1、Designation: E1256 11aStandard Test Methods forRadiation Thermometers (Single Waveband Type)1This standard is issued under the fixed designation E1256; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 The test methods described in these test methods can beutilized to evaluate the following six basic operational param-eters of a radiatio
3、n thermometer (single waveband type):SectionCalibration Accuracy 8Repeatability 9Field-of-View 10Response Time 11Warm-Up Time 12Long-Term Stability 131.2 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
4、standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 IEC DocumentsIEC 629421 TS Industrial Process Control Devices Radiation Thermometers Part 1: Technical Data forRadiation Thermometers3. Te
5、rminology3.1 Definitions:3.1.1 blackbody, nthe perfect or ideal source of thermalradiant power having a spectral distribution described by thePlanck equation.3.1.1.1 DiscussionThe term blackbody is often used todescribe a furnace or other source of radiant power whichapproximates the ideal.3.1.2 cen
6、ter wavelength, na wavelength, usually near themiddle of the band of radiant power over which a radiationthermometer responds, that is used to characterize its perfor-mance.3.1.2.1 DiscussionThe value of the center wavelength isusually specified by the manufacturer of the instrument.3.1.3 field-of-v
7、iew, na usually circular, flat surface of ameasured object from which the radiation thermometer re-ceives radiation.2NOTE 1Field-of-view traditionally has been referred to as target size.3.1.4 measuring distance, ndistance or distance rangebetween the radiation thermometer and the target (measuredob
8、ject) for which the radiation thermometer is designed.2NOTE 2Measuring distance traditionally has been referred to as targetdistance.3.1.5 radiation thermometer, na radiometer calibrated toindicate the temperature of a blackbody.3.1.6 radiometer, na device for measuring radiant powerthat has an outp
9、ut proportional to the intensity of the inputpower.3.1.7 target distance, nsee measuring distance.3.1.8 target plane, nthe plane, perpendicular to the line ofsight of a radiation thermometer, that is in focus for thatinstrument.3.1.9 target size, nsee field-of-view.3.2 Definitions of Terms Specific
10、to This Standard:3.2.1 reference temperature source, na source of thermalradiant power of known temperature or emissivity, or both,used in the testing of radiation thermometers.3.2.2 temperature resolution, nthe minimum simulated oractual change in target temperature that gives a usable changein out
11、put or indication, or both.4. Significance and Use4.1 The purpose of these test methods is to establishconsensus test methods by which both manufacturers and endusers may make tests to establish the validity of the readings oftheir radiation thermometers. The test results can also serve asstandard p
12、erformance criteria for instrument evaluation orselection, or both.4.2 The goal is to provide test methods that are reliable andcan be performed by a sufficiently skilled end user or manu-facturer in the hope that it will result in a better understandingof the operation of radiation thermometers and
13、 also promoteimproved communication between the manufacturers and the1These test methods are under the jurisdiction of ASTM Committee E20 onTemperature Measurement and are the direct responsibility of Subcommittee E20.02on Radiation Thermometry.Current edition approved May 1, 2011. Published June 20
14、11. Originallyapproved in 1988. Last previous edition approved in 2011 as E1256 11. DOI:10.1520/E1256-11a.2IEC 6294291.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.end users. A user without sufficient knowledge and experienceshoul
15、d seek assistance from the equipment makers or otherexpert sources, such as those found at the National Institute ofStandards and Technology in Gaithersburg, Maryland.4.3 Use these test methods with the awareness that there areother parameters, particularly spectral range limits and tem-perature res
16、olution, which impact the use and characterizationof radiation thermometers for which test methods have not yetbeen developed.4.3.1 Temperature resolution is the minimum simulated oractual change in target temperature that results in a usablechange in output or indication, or both. It is usually exp
17、ressedas a temperature differential or a percent of full-scale value, orboth, and usually applies to value measured. The magnitude ofthe temperature resolution depends upon a combination of fourfactors: detector noise equivalent temperature difference(NETD), electronic signal processing, signal-to-n
18、oise charac-teristics (including amplification noise), and analog-to-digitalconversion “granularity.”4.3.2 Spectral range limits are the upper and lower limits tothe wavelength band of radiant energy to which the instrumentresponds. These limits are generally expressed in micrometers(m) and include
