1、Designation: E2758 15Standard Guide forSelection and Use of Wideband, Low Temperature InfraredThermometers1This standard is issued under the fixed designation E2758; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、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 This guide covers electronic instruments intended formeasurement of temperature by detecting intensity of thermalradiation
3、exchanged between the subject of measurement andthe sensor.1.2 The devices covered by this guide are referred to as IRthermometers.1.3 The IR thermometers covered in this guide are instru-ments that are intended to measure temperatures below 1000C and measure a wide band of thermal radiation in the
4、infraredregion.1.4 This guide covers best practice in using IR thermom-eters. It addresses concerns that will help the user make bettermeasurements. It also provides graphical tables to help deter-mine the accuracy of measurements.1.5 Details on the design and construction of IR thermom-eters are no
5、t covered in this guide.1.6 This guide does not cover medium- and high-temperature IR thermometry (above 1000 C). It does notaddress the use of narrowband IR thermometers.1.7 The values of quantities stated in SI units are to beregarded as the standard. The values of quantities in parenthe-ses are n
6、ot in SI and are optional.1.8 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 pr
7、ior to use.2. Referenced Documents2.1 ASTM Standards:2E1256 Test Methods for Radiation Thermometers (SingleWaveband Type)E1862 Practice for Measuring and Compensating for Re-flected Temperature Using Infrared Imaging RadiometersE1897 Practice for Measuring and Compensating for Trans-mittance of an A
8、ttenuating Medium Using Infrared Imag-ing RadiometersE1933 Practice for Measuring and Compensating for Emis-sivity Using Infrared Imaging Radiometers2.2 IEC Standards:3IEC 62492-1 TS Industrial Process Control DevicesRadiation ThermometersPart 1: Technical Data forRadiation Thermometers2.3 BIPM Stan
9、dards:JCGM 200:2012 International Vocabulary of MetrologyBasic and General Concepts and Associated Terms (VIM)3. Terminology3.1 Definitions:3.1.1 absolute zero, na temperature of 0 K (-273.15 C).3.1.2 atmospheric attenuation, na ratio showing howmuch thermal radiation in a given spectral range is ab
10、sorbed orscattered in air over a given distance.3.1.3 atmospheric transmission, na ratio showing howwell thermal radiation in a given spectral range at a givendistance travels through a certain distance of air.3.1.4 attenuating medium, na semi-transparent solid, liq-uid or gas, such as a window, fil
11、ter, external optics, or anatmosphere that reduces thermal radiation, or combinationsthereof.3.1.5 background radiationsee reflected radiation.1This guide is under the jurisdiction of ASTM Committee E20 on TemperatureMeasurement and is the direct responsibility of Subcommittee E20.02 on RadiationThe
12、rmometry.Current edition approved March 1, 2015. Published March 2015. Originallyapproved in 2010. Last previous edition approved in 2010 as E2758 10.DOI:10.1520/E2758-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
13、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Electrotechnical Commission (IEC), 3, Rue deVaremb, CH-1211 Geneva 20, Switzerland, www.iec.ch.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700,
14、 West Conshohocken, PA 19428-2959. United States13.1.6 blackbody, nthe perfect or ideal source of thermalradiant power having a spectral distribution described byPlancks Law.3.1.7 blackbody simulator, na device with an emissivityclose to unity that can be heated or cooled to a stabletemperature.3.1.
