ASTM_G_207_-_11.pdf

Designation:G20711Standard Test Method forIndoor Transfer of Calibration from Reference to FieldPyranometers1This standard is issued under the fixed designation G207;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONAccurate 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 tovarious climatic factors that characterize a test site,(2)the determination of solar irradiance andradiant exposure to ascertain the energy available to solar collection devices such as flat-platecollectors,and(3)the assessment of the irradiance and radiant exposure in various wavelength bandsfor meteorological,climatic and earth energy-budget purposes.The solar components of principalinterest include total solar radiant exposure(all wavelengths)and various ultraviolet components ofnatural sunlight that may be of interest,including both total and narrow-band ultraviolet radiantexposure.This test method for indoor transfer of calibration from reference to field instruments is onlyapplicable to pyranometers and radiometers whose field angles closely approach 180.instrumentswhich therefore may be said to measure hemispherical radiation,or all radiation incident on a flatsurface.Hemispherical radiation includes both the direct and sky(diffuse)geometrical components ofsunlight,while global solar irradiance refers only to hemispherical irradiance on a horizontal surfacesuch 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.Scope1.1 The method described in this standard applies to theindoor transfer of calibration from reference to field radiom-eters to be used for measuring and monitoring outdoor radiantexposure levels.1.2 This test method is applicable to field radiometersregardless of the radiation receptor employed,but is limited toradiometers having approximately 180(2 Steradian),fieldangles.1.3 The calibration covered by this test method employs theuse of artificial light sources(lamps).1.4 Calibrations of field radiometers are performed withsensors horizontal(at 0 tilt from the horizontal to the earth).The essential requirement is that the reference radiometer shallhave been calibrated at horizontal tilt as employed in thetransfer of calibration.1.5 The primary reference instrument shall not be used as afield instrument and its exposure to sunlight shall be limited tooutdoor calibration or intercomparisons.NOTE1At a laboratory where calibrations are performed regularly itis advisable to maintain a group of two or three reference radiometers thatare included in every calibration.These serve as controls to detect anyinstability or irregularity in the standard reference instrument.1.6 Reference standard instruments shall be stored in amanner as to not degrade their calibration.1.7 The method of calibration specified for total solarpyranometers shall be traceable to the World RadiometricReference(WRR)through the calibration methods of thereference standard instruments(Method G167 and Test MethodE816),and the method of calibration specified for narrow-andbroad-band ultraviolet radiometers shall be traceable to theNational Institute of Standards and Technology(NIST),orother internationally recognized national standards laboratories(Standard G138).1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1This test method is under the jurisdiction of ASTM Committee G03 onWeathering and Durability and is the direct responsibility of Subcommittee G03.09on Radiometry.Current edition approved July 1,2011.Published August 2011.DOI:10.1520/G020711Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.Referenced Documents2.1 ASTM Standards:2E772 Terminology of Solar Energy ConversionE816 Test Method for Calibration of Pyrheliometers byComparison to Reference PyrheliometersE824 Test Method for Transfer of Calibration From Refer-ence to Field RadiometersG113 Terminology Relating to Natural and Artificial Weath-ering Tests of Nonmetallic MaterialsG138 Test Method for Calibration of a SpectroradiometerUsing a Standard Source of IrradianceG167 Test Method for Calibration of a Pyranometer Using aPyrheliometer2.2 Other Standards:3ISO 9847 Solar Energy Calibration of Field Pyranometersby Comparison to a Reference Pyranometer3.Terminology3.1 Definitions:3.1.1 See Terminology E772 and G1