ASTM_E_1862_-_14.pdf

Designation:E186214Standard Practice forMeasuring and Compensating for Reflected TemperatureUsing Infrared Imaging Radiometers1This standard is issued under the fixed designation E1862;the number immediately following the designation indicates the year oforiginal adoption 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.Scope*1.1 This practice covers procedures for measuring andcompensating for reflected temperature when measuring thesurface temperature of a specimen with an infrared imagingradiometer.21.2 These procedures may involve use of equipment andmaterials in the presence of heated or electrically energizedequipment,or both.1.3 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 practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3E1316 Terminology for Nondestructive Examinations3.Terminology3.1 Definitions:3.1.1 diffuse reflector,na surface that produces a diffuseimage of a reflected source.3.1.2 infrared thermographer,nthe person using an infra-red imaging radiometer.3.1.3 infrared reflector,na material with a reflectance asclose as possible to 1.00.3.1.4 reflected temperature,nthe temperature of the en-ergy incident upon and reflected from the measurement surfaceof a specimen.3.1.5 specular reflector,na surface that produces a directimage of a reflected source.3.2 See also Terminology E1316.4.Summary of Procedure4.1 Two procedures are given for measuring the reflectedtemperature of a specimen,the Reflector Method and theDirect Method.4.2 Aprocedure is also given for compensating for the errorproduced by reflected temperature using the computer builtinto an infrared imaging radiometer.5.Significance and Use5.1 The infrared energy that is reflected by a specimen cancause measurement errors for an infrared thermographer mea-suring its surface temperature.Two procedures are provided formeasuring and compensating for this reflected temperatureerror source,the Reflector Method and the Direct Method.5.2 These procedures can be used in the field or laboratoryusing commonly available materials.5.3 These procedures can be used with any infrared radi-ometers that have the required computer capabilities.5.4 Due to the nature of the specimens,the repeatability andreproducibility are subjective.However,a measure of theprecision of the procedures can be inferred from the results ofthe replicate procedures specified in 8.1.6 and 8.2.7.6.Interferences6.1 Reflector Method:6.1.1 This procedure uses an infrared reflector with anassumed reflectance of 1.00,which is an ideal property.Errorscan be minimized by using a reflector having a reflectance asclose as possible to 1.00.6.1.2 Specimens vary in that they can be diffuse or spectralreflectors,or both.Use of an infrared reflector with reflectanceproperties as close as possible to those of the specimen willreduce errors.6.2 Direct Method:6.2.1 The Direct Method usually does not account for theheat from the infrared thermographers body as a source of1This practice is under the jurisdiction of ASTM Committee E07 on Nonde-structive Testing and are the direct responsibility of Subcommittee E07.10 onSpecialized NDT Methods.Current edition approved Dec.1,2014.Published December 2014.Originallyapproved in 1997.Last previous edition approved in 2010 as E1862-97(2010).DOI:10.1520/E1862-14.2This practice was originally adapted in 1997,by agreement,from the Guidelinefor Measuring and Compensating for Reflected Temperature,Emittance andTransmittance developed by Infraspection Institute,425 Ellis Street,Burlington,NJ08016.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 reflected temperature.If this heat source creates a significanterror,use the Reflector Method.6.3 Reflected temperature errors produced by a pointsource,such as the sun or a lamp,are difficult to measureaccurately.These error sources can often be avoided by movingthe infrared imaging radiometers position and angle relative tothe specimen.6.4 The measured reflected temperature of a specimen maybe specific to the waveband of the infrared imaging radiometerused.Therefore,the infrared imaging radiometers wavebandshould be noted with the measured value.6.5 The significance of the error contributed by reflectedtemperature can be estimated by shielding the specimen fromvarious angles and observing any c