ASTM E1256-17(2022)
(Test Method)Standard Test Methods for Radiation Thermometers (Single Waveband Type)
Standard Test Methods for Radiation Thermometers (Single Waveband Type)
SIGNIFICANCE AND USE
4.1 The purpose of these test methods is to establish consensus test methods by which both manufacturers and end users may perform tests to establish the validity of the readings of their radiation thermometers. The test results can also serve as standard performance criteria for instrument evaluation or selection, or both.
4.2 The goal is to provide test methods that are reliable and can be performed by a sufficiently skilled end user or manufacturer. It is hoped that it will result in a better understanding of the operation of radiation thermometers and also promote improved communication between the manufacturers and the end users. A user without sufficient knowledge and experience should seek assistance from the equipment makers or other expert sources, such as those found at the National Institute of Standards and Technology in Gaithersburg, Maryland.
4.3 These test methods should be used with the awareness that there are other parameters, particularly spectral range limits and temperature resolution, which impact the use and characterization of radiation thermometers and for which test methods have not yet been developed.
4.3.1 Temperature resolution is the minimum simulated or actual change in target temperature that results in a usable change in output or indication, or both. It is usually expressed as a temperature differential or a percent of full-scale value, or both, and usually applies to value measured. The magnitude of the temperature resolution depends upon a combination of four factors: detector noise equivalent temperature difference (NETD), electronic signal processing, signal-to-noise characteristics (including amplification noise), and analog-to-digital conversion “granularity.”
4.3.2 Spectral range limits are the upper and lower limits to the wavelength band of radiant energy to which the instrument responds. These limits are generally expressed in micrometers (μm) and include the effects of all elements in the measuring optical pat...
SCOPE
1.1 The test methods described in these test methods can be utilized to evaluate the following six basic operational parameters of a radiation thermometer (single waveband type):
Section
Calibration Accuracy
8
Repeatability
9
Field-of-View
10
Response Time
11
Warm-Up Time
12
Long-Term Stability
13
1.2 The term single waveband refers to radiation thermometers that operate in a single band of spectral radiation. This term is used to differentiate single waveband radiation thermometers from those termed as ratio radiation thermometers, two channel radiation thermometers, two color radiation thermometers, multiwavelength radiation thermometers, multichannel radiation thermometers, or multicolor radiation thermometers. The term single waveband does not preclude wideband radiation thermometers such as those operating in the 8–14 μm band.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E1256 − 17 (Reapproved 2022)
Standard Test Methods for
Radiation Thermometers (Single Waveband Type)
This standard is issued under the fixed designation E1256; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 IEC Documents
IEC/TS 62492-1 ed 1.0 TS Industrial Process Control
1.1 The test methods described in these test methods can be
Devices—Radiation Thermometers—Part 1: Technical
utilized to evaluate the following six basic operational param-
Data for Radiation Thermometers
eters of a radiation thermometer (single waveband type):
Section
3. Terminology
Calibration Accuracy 8
Repeatability 9
3.1 Definitions:
Field-of-View 10
3.1.1 blackbody, n—the perfect or ideal source of thermal
Response Time 11
Warm-Up Time 12
radiant power having a spectral distribution described by the
Long-Term Stability 13
Planck equation.
3.1.1.1 Discussion—The term blackbody is often used to
1.2 The term single waveband refers to radiation thermom-
describe a furnace or other source of radiant power which
eters that operate in a single band of spectral radiation. This
approximates the ideal.
term is used to differentiate single waveband radiation ther-
3.1.2 center wavelength, n—a wavelength, usually near the
mometers from those termed as ratio radiation thermometers,
middle of the band of radiant power over which a radiation
two channel radiation thermometers, two color radiation
thermometer responds, that is used to characterize its perfor-
thermometers, multiwavelength radiation thermometers, mul-
mance.
tichannel radiation thermometers, or multicolor radiation ther-
3.1.2.1 Discussion—The value of the center wavelength is
mometers. The term single waveband does not preclude
usually specified by the manufacturer of the instrument.
wideband radiation thermometers such as those operating in
3.1.3 field-of-view, n—a usually circular, flat surface of a
the 8–14 µm band.
measured object from which the radiation thermometer re-
1.3 This standard does not purport to address all of the
ceives radiation.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
NOTE 1—Field-of-view traditionally has been referred to as target size.
priate safety, health, and environmental practices and deter-
3.1.4 measuring distance, n—distance or distance range
mine the applicability of regulatory limitations prior to use.
between the radiation thermometer and the target (measured
1.4 This international standard was developed in accor-
object) for which the radiation thermometer is designed.
dance with internationally recognized principles on standard-
NOTE2—Measuring distancetraditionallyhasbeenreferredtoas target
ization established in the Decision on Principles for the
distance.
Development of International Standards, Guides and Recom-
3.1.5 radiation thermometer, n—a radiometer calibrated to
mendations issued by the World Trade Organization Technical
indicate the temperature of a blackbody.
Barriers to Trade (TBT) Committee.
3.1.6 radiometer, n—a device for measuring radiant power
2. Referenced Documents
that has an output proportional to the intensity of the input
power.
