1、Designation: E 1256 95 (Reapproved 2001)Standard Test Methods forRadiation Thermometers (Single Waveband Type)1This standard is issued under the fixed designation E 1256; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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.1. Scope1.1 The test methods described in these test methods can beutilized to evaluate the following six basic operational param
3、-eters of a radiation thermometer (single waveband type):SectionCalibration Accuracy 7Repeatability 8Target Size 9Response Time 10Warm-Up Time 11Long-Term Drift 121.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the
4、user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 blackbody, nthe perfect or ideal source of thermalradiant power having a spectral distribution described by thePlanc
5、k equation.2.1.1.1 DiscussionThe term blackbody is often used todescribe a furnace or other source of radiant power whichapproximates the ideal.2.1.2 center wavelength, na wavelength, usually near themiddle of the band of radiant power over which a radiationthermometer responds, that is used to char
6、acterize its perfor-mance.2.1.2.1 DiscussionThe value of the center wavelength isusually specified by the manufacturer of the instrument.2.1.3 radiation thermometer, na radiometer calibrated toindicate the temperature of a blackbody.2.1.4 radiometer, na device for measuring radiant powerthat has an
7、output proportional to the intensity of the inputpower.2.1.5 target plane, nthe plane, perpendicular to the line ofsight of a radiation thermometer, that is in focus for thatinstrument.2.2 Definitions of Terms Specific to This Standard:2.2.1 reference temperature source, na source of thermalradiant
8、power of known temperature or emissivity, or both,used in the testing of radiation thermometers.2.2.2 target size, nthe diameter of a circle in the targetplane of a radiation thermometer that is centered on its line ofsight and contains 99 % of the input radiant power received bythat instrument.2.2.
9、3 temperature resolution, nthe minimum simulated oractual change in target temperature that gives a usable changein output or indication, or both.3. Significance and Use3.1 The purpose of these test methods is to establishconsensus test methods by which both manufacturers and endusers may make tests
10、 to establish the validity of the readings oftheir radiation thermometers. The test results can also serve asstandard performance criteria for instrument evaluation orselection, or both.3.2 The goal is to provide test methods that are reliable andcan be performed by a sufficiently skilled end user o
11、r manu-facturer in the hope that it will result in a better understandingof the operation of radiation thermometers and also promoteimproved communication between the manufacturers and theend users. A user without sufficient knowledge and experienceshould seek assistance from the equipment makers or
12、 otherexpert sources, such as those found at the National Institute ofStandards and Technology in Gaithersburg, Maryland.3.3 Use these test methods with the awareness that there areother parameters, particularly spectral response limits andtemperature resolution, which impact the use and characteriz
13、a-tion of radiation thermometers for which test methods have notyet been developed.3.3.1 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 expressedas a temperature differential or a pe
14、rcent 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 power (NEP) or noiseequivalent temperature, electronic signal processing, signal-to-noise characteristics (includi
15、ng amplification noise), andanalog-to-digital conversion “granularity.”3.3.2 Spectral response limits are the upper and lower limits1These test methods are under the jurisdiction of ASTM Committee E20 onTemperature Measurement and are the direct responsibility of Subcommittee E20.02on Radiation Ther
16、mometry.Current edition approved Oct. 10, 1995. Published January 1996. Originallypublished as E 1256 88. Last previous edition E 1256 88.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to the wavelength band of radiant energy to whi
17、ch theinstrument responds. These limits are generally expressed inmicrometers (m) and include the effects of all elements in themeasuring optical path. At the spectral response limits, thetransmission of the measuring optics is 5 % of peak transmis-sion (see Fig. 1).4. Apparatus4.1 The following app
18、aratus, set up as illustrated in Fig. 2,can be used to perform the standard tests for all six parameters.4.1.1 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 meth
19、ods.NOTE 1Typical examples include nearly isothermal furnaces withinternal geometries, such as a sphere with an opening small relative to itsradius, or a right circular cylinder with one end closed having a radiussmall relative to its length. Consult footnote2for greater detail.4.1.2 Temperature Ind
20、icatorEither contact or radiometric,which accurately displays the temperature of the referencetemperature source.4.1.3 Shutter MechanismOf 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 sha
