ASTM B77-07(2013)
(Test Method)Standard Test Method for Thermoelectric Power of Electrical-Resistance Alloys
Standard Test Method for Thermoelectric Power of Electrical-Resistance Alloys
SIGNIFICANCE AND USE
4.1 The purpose of this method is to determine the suitability of different metals for use in resistance apparatus in which a low thermoelectric power is desired. As most electric circuits are largely composed of copper, the thermoelectric power of a resistance metal will generally be measured against copper.
SCOPE
1.1 This test method covers the determination of the thermoelectric power of a metal or alloy with respect to copper when the temperatures of the junctions lie between 0 and 100°C.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.3 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 become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.
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Designation: B77 − 07 (Reapproved 2013)
Standard Test Method for
Thermoelectric Power of Electrical-Resistance Alloys
This standard is issued under the fixed designation B77; 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.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope where:
E = the electromotive force developed in the circuit,
1.1 This test method covers the determination of the ther-
t' = the higher temperature at one junction, °C, and
moelectric power of a metal or alloy with respect to copper
t = the lower temperature at the other junction, °C.
when the temperatures of the junctions lie between 0 and
100°C.
4. Significance and Use
1.2 The values stated in inch-pound units are to be regarded
4.1 The purpose of this method is to determine the suitabil-
as standard. The values given in parentheses are mathematical
ity of different metals for use in resistance apparatus in which
conversions to SI units that are provided for information only
a low thermoelectric power is desired.As most electric circuits
and are not considered standard.
are largely composed of copper, the thermoelectric power of a
1.3 This standard does not purport to address all of the
resistance metal will generally be measured against copper.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to become familiar
5. Test Specimen
with all hazards including those identified in the appropriate
5.1 The metal or alloy to be tested shall be in the form of
Material Safety Data Sheet (MSDS) for this product/material
sheet, ribbon, or wire and the test specimen shall be of such
as provided by the manufacturer, to establish appropriate
length that the two ends can be readily maintained at different
safety and health practices, and determine the applicability of
temperatures. At each end of the specimen a copper lead of
regulatory limitations prior to use.
convenient size shall be fastened. These leads shall make good
2. Referenced Documents electrical contact with the specimen, such as that obtained by
2 welding, brazing, or soldering. Slight impurities in the copper
2.1 ASTM Standards:
have a negligible effect on the thermoelectric power.
B3 Specification for Soft or Annealed Copper Wire
NOTE 1—When necessary to specify the quality of the copper leads,
3. Terminology
reference should be made to Specification B3.
3.1 thermoelectric power, Q, n—the electromotive force in
6. Procedure
an electric circuit consisting of two metals when the junctions
between them have a difference in temperature of 1°C.
6.1 Measurement of Temperature—As a matter of
3.1.1 Discussion—Experimentally, it has been found that
precaution, the average temperature used in determining the
the thermoelectric power of two metals is not a constant but
thermoelectric power shall be approximately the same as that
depends on the mean temperature of the junctions. However,
to which the material will be subjected in practice, and in no
over a range of temperature from 0 to 100°C it is usually
case shall the temperature difference between the two junctions
sufficient to assume that the thermoelectric power is indepen-
be less than 20°C. The temperature at each of two junctions
dent of temperature so that for this range of temperature:
shall be measured by a device that is sufficiently accurate to
determine the temperature difference within 5 %.Aconvenient
Q 5 E/~t'2t!
method for determining the temperatures of the junctions is to
immerse each junction in separate oil baths maintained at the
This test method is under the jurisdiction of ASTM Committee B02 on
desired temperatures. Baths that are stirred and the tempera-
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
tures of which are thermostatically controlled are to be
B02.10 on Thermostat Metals and Electrical Resistance Heating Materials.
preferred. However, beakers of oil which are supported by
Current edition approved May 1, 2013. Published May 2013. Originally
blocks of metal, sand baths, or other means may be used,
approved in 1930. Last previous edition approved in 2007 as B77 – 07. DOI:
10.1520/B0077-07R13.
provided the thermal capacity of these assemblies is such that
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
whentheheatiscutofftheirtemperatureswilldecreaseatrates
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