2.1 ASTM Standards:
E2758Guide for Selection and Use of Wideband, Low 3.1.7 target distance, n—see measuring distance.
Temperature Infrared Thermometers
3.1.8 target plane, n—the plane, perpendicular to the line of
sight of a radiation thermometer, that is in focus for that
instrument.
These test methods are under the jurisdiction of ASTM Committee E20 on
3.1.9 target size, n—see field-of-view.
TemperatureMeasurementandarethedirectresponsibilityofSubcommitteeE20.02
on Radiation Thermometry.
Current edition approved May 1, 2022. Published May 2022. Originally
approved in 1988. Last previous edition approved in 2017 as E1256–17. DOI:
10.1520/E1256-17R22. IEC 62492-1.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1256 − 17 (2022)
3.2 Definitions of Terms Specific to This Standard:
3.2.1 reference temperature source, n—a source of thermal
radiant power of known temperature or emissivity, or both,
used in the testing of radiation thermometers.
3.2.2 temperature resolution, n—the minimum simulated or
actual change in target temperature that gives a usable change
in output or indication, or both.
4. Significance and Use
4.1 The purpose of these test methods is to establish
consensus test methods by which both manufacturers and end
usersmayperformteststoestablishthevalidityofthereadings
of their radiation thermometers. The test results can also serve
as standard performance criteria for instrument evaluation or
selection, or both.
FIG. 1 Spectral Range Limits
4.2 The goal is to provide test methods that are reliable and
can be performed by a sufficiently skilled end user or manu-
small relative to its length.
facturer. It is hoped that it will result in a better understanding
of the operation of radiation thermometers and also promote
5.1.2 Temperature Indicator—Either contact or radiometric,
improved communication between the manufacturers and the
which accurately displays the temperature of the reference
end users.Auser without sufficient knowledge and experience
temperature source.
should seek assistance from the equipment makers or other
5.1.3 Shutter Mechanism—Of sufficient size so as to com-
expert sources, such as those found at the National Institute of
pletely block the opening of the reference temperature source
Standards and Technology in Gaithersburg, Maryland.
from the field-of-view of the test instrument. The shutter
mechanism shall activate within a time interval that is short
4.3 These test methods should be used with the awareness
when compared with the response time of the test instrument.
that there are other parameters, particularly spectral range
5.1.4 Iris Diaphragm—Of sufficient size so that when fully
limits and temperature resolution, which impact the use and
open the iris diameter is greater than the opening of the
characterization of radiation thermometers and for which test
reference temperature source. It shall be located with its
methods have not yet been developed.
opening concentric with and perpendicular to the line of sight
4.3.1 Temperature resolution is the minimum simulated or
of the radiation thermometer.
actual change in target temperature that results in a usable
5.1.4.1 The side of the diaphragm facing the radiation
change in output or indication, or both. It is usually expressed
thermometer should be blackened (nearly nonreflective) so as
as a temperature differential or a percent of full-scale value, or
to minimize the effect of radiation reflected from the surround-
both, and usually applies to value measured.The magnitude of
ing environment. In addition the iris should be shaded from
thetemperatureresolutiondependsuponacombinationoffour
sources of intense extraneous radiation. (See Note 11.)
factors: detector noise equivalent temperature difference
5.1.5 Aperture Set—If an iris diaphragm is not available, an
(NETD), electronic signal processing, signal-to-noise charac-
aperture disc set of appropriate diameters can be used. Each
teristics (including amplification noise), and analog-to-digital
aperture should be blackened and also mounted and protected
conversion “granularity.”
from extraneous sources of radiation as discussed in 5.1.4.1.
4.3.2 Spectral range limits are the upper and lower limits to
5.1.6 Data Acquisition Systems—Of appropriate speed and
the wavelength band of radiant energy to which the instrument
storage capacity to measure and record the output signal of the
responds. These limits are generally expressed in micrometers
radiation thermometer in Section 10 (“Response Time Test
(µm) and include the effects of all elements in the measuring
Method”).
opticalpath.Atthespectralresponselimits,thetransmissionof
5.1.7 Power Supply—Capable of supplying the proper volt-
the measuring optics is 5% of peak transmission. (See Fig. 1.)
age and frequency, if necessary, to the radiation thermometer.
5. Apparatus
6. Calibration Accuracy Test Method
5.1 The following apparatus, set up as illustrated in Fig. 2, 6.1 Summary—Thistestmethodoutlinestheproceduretobe
canbeusedtoperformthestandardtestsforallsixparameters.
used to evaluate the maximum deviation between the tempera-
ture indicated by the radiation thermometer and the known
5.1.1 Reference Temperature Source—A blackbody (or
other stable isothermal radiant source of high and known temperature of a reference temperature source, including the
uncertainty of the reference temperature source relative to the
emissivity) with an opening diameter at least as large as that
current International Temperature Scale.
specified in these test methods.
NOTE 3—Typical examples include nearly isothermal furnaces with
internal geometries, such as a sphere with an opening small relative to its DeWitt, D. P., and Nutter, G. D., eds., “Theory and Practice of Radiation
radius, or a right circular cylinder with one end closed having a radius Thermometry,” John Wiley and Sons, New York, NY.
