ASTM G183-05(2010)
(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(Reapproved 2010)
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 ering Tests of Nonmetallic Materials
2.2 ISO Standards:
1.1 This practice describes deployment conditions, mainte-
ISO 877 Plastics—Methods of Exposure to Direct
nance requirements, verification procedures and calibration
Weathering, Indirect Weathering Using Glass-Filtered
frequencies for use of pyranometers, pyrheliometers and UV
Daylight and Indirect Weathering by Daylight Using
radiometers in outdoor testing environments.This practice also
Fresnel Mirrors
discusses the conditions that dictate the level of accuracy
ISO 9060 Solar Energy—Specification and Classification of
required for instruments of different classes.
Instruments for Measuring Hemispherical Solar and Di-
1.2 While both pyranometers and UV radiometers may be
rect Solar Radiation
employed indoors to measure light radiation sources, the
ISO 9370 Plastics—Instrumental Determination of Radiant
measurement of ultraviolet and light radiation in accelerated
Exposure in Weathering Tests—General Guidance
weathering enclosures using manufactured light sources gen-
ISO TR 9901 Solar Energy—Field Pyranometers—
erally requires specialized radiometric instruments. Use of
Recommended Practice for Use
radiometric instrumentation to measure laboratory light
2.3 Other Reference:
sources is covered in ISO 9370.
World Meteorological Organization (WMO), 1983 “Mea-
NOTE 1—An ASTM standard that is similar to ISO 9370 is under
development and deals with the instrumental determination of irradiance surement of Radiation,” Guide to Meteorological Instru-
and radiant exposure in weathering tests.
ments and Methods of Observation,fifthed.,WMO-No.8,
Geneva
1.3 The characterization of radiometers is outside the scope
of the activities required of users of radiometers, as contem-
3. Terminology
plated by this standard.
3.1 Definitions—The definitions given in Terminologies
2. Referenced Documents
E772 and G113 are applicable to this practice.
2.1 ASTM Standards:
4. Radiometer Selection
E772 Terminology of Solar Energy Conversion
G7 Practice for Atmospheric Environmental Exposure Test- 4.1 Criteria for the Selection of Radiometers:
ing of Nonmetallic Materials
4.1.1 There are several criteria that need to be considered
G24 Practice for Conducting Exposures to Daylight Filtered for selection of the radiometer that will be used:
Through Glass
4.1.1.1 Function specific criteria, such as whether a
G90 Practice for Performing Accelerated Outdoor Weather- pyranometer, pyrheliometer or UV radiometer is required,
ing of Nonmetallic Materials Using Concentrated Natural
4.1.1.2 Task specific criteria, such as the accuracy require-
Sunlight ments for the selected incident angle and temperature ranges,
G113 Terminology Relating to Natural andArtificial Weath-
and maximum response time,
4.1.1.3 Operational criteria, such as dimensions, weight,
stability and maintenance, and
This practice is under the jurisdiction ofASTM Committee G03 on Weathering 4.1.1.4 Economiccriteria,suchaswhennetworkshavetobe
and Durability and is the direct responsibility of Subcommittee G03.09 on
equipped, or whether the instrument is being acquired for
Radiometry.
internal reference purposes, or for research purposes, etc.
Current edition approved Dec. 1, 2010. Published December 2010. Originally
approved in 2005. Last previous edition approved in 2005 as G183 – 05. DOI:
4.2 Selection Related to Radiometer Type:
10.1520/G0183-05R10.
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, http://www.ansi.org.
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G183 − 05 (2010)
4.2.1 Pyranometers, which measure global solar irradiance 4.3.3 Iftheaccuracyofthehighestcategoryofinstrumentis
inthe300to2500nmwavelengthregion,arerequiredtoassess insufficient for the application contemplated, the following
thehemisphericalsolarirradianceonsurfacesoftestspecimens recommendations are given:
mounted on weathering test racks that are used by the outdoor
4.3.3.1 Hemispherical solar radiation may be measured by
weathering exposure community. Typically, pyranometers are
the simultaneous deployment of a pyrheliometer and a con-
required to measure the exposure levels specified in the
tinuously shaded secondary standard pyranometer to achieve
applicable ASTM and/or ISO outdoor weathering standards
accuracies that are greater than can be achieved by a secondary
such as those described in Practices G7, G24, G90, and ISO
standard pyranometer alone,
877.
4.3.3.2 Direct (beam) solar radiation may be measured
4.2.2 Pyrheliometers, which measure direct (or, beam) solar using an absolute cavity pyrheliometer employing electrical
irradiance in the 300 to 2500 nm wavelength region, are substitution of thermally absorbed radiation to achieve accu-
required to assess the solar irradiance reflected onto the target racies that are greater than can be achieved by a First-class
board by the mirrors of Fresnel Reflecting Concentrators used pyrheliometer, and
in outdoor accelerated tests specified by ASTM and ISO
4.3.3.3 Specific ultraviolet wavelength bands may be deter-
Standards described in Practice G90 and ISO 877.
mined by integration of the selected wavelength bands using a
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:
NOTE 2—Certain UVradiometers that are designated as total ultraviolet
5.1.1 When performing measurements in support of testing,
radiometers are advertised to measure over the total wavelength range
from the so called UV cutoff at approximately 300 nm to 385 or 400 nm, thetestobjectandthefieldradiometershallbeequallyexposed
but in fact measure mostly UV-A radiation by virtue of their very low
with respect to field of view, ground radiation and any stray
responsivity to wavelengths below 315 nm.