19、the effects of all elements in the measuringoptical path.At the spectral response limits, the transmission ofthe measuring optics is 5 % of peak transmission (see Fig. 1).5. Apparatus5.1 The following apparatus, set up as illustrated in Fig. 2,can be used to perform the standard tests for all six pa
20、rameters.5.1.1 Reference Temperature SourceA blackbody (orother stable isothermal radiant source of high and knownemissivity) with an opening diameter at least as large as thatspecified in these test methods.NOTE 3Typical examples include nearly isothermal furnaces withinternal geometries, such as a
21、 sphere with an opening small relative to itsradius, or a right circular cylinder with one end closed having a radiussmall relative to its length.35.1.2 Temperature IndicatorEither contact or radiometric,which accurately displays the temperature of the referencetemperature source.5.1.3 Shutter Mecha
22、nismOf sufficient size so as to com-pletely block the opening of the reference temperature sourcefrom the field of view of the test instrument. The shuttermechanism shall activate in a time interval that is short whencompared with the response time of the test instrument.5.1.4 Iris DiaphragmOf suffi
23、cient size so that when fullyopen the iris diameter is greater than the opening of thereference temperature source. It shall be located with itsopening concentric with and perpendicular to the line of sightof the radiation thermometer.5.1.4.1 The side of the diaphragm facing the radiationthermometer
24、 should be blackened (nearly nonreflective) so asto minimize the effect of radiation reflected from the surround-ing environment. In addition the iris should be shaded fromsources of intense extraneous radiation. (See Note 11).5.1.5 Aperture SetIf an iris diaphragm is not available, anaperture disc
25、set of appropriate diameters can be used. Eachaperture should be blackened and also mounted and protectedfrom extraneous sources of radiation as discussed in 5.1.4.1.5.1.6 Data Acquisition SystemsOf appropriate speed andstorage capacity to measure and record the output signal of theradiation thermom
26、eter in the Response Time Test Method,Section 10.5.1.7 Power SupplyCapable of supplying the proper volt-age and frequency, if necessary, to the radiation thermometer.6. Calibration Accuracy Test Method6.1 SummaryThis test method outlines the procedure tobe used to evaluate the maximum deviation betw
27、een thetemperature indicated by the radiation thermometer and theknown temperature of a reference temperature source, includ-ing the uncertainty of the reference temperature source relativeto the current International Temperature Scale.6.2 Test Conditions:6.2.1 Rated supply voltage and frequency.6.2
28、.2 Prescribed warm-up period.6.2.3 After execution of internal standardization check (ifavailable).6.2.4 Emissivity compensation set to one (1).6.2.5 Minimum opening of the reference temperature sourceshall not obstruct the field of view of the radiation thermometerwith the test aperture as specifie
29、d by the manufacturer.6.2.6 Laboratory ambient temperature range (20 to 25C).6.2.7 Manufacturer shall specify any special conditionssuch as atmospheric absorption effects, measuring distance,etc.6.2.8 Manufacturer shall specify the output for determiningthe indicated temperature.6.3 Test Method:6.3.
30、1 The radiation thermometer is sighted at the referencetemperature source whose temperature is sequentially stabi-lized at three calibration points distributed uniformly over themeasurement range of the instrument.3DeWitt, D. P., and Nutter, G. D., eds., “Theory and Practice of RadiationThermometry,
31、” John Wiley and Sons, New York, NY.FIG. 1 Spectral Range LimitsE1256 11a26.3.2 The temperature of the reference temperature sourceand the temperature indicated by the radiation thermometer arerecorded, then the difference between the two values iscalculated and recorded (see Fig. 3).6.3.3 The test
32、sequence is repeated twice for the same threecalibration points, and an average temperature difference iscalculated and recorded for each calibration point.6.4 Test ResultThe value for the calibration accuracy ofthe temperature indication of the radiation thermometer istaken to be the largest of the
33、 three average temperaturedifferences determined in 6.3.2 plus or minus the uncertainty ofthe temperature of the reference temperature source relative tothe current International Temperature Scale.NOTE 4The calibration accuracy is generally expressed as a tempera-ture difference or a percent of full
34、-scale value, or both.NOTE 5The value applies across the entire measurement range.NOTE 6If the reference temperature source is measured with otherthan a calibrated reference or secondary standard radiation thermometer,then the emissivity of the source enters into the calibration of the testradiation
