ASTM E824-10(2018)e1
(Test Method)Standard Test Method for Transfer of Calibration From Reference to Field Radiometers
Standard Test Method for Transfer of Calibration From Reference to Field Radiometers
SIGNIFICANCE AND USE
5.1 The methods described represent the preferable means for calibration of field radiometers employing standard reference radiometers. Other methods involve the employment of an optical bench and essentially a point source of artificial light. While these methods are useful for cosine and azimuth correction analyses, they suffer from foreground view factor and directionality problems. Transfer of calibration indoors using artificial sources is not covered by this test method.
5.2 Traceability of calibration of global pyranometers is accomplished when employing the method using a reference global pyranometer that has been calibrated, and is traceable to the World Radiometric Reference (WRR). For the purposes of this test method, traceability shall have been established if a parent instrument in the calibration chain participated in an International Pyrheliometric Comparison (IPC) conducted at the World Radiation Center (WRC) in Davos, Switzerland. Traceability of calibration of narrow- and broad-band radiometers is accomplished when employing the method using a reference ultraviolet radiometer that has been calibrated and is traceable to the National Institute of Standards and Technology (NIST), or other national standards organizations. See Zerlaut4 for a discussion of the WRR, the IPC's and their results.
5.2.1 The reference global pyranometer (for example, one measuring hemispherical solar radiation at all wavelengths) shall have been calibrated by the shading-disk or component summation method against one of the following instruments:
5.2.1.1 An absolute cavity pyrheliometer that participated in a WMO sanctioned IPC's (and therefore possesses a WRR reduction factor),
5.2.1.2 An absolute cavity radiometer that has been intercompared (in a local or regional comparison) with an absolute cavity pyrheliometer meeting the requirements given in 5.2.1.1.
5.2.1.3 A WMO First Class pyrheliometer that was calibrated by direct transfer from such an absolute cavi...
SCOPE
1.1 The method described in this standard applies to the transfer of calibration from reference to field radiometers to be used for measuring and monitoring outdoor radiant exposure levels. This standard has been harmonized with ISO 9847.
1.2 This test method is applicable to field radiometers regardless of the radiation receptor employed, but is limited to radiometers having approximately 180° (2π Steradian), field angles.
1.3 The calibration covered by this test method employs the use of natural sunshine as the source.
1.4 Calibrations of field radiometers may be performed at tilt as well as horizontal (at 0° from the horizontal to the earth). The essential requirement is that the reference radiometer shall have been calibrated at essentially the same tilt from horizontal as the tilt employed in the transfer of calibration.
1.5 The primary reference instrument shall not be used as a field instrument and its exposure to sunlight shall be limited to calibration or intercomparisons.
Note 1: At a laboratory where calibrations are performed regularly it is advisable to maintain a group of two or three reference radiometers that are included in every calibration. These serve as controls to detect any instability or irregularity in the standard reference instrument.
1.6 Reference standard instruments shall be stored in a manner as to not degrade their calibration.
1.7 The method of calibration specified for total solar pyranometers shall be traceable to the World Radiometric Reference (WRR) through the calibration methods of the reference standard instruments (Test Methods G167 and E816), and the method of calibration specified for narrow- and broad-band ultraviolet radiometers shall be traceable to the National Institute of Standards and Technology (NIST), or other internationally recognized national standards laboratories (Test Method G138).
1.8 This standard does not purport to address all of the saf...
General Information
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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.
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Designation: E824 − 10 (Reapproved 2018)
Standard Test Method for
Transfer of Calibration From Reference to Field
Radiometers
This standard is issued under the fixed designation E824; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial changes made to subsections 4.4 and 10.1.1 and the organization of Section 8.