light that may be present. This means that the test surface and
4.2.3.2 Narrow-band UV radiometers are essentially con- the radiometer shall receive the same irradiance.
structed using interference filters that isolate narrow bands of 5.1.2 When used to determine the irradiance accumulated
radiation having FWHM values of 20 nm, or less; their center
on solar concentrating devices such as the Fresnel reflecting
wavelengths (CW) may reside anywhere in the UV spectrum concentrators used in the practice of Practice G90, and other
from280to400nmwavelength—dependingontheapplication
types of solar concentrators, it is essential that the collection
for which they are intended.
system of the solar concentrators, such as the flat mirrors used
in the practice of Practice G90, do not receive direct irradiance
NOTE 3—While the World Meteorological Organization (WMO) and
that is unavailable to the optical system that connotes the
the International Standards Organization (ISO) have established require-
pyrheliometer required.
ments for Secondary Standard and First-, Second- and Third-class
pyranometers and pyrheliometers, specifications and required operational
5.1.3 The need for easy access to the radiometer for
characteristics of different classes of ultraviolet radiometers have not been
maintenance operations shall be considered in selecting the
addressed by either organization.
installation site, mount, etc.
NOTE 4—First-class instruments are not necessary for all applications.
5.2 Electrical Installation:
4.3 Selection Related to Measuring Specifications:
5.2.1 The electrical cable employed shall be secured firmly
4.3.1 As a first step, all possible ranges of measuring
to the mounting stand to minimize the possibility of breakage
parameters such as temperature, irradiance levels, angles of
or intermittent disconnection in severe weather.
incidence, tilt angles, and station latitude, must be compiled.
5.2.2 Wherever possible, the electrical cable shall be pro-
4.3.2 Next, documentation must be compiled of available
tected and buried underground—particularly when recording
information about the technical characteristics, and the techni-
devices,controllers,orconvertersarelocatedatadistance.Use
cal and physical specifications of the relevant radiometers
of shielded cable is highly recommended. The cable, recorder
given by:
and other electronic devices, shall be connected by a very low
4.3.2.1 The WMO and ISO classification of pyranometers
resistance conductor to a common ground.
given in the WMO Guide, and in ISO 9060 and ISO 9370
5.2.3 Contact the manufacturer of the radiometer being
(which together define the specifications to be met by different
installed to establish the maximum allowable cable length
categories of pyranometers and pyrheliometers),
permissible for the instrument’s impedance so as to preclude
4.3.2.2 The data specification sheets obtained from the significant signal loss (see 5.4.5.2 for additional requirements).
manufacturer, and
5.2.4 When hard wiring electrical connections, all exposed
junctions shall be weatherproofed and protected from physical
4.3.2.3 Preferably, data on the technical characteristics and
damage.
performance obtained from independent sources such as inde-
pendent testing laboratories, research institutes and govern- 5.2.5 Establish and identify the polarity of all relevant
ment laboratories. connections prior to connecting to the recording device,
G183 − 05 (2010)
tion into the instrument case, or a defective O-ring associated with the
converters, or controllers. Make all connections in accordance
desiccant chamber.
with the manufacturer’s instructions.
5.3.3.2 Attention should be paid to the transmission and
5.3 Required Maintenance Activities:
amplification of signals. Perform both visual and electrical
5.3.1 Inspection:
checks of the cable and amplifier (when used). These inspec-
5.3.1.1 Whenever possible, inspect radiometers employed
tions shall also be performed when any component of a
in continuous operation at least once each day. Inspection and
measuring system has been replaced, or after any anomalies
maintenance activities of specific attributes described in the
have been detected in the data.
following sections should be carried out daily, monthly and
5.3.4 Quarterly Inspection and Maintenance:
yearly as indicated.
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
be followed with respect to ensuring the tightness of the cover,
windows, shall be inspected daily and cleaned at least once or cap).
each week or more often whenever dust or other deposits are
5.3.4.2 Verify that the responsivities of all radiometers have
visible. Cleaning shall occur by spraying with deionized water not changed to the extent that they are out of tolerance. This
and wiping dry with non-abrasive and lint-free cloth or tissue.
can be done by comparison to another radiometer that has the
Itisrecommendedthatthisinspectionandpossiblecleaningbe 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
present, remove the deposit very gently, initially with the performed), or, as will usually be the case, if the ratio of total
sparing use of a de-icing fluid, after which the window shall be solar UV irradiance to total solar irradiance has remained
wiped clean and dry. essentially the same for clear day solar noon conditions.
5.3.5 Semi-annual Inspection and Maintenance:
5.3.2.3 After heavy dew, rain, sleet, snow or frost buildup,
check to determine if condensation is present inside the dome, 5.3.5.1 Use an inclinometer to determine the inclination of
all radiometers mounted at tilts from the horizontal. Inspect the
or on the receptor or diffuser surface. If condensation is
discovered inside the dome, on the receptor or diffuser surface inclination angles of all pyranometers and UV-radiometers
including the spirit level of all horizontally mounted radiom-
of domed radiometers, the instrument’s manufacturer shall be
contacted to determine a course of action. eters.
5.3.6 Yearly Inspection and Maintenance:
NOTE6—Theusermayattemptto“dryout”theradiometerbyelevating
5.3.6.1 When calibration schedules do not require annual re
its temperature, either in natural sunlight or in the laboratory, to 50°C. If
calibration,specialattentionshouldbepaidtothepossibilityof
the condensation is eliminated, the radiometer‘s calibration constant shall
drift in the sensitivity (that is, the calibration factor) of the
be checked prior to being returned to service.
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 deterg
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