15、8 calibration adjustment, nthe correction to an IRthermometer based on its calibration.3.1.9 center wavelength, nthe simple average of the lowerand upper spectral range limits.3.1.10 celestial radiation, nflux coming from the sky.3.1.11 contact thermometer, nan instrument that isadapted for measurin
16、g temperature by means of thermalconductance by determining the temperature at the momentwhen negligible thermal energy flows between the thermom-eter and the object of measurement.3.1.12 dew point, nthe temperature at which water vaporcondenses into liquid water.3.1.13 diffuse reflector, na surface
17、 that produces a diffuseimage of a reflected source.3.1.14 distance ratio, nthe ratio of the measuring distanceto the diameter of the field-of-view, when the target is infocus.43.1.15 electromagnetic radiation, nphysically occurringradiant flux classified according to wavelength or frequency.3.1.16
18、emissivity (), nthe emissivity of a surface is theratio between the radiation emitted from this surface and theradiation from a blackbody at the same temperature.3.1.16.1 DiscussionThe emissivity describes a thermo-physical material characteristic, which in addition to thechemical composition of the
19、 material may also be dependenton the surface structure (rough, smooth), the emission directionas well as on the observed wavelength and the temperature ofthe measured object.43.1.17 emissivity setting, nan adjustment on an IR ther-mometer to compensate for an emissivity of non-unity.3.1.17.1 Discus
20、sionIn most measuring situations a radia-tion thermometer is used on a surface with an emissivitysignificantly lower than one. For this purpose most thermom-eters have the possibility of adjusting the emissivity setting.The temperature reading is then automatically corrected.43.1.18 emissivity table
21、s, na list of objects and their mea-sured emissivity for a particular IR thermometer.3.1.19 field-of-view (FOV), na usually circular, flat sur-face of a measured object from which the radiation thermom-eter receives radiation.43.1.20 frost point, nthe temperature at which water vaporcondenses into s
22、olid water or ice.3.1.21 infrared (IR), adjreferring to electromagnetic ra-diation with a wavelength from approximately 0.7 to 30 m.3.1.22 infrared reflector, na material with a reflectance inthe infrared region as close as possible to unity.3.1.23 infrared sensing device, none of a wide class ofins
23、truments used to display or record (or both) informationrelated to the thermal radiation received from any objectsurfaces viewed by the instrument.3.1.24 infrared (IR) thermometer, noptoelectronic instru-ment adapted for noncontact measurement of temperature of asubject by utilizing thermal radiatio
24、n exchange between thesubject and the sensor.3.1.24.1 DiscussionIR thermometers are a subset of radia-tion thermometers. Most manufacturers use the term IR ther-mometer for handheld radiation thermometers. In general,these devices are wideband and use a thermopile detector.3.1.25 IR thermometry, nth
25、e use of IR thermometers todetermine temperature by measuring thermal radiation.3.1.26 irradiance (E), nthe radiant flux (power) per unitarea incident on a given surface in units of W/m2.3.1.27 limit of error, nthe extreme value of measurementerror of an infrared thermometer reading, relative to ref
26、erencetemperature standards, as permitted by a specification.3.1.27.1 DiscussionManufacturers sometimes use theterm accuracy in their specifications to represent limit of error.3.1.27.2 DiscussionA manufacturers accuracy specifica-tion may apply only to well defined conditions.3.1.28 low-temperature
27、, adjfor radiation and IRthermometry, referring to any temperature below 660 C.3.1.29 measurement uncertainty (accuracy), nnon-negative parameter, characterizing the dispersion of the quan-tity values being attributed to a measurand, based on theinformation used.4,53.1.30 measuring distance, ndistan
28、ce or distance rangebetween the radiation thermometer and the target (measuredobject) for which the radiation thermometer is designed.43.1.31 measuring temperature range, ntemperature rangefor which the radiation thermometer is designed.43.1.32 noise equivalent temperature difference (NETD),nparamet
29、er which indicates the contribution of the measure-ment uncertainty in C, which is due to instrument noise.43.1.33 opaque, adjreferring to the property of a materialwhose transmittance is zero for a given spectral range.3.1.34 operating temperature range and air humidity range,nthe permissible tempe
30、rature range and humidity rangewithin which the radiation thermometer may be operated. Forthis temperature range and humidity range the specificationsare valid.43.1.34.1 DiscussionThis is the range of ambient tempera-ture and humidity the instrument may operate within and beexpected to meet its spec
31、ification. It may be thought of as theambient operating temperature range and the ambient operatinghumidity range.3.1.35 radiance (L), nthe flux per unit projected area perunit solid angle leaving a source or, in general, any referencesurface.3.1.35.1 DiscussionIf 2 is the flux emitted into a solid4
32、See IEC 62492-1.5See BIPM JCGM 200:2012.E2758 152angle by a source element of projected area Acos(), theradiance is defined as:L 52Acos!where: = the angle between the outward surface normal of the areaelement A and the direction of observation (unit =W/srm2).3.1.36 radiant power density (M), nthe ra