INTRODUCTION
Accurate and precise measurements of total solar and solar ultraviolet irradiance are required in: (1)
the determination of the energy incident on surfaces and specimens during exposure outdoors to
various climatic factors that characterize a test site, (2) the determination of solar irradiance and
radiant exposure to ascertain the energy available to solar collection devices such as flat-plate
collectors, and (3) the assessment of the irradiance and radiant exposure in various wavelength bands
for meteorological, climatic and earth energy-budget purposes. The solar components of principal
interest include total solar radiant exposure (all wavelengths) and various ultraviolet components of
natural sunlight that may be of interest, including both total and narrow-band ultraviolet radiant
exposure.
This test method for transferring calibration from reference to field instruments is only applicable
to pyranometers and radiometers whose field angles closely approach 180° . instruments which
therefore may be said to measure hemispherical radiation, or all radiation incident on a flat surface.
Hemisphericalradiationincludesboththedirectandsky(diffuse)geometricalcomponentsofsunlight,
while global solar irradiance refers only to hemispherical irradiance on a horizontal surface such that
the field of view includes all of the hemispherical sky dome.
For the purposes of this test method, the terms pyranometer and radiometer are used interchange-
ably.
1. Scope The essential requirement is that the reference radiometer shall
havebeencalibratedatessentiallythesametiltfromhorizontal
1.1 The method described in this standard applies to the
as the tilt employed in the transfer of calibration.
transfer of calibration from reference to field radiometers to be
used for measuring and monitoring outdoor radiant exposure
1.5 The primary reference instrument shall not be used as a
levels. This standard has been harmonized with ISO 9847. field instrument and its exposure to sunlight shall be limited to
calibration or intercomparisons.
1.2 This test method is applicable to field radiometers
NOTE 1—At a laboratory where calibrations are performed regularly it
regardless of the radiation receptor employed, but is limited to
is advisable to maintain a group of two or three reference radiometers that
radiometers having approximately 180° (2π Steradian), field
are included in every calibration. These serve as controls to detect any
angles.
instability or irregularity in the standard reference instrument.
1.3 The calibration covered by this test method employs the
1.6 Reference standard instruments shall be stored in a
use of natural sunshine as the source.
manner as to not degrade their calibration.
1.4 Calibrations of field radiometers may be performed at
1.7 The method of calibration specified for total solar
tilt as well as horizontal (at 0° from the horizontal to the earth).
pyranometers shall be traceable to the World Radiometric
Reference (WRR) through the calibration methods of the
referencestandardinstruments(TestMethodsG167andE816),
and the method of calibration specified for narrow- and
This test method is under the jurisdiction of ASTM Committee G03 on
Weathering and Durability and is the direct responsibility of Subcommittee G03.09
broad-band ultraviolet radiometers shall be traceable to the
on Radiometry.
National Institute of Standards and Technology (NIST), or
Current edition approved April 15, 2018. Published June 2018. Originally
other internationally recognized national standards laboratories
approved in 1994. Last previous edition approved in 2010 as E824 – 10. DOI:
10.1520/E0824-10R18E01. (Test Method G138).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E824 − 10 (2018)
1.8 This standard does not purport to address all of the desired tilt angle; both instruments must be oriented at the tilt
safety concerns, if any, associated with its use. It is the angle and facing the equator.
responsibility of the user of this standard to establish appro-
4.4 The analog voltage signal reading from each radiometer
priate safety, health, and environmental practices and deter-
is measured, digitized, and stored using a calibrated data-
mine the applicability of regulatory limitations prior to use.
acquisitioninstrument,orsystem.Aminimumoffifteen10min
1.9 This international standard was developed in accor-
measurement sequences are obtained, each sequence compris-
dance with internationally recognized principles on standard-
ing a minimum of 21 instantaneous readings. It is preferable
ization established in the Decision on Principles for the
that a larger number of measurement sequences be performed
Development of International Standards, Guides and Recom-
over several days duration and that data be taken in early
mendations issued by the World Trade Organization Technical
morning or late afternoon, as well as near solar noon.
Barriers to Trade (TBT) Committee.
