1、Designation: E 1933 99a (Reapproved 2005)e1Standard Test Methods forMeasuring and Compensating for Emissivity Using InfraredImaging Radiometers1This standard is issued under the fixed designation E 1933; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEFootnote 2 was editorially changed to include the publication suppliers new address in Mar
3、ch 2005.1. Scope1.1 These test methods cover procedures for measuring andcompensating for emissivity when measuring 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
4、 equipment andmaterials in the presence of heated or electrically-energizedequipment, or both.1.4 This standard 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 pra
5、ctices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E 1316 Terminology for Nondestructive Testing3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 reflected temperaturethe temperature of the energyincident upo
6、n and reflected from the measurement surface ofthe specimen.3.1.2 surface-modifying materialany tape, spray, paint orthe like that is used to change the emissivity of the specimensurface.3.2 See also Terminology E 1316.4. Summary of Test Method4.1 Two test methods are given for measuring the emissiv
7、ityof a specimen surface, the contact thermometer method and thenon-contact thermometer method.4.2 A test 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
8、cause surface tem-perature measurement errors. Two test methods are providedfor measuring and compensating 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
9、the required computer capabilities.6. Interferences6.1 Contact Thermometer MethodContact thermometerscan act 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 o
10、f the specimen.Any such errors can be minimized by applying surface-modifying materials to the smallest area 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 th
11、e area where the emissivityis to be measured (as directed in 8.2.4), errors can beminimized by viewing the 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
12、 returned to its original condition.6.3 Both test methods require the specimen to be at atemperature that is at least 10C warmer or cooler than theambient temperature. Potential errors can be minimized byensuring the stability of the temperature difference between the1These test methods are under th
13、e jurisdiction of ASTM Committee E07 onNondestructive Testing and is the direct responsibility of Subcommittee E07.10 onEmerging NDT Methods.Current edition approved March 1, 2005. Published May 2005. Originallyapproved in 1997. Last previous edition approved in 1999 as E 1933 - 99a.2These test meth
14、ods 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 Servic
15、e at 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.specimen and the ambient temperature during th
16、e test.Also, theemissivity measurement accuracy can be increased by 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 tempe
17、rature of the specimen and the spectralwaveband of the radiometer 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
18、-ity increases. Careful consideration and avoidance of potentialerror 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,r
19、adiometric temperature measurements and emissivity mea-surements may 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 su
20、pport the infrared imaging radi-ometer.7.3 A natural or induced means 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
21、material with a known emissivity at a temperatureclose to that of 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
22、:8.1.1 Place the infrared imaging radiometer on the tripod orsupport 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 radiom
23、eter mea-surement function (such as spot temperature, crosshairs, 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 anavera
24、ge temperature box or a narrow band isotherm will produce morereproducible 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 computersemi
25、ssivity control until the imagers computer indicates thesame temperature 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 emissivit
26、y values to yield anaverage emissivity.8.2 Noncontact Thermometer 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 emis
27、sivity is to bemeasured.8.2.3 Use an appropriate infrared imaging 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-ate
28、ly adjacent to, the portion of the specimen where theemissivity is 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 (some
29、times referred to as emittance or E).8.2.6 Use the radiometer to measure 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
30、to be measured), or removethe surface-modifying material and focus 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.
31、 The indicated emissivityvalue is the measured emissivity of the specimen, 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 knownave
32、rage emissivity value of the specimen in the radiometerscomputer under 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 precisio
33、n of the methods can be inferred fromthe results of the replicate 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.E 1933 99a (2005)e1210. Keywords10.1 emissivity; imaging;
34、 infrared; infrared testing; infraredthermography; nondestructive testing; radiometry; reflectedtemperature; surface-modifying material; target-width/distanceratio; temperature compensation; temperature measurementASTM International takes no position respecting the validity of any patent rights asse
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37、ve careful consideration at a meeting of theresponsible technical committee, 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 Inter
38、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E 1933 99a (2005)e13
