1、Designation: E1933 99a (Reapproved 2010)Standard Test Methods forMeasuring and Compensating for Emissivity Using InfraredImaging Radiometers1This standard is issued under the fixed designation E1933; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover procedures for measuring andcompensating for emissivity when mea
3、suring the surfacetemperature of a specimen with an infrared imaging radiom-eter.21.2 The values stated in SI units are to be regarded as thestandard.1.3 These test methods may involve use of equipment andmaterials in the presence of heated or electrically-energizedequipment, or both.1.4 This standa
4、rd does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 AST
5、M Standards:3E1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 reflected temperaturethe temperature of the energyincident upon and reflected from the measurement surface ofthe specimen.3.1.2 surface-modifying materialany tape, spr
6、ay, paint orthe like that is used to change the emissivity of the specimensurface.3.2 See also Terminology E1316.4. Summary of Test Method4.1 Two test methods are given for measuring the emissivityof a specimen surface, the contact thermometer method and thenon-contact thermometer method.4.2 A test
7、method is also given for compensating for theerror produced by emissivity using the computer built into aninfrared imaging radiometer.5. Significance and Use5.1 The emissivity of a specimen can cause surface tem-perature measurement errors. Two test methods are providedfor measuring and compensating
8、 for this error source.5.2 These test methods can be used in the field or laboratory,using commonly available materials.5.3 These test methods can be used with any infraredradiometers that have the required computer capabilities.6. Interferences6.1 Contact Thermometer MethodContact thermometerscan a
9、ct as heat sinks and change the temperature of thespecimen.6.2 Noncontact Thermometer Method:6.2.1 The use of surface-modifying materials can changethe heat transfer properties and temperature of the specimen.Any such errors can be minimized by applying surface-modifying materials to the smallest ar
10、ea that satisfies themeasurement accuracy requirements of the radiometer andinfrared thermographer.6.2.2 Before the surface-modifying material is applied to anarea of the specimen adjacent to the area where the emissivityis to be measured (as directed in 8.2.4), errors can beminimized by viewing the
11、 imager display to ensure that bothareas have the same temperature.6.2.3 When removing a surface-modifying material, as di-rected in 8.2.7, errors can be minimized by ensuring that thesurface is returned to its original condition.6.3 Both test methods require the specimen to be at atemperature that
12、is at least 10C warmer or cooler than theambient temperature. Potential errors can be minimized byensuring the stability of the temperature difference between thespecimen and the ambient temperature during the test.Also, the1These test methods are under the jurisdiction of ASTM Committee E07 onNonde
13、structive Testing and is the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved June 1, 2010. Published November 2010. Originallyapproved in 1997. Last previous edition approved in 2005 as E1933 - 99a (2005)1.DOI: 10.1520/E1933-99AR10.2These test methods
14、are adapted from the Guideline for Measuring andCompensating for Reflected Temperature, Emittance and Transmittance developedby the Infraspection Institute, 425 Ellis Street, Burlington, NJ 08016.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.emissivity measurement accuracy can be increased b
16、y increas-ing this temperature difference.6.4 The emissivity of a specimen may be specific to thetemperature of the specimen and the spectral waveband of theinfrared imaging radiometer used to make the measurement.Therefore, the temperature of the specimen and the spectralwaveband of the radiometer
17、should be noted along with themeasured emissivity value.6.5 These test methods are valid only for specimens that areopaque in the waveband of the infrared imaging radiometer.6.6 As the emissivity of a specimen decreases, its reflectiv-ity increases. Careful consideration and avoidance of potentialer
18、ror sources, including the precise determination of reflectedtemperature in 8.1.3 and 8.2.3, is required to accuratelymeasure the emissivity values of specimens having loweremissivities. For materials with emissivities less than 0.5,radiometric temperature measurements and emissivity mea-surements m
19、ay have a high likelihood of error.7. Apparatus7.1 Calibrated Infrared Imaging Radiometer, with a built-incomputer that allows the infrared thermographer to inputreflected temperatures and emissivity values.7.2 Tripod, or device to support the infrared imaging radi-ometer.7.3 A natural or induced me