33、diant flux perunit area leaving a surface that is,M 5Awhere: = flux leaving a surface element A (unit = W/m2).3.1.37 reflectance, nthe ratio of the radiant flux reflectedfrom a surface to that incident upon it.3.1.38 reflected radiation, nthe thermal radiation incidentupon and reflected from the mea
34、surement surface of thespecimen.3.1.39 reflected temperature, nthe temperature of theradiant flux incident upon and reflected from the measurementsurface of a specimen.3.1.40 response time, ntime interval between the instantof an abrupt change in the value of the input parameter (objecttemperature o
35、r object radiation) and the instant from which themeasured value of the radiation thermometer (output param-eter) remains within specified limits of its final value.43.1.41 sensor, ndevice designed to respond to IR radiationand convert that response into electrical signals.3.1.42 size-of-source effe
36、ct, nthe difference in theradiance- or temperature reading of the radiation thermometerwhen changing the size of the radiating area of the observedsource.43.1.43 spectral range, nparameter which gives the lowerand upper limits of the wavelength range over which theradiation thermometer operates.43.1
37、.43.1 DiscussionSpectral range is sometimes referredto as bandwidth.3.1.43.2 DiscussionThese limits are generally defined asthe wavelengths where the power or signal is attenuated by adefined amount.3.1.44 spectral response, nthe numerical quantity of agiven phenomenon at a specific wavelength in th
38、e electromag-netic spectrum.3.1.45 standard atmosphere, na model of how electro-magnetic radiation is transmitted through the atmosphere basedon variations in pressure, temperature and humidity.3.1.46 surface-modifying material, nany material that isused to change the emissivity of the specimen surf
39、ace.3.1.47 table of offsets, na list of calibration points andcalibration adjustments to be used when no internal calibrationadjustment is available.3.1.48 thermal radiation, nelectromagnetic radiationwhich is caused by an objects temperature and is predicted byPlancks Law.3.1.49 thermal shock, nsub
40、jecting an IR thermometer to arapid temperature change.3.1.50 thermopile detector, na series of thermocouplesconnected in series to a disk of finite mass.3.1.50.1 Discussiona thermopile detectors output is volt-age. Incident radiation heats the disk. When the disk is heated,its temperature rises abo
41、ve the sensors reference temperature(ambient temperature) producing a temperature difference(T). The potential of the thermopile is related to the tempera-ture difference based on the Seebeck Effect.3.1.51 transmittance (t), nthe ratio of the radiant fluxtransmitted through a body to that incident u
42、pon it.3.1.52 true temperature, ntemperature attributed to aparticular site of a subject or object of measurement andaccepted as having a specified uncertainty.3.1.53 wideband, adjreferring to the situation where thespectral range of an instrument is at least110 of its centerwavelength.4. Significan
43、ce and Use4.1 This guide provides guidelines and basic test methodsfor the use of infrared thermometers. The purpose of this guideis to provide a basis for users of IR thermometers to make moreaccurate measurements, to understand the error inmeasurements, and reduce the error in measurements.5. Basi
44、c Use of IR Thermometry5.1 General Considerations:5.1.1 An IR thermometer can be used in a number ofapplications. Although they are generally not as accurate ascontact thermometers, their quickness of measurement andtheir ability to measure the temperature of an opaque surfacewithout contacting it m
45、ake them desirable instruments forsome temperature measurements.5.1.2 Most handheld IR thermometers are equipped with atrigger to start and stop the measurements.5.1.3 As objects vary in temperature, they emit a varyingamount of thermal radiation. This amount of thermal radiationis predictable based
46、 on the objects temperature, emissivity andreflected temperature.5.1.4 Handheld IR thermometers measure thermal radiationin a given spectral range and determine the relationshipbetween the measured thermal radiation and temperature. Thesensor mainly used in these instruments is a thermopile.5.2 Basi
47、c IR Measurement:5.2.1 Before making a measurement, the emissivity settingof the IR thermometer should be set to the objects effectiveemissivity in the instruments spectral range. Some IR ther-mometers do not allow the user to adjust the emissivity becausetheir emissivity is fixed. In these cases th
48、ere are mathematicalcompensations that can be made.5.2.2 To make a measurement, the IR thermometers lensshould be pointed at the object being measured. The measure-ment should be initiated. If the IR thermometer has a trigger,E2758 153this is done by pulling the trigger. The trigger should be held a
49、tleast as long as the IR thermometers specified response time.The measured temperature is usually frozen on the display afterthe trigger is released.5.2.3 Fig. 1 shows a diagram of how much of a surface anIR thermometer measures. Subsection 11.1 discusses spot sizeand distance-to-size ratio.5.2.4 Fig. 2 shows how much surface area is needed fortemperature measurement when considering the IR thermom-eters spot size. The part of the figure labeled poor shows asituation w
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