ASTM E824-94(2002)
(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
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 (Method E 913 and Test Method E 941), 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.
1.8 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E824–94 (Reapproved 2002)
Standard Test Method for
Transfer of Calibration From Reference to Field
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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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Accurateandprecisemeasurementsoftotalsolarandsolarultravioletirradiancearerequiredin:(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 havebeencalibratedatessentiallythesametiltfromhorizontal
as the tilt employed in the transfer of calibration.
1.1 The method described in this standard applies to the
1.5 The primary reference instrument shall not be used as a
transfer of calibration from reference to field radiometers to be
field instrument and its exposure to sunlight shall be limited to
used for measuring and monitoring outdoor radiant exposure
calibration or intercomparisons.
levels. This standard has been harmonized with ISO 9847.
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
are included in every calibration. These serve as controls to detect any
radiometers having approximately 180° (2p Steradian), field
instability or irregularity in the standard reference instrument.
angles.
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
tiltaswellashorizontal(at0°fromthehorizontaltotheearth).
pyranometers shall be traceable to the World Radiometric
The essential requirement is that the reference radiometer shall
Reference (WRR) through the calibration methods of the
reference standard instruments (Method E 913 and Test
Method E941), and the method of calibration specified for
narrow- and broad-band ultraviolet radiometers shall be trace-
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This test method is under the jurisdiction of ASTM Committee G3 on
able to the National Institute of Standards and Technology
DurabilityofNonmetallicMaterialsandisthedirectresponsibilityofSubcommittee
(NIST), or other internationally recognized national standards
G3.09 on Solar and Ultraviolet Radiation Measurement Standards.
Current edition approved May 15, 1994. Published July 1994. laboratories.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E824–94 (2002)
1.8 This standard does not purport to address all of the performed over several days duration and that data be taken in
safety concerns, if any, associated with its use. It is the early morning or late afternoon, as well as near solar noon.
responsibility of the user of this standard to establish appro-
NOTE 3—Transfer of calibration to both total and narrow-band ultra-
priate safety and health practices and determine the applica-
violetradiometersmayrequirealargernumberofmeasurementsequences
bility of regulatory limitations prior to use.
in order to account for spectral changes due to
...
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