ASTM E988-96
(Specification)Standard Temperature-Electromotive Force (EMF) Tables for Tungsten-Rhenium Thermocouples
Standard Temperature-Electromotive Force (EMF) Tables for Tungsten-Rhenium Thermocouples
SCOPE
1.1 This standard consists of reference tables that give temperature-electromotive force (emf) relationships for 97% Tungsten 3% Rhenium versus 75% Tungsten 25% Rhenium and 95% Tungsten 5% Rhenium versus 74% Tungsten 26% Rhenium thermocouples. These are the refractory metal thermocouple types most commonly used in industry.
1.2 Also included is a list (Table 1) of initial calibration tolerances for the thermocouple types referred to in 1.1, and their respective compensating extension wires (Table 2).
1.3 These data are intended for industrial and laboratory use.
General Information
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.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 988 – 96
Standard Temperature-Electromotive Force (EMF) Tables for
Tungsten-Rhenium Thermocouples
This standard is issued under the fixed designation E 988; 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 required, the reader should refer to the equations in Table 7
which permit further generation of the temperature-emf rela-
1.1 This standard consists of reference tables that give
tionships. In addition, Tables 8 and 9 present polynomial
temperature-electromotive force (emf) relationships for 97 %
approximations giving temperature as a function of the ther-
Tungsten 3 % Rhenium versus 75 % Tungsten 25 % Rhenium
mocouple EMF.
and 95 % Tungsten 5 % Rhenium versus 74 % Tungsten 26 %
Rhenium thermocouples. These are the refractory metal ther-
4. Identification of Thermocouple Types
mocouple types most commonly used in industry.
4.1 Letter symbols have not been assigned. Identification is
1.2 Also included is a list (Table 1) of initial calibration
made by composition.
tolerances for the thermocouple types referred to in 1.1, and
4.2 W3Re/W25Re—97 % Tungsten 3 % Rhenium ( + ) ver-
their respective compensating extension wires (Table 2).
sus 75 % Tungsten 25 % Rhenium (−).
1.3 These data are intended for industrial and laboratory
4.3 W5Re/W26Re—95 % Tungsten 5 % Rhenium ( + ) ver-
use.
sus 74 % Tungsten 26 % Rhenium (−).
2. Referenced Documents
5. Initial Calibration Tolerances
2.1 ASTM Standards:
5.1 Thermocouples and matched thermocouple wire are
E 380 Practice for Use of the International System of Units
2 supplied to the initial calibration tolerances listed in Table 1.
(SI) (the Modernized Metric System)
6. List of Tables
3. Source of Data
6.1 Following is a list of tables included in this standard:
3.1 The data in these tables are based upon the SI volt (see
Table
Practice E 380) and the International Temperature Scale of
Title
Number
1990.
1 Initial Calibration Tolerances and Suggested Temperature
3.2 All temperature-electromotive force data in Tables 3-6 Ranges for Thermocouples
2 Initial Calibration Tolerances and Suggested Temperature
have been developed from wire manufacturers’ data.
Ranges for Thermocouple Compensating Extension Wires
3.3 These tables give emf values to three decimal places (1
3 Temperature versus EMF for W3Re/W25Re from 0 to 2315°C
μV) for each degree of temperature. Such tables are satisfac- 4 Temperature versus EMF for W3Re/W25Re from 32 to 4200°F
5 Temperature versus EMF for W5Re/W26Re from 0 to 2315°C
tory for most industrial uses but may not be adequate for
6 Temperature versus EMF for W5Re/W26Re from 32 to 4200°F
computer and similar applications. If greater precision is
7 Equations Used to Derive Tables 3-6
8 Polynomial Coefficients for the Computation of Temperatures in
°C as a Function of the Thermocouple EMF
1 9 Polynomial Coefficients for the Computation of Temperatures in
These tables are under the jurisdiction of ASTM Committee E-20 on Tempera-
°F as a Function of the Thermocouple EMF
ture Measurement and are the direct responsibility of Subcommittee E20.04 on
Thermocouples.
