1、Designation:E125610 Designation: E1256 11Standard 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
2、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 The test methods described in these test methods can be utilized to evaluate the following six basic operational param
3、etersof a radiation thermometer (single waveband type):SectionCalibration Accuracy 7Repeatability 8Target Size 9Response Time 10Warm-Up Time 11Long-Term Stability 121.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof t
4、he user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Terminology2.1 Definitions:2.1.1 blackbody, nthe perfect or ideal source of thermal radiant power having a spectral distribution described by the Pla
5、nckequation.2.1.1.1 DiscussionThe term blackbody is often used to describe a furnace or other source of radiant power whichapproximates the ideal.2.1.2 center wavelength, na wavelength, usually near the middle of the band of radiant power over which a radiationthermometer responds, that is used to c
6、haracterize its performance.2.1.2.1 DiscussionThe value of the center wavelength is usually specified by the manufacturer of the instrument.2.1.3 radiation thermometer, na radiometer calibrated to indicate the temperature of a blackbody.2.1.4 radiometer, na device for measuring radiant power that ha
7、s an output proportional to the intensity of the input power.2.1.5 target plane, nthe plane, perpendicular to the line of sight of a radiation thermometer, that is in focus for that instrument.2.2 Definitions of Terms Specific to This Standard:2.2.1 reference temperature source, na source of thermal
8、 radiant power of known temperature or emissivity, or both, used inthe testing of radiation thermometers.2.2.2 target size, nthe diameter of a circle in the target plane of a radiation thermometer that is centered on its line of sightand contains 99 % of the input radiant power received by that inst
9、rument.2.2.3 temperature resolution, nthe minimum simulated or actual change in target temperature that gives a usable change inoutput or indication, or both.3. Significance and Use3.1 The purpose of these test methods is to establish consensus test methods by which both manufacturers and end users
10、maymake tests to establish the validity of the readings of their radiation thermometers. The test results can also serve as standardperformance criteria for instrument evaluation or selection, or both.3.2 The goal is to provide test methods that are reliable and can be performed by a sufficiently sk
11、illed end user or manufacturerin the hope that it will result in a better understanding of the operation of radiation thermometers and also promote improvedcommunication between the manufacturers and the end users. A user without sufficient knowledge and experience should seek1These test methods are
12、 under the jurisdiction of ASTM Committee E20 on Temperature Measurement and are the direct responsibility of Subcommittee E20.02 onRadiation Thermometry.Current edition approved Dec. 1, 2010. Published January 2011. Originally approved in 1988. Last previous edition approved in 2007 as E125695 (200
13、7). DOI:10.1520/E1256-10.Current edition approved Feb. 15, 2011. Published March 2011. Originally approved in 1988. Last previous edition approved in 2010 as E1256 10. DOI:10.1520/E1256-11.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indicati
14、on 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 versionof the standard as published by ASTM is to be consi
15、dered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.assistance from the equipment makers or other expert sources, such as those found at the National Institute of Standards andTechnology in Gaithersburg, Maryla
16、nd.3.3 Use these test methods with the awareness that there are other parameters, particularly spectral range limits and temperatureresolution, which impact the use and characterization of radiation thermometers for which test methods have not yet beendeveloped.3.3.1 Temperature resolution is the mi
17、nimum simulated or actual change in target temperature that results in a usable changein output or indication, or both. It is usually expressed as a temperature differential or a percent of full-scale value, or both, andusually applies to value measured. The magnitude of the temperature resolution d
18、epends upon a combination of four factors:detector noise equivalent temperature difference (NETD), electronic signal processing, signal-to-noise characteristics (includingamplification noise), and analog-to-digital conversion “granularity.”3.3.2 Spectral range limits are the upper and lower limits t
19、o the wavelength band of radiant energy to which the instrumentresponds. These limits are generally expressed in micrometers (m) and include the effects of all elements in the measuring opticalpath. At the spectral response limits, the transmission of the measuring optics is 5 % of peak transmission
20、 (see Fig. 1).4. Apparatus4.1 The following apparatus, 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 (or other stable isothermal radiant source of high and known emissivity)with an opening diameter at l
21、east as large as that specified in these test methods.NOTE 1Typical examples include nearly isothermal furnaces with internal geometries, such as a sphere with an opening small relative to its radius,or a right circular cylinder with one end closed having a radius small relative to its length.24.1.2
22、 Temperature IndicatorEither contact or radiometric, which accurately displays the temperature of the referencetemperature source.4.1.3 Shutter MechanismOf sufficient size so as to completely block the opening of the reference temperature source fromthe field of view of the test instrument. The shut
23、ter mechanism shall activate in a time interval that is short when compared withthe response time of the test instrument.4.1.4 Iris DiaphragmOf sufficient size so that when fully open the iris diameter is greater than the opening of the referencetemperature source. It shall be located with its openi
24、ng concentric with and perpendicular to the line of sight of the radiationthermometer.4.1.4.1 The side of the diaphragm facing the radiation thermometer should be blackened (nearly nonreflective) so as to minimizethe effect of radiation reflected from the surrounding environment. In addition the iri
25、s should be shaded from sources of intenseextraneous radiation. (See Note 9).4.1.5 Aperture SetIf an iris diaphragm is not available, an aperture disc set of appropriate diameters can be used. Eachaperture should be blackened and also mounted and protected from extraneous sources of radiation as dis
26、cussed in 4.1.4.1.4.1.6 Data Acquisition SystemsOf appropriate speed and storage 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 voltage and frequency, if necessary, to the radi
27、ation thermometer.5. Calibration Accuracy Test Method5.1 SummaryThis test method outlines the procedure to be used to evaluate the maximum deviation between the temperature2DeWitt, D. P., and Nutter, G. D., eds., “Theory and Practice of Radiation Thermometry,” John Wiley and Sons, New York, NY.FIG.