NOTE 3—Transfer of calibration to both total and narrow-band ultra-
violetradiometersmayrequirealargernumberofmeasurementsequences
2. Referenced Documents
in order to account for spectral changes due to changing air mass both
2.1 ASTM Standards:
early and late in the day, and to the loss of north-sky ultraviolet when
calibrating at tilts.
E772 Terminology of Solar Energy Conversion
E816 Test Method for Calibration of Pyrheliometers by
4.5 The data are mathematically ratioed, employing the
Comparison to Reference Pyrheliometers
instrument constant of the reference instrument to determine
G113 Terminology Relating to Natural andArtificial Weath-
the instrument constant of the radiometer being calibrated.The
ering Tests of Nonmetallic Materials
mean value and the standard deviation are determined.
G138 Test Method for Calibration of a Spectroradiometer
Using a Standard Source of Irradiance
5. Significance and Use
G167 Test Method for Calibration of a Pyranometer Using a
5.1 The methods described represent the preferable means
Pyrheliometer
for calibration of field radiometers employing standard refer-
2.2 Other Standard:
ence radiometers. Other methods involve the employment of
ISO 9847 Solar Energy—Calibration of Field Pyranometers
an optical bench and essentially a point source of artificial
by Comparison to a Reference Pyranometer
light. While these methods are useful for cosine and azimuth
correction analyses, they suffer from foreground view factor
3. Terminology
and directionality problems. Transfer of calibration indoors
3.1 Definitions:
using artificial sources is not covered by this test method.
3.1.1 See Terminologies E772 and G113 for terminology
5.2 Traceability of calibration of global pyranometers is
relating to this test method.
accomplished when employing the method using a reference
global pyranometer that has been calibrated, and is traceable to
4. Summary of Test Method
the World Radiometric Reference (WRR). For the purposes of
4.1 Mountthereferenceradiometer,orpyranometer,andthe
this test method, traceability shall have been established if a
field (or test) radiometers, or pyranometers, on a common
parent instrument in the calibration chain participated in an
calibration table for horizontal calibration (Type A), on a tilted
International Pyrheliometric Comparison (IPC) conducted at
platform for calibration at tilt (Type B), or on an altazimuth or
the World Radiation Center (WRC) in Davos, Switzerland.
sun-pointing mount for normal-incidence calibration (Type C).
Traceability of calibration of narrow- and broad-band radiom-
Adjust the height of the photoreceptor, or radiation receptor, of
eters is accomplished when employing the method using a
all instruments to a common elevation.
reference ultraviolet radiometer that has been calibrated and is
4.2 Ensure that the pyranometer’s, or radiometer’s, azimuth traceable to the National Institute of Standards andTechnology
(NIST), or other national standards organizations. See Zerlaut
reference marks point in a common direction.
NOTE 2—Current convention is to use the electrical connector as the
for a discussion of the WRR, the IPC’s and their results.
azimuth reference and to point it towards the equator and downward. The
5.2.1 The reference global pyranometer (for example, one
reasons are (1) this convention diminishes the possibility of moisture
measuring hemispherical solar radiation at all wavelengths)
intrusion into the connector, and (2) it ensures that instruments with
shall have been calibrated by the shading-disk or component
disparities in the hemispherical domes, or with domes not properly
summation method against one of the following instruments:
centered over the receptor, are not operated in such a manner that they
amplify deviations from the cosine law.
5.2.1.1 Anabsolutecavitypyrheliometerthatparticipatedin
a WMO sanctioned IPC’s (and therefore possesses a WRR
4.3 For a transfer of calibration to a field instrument that
reduction factor),
will be used in a tilted position the following conditions must
5.2.1.2 An absolute cavity radiometer that has been inter-
be met:The reference instrument must have a calibration at the
compared (in a local or regional comparison) with an absolute
cavity pyrheliometer meeting the requirements given in
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.2.1.1.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St., Zerlaut, G. A., “Solar Radiation Instrumentation,” Chapter 5 in Solar
4th Floor, New York, NY 10036, http://www.ansi.org. Resources, The MIT Press, Cambridge, MA, 1989, pp. 173–308.