21、ll activate in a time interval that is short whencompared with the response time of the test instrument.4.1.4 Iris DiaphragmOf sufficient 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
22、and perpendicular to the line of sightof the radiation thermometer.4.1.4.1 The side of the diaphragm facing the radiationthermometer 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
23、fromsources of intense extraneous radiation. (See Note 9).4.1.5 Aperture SetIf an iris diaphragm is not available, anaperture disc set of appropriate diameters can be used. Eachaperture should be blackened and also mounted and protectedfrom extraneous sources of radiation as discussed in 4.1.4.1.4.1
24、.6 Data Acquisition SystemsOf appropriate speed andstorage capacity to measure and record the output signal of theradiation thermometer in the Response Time Test Method,Section 9.4.1.7 Power SupplyCapable of supplying the proper volt-age and frequency, if necessary, to the radiation thermometer.5. C
25、alibration Accuracy Test Method5.1 SummaryThis test method outlines the procedure tobe used to evaluate the maximum deviation between thetemperature indicated by the radiation thermometer and theknown temperature of a reference temperature source, includ-ing the uncertainty of the reference temperat
26、ure source relativeto the current International Temperature Scale.5.2 Test Conditions:5.2.1 Rated supply voltage and frequency.5.2.2 Prescribed warm-up period.5.2.3 After execution of internal standardization check (ifavailable).5.2.4 Emissivity compensation set to one (1).5.2.5 Minimum opening of t
27、he reference temperature sourceshall not obstruct the field of view of the radiation thermometerwith the test aperture as specified by the manufacturer.5.2.6 Laboratory ambient temperature range (20 to 25 C).5.2.7 Manufacturer shall specify any special conditionssuch as atmospheric absorption effect
28、s, target distance, etc.5.2.8 Manufacturer shall specify the output for determiningthe indicated temperature.5.3 Test Method:5.3.1 The radiation thermometer is sighted at the referencetemperature source whose temperature is sequentially stabi-lized at three calibration points distributed uniformly o
29、ver themeasurement range of the instrument.5.3.2 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).5.3.3 The test sequence is repeated twice for
30、the same threecalibration points, and an average temperature difference iscalculated and recorded for each calibration point.5.4 Test ResultThe value for the calibration accuracy ofthe temperature indication of the radiation thermometer istaken to be the largest of the three average temperaturediffe
31、rences determined in 5.3.2 plus or minus the uncertainty ofthe temperature of the reference temperature source relative tothe current International Temperature Scale.NOTE 2The calibration accuracy is generally expressed as a tempera-ture difference or a percent of full-scale value, or both.NOTE 3The
32、 value applies across the entire measurement range.NOTE 4If 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 thermometer.6. Procedure6.1 De
33、tailed directions for evaluation of each parameterlisted in 1.1 are included in each parameter test method.2DeWitt, D. P., and Nutter, G. D., eds., “Theory and Practice of RadiationThermometry,” John Wiley and Sons, New York, NY.FIG. 1 Spectral Response LimitsE 125626.2 Each parameter test method is
34、 organized by: parameterterm, summary, test conditions, test method, test result, andapplicable notes.7. Repeatability Test Method7.1 SummaryThis test method outlines the procedure tobe used to evaluate the repeatability of the temperatureindication of a radiation thermometer for a number of consecu
35、-tive measurements made under the same conditions over aspecified interval of time.7.2 Test Conditions:7.2.1 Rated supply of voltage and frequency.7.2.2 Prescribed warm-up period.7.2.3 After execution of internal standardization check (ifavailable).7.2.4 Diameter of the reference temperature source
36、openingshall be greater than the radiation thermometer target size, asspecified by the manufacturer.7.2.5 Laboratory ambient temperature range (20 to 25 C).7.2.6 Emissivity compensation, if any, set to one (1).7.2.7 Manufacturer shall specify any special conditionssuch as response time, atmospheric
37、absorption effects, targetdistance, etc.7.3 Test Method:7.3.1 Once a day for twelve consecutive working days, theradiation thermometer is sighted at the reference temperatureFIG. 2 Test Method ApparatusFIG. 3 Worksheet for Calibration Accuracy Test MethodE 12563source whose temperature is stabilized
38、 at the approximatemidpoint of the radiation thermometer calibration range.NOTE 5The selected reference temperature source temperature shallbe reproduced for each of the twelve consecutive tests.7.3.2 The temperature of the reference temperature sourceand the temperature(s) indicated by the radiatio
39、n thermometerduring each days test are recorded.7.3.3 The radiation thermometer shall be switched off aftereach series of measurements.7.4 Test ResultThe value for the repeatability of thereadings of the radiation thermometer is taken to be thestandard deviation of the twelve recorded readings.S.D.
