1、Designation: E1933 99a (Reapproved 2010)E1933 14Standard Test Methods Practice 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 adop
2、tion or, in the case 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 and compensating for e
3、missivity when measuring the surfacetemperature of a specimen with an infrared imaging radiometer.21.2 The values stated in SI units are to be regarded as the standard.1.3 These test methods may involve use of equipment and materials in the presence of heated or electrically-energizedequipment, or b
4、oth.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced
5、 Documents2.1 ASTM Standards:3E1316 Terminology for Nondestructive Examinations3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 reflected temperaturethe temperature of the energy incident upon and reflected from the measurement surface of thespecimen.3.1.2 surface-modifying mat
6、erialany tape, spray, paint or the like that is used to change the emissivity of the specimen surface.3.2 See also Terminology E1316.4. Summary of Test Method4.1 Two test methods are given for measuring the emissivity of a specimen surface, the contact thermometer method and thenon-contact thermomet
7、er method.4.2 A test method is also given for compensating for the error produced by emissivity using the computer built into an infraredimaging radiometer.5. Significance and Use5.1 The emissivity of a specimen can cause surface temperature measurement errors. Two test methods are provided formeasu
8、ring 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 infrared radiometers that have the required computer capabilities.1 These test methods are This practice is under
9、the jurisdiction ofASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.10on Specialized NDT Methods.Current edition approved June 1, 2010Oct. 1, 2014. Published November 2010October 2014. Originally approved in 1997. Last previous edition approved in 200
10、5 asE1933 - 99a (2005)(2010).1. DOI: 10.1520/E1933-99AR10.10.1520/E1933-14.2 These test methods procedures are adapted from the Guideline for Measuring and Compensating for Reflected Temperature, Emittance and Transmittance developedby the Infraspection Institute, 425 Ellis Street, Burlington, NJ 08
11、016.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended onl
12、y to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versi
13、onof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Interferences6.1 Contact Thermometer MethodContact thermometers can act as heat sinks and change the t
14、emperature of the specimen.6.2 Noncontact Thermometer Method:6.2.1 The use of surface-modifying materials can change the heat transfer properties and temperature of the specimen.Any sucherrors can be minimized by applying surface-modifying materials to the smallest area that satisfies the measuremen
15、t accuracyrequirements of the radiometer and infrared thermographer.6.2.2 Before the surface-modifying material is applied to an area of the specimen adjacent to the area where the emissivity isto be measured (as directed in 8.2.4), errors can be minimized by viewing the imager display to ensure tha
16、t both areas have thesame temperature.6.2.3 When removing a surface-modifying material, as directed in 8.2.7, errors can be minimized by ensuring that the surfaceis returned to its original condition.6.3 Both test methods require the specimen to be at a temperature that is at least 10C warmer or coo
17、ler than the ambienttemperature. Potential errors can be minimized by ensuring the stability of the temperature difference between the specimen andthe ambient temperature during the test.Also, the emissivity measurement accuracy can be increased by increasing this temperaturedifference.6.4 The emiss
18、ivity of a specimen may be specific to the temperature of the specimen and the spectral waveband of the infraredimaging radiometer used to make the measurement. Therefore, the temperature of the specimen and the spectral waveband of theradiometer should be noted along with the measured emissivity va
19、lue.6.5 These test methods are valid only for specimens that are opaque in the waveband of the infrared imaging radiometer.6.6 As the emissivity of a specimen decreases, its reflectivity increases. Careful consideration and avoidance of potential errorsources, including the precise determination of
20、reflected temperature in 8.1.3 and 8.2.3, is required to accurately measure theemissivity values of specimens having lower emissivities. For materials with emissivities less than 0.5, radiometric temperaturemeasurements and emissivity measurements may have a high likelihood of error.7. Apparatus7.1
21、Calibrated Infrared Imaging Radiometer, with a built-in computer that allows the infrared thermographer to input reflectedtemperatures and emissivity values.7.2 Tripod, or device to support the infrared imaging radiometer.7.3 A natural or induced means of heating or cooling the specimen at least 10C
22、 above or below the ambient temperature.7.4 The contact thermometer method requires a calibrated contact thermometer.7.5 The noncontact thermometer method requires a surface-modifying material with a known emissivity at a temperature closeto that of the specimen and in the same spectral waveband of
23、the infrared imaging radiometer.NOTE 1For best results, the surface modifying material should have a high emissivity, preferably 0.9 or greater.8. Procedure8.1 Contact Thermometer Method:8.1.1 Place the infrared imaging radiometer on the tripod or support device at the desired location and distance
24、from thespecimen.8.1.2 Point the infrared imaging radiometer at the specimen and focus on the portion where the emissivity is to be measured.8.1.3 Use an appropriate infrared imaging radiometer measurement function (such as spot temperature, crosshairs, or isotherm)to measure and compensate for the
25、reflected temperature error incident upon the specimen.NOTE 2Such measurements are generally more accurate when the measurement is averaged over a small region of the image. Use of an averagetemperature box or a narrow band isotherm will produce more reproducible results than single pixel measuremen