20、ans of heating or cooling thespecimen at least 10C above or below the ambient tempera-ture.7.4 The contact thermometer method requires a calibratedcontact thermometer.7.5 The noncontact thermometer method requires a surface-modifying material with a known emissivity at a temperatureclose to that of
21、the specimen and in the same spectralwaveband of the infrared imaging radiometer.NOTE 1For best results, the surface modifying material should have ahigh emissivity, preferably 0.9 or greater.8. Procedure8.1 Contact Thermometer Method:8.1.1 Place the infrared imaging radiometer on the tripod orsuppo
22、rt device at the desired location and distance from thespecimen.8.1.2 Point the infrared imaging radiometer at the specimenand focus on the portion where the emissivity is to bemeasured.8.1.3 Use an appropriate infrared imaging radiometer mea-surement function (such as spot temperature, crosshairs,
23、orisotherm) to measure and compensate for the reflected tem-perature error incident upon the specimen.NOTE 2Such measurements are generally more accurate when themeasurement is averaged over a small region of the image. Use of anaverage temperature box or a narrow band isotherm will produce morerepr
24、oducible results than single pixel measurements.8.1.4 Use the contact thermometer to measure the tempera-ture of the point or area just measured in 8.1.3. Record thistemperature.8.1.5 Without moving the imager, adjust its computersemissivity control until the imagers computer indicates thesame tempe
25、rature recorded in 8.1.4. The indicated emissivityvalue is the measured emissivity of the specimen, at thistemperature and spectral waveband.8.1.6 Repeat procedures 8.1.1 through 8.1.5 a minimum ofthree times and average the emissivity values to yield anaverage emissivity.8.2 Noncontact Thermometer
26、Method:8.2.1 Place the infrared imaging radiometer on the tripod orsupport device at the desired location and distance from thespecimen.8.2.2 Point the infrared imaging radiometer at the specimenand focus on the portion where the emissivity is to bemeasured.8.2.3 Use an appropriate infrared imaging
27、radiometer mea-surement function (such as spot temperature, crosshairs, orisotherm) to measure and compensate for the reflected tem-perature error incident upon the specimen.8.2.4 Apply the surface-modifying material to, or immedi-ately adjacent to, the portion of the specimen where theemissivity is
28、 to be measured. Make sure the surface-modifyingmaterial is dry and in good contact with the specimen.8.2.5 Enter the known emissivity value of the surface-modifying material in the radiometers computer under theemissivity input (sometimes referred to as emittance or E).8.2.6 Use the radiometer to m
29、easure the temperature of thesurface-modifying material. Record this temperature.8.2.7 Focus the infrared imaging radiometer on the portionof the specimen immediately adjacent to the surface-modifyingmaterial (where the emissivity is to be measured), or removethe surface-modifying material and focus
30、 the imager on thepreviously-modified specimen (where the emissivity is to bemeasured).8.2.8 Without moving the imager, adjust its computersemissivity control until the imagers computer indicates thesame temperature recorded in 8.2.6. The indicated emissivityvalue is the measured emissivity of the s
31、pecimen, at thistemperature and spectral waveband.8.2.9 Repeat 8.2.1 through 8.2.8 a minimum of three timesand average the emissivity values to yield an average emissiv-ity.8.3 Compensate for emissivity errors by entering the knownaverage emissivity value of the specimen in the radiometerscomputer u
32、nder the emissivity input (sometimes referred to asemittance or E).9. Precision and Bias9.1 PrecisionAn interlaboratory test program is not prac-tical here because of the nature of the test specimens. However,a measure of the precision of the methods can be inferred fromthe results of the replicate
33、tests specified in 8.1.6 and 8.2.8.9.2 BiasThese test methods for measuring emissivityhave no bias because the values of emissivity are defined onlyin terms of the test methods.10. Keywords10.1 emissivity; imaging; infrared; infrared testing; infraredthermography; nondestructive testing; radiometry;
34、 reflectedtemperature; surface-modifying material; target-width/distanceratio; temperature compensation; temperature measurementE1933 99a (2010)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of
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37、mittee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
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