E1256 − 17 (2022)
FIG. 2 Test Method Apparatus
NOTE 4—The calibration accuracy is generally expressed as a tempera-
6.2 Test Conditions:
ture difference or a percent of full-scale value, or both.
6.2.1 Rated supply voltage and frequency.
NOTE 5—The value applies across the entire measurement range.
6.2.2 Prescribed warm-up period.
NOTE 6—If the reference temperature source is measured with other
6.2.3 After execution of internal standardization check (if
than a calibrated reference or secondary standard radiation thermometer,
available).
then the emissivity of the source enters into the calibration of the test
radiation thermometer.
6.2.4 Emissivity compensation set to one (1).
6.2.5 Minimumopeningofthereferencetemperaturesource
7. Procedure
shall not obstruct the field-of-view of the radiation thermom-
7.1 Detailed directions for evaluation of each parameter
eter with the test aperture as specified by the manufacturer.
listed in 1.1 are included in each parameter test method.
6.2.6 Laboratory ambient temperature range of 20 °C to
25°C.
7.2 Each parameter test method is organized by: parameter
6.2.7 The manufacturer shall specify any special conditions
term, summary, test conditions, test method, test result, and
such as atmospheric absorption effects, measuring distance,
applicable notes.
and so forth.
6.2.8 The manufacturer shall specify the output for deter- 8. Repeatability Test Method
mining the indicated temperature.
8.1 Summary—Thistestmethodoutlinestheproceduretobe
6.3 Test Method: used to evaluate the repeatability of the temperature indication
6.3.1 The radiation thermometer is sighted at the reference of a radiation thermometer for a number of consecutive
temperature source whose temperature is sequentially stabi- measurementsmadeunderthesameconditionsoveraspecified
lized at three calibration points distributed uniformly over the interval of time.
measurement range of the instrument.
8.2 Test Conditions:
6.3.2 The temperature of the reference temperature source
8.2.1 Rated supply of voltage and frequency.
andthetemperatureindicatedbytheradiationthermometerare
8.2.2 Prescribed warm-up period.
recorded, then the difference between the two values is
8.2.3 After execution of internal standardization check (if
calculated and recorded. (See Fig. 3.)
available).
6.3.3 The test sequence is repeated twice for the same three
8.2.4 Diameter of the reference temperature source opening
calibration points, and an average temperature difference is
shall be greater than the radiation thermometer field-of-view,
calculated and recorded for each calibration point.
as specified by the manufacturer.
6.4 Test Result—The value for the calibration accuracy of 8.2.5 Laboratory ambient temperature range of 20 °C to
the temperature indication of the radiation thermometer is 25°C.
taken to be the largest of the three average temperature 8.2.6 Emissivity compensation, if any, set to one (1).
differencesdeterminedin6.3.2plusorminustheuncertaintyof 8.2.7 The manufacturer shall specify any special conditions
the temperature of the reference temperature source relative to such as response time, atmospheric absorption effects, measur-
the current International Temperature Scale. ing distance, and so forth.
E1256 − 17 (2022)
FIG. 3 Worksheet for Calibration Accuracy Test Method
8.3 Test Method: 9. Field-of-View Test Method
8.3.1 Once a day for twelve consecutive working days, the
9.1 Summary—Thistestmethodoutlinestheproceduretobe
radiation thermometer is sighted at the reference temperature
used to evaluate the diameter of the circle located in the target
source whose temperature is stabilized at the approximate
plane of the reference temperature source, at a known distance
midpoint of the radiation thermometer calibration range.
along and perpendicular to a radiation thermometer’s line of
sight, and from which 99% of the radiant power received by
NOTE 7—The selected reference temperature source temperature shall
be reproduced for each of the twelve consecutive tests.
the radiation thermometer is collected. (See Figs. 3 and 4.)
8.3.2 The temperature of the reference temperature source
9.2 Test Conditions:
and the temperature(s) indicated by the radiation thermometer
9.2.1 Rated supply voltage and frequency.
during each day’s test are recorded.
9.2.2 Prescribed warm-up period.
8.3.3 The radiation thermometer shall be switched off after
9.2.3 After execution of internal standardization check (if
each series of measurements.
applicable).
9.2.4 Laboratory ambient temperature range of 20 °C to
8.4 Test Result—The value for the repeatability of the
25°C.
readings of the radiation thermometer is taken to be the
9.2.5 Minimumopeningofthereferencetemperaturesource
standard deviation of the twelve recorded readings.
shall be large enough so as to not obstruct the optical path of
N 2
the radiation thermometer, as specified by the manufacturer,
X
S D
N N i
(
2 i51
whenitissightedthroughanaperturethatistwicethediameter
¯ 2
~X 2 X! X 2
( i ( i
N
i51 i51 of the instrument’s field-of-view at the plane of the aperture.
!
S.D. 5 5
!
N 2 1 N 2 1
NOTE 10—Some radiation thermometers ha
...
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