26、ts.8.1.4 Use the contact thermometer to measure the temperature of the point or area just measured in 8.1.3. Record thistemperature.8.1.5 Without moving the imager, adjust its computers emissivity control until the imagers computer indicates the sametemperature recorded in 8.1.4. The indicated emiss
27、ivity value is the measured emissivity of the specimen, at this temperature andspectral waveband.8.1.6 Repeat procedures 8.1.1 through 8.1.5 a minimum of three times and average the emissivity values to yield an averageemissivity.8.2 Noncontact Thermometer Method:8.2.1 Place the infrared imaging rad
28、iometer on the tripod or support device at the desired location and distance from thespecimen.8.2.2 Point the infrared imaging radiometer at the specimen and focus on the portion where the emissivity is to be measured.E1933 1428.2.3 Use an appropriate infrared imaging radiometer measurement function
29、 (such as spot temperature, crosshairs, or isotherm)to measure and compensate for the reflected temperature error incident upon the specimen.8.2.4 Apply the surface-modifying material to, or immediately adjacent to, the portion of the specimen where the emissivity isto be measured. Make sure the sur
30、face-modifying material 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 the emissivityinput (sometimes referred to as emittance or E).8.2.6 Use the radiometer to measure the temperature of the sur
31、face-modifying material. Record this temperature.8.2.7 Focus the infrared imaging radiometer on the portion of the specimen immediately adjacent to the surface-modifyingmaterial (where the emissivity is to be measured), or remove the surface-modifying material and focus the imager on thepreviously-m
32、odified specimen (where the emissivity is to be measured).8.2.8 Without moving the imager, adjust its computers emissivity control until the imagers computer indicates the sametemperature recorded in 8.2.6. The indicated emissivity value is the measured emissivity of the specimen, at this temperatur
33、e andspectral waveband.8.2.9 Repeat 8.2.1 through 8.2.8 a minimum of three times and average the emissivity values to yield an average emissivity.8.3 Compensate for emissivity errors by entering the known average emissivity value of the specimen in the radiometerscomputer under the emissivity input
34、(sometimes referred to as emittance or E).9. Precision and Bias9.1 PrecisionAn interlaboratory test program is not practical here because of the nature of the test specimens. However, ameasure of the precision of the methods can be inferred from the results of the replicate tests specified in 8.1.6
35、and 8.2.8.9.2 BiasThese test methods for measuring emissivity have no bias because the values of emissivity are defined only in termsof the test methods.10. Keywords10.1 emissivity; imaging; infrared; infrared testing; infrared thermography; nondestructive testing; radiometry; reflectedtemperature;
36、surface-modifying material; target-width/distance ratio; temperature compensation; temperature measurementASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised tha
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39、l 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 19428-2959,United States. Individual repr
40、ints (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). Permission rights to photocopy the standard may also be secured from the Co
41、pyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ Scope*1.1 This practice covers procedures for measuring and compensating for emissivity when measuring the surface temperature ofa specimen with an infrared imaging radiometer.21.2 The values stated in SI uni
42、ts are to be regarded as standard. No other units of measurement are included in this standard.1.3 These procedures may involve use of equipment and materials in the presence of heated or electrically-energized equipment,or both.1.4 This standard does not purport to address all of the safety concern
43、s, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E1316 Terminology for Nondestructive Examinat
44、ions3. Terminology3.1 Definitions of Terms Specific to This Standard:E1933 1433.1.1 reflected temperaturethe temperature of the energy incident upon and reflected from the measurement surface of thespecimen.3.1.2 surface-modifying materialany tape, spray, paint or the like that is used to change the
45、 emissivity of the specimen surface.3.2 See also Terminology E1316.4. Summary of Practice4.1 Two procedures are given for measuring the emissivity of a specimen surface, the contact thermometer method and thenon-contact thermometer method.4.2 A procedure is also given for compensating for the error
46、produced by emissivity using the computer built into an infraredimaging radiometer.5. Significance and Use5.1 The emissivity of a specimen can cause surface temperature measurement errors. Two procedures are provided formeasuring and compensating for this error source.5.2 These procedures can be use
47、d in the field or laboratory, using commonly available materials.5.3 These procedures can be used with any infrared radiometers that have the required computer capabilities.5.4 The values of emissivity are defined only in terms of the procedure for the purpose of process control and nondestructiveev
48、aluation of materials.6. Interferences6.1 Contact Thermometer MethodContact thermometers can act as heat sinks and change the temperature of the specimen.6.2 Noncontact Thermometer Method:6.2.1 The use of surface-modifying materials can change the heat transfer properties and temperature of the spec
49、imen.Any sucherrors can be minimized by applying surface-modifying materials to the smallest area that satisfies the measurement accuracyrequirements of the radiometer and infrared thermographer.6.2.2 Before the surface-modifying material is applied to an area of the specimen adjacent to the area where the emissivity isto be measured (as directed in 8.2.4), errors can be minimized by viewing the imager display to ensure that both areas have thesame temperature.6.2.3 When removing a surface-modifying material, as directed in 8.2.7, errors ca