35、 thermometer.7. Procedure7.1 Detailed directions for evaluation of each parameterlisted in 1.1 are included in each parameter test method.7.2 Each parameter test method is organized by: parameterterm, summary, test conditions, test method, test result, andapplicable notes.8. Repeatability Test Metho
36、d8.1 SummaryThis test method outlines the procedure tobe used to evaluate the repeatability of the temperatureindication of a radiation thermometer for a number of consecu-tive measurements made under the same conditions over aspecified interval of time.8.2 Test Conditions:8.2.1 Rated supply of volt
37、age and frequency.8.2.2 Prescribed warm-up period.8.2.3 After execution of internal standardization check (ifavailable).8.2.4 Diameter of the reference temperature source openingshall be greater than the radiation thermometer field-of-view,as specified by the manufacturer.8.2.5 Laboratory ambient te
38、mperature range (20 to 25C).8.2.6 Emissivity compensation, if any, set to one (1).8.2.7 Manufacturer shall specify any special conditionssuch as response time, atmospheric absorption effects, measur-ing distance, etc.8.3 Test Method:8.3.1 Once a day for twelve consecutive working days, theradiation
39、thermometer is sighted at the reference temperaturesource whose temperature is stabilized at the approximatemidpoint of the radiation thermometer calibration range.NOTE 7The selected reference temperature source temperature shallbe reproduced for each of the twelve consecutive tests.8.3.2 The temper
40、ature of the reference temperature sourceand the temperature(s) indicated by the radiation thermometerduring each days test are recorded.8.3.3 The radiation thermometer shall be switched off aftereach series of measurements.8.4 Test ResultThe value for the repeatability of thereadings of the radiati
41、on thermometer is taken to be thestandard deviation of the twelve recorded readings.S.D. 5(i 5 1NXi2 X!2N 2 15 !(i 5 1NXi22(i 5 1NXi!2NN 2 1FIG. 2 Test Method ApparatusE1256 11a3where:S.D. = standard deviation,N = number of measurements,Xi= value of the ith measurement, andX=average of the twelve me
42、asurements =(i 5 1NXiN.NOTE 8The repeatability of the temperature indication is generallyexpressed as a temperature difference or a percent of full-scale value, orboth.NOTE 9The value for the repeatability can be applied across the entiremeasuring temperature range, or, the same test can be performe
43、d at otherselected temperatures across the measuring temperature range in order toassess the repeatability of the radiation thermometer at those temperatures.9. FieldofView Test Method9.1 SummaryThis test method outlines the procedure tobe used to evaluate the diameter of the circle located in theta
44、rget plane of the reference temperature source, at a knowndistance along and perpendicular to a radiation thermometersline of sight, and from which 99 % of the radiant powerreceived by the radiation thermometer is collected (see Figs. 3and 4).9.2 Test Conditions:9.2.1 Rated supply voltage and freque
45、ncy.9.2.2 Prescribed warm-up period.9.2.3 After execution of internal standardization check (ifapplicable).9.2.4 Laboratory ambient temperature range (20 to 25C).9.2.5 Minimum opening of the reference temperature sourceshall be large enough so as to not obstruct the optical path ofthe radiation ther
46、mometer, as specified by the manufacturer,when it is sighted through an aperture that is twice the diameterof the instruments field-of-view at the plane of the aperture.NOTE 10Some radiation thermometers have a field-of-view so largethat a commercially available reference temperature source cannot b
47、eused; a separate test method is under preparation for use in such cases.9.2.6 Manufacturer shall specify any special conditionssuch as atmospheric absorption effects, measuring distance,how and when to clean the radiation thermometer lens, etc.9.3 Test Method:9.3.1 The temperature of the reference
48、temperature source isstabilized at a value near the top of the calibration range of theradiation thermometer.9.3.2 The iris is positioned in the front of and concentricwith the opening of the reference temperature source (asillustrated in Fig. 2). The iris is then adjusted to a diameterslightly smal
49、ler (typically 10 %) than the expected targetdiameter.NOTE 11The iris should be kept cool enough so that its thermalemission does not contribute significantly to the output signal. Uncoveringthe iris quickly can minimize heating, but this requires care. Evaluation ofthe error from this source requires computational procedures beyond thescope of this test method.3In most cases, however, the error is insignifi-cant if the iris is maintained near room temperature (20C) and thereference temperature source temperature is at or above
