ASTM E1933-99a(2010)

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Designation: E1933 − 99a(Reapproved 2010)
Standard Test Methods for
Measuring and Compensating for Emissivity Using Infrared
Imaging Radiometers
This standard is issued under the fixed designation E1933; 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 4. Summary of Test Method
1.1 These test methods cover procedures for measuring and 4.1 Twotestmethodsaregivenformeasuringthe emissivity
compensating for emissivity when measuring the surface of a specimen surface, the contact thermometer method and the
temperature of a specimen with an infrared imaging radiom- non-contact thermometer method.
eter.
4.2 A test method is also given for compensating for the
1.2 The values stated in SI units are to be regarded as the error produced by emissivity using the computer built into an
standard. infrared imaging radiometer.
1.3 These test methods may involve use of equipment and
5. Significance and Use
materials in the presence of heated or electrically-energized
5.1 The emissivity of a specimen can cause surface tem-
equipment, or both.
perature measurement errors. Two test methods are provided
1.4 This standard does not purport to address all of the
for measuring and compensating for this error source.
safety concerns, if any, associated with its use. It is the
5.2 Thesetestmethodscanbeusedinthefieldorlaboratory,
responsibility of the user of this standard to establish appro-
using commonly available materials.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 5.3 These test methods can be used with any infrared
radiometers that have the required computer capabilities.
2. Referenced Documents
6. Interferences
2.1 ASTM Standards:
6.1 Contact Thermometer Method—Contact thermometers
E1316 Terminology for Nondestructive Examinations
can act as heat sinks and change the temperature of the
3. Terminology
specimen.
3.1 Definitions of Terms Specific to This Standard:
6.2 Noncontact Thermometer Method:
3.1.1 reflected temperature—the temperature of the energy
6.2.1 The use of surface-modifying materials can change
incident upon and reflected from the measurement surface of
the heat transfer properties and temperature of the specimen.
the specimen.
Any such errors can be minimized by applying surface-
modifying materials to the smallest area that satisfies the
3.1.2 surface-modifying material—any tape, spray, paint or
measurement accuracy requirements of the radiometer and
the like that is used to change the emissivity of the specimen
infrared thermographer.
surface.
6.2.2 Before the surface-modifying material is applied to an
3.2 See also Terminology E1316.
area of the specimen adjacent to the area where the emissivity
is to be measured (as directed in 8.2.4), errors can be
These test methods are under the jurisdiction of ASTM Committee E07 on
minimized by viewing the imager display to ensure that both
Nondestructive Testing and is the direct responsibility of Subcommittee E07.10 on
areas have the same temperature.
Specialized NDT Methods.
6.2.3 When removing a surface-modifying material, as di-
Current edition approved June 1, 2010. Published November 2010. Originally
´1
rected in 8.2.7, errors can be minimized by ensuring that the
approved in 1997. Last previous edition approved in 2005 as E1933 - 99a (2005) .
DOI: 10.1520/E1933-99AR10.
surface is returned to its original condition.
These test methods are adapted from the Guideline for Measuring and
6.3 Both test methods require the specimen to be at a
Compensating for Reflected Temperature, Emittance and Transmittance developed
by the Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016.
temperature that is at least 10°C warmer or cooler than the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ambient temperature. Potential errors can be minimized by
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ensuring the stability of the temperature difference between the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. specimenandtheambienttemperatureduringthetest.Also,the
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E1933 − 99a (2010)
emissivity measurement accuracy can be increased by increas- 8.1.5 Without moving the imager, adjust its computer’s
ing this temperature difference. emissivity control until the imager’s computer indicates the
same temperature recorded in 8.1.4. The indicated emissivity
6.4 The emissivity of a specimen may be specific to the
value is the measured emissivity of the specimen, at this
temperature of the specimen and the spectral waveband of the
temperature and spectral waveband.
infrared imaging radiometer used to make the measurement.
8.1.6 Repeat procedures 8.1.1 through 8.1.5 a minimum of
Therefore, the temperature of the specimen and the spectral
three times and average the emissivity values to yield an
waveband of the radiometer should be noted along with the
average emissivity.
measured emissivity value.
6.5 These test methods are valid only for specimens that are 8.2 Noncontact Thermometer Method:
opaque in the waveband of the infrared imaging radiometer.
8.2.1 Place the infrared imaging radiometer on the tripod or
support device at the desired location and distance from the
6.6 As the emissivity of a specimen decreases, its reflectiv-
specimen.
ity increases. Careful consideration and avoidance of potential
error s
...