28、1 Spectral Range LimitsE1256 112indicated by the radiation thermometer and the known temperature of a reference temperature source, including the uncertainty ofthe reference temperature source relative to the current International Temperature Scale.5.2 Test Conditions:5.2.1 Rated supply voltage and
29、frequency.5.2.2 Prescribed warm-up period.5.2.3 After execution of internal standardization check (if available).5.2.4 Emissivity compensation set to one (1).5.2.5 Minimum opening of the reference temperature source shall not obstruct the field of view of the radiation thermometerwith the test apert
30、ure as specified by the manufacturer.5.2.6 Laboratory ambient temperature range (20 to 25C).5.2.7 Manufacturer shall specify any special conditions such as atmospheric absorption effects, target distance, etc.5.2.8 Manufacturer shall specify the output for determining the indicated temperature.5.3 T
31、est Method:5.3.1 The radiation thermometer is sighted at the reference temperature source whose temperature is sequentially stabilized atthree calibration points distributed uniformly over the measurement range of the instrument.5.3.2 The temperature of the reference temperature source and the tempe
32、rature indicated by the radiation thermometer arerecorded, then the difference between the two values is calculated and recorded (see Fig. 3).5.3.3 The test sequence is repeated twice for the same three calibration points, and an average temperature difference iscalculated and recorded for each cali
33、bration point.5.4 Test ResultThe value for the calibration accuracy of the temperature indication of the radiation thermometer is taken tobe the largest of the three average temperature differences determined in 5.3.2 plus or minus the uncertainty of the temperatureof the reference temperature sourc
34、e relative to the current International Temperature Scale.NOTE 2The calibration accuracy is generally expressed as a temperature difference or a percent of full-scale value, or both.NOTE 3The value applies across the entire measurement range.NOTE 4If the reference temperature source is measured with
35、 other than a calibrated reference or secondary standard radiation thermometer, then theemissivity of the source enters into the calibration of the test radiation thermometer.6. Procedure6.1 Detailed directions for evaluation of each parameter listed in 1.1 are included in each parameter test method
36、.6.2 Each parameter test method is organized by: parameter term, summary, test conditions, test method, test result, andapplicable notes.7. Repeatability Test Method7.1 SummaryThis test method outlines the procedure to be used to evaluate the repeatability of the temperature indication ofa radiation
37、 thermometer for a number of consecutive measurements made under the same conditions over a specified interval oftime.FIG. 2 Test Method ApparatusE1256 1137.2 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
38、 check (if available).7.2.4 Diameter of the reference temperature source opening shall be greater than the radiation thermometer target size, asspecified by the manufacturer.7.2.5 Laboratory ambient temperature range (20 to 25C).7.2.6 Emissivity compensation, if any, set to one (1).7.2.7 Manufacture
39、r shall specify any special conditions such as response time, atmospheric absorption effects, target distance,etc.7.3 Test Method:7.3.1 Once a day for twelve consecutive working days, the radiation thermometer is sighted at the reference temperature sourcewhose temperature is stabilized at the appro
40、ximate midpoint of the radiation thermometer calibration range.NOTE 5The selected reference temperature source temperature shall be reproduced for each of the twelve consecutive tests.7.3.2 The temperature of the reference temperature source and the temperature(s) indicated by the radiation thermome
41、ter duringeach days test are recorded.7.3.3 The radiation thermometer shall be switched off after each series of measurements.7.4 Test ResultThe value for the repeatability of the readings of the radiation thermometer is taken to be the standard deviationof the twelve recorded readings.S.D. 5(i 5 1N
42、Xi2 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 generally expressed as a temperature difference or a pe
43、rcent of full-scale value, or both.NOTE 7The value for the repeatability can be applied across the entire measuring temperature range, or, the same test can be performed at otherselected temperatures across the measuring temperature range in order to assess the repeatability of the radiation thermom
44、eter at those temperatures.FIG. 3 Worksheet for Calibration Accuracy Test MethodE1256 1148. Target Size Test Method8.1 SummaryThis test method outlines the procedure to be used to evaluate the diameter of the circle located in the targetplane of the reference temperature source, at a known distance
45、along and perpendicular to a radiation thermometers line of sight,and from which 99 % of the radiant power received by the radiation thermometer is collected (see Figs. 3 and 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 inte
46、rnal standardization check (if applicable).8.2.4 Laboratory ambient temperature range (20 to 25C).8.2.5 Minimum opening of the reference temperature source shall be large enough so as to not obstruct the optical path of theradiation thermometer, as specified by the manufacturer, when it is sighted t
47、hrough an aperture that is twice the diameter of theinstruments target size at the plane of the aperture.NOTE 8Some radiation thermometers have a target size so large that a commercially available reference temperature source cannot be used; a separatetest method is under preparation for use in such
48、 cases.8.2.6 Manufacturer shall specify any special conditions such as atmospheric absorption effects, distance, how and when to cleanthe radiation thermometer lens, etc.8.3 Test Method:8.3.1 The temperature of the reference temperature source is stabilized at a value near the top of the calibration
49、 range of theradiation thermometer.8.3.2 The iris is positioned in the front of and concentric with the opening of the reference temperature source (as illustratedin Fig. 2). The iris is then adjusted to a diameter slightly smaller (typically 10 %) than the expected target diameter.NOTE 9The iris should be kept cool enough so that its thermal emission does not contribute significantly to the output signal. Uncovering the irisquickly can minimize heating, but this requires care. Evaluation of the error from this source requires computati
