
tionships of individual thermoelements with respect to plati-
having an identifying color in the outer jacket as shown in
num (NIST Pt-67). Although tolerances on initial values of emf
Table 5, where letter designations for the extension thermoele-
versus temperature, in most cases, are not established for
ments and pairs are also presented.
individual thermoelements with respect to platinum, the appro-
6.3 Information in Tables 4–5 is based on customary United
priate letter designation may be applied to any thermoelement
States practice.
which, when combined with its mating thermoelement, will
form a thermocouple conforming to the corresponding table
NOTE 3—Other insulation color coding conventions may be found in
within the stated tolerances. use elsewhere in the world.
E 230
7. List of Tables 7.1.3 EMF versus Temperature Tables for Thermoelements:
Thermoele- Temperature
7.1 Following is a list of the tables included in this standard:
Table Number Thermocouple Type
A
ment Type Range
7.1.1 General Tables:
24 B BP 0 to 1768°C
Table
25 B BP 32 to 3214°F
Number Title
26 B BN 0 to 1768°C
1 Tolerances on Initial Values of Emf versus Temperature for
27 B BN 32 to 3214°F
Thermocouples
28 J JP −210 to 760°C
2 Tolerances on Initial Values of Emf versus Temperature for Ex-
29 J JP −346 to 1400°F
tension Wires
30 J JN −210 to 760°C
3 Tolerances on Initial Values of Emf versus Temperature for
31 J JN −346 to 1400°F
Compensating Extension Wires
32 K or E KP or EP −270 to 1372°C
4 United States Color Codes for Single and Duplex Insulated
33 K or E KP or EP −454 to 2500°F
Thermocouple Wires
34 K KN −270 to 1372°C
5 United States Color Codes for Single and Duplex Insulated
35 K KN −454 to 2500°F
Extension Wires
36 N NP −200 to 1300°C
6 Suggested Upper Temperature Limits for Protected Thermo-
37 N NP −328 to 2372°F
couples
38 N NN −200 to 1300°C
7 Polynomial Coefficients for Generating Thermocouple EMF as
39 N NN −328 to 2372°F
a Function of Temperature
40 T TP −270 to 400°C
41 T TP −454 to 752°F
42 T or E TN or EN −270 to 1000°C
7.1.2 EMF versus Temperature Tables for Thermocouples:
43 T or E TN or EN −454 to 1832°F
Table Thermocouple Temperature
A
Number Type Range
A
These temperature ranges represent the range of published temperature
versus emf data for the thermocouple and thermoelement types listed. Refer to
8 B 0 to 1820°C
Table 6 for recommended maximum upper use temperature limits for a specific
9 B 32 to 3308°F
thermocouple wire size and type.
10 E −270 to 1000°C
7.1.4 Supplementary Table:
11 E −454 to 1832°F
12 J −210 to 1200°C
Table
Title
13 J −346 to 2192°F
Number
14 K −270 to 1372°C
44 Coefficients of Inverse Polynomials for Computation
15 K −454 to 2500°F
of Approximate Temperature as a Function of Ther-
16 N −270 to 1300°C
mocouple EMF
17 N −454 to 2372°F
18 R −50 to 1768°C
8. Keywords
19 R −58 to 3214°F
20 S −50 to 1768°C
8.1 emf computation; compensating extension wire; inverse
21 S −58 to 3214°F
polynomial; polynomial coefficient; reference tables; thermo-
22 T −270 to 400°C
23 T −454 to 752°F couple; thermocouple extension wire; thermoelement; upper
temperature limit
APPENDIX
(Nonmandatory Information)
X1. IEC COLOR CODE SYSTEM
X1.1 General code systems, either now in use, or in process of being
implemented.
X1.1.1 The data presented in Tables 4–5 of this specification
X1.1.3 One such color code system is that established by the
show the color coding required by this specification. Those
colors are well established in the United States and have been IEC. The IEC color code system is outlined here for reference.
Table X1.1 shows the IEC standard colors for thermocouple
in use as the national standard there for many years.
X1.1.2 In other parts of the world, there are alternative color cables, extension cables, and compensating cables.
E 230
TABLE 1 Tolerances on Initial Values of Emf vs. Temperature for Thermocouples
NOTE 1—Tolerances in this table apply to new essentially homogeneous thermocouple wire, normally in the size range 0.25 to 3 mm in diameter
(No. 30 to No. 8 Awg) and used at temperatures not exceeding the recommended limits of Table 6. If used at higher temperatures these tolerances may
not apply.
NOTE 2—At a given temperature that is expressed in °C, the tolerance expressed in °F is 1.8 times larger than the tolerance expressed in °C. Note that
wherever applicable, percentage-based tolerances must be computed from temperatures that are expressed in °C.
NOTE 3—Caution: Users should be aware that certain characteristics of thermocouple materials, including the emf versus temperature relationship may
change with time in use; consequently, test results and performance obtained at time of manufacture may not necessarily apply throughout an extended
period of use. Tolerances given in this table apply only to new wire as delivered to the user and do not allow for cha
...