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E824 − 10 (2018)
5.2.1.3 A WMO First Class pyrheliometer that was cali- such as ground reflectance or shading, or both, must be
brated by direct transfer from such an absolute cavity. minimized and affect both instruments similarly.
5.2.2 Alternatively, the reference pyranometer may have
5.6 The reference radiometer must be of the same type as
been calibrated by direct transfer from a World Meteorological
the test radiometer, since any difference in spectral sensitivity
Organization (WMO) First Class pyranometer that was cali-
between instruments will result in erroneous calibrations. The
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brated by the shading-disk method against an absolute cavity
reader is referred to ISO TR 9673 and ISO TR 9901 for
pyrheliometer possessing a WRR reduction factor, or by direct
discussions of the types of instruments available and their use.
transfer from a WMO Standard Pyranometer (see WMO’s
Guide WMO—No. 8 for a discussion of the classification of
6. Interferences
solar radiometers).
6.1 In order to minimize systematic errors the reference and
test radiometers must be as nearly alike in all respects as
NOTE 4—Any of the absolute radiometers participating in the above
intercomparisons and being within 60.5 % of the mean of all similar
possible.
instruments compared in any of those intercomparisons, shall be consid-
6.1.1 The spectral response of both the reference and test
ered suitable as the primary reference instrument.
radiometers must be as nearly identical as possible.
5.2.3 The reference ultraviolet radiometer, regardless of
6.2 Sky Conditions—The measurements selected in deter-
whether it measures total ultraviolet solar radiation, or narrow-
mining the instrument constant shall be for periods of essen-
band UV-A or UV-B radiation, or a defined narrow band
tially uniform rates of change of radiation (either cloudless or
segment of ultraviolet radiation, shall have been calibrated by
overcast conditions). Periods selected shall be for 10 to 20 min
one of the following:
segments. Measurements selected under varying cloudy con-
5.2.3.1 By comparison to a standard source of spectral
ditions may result in erroneous calibrations if the reference and
irradiance that is traceable to NIST or to the appropriate
test radiometers possess significantly different response times
national standards organizations of other countries (using
(see also 5.6).
appropriate filter correction factors),
5.2.3.2 By comparison to the integrated spectral irradiance
7. Apparatus
in the appropriate wavelength band of a spectroradiometer that
7.1 Data Acquisition Instrument—A digital voltmeter or
has itself been calibrated against such a standard source of
data logger capable of repeatability to 0.1 % of average
spectral irradiance, and
reading, and an uncertainty of 60.2 % with an input imped-
5.2.3.3 By comparison to a spectroradiometer that has
ance of at least 1 MΩ may be employed. Data loggers having
participated in a regional or national Intercomparison of
printout must be capable of a measurement frequency of at
Spectroradiometers, the results of which are of reference
least two per minute. A data logger having three-channel
quality.
capacity may be useful.
NOTE 5—The calibration of reference ultraviolet radiometers using a
7.2 Fixed-Angle Calibration Table—A precision calibration
spectroradiometer, or by direct calibration against standard sources of
table required for all horizontal and fixed angle tilt tests that is
spectral irradiance (for example, deuterium or 1000 W tungsten-halogen
levelat0°horizontalandthatisadjustableintiltoverasuitable
lamps) is the subject of Test Method G138.
range of angles from the horizontal.
5.3 The calibration method employed assumes that the
7.3 Tracking Calibration Table—A precision calibration
accuracyofthevaluesobtainedareindependentoftimeofyear
table required for normal incident calibrations and capable of
within the constraints imposed by the test instrument’s tem-
tracking the sun to within 60.5°.
perature compensation (neglecting cosine errors). The method
permits the determination of possible tilt effects on the sensi-
8. Procedure
tivity of the test instrument’s light r
...
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