ASTM G183-05
(Practice)Standard Practice for Field Use of Pyranometers, Pyrheliometers and UV Radiometers
Standard Practice for Field Use of Pyranometers, Pyrheliometers and UV Radiometers
SCOPE
1.1 This practice describes deployment conditions, maintenance requirements, verification procedures and calibration frequencies for use of pyranometers, pyrheliometers and UV radiometers in outdoor testing environments. This practice also discusses the conditions that dictate the level of accuracy required for instruments of different classes.
1.2 While both pyranometers and UV radiometers may be employed indoors to measure light radiation sources, the measurement of ultraviolet and light radiation in accelerated weathering enclosures using manufactured light sources generally requires specialized radiometric instruments. Use of radiometric instrumentation to measure laboratory light sources is covered in ISO 9370.Note 1
An ASTM standard that is similar to ISO 9370 is under development and deals with the instrumental determination of irradiance and radiant exposure in weathering tests.
1.3 The characterization of radiometers is outside the scope of the activities required of users of radiometers, as contemplated by this standard.
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Designation:G183–05
Standard Practice for
Field Use of Pyranometers, Pyrheliometers and UV
Radiometers
This standard is issued under the fixed designation G183; 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.
1. Scope ISO 877 Plastics—Methods of Exposure to Direct Weath-
ering, Indirect Weathering Using Glass-Filtered Daylight
1.1 This practice describes deployment conditions, mainte-
and Indirect Weathering by Daylight Using Fresnel Mir-
nance requirements, verification procedures and calibration
rors
frequencies for use of pyranometers, pyrheliometers and UV
ISO 9060 Solar Energy—Specification and Classification of
radiometers in outdoor testing environments.This practice also
Instruments for Measuring Hemispherical Solar and Di-
discusses the conditions that dictate the level of accuracy
rect Solar Radiation
required for instruments of different classes.
ISO 9370 Plastics—Instrumental Determination of Radiant
1.2 While both pyranometers and UV radiometers may be
Exposure in Weathering Tests—General Guidance
employed indoors to measure light radiation sources, the
ISO TR 9901 Solar Energy—Field Pyranometers—
measurement of ultraviolet and light radiation in accelerated
Recommended Practice for Use
weathering enclosures using manufactured light sources gen-
2.3 Other Reference:
erally requires specialized radiometric instruments. Use of
World Meteorological Organization (WMO), 1983 “Mea-
radiometric instrumentation to measure laboratory light
surement of Radiation,” Guide to Meteorological Instru-
sources is covered in ISO 9370.
ments and Methods of Observation,fifthed.,WMO-No.8,
NOTE 1—An ASTM standard that is similar to ISO 9370 is under
Geneva
development and deals with the instrumental determination of irradiance
and radiant exposure in weathering tests.
3. Terminology
1.3 The characterization of radiometers is outside the scope
3.1 Definitions—The definitions given in Terminologies
of the activities required of users of radiometers, as contem-
E772 and G113 are applicable to this practice.
plated by this standard.
4. Radiometer Selection
2. Referenced Documents
4.1 Criteria for the Selection of Radiometers:
2.1 ASTM Standards:
4.1.1 There are several criteria that need to be considered
E772 Terminology Relating to Solar Energy Conversion
for selection of the radiometer that will be used:
G7 Practice forAtmospheric Environmental Exposure Test-
4.1.1.1 Function specific criteria, such as whether a pyra-
ing of Nonmetallic Materials
nometer, pyrheliometer or UV radiometer is required,
G24 PracticeforConductingExposurestoDaylightFiltered
4.1.1.2 Task specific criteria, such as the accuracy require-
Through Glass
ments for the selected incident angle and temperature ranges,
G90 Practice for PerformingAccelerated Outdoor Weather-
and maximum response time,
ing of Nonmetallic Materials Using Concentrated Natural
4.1.1.3 Operational criteria, such as dimensions, weight,
Sunlight
stability and maintenance, and
G113 TerminologyRelatingtoNaturalandArtificialWeath-
4.1.1.4 Economiccriteria,suchaswhennetworkshavetobe
ering Tests of Nonmetallic Materials
equipped, or whether the instrument is being acquired for
2.2 ISO Standards:
internal reference purposes, or for research purposes, etc.