40、5(i 5 1NXi2 X!2N 2 15 !(i 5 1NXi22(i 5 1NXi!2NN 2 1where:S.D. = standard deviation,N = number of measurements,Xi= value of the ith measurement, andX=average of the twelve measurements =(i 5 1NXiN.NOTE 6The repeatability of the temperature indication is generallyexpressed as a temperature difference
41、or a percent of full-scale value, orboth.NOTE 7The value for the repeatability can be applied across the entiremeasurement range, or, the same test can be performed at other selectedtemperatures across the measurement range in order to assess therepeatability of the radiation thermometer at those te
42、mperatures.8. Target Size Test Method8.1 SummaryThis test method outlines the procedure tobe used to evaluate the diameter of the circle located in thetarget plane of the reference temperature source, at a knowndistance along and perpendicular to a radiation thermometersline of sight, and from which
43、 99 % of the radiant powerreceived by the radiation thermometer is collected (see Figs. 3and 4).8.2 Test Conditions:8.2.1 Rated supply voltage and frequency.8.2.2 Prescribed warm-up period.8.2.3 After execution of internal standardization check (ifapplicable).8.2.4 Laboratory ambient temperature ran
44、ge (20 to 25 C).8.2.5 Minimum opening of the reference temperature sourceshall be large enough so as to not obstruct the optical path ofthe radiation thermometer, as specified by the manufacturer,when it is sighted through an aperture that is twice the diameterof the instruments target size at the p
45、lane of the aperture.NOTE 8Some radiation thermometers have a target size so large thata commercially available reference temperature source cannot be used; aseparate test method is under preparation for use in such cases.8.2.6 Manufacturer shall specify any special conditionssuch as atmospheric abs
46、orption effects, distance, how andwhen to clean the radiation thermometer lens, etc.8.3 Test Method:8.3.1 The temperature of the reference temperature source isstabilized at a value near the top of the calibration range of theradiation thermometer.8.3.2 The iris is positioned in the front of and con
47、centricwith the opening of the reference temperature source (asillustrated in Fig. 2). The iris is then adjusted to a diameterslightly smaller (typically 10 %) than the expected targetdiameter.NOTE 9The iris should be kept cool enough so that its thermalemission does not contribute significantly to
48、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; a discussion of such procedures can be found infootnote 2. In most cases, however, the error is i
49、nsignificant if the iris ismaintained near room temperature (20 C) and the reference temperaturesource temperature is at or above 200 C.8.3.3 The position of the radiation thermometer is thenadjusted vertically and horizontally and focused to producemaximum output while also maintaining the line of sightperpendicular to the iris.8.3.4 The iris is then opened to the point where thetemperature indicated by the radiation thermometer stopsincreasing, but its diameter is still smaller than the referencetemperature source opening.8.3.5 The tempera
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1