Current edition approved Sept. 10, 1996. Published October 1996. Originally
7. Keywords
published as E 988 – 84. Last previous edition E 988 – 90.
7.1 emf; rhenium; thermocouple; tungsten
Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 988
TABLE 1 Initial Calibration Tolerances and Suggested
A
Temperature Ranges for Thermocouples
NOTE 1—Initial calibration tolerances in this table apply to new
thermocouple wire, normally in the size range 0.125 to 0.5 mm in
diameter (No. 36 to 24 Awg) and used at temperatures not exceeding the
suggested upper temperatures of Table 1. If used at higher temperatures
these initial calibration tolerances may not apply.
NOTE 2—Initial calibration tolerances apply to new wire as delivered to
the user and do not allow for calibration drift during use. The magnitude
of such changes depends on such factors as wire size, temperature, time of
exposure, and environment.
NOTE 3—Where initial calibration tolerances are given in percent, the
percentage applies to the temperature being measured when expressed in
degrees Fahrenheit. To determine the tolerance in degrees Celsius multiply
the tolerance in degrees Fahrenheit by 5/9.
NOTE 4—Tables 1 and 2 also describe suggested upper temperature
limits for the thermocouples and extension wires. These limits apply to
protected thermocouples, that is, thermocouples in inert or non-oxidizing
atmospheres.
Thermocouple Temperature Initial Calibration
Type Range Tolerances
W3%Re/W25%Re 0 to 426°C 64.4°C
and 32 to 800°F 68°F
W5%Re/W26%Re 426 to 2315°C 61 % of actual
temperature
800 to 4200°F%
A
CAUTION—Users should be aware that certain characteristics of thermocouple
materials including calibration may change in time with use; consequently, test
results obtained at time of manufacture may not necessarily apply throughout an
extended period of use.
TABLE 2 Initial Calibration Tolerances and Suggested
Temperature Ranges for Thermocouple Compensating Extension
Wires
Temperature Initial Calibration
Designation
Range Tolerances
For
W3%Re/W25%Re
A
300P( + ) 97.7Ni BAL Cr,Al,Si 0 to 330°C
60.125 mV
A
300N(−) 96Ni, 4W
32 to 625°F%
B
203( + ) 90Ni, 10Cr 0 to 260°C
60.110 mV
B
225(−) 98Ni, 2Cr 32 to 500°F%
For
W5%Re/W26%Re 0 to 871°C
60.110 mV
B
405( + ) 94.5Ni 32 to 1600°F
%
2Mn
1Si
1.5 AL
B
426(−) 80 Ni, 20 Cu
A
U.S. Patent 3,502,510 assigned to Engelhard Industries.
B
Designation of Hoskins Mfg.
E 988
TABLE 3 Tungsten-3 % Rhenium versus Tungsten-25 % Rhenium Thermocouples—
Thermoelectric Voltage as a Function of Temperature (°C)
EMF in Millivolts Reference Junctions at 0°C
DEGC 0123456789 10 DEGC
Thermoelectric Voltage in Millivolts
E 988
TABLE 3 (continued)
EMF in Millivolts Reference Junctions at 0°C
DEGC 0123456789 10 DEGC
Thermoelectric Voltage in Millivolts
E 988
TABLE 3 (continued)
EMF in Millivolts Reference Junctions at 0°C
DEGC 0123456789 10 DEGC
Thermoelectric Voltage in Millivolts
E 988
TABLE 3 (continued)
EMF in Millivolts Reference Junctions at 0°C
DEGC 0123456789 10 DEGC
Thermoelectric Voltage in Millivolts
E 988
TABLE 3 (continued)
EMF in Millivolts Reference Junctions at 0°C
DEGC 0123456789 10 DEGC
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 Tungsten-3 % Rhenium versus Tungsten-25 % Rhenium Thermocouples—
Thermoelectric Voltage as a Function of Temperature (°F)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF 0123456789 10 DEGF
Thermoelectric Voltage in Millivolts
E 988
TABLE 4 (continued)
EMF in Millivolts Reference Junctions at 32°F
DEGF
...
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