4.2 Selection Related to Radiometer Type:
4.2.1 Pyranometers, which measure global solar irradiance
This practice is under the jurisdiction ofASTM Committee G03 onWeathering
in the 300 to 2500-nm wavelength region, are required to
and Durability and is the direct responsibility of Subcommittee G03.09 on
Radiometry. assess the hemispherical solar irradiance on surfaces of test
Current edition approved Feb. 1, 2005. Published March 2005. DOI: 10.1520/
specimens mounted on weathering test racks that are used by
G0183-05.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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 Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G183–05
the outdoor weathering exposure community. Typically, pyra- tinuously shaded secondary standard pyranometer to achieve
nometers are required to measure the exposure levels specified accuracies that are greater than can be achieved by a secondary
in the applicable ASTM and/or ISO outdoor weathering standard pyranometer alone,
standards such as those described in Practices G7, G24, G90, 4.3.3.2 Direct (beam) solar radiation may be measured
and ISO 877.
using an absolute cavity pyrheliometer employing electrical
4.2.2 Pyrheliometers, which measure direct (or, beam) solar substitution of thermally absorbed radiation to achieve accu-
irradiance in the 300 to 2500-nm wavelength region, are
racies that are greater than can be achieved by a First-class
required to assess the solar irradiance reflected onto the target pyrheliometer, and
board by the mirrors of Fresnel Reflecting Concentrators used
4.3.3.3 Specific ultraviolet wavelength bands may be deter-
in outdoor accelerated tests specified by ASTM and ISO mined by integration of the selected wavelength bands using a
Standards described in Practice G90 and ISO 877.
scanning spectroradiometer possessing good slit function and
4.2.3 Ultraviolet radiometers are either broad band or nar- narrow band pass characteristics to achieve accuracies that are
row band instruments covering defined wavelength regions of
greater than the most accurate narrow or broad band ultraviolet
the solar ultraviolet spectrum. radiometers currently commercially available.
4.2.3.1 Broad-band UV radiometers usually are designed to
measure either UV-A, UV-B or some component of both UV-A
5. Practice for Use—General
and UV-B radiation.
5.1 Installation of Radiometers:
5.1.1 When performing measurements in support of testing,
NOTE 2—CertainUVradiometersthataredesignatedastotalultraviolet
radiometers are advertised to measure over the total wavelength range
thetestobjectandthefieldradiometershallbeequallyexposed
from the so called UV cutoff at approximately 300 nm to 385 or 400 nm,
with respect to field of view, ground radiation and any stray
but in fact measure mostly UV-A radiation by virtue of their very low
light that may be present. This means that the test surface and
responsivity to wavelengths below 315 nm.
the radiometer shall receive the same irradiance.
4.2.3.2 Narrow-band UV radiometers are essentially con- 5.1.2 When used to determine the irradiance accumulated
structed using interference filters that isolate narrow bands of
on solar concentrating devices such as the Fresnel reflecting
radiation having FWHM values of 20 nm, or less; their center concentrators used in the practice of Practice G90, and other
wavelengths (CW) may reside anywhere in the UV spectrum
types of solar concentrators, it is essential that the collection
from280to400nmwavelength—dependingontheapplication system of the solar concentrators, such as the flat mirrors used
for which they are intended.
in the practice of Practice G90, do not receive direct irradiance
that is unavailable to the optical system that connotes the
NOTE 3—While the World Meteorological Organization (WMO) and
pyrheliometer required.
the International Standards Organization (ISO) have established require-
5.1.3 The need for easy access to the radiometer for
ments for Secondary Standard and First-, Second- and Third-class
pyranometers and pyrheliometers, specifications and required operational maintenance operations shall be considered in selecting the
characteristics of different classes of ultraviolet radiometers have not been
installation site, mount, etc.
addressed by either organization.
5.2 Electrical Installation:
NOTE 4—First-class instruments are not necessary for all applications.
5.2.1 The electrical cable employed shall be secured firmly
to the mounting stand to minimize the possibility of breakage
4.3 Selection Related to Measuring Specifications:
or intermittent disconnection in severe weather.
4.3.1 As a first step, all possible ranges of measuring
5.2.2 Wherever possible, the electrical cable shall be pro-
parameters such as temperature, irradiance levels, angles of
tected and buried underground—particularly when recording
incidence, tilt angles, and station latitude, must be compiled.
devices,controllers,orconvertersarelocatedatadistance.Use
4.3.2 Next, documentation must be compiled of available
of shielded cable is highly recommended. The cable, recorder
information about the technical characteristics, and the techni-
and other electronic devices, shall be connected by a very low
cal and physical specifications of the relevant radiometers
resistance conductor to a common ground.
given by:
5.2.3 Contact the manufacturer of the radiometer being
4.3.2.1 The WMO and ISO classification of pyranometers
installed to establish the maximum allowable cable length
given in the WMO Guide, and in ISO 9060 and ISO 9370
permissible for the instrument’s impedance so as to preclude
(which together define the specifications to be met by different
significant signal loss (see 5.4.5.2 for additional requirements).
categories of pyranometers and pyrheliometers),
5.2.4 When hard wiring electrical connections, all exposed
4.3.2.2 The data specification sheets obtained from the
junctions shall be weatherproofed and protected from physical
manufacturer, and
damage.
