ASTM G207-11
(Test Method)Standard Test Method for Indoor Transfer of Calibration from Reference to Field Pyranometers
Standard Test Method for Indoor Transfer of Calibration from Reference to Field Pyranometers
SIGNIFICANCE AND USE
The methods described represent a means for calibration of field radiometers employing standard reference radiometers indoors. Other methods involve the natural sunlight outdoors under clear skies, and various combinations of reference radiometers. Outdoor these methods are useful for cosine and azimuth correction analyses, but may suffer from a lack of available clear skies, foreground view factor and directionality problems. Outdoor transfer of calibrations is covered by standards , , and .
Several configurations of artificial sources are possible, including:
Point sources (lamps) at a distance, to which the sensors are exposed
Extended sources (banks of lamps, or lamp(s) behind diffusing or “homogenizing” screens) to which the sensors are exposed
Various configurations of enclosures (usually spherical or hemispherical) with the interior walls illuminated indirectly with lamps. The sensors are exposed to the radiation emanating from the enclosure walls.
Traceability of calibration for 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 can be traced to a reference pyrheliometer which has participated in an International Pyrheliometric Comparison (IPC) conducted at the World Radiation Center, (WRC), Davos, Switzerland.
The reference global pyranometer (for example, one measuring hemispherical solar radiation at all wavelengths) shall have been calibrated by the shading-disk, component summation, or outdoor comparison method against one of the following instruments:
An absolute cavity pyrheliometer that participated in a World Meteorological Organization (WMO) sanctioned IPC's (and therefore possesses a WRR reduction factor).
An absolute cavity radiometer that has been intercompared (in a local or regi...
SCOPE
1.1 The method described in this standard applies to the indoor transfer of calibration from reference to field radiometers to be used for measuring and monitoring outdoor radiant exposure levels.
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 artificial light sources (lamps).
1.4 Calibrations of field radiometers are performed with sensors horizontal (at 0° tilt from the horizontal to the earth). The essential requirement is that the reference radiometer shall have been calibrated at horizontal tilt as 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 outdoor 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 and Test Method ), 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 (Standard ).
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 t...
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G207 − 11
Standard Test Method for
Indoor Transfer of Calibration from Reference to Field
1
Pyranometers
This standard is issued under the fixed designation G207; 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.
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 indoor transfer of 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. Hemispherical radiation includes both the direct and sky (diffuse) geometrical components of
sunlight, while global solar irradiance refers only to hemispherical irradiance on a horizontal surface
such that the field of view includes the entire hemispherical sky dome.
For the purposes of this test method, the terms pyranometer and radiometer are used interchangeably.
1. Scope 1.5 The primary reference instrument shall not be used as a
field instrument and its exposure to sunlight shall be limited to
1.1 The method described in this standard applies to the
outdoor calibration or intercomparisons.
indoor transfer of calibration from reference to field radiom-
eters to be used for measuring and monitoring outdoor radiant
NOTE 1—At a laboratory where calibrations are performed regularly it
is advisable to maintain a group of two or three reference radiometers that
exposure levels.
are included in every calibration. These serve as controls to detect any
1.2 This test method is applicable to field radiometers
instability or irregularity in the standard reference instrument.
regardless of the radiation receptor employed, but is limited to
1.6 Reference standard instruments shall be stored in a
radiometers having approximately 180° (2π Steradian), field
manner as to not degrade their calibration.
angles.
1.7 The method of calibration specified for total solar
1.3 The calibration covered by this test method employs the
pyranometers shall be traceable to the World Radiometric
use of artificial light sources (lamps).
Reference (WRR) through the calibration methods of the
1.4 Calibrations of field radiometers are performed with
referencestandardinstruments(MethodG167andTestMethod
sensors horizontal (at 0° tilt from the horizontal to the earth).
E816), and the method of calibration specified for narrow- and
The essential requirement is that the reference radiometer shall
broad-band ultraviolet radiometers shall be traceable to the
have been calibrated at horizontal tilt as employed in the
National Institute of Standards and Technology (NIST), or
transfer of calibration.
other internationally recognized national standards laboratories
(Standard G138).
1.8 This standard does not purport to address all of the
1
This test method is under the jurisdiction of ASTM Committee G03 on
safety concerns, if any, associated with its use. It is the
Weathering and Durability and is the direct responsibility of Subcommittee G03.09
responsibility of the user of this standard to establish appro-
on Radiometry.
priate safety and health practices and determine the applica-
Current edition approved July 1, 2011. Published August 2011. DOI: 10.1520/
G0207–11 bility of regulatory limitations prior to use.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
G207 − 11
response (for example, black thermopile), or has been calibrated outdoors,
2. Referenced Documents
the difference between calibration and source spectral distributions is less
2
2.1 ASTM Standards:
important, however should be taken into consideration.
E772 Terminology of Solar Energy Conversion
4.5 Monitor the output signal of the referen
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.