4.3.2.3 Preferably, data on the technical characteristics and
5.2.5 Establish and identify the polarity of all relevant
performance obtained from independent sources such as inde-
connections prior to connecting to the recording device,
pendent testing laboratories, research institutes and govern-
converters, or controllers. Make all connections in accordance
ment laboratories.
with the manufacturer’s instructions.
4.3.3 If the accuracy of the highest category of instrument is
insufficient for the application contemplated, the following 5.3 Required Maintenance Activities:
recommendations are given: 5.3.1 Inspection:
4.3.3.1 Hemispherical solar radiation may be measured by 5.3.1.1 Whenever possible, inspect radiometers employed
the simultaneous deployment of a pyrheliometer and a con- in continuous operation at least once each day. Inspection and
G183–05
maintenance activities of specific attributes described in the measuring system has been replaced, or after any anomalies
following sections should be carried out daily, monthly and have been detected in the data.
yearly as indicated. 5.3.4 Quarterly Inspection and Maintenance:
5.3.4.1 In those radiometers where the desiccant is not
NOTE 5—It should be noted that the quality of data obtained using total
visible, remove the desiccant cover and inspect the desiccant
solar and solar ultraviolet radiometers depends strongly on the amount of
fordryness.Ifmoistureisindicated,replacethedesiccant.Care
personal attention given during the observation program.
should be exercised to ensure that the desiccant container’s
5.3.2 Daily Routine Inspection and Maintenance:
cover is closed completely (manufacturer’s instructions should
5.3.2.1 The exterior glass domes and/or diffusers or win-
be followed with respect to ensuring the tightness of the cover,
dows, shall be inspected daily and cleaned at least once each
or cap).
weekormoreoftenwheneverdustorotherdepositsarevisible.
5.3.4.2 Verify that the responsivities of all radiometers have
Cleaning shall occur by spraying with deionized water and
not changed to the extent that they are out of tolerance. This
wiping dry with non-abrasive and lint-free cloth or tissue. It is
can be done by comparison to another radiometer that has the
recommended that this inspection and possible cleaning be 4
same spectral response function or by determination that the
performed early each day.
ratio of, for example, UV-B to UV-A irradiance has remained
5.3.2.2 If frozen snow, glazed frost, hoar frost or rime is
essentially the same (if both measurements are being per-
present, remove the deposit very gently, initially with the
formed),or,aswillusuallybethecase,iftheratiooftotalsolar
sparing use of a de-icing fluid, after which the window shall be
UVirradiance to total solar irradiance has remained essentially
wiped clean and dry.
the same for clear day solar noon conditions.
5.3.2.3 After heavy dew, rain, sleet, snow or frost buildup,
5.3.5 Semi-annual Inspection and Maintenance:
check to determine if condensation is present inside the dome, 5
5.3.5.1 Use an inclinometer to determine the inclination of
or on the receptor or diffuser surface. If condensation is
all radiometers mounted at tilts from the horizontal. Inspect the
discovered inside the dome, on the receptor or diffuser surface
inclination angles of all pyranometers and UV-radiometers
of domed radiometers, the instrument’s manufacturer shall be
including the spirit level of all horizontally mounted radiom-
contacted to determine a course of action.
eters.
5.3.6 Yearly Inspection and Maintenance:
NOTE 6—Theusermayattemptto“dryout”theradiometerbyelevating
its temperature, either in natural sunlight or in the laboratory, to 50°C. If 5.3.6.1 When calibration schedules do not require annual re
the condensation is eliminated, the radiometer‘s calibration constant shall
calibration,specialattentionshouldbepaidtothepossibilityof
be checked prior to being returned to service.
drift in the sensitivity (that is, the calibration factor) of the
radiometer. This shall be accomplished by use of either a field
5.3.2.4 When hard-to-remove deposits of air pollution or
re calibrator (in the case of certain UV-A and UV-B radiom-
local contamination is observed on a radiometer’s exterior
eters) or a field reference radiometer maintained by the
window, first apply deionized or distilled water on the surface.
testing/measuring facility for that purpose.
If the use of a detergent solution is indicated, a prepare a 2 %
5.3.6.2 Inspect all radiometers for general deterioration of
solution of a mild dish washing detergent and gently apply to
the instrument—including domes and windows (to detect
the surface. Use a soft, lint-free muslin cloth to gently rub the
chips, cracks, or the development of any optical disparity), the
surface if required. In either case, thoroughly rinse the surface
receiver coating (to detect discolora
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