ASTM E782-95(2015)

Standard Practice for Exposure of Cover Materials for Solar Collectors to Natural Weathering Under Conditions Simulating Operational Mode

SIGNIFICANCE AND USE
3.1 This practice describes a weathering box test fixture and provides uniform exposure guidelines to minimize the variables encountered during outdoor exposure testing.  
3.2 This practice may be useful in comparing the performance of different materials at one site or the performance of the same material at different sites, or both.  
3.3 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade more rapidly than either alone, a weathering box that elevates the temperature of the cover materials is used.  
3.4 This practice is intended to assist in the evaluation of solar collector cover materials in the operational, not stagnation mode. Insufficient data exist to obtain exact correlation between the behavior of materials exposed according to this practice and actual in-service performance.  
3.5 Means of evaluation of effects of weathering are provided in Practice E781, and in other ASTM test methods that evaluate material properties.  
3.6 Tests of the type described in this practice may be used to evaluate the stability of solar collector cover materials when exposed outdoors to the varied influences which comprise weather. Exposure conditions are complex and changeable. Important factors are solar radiation, temperature, moisture, time of year, presence of pollutants, etc. These factors vary from site to site and should be considered in selecting locations for exposure. Control samples must always be used in weathering tests for comparative analysis. Outdoor exposure for at least two years is required to make evident changes, such as surface degradation without the use of sophisticated analytical equipment.  
3.7 Temperature conditions attained with this box may not exactly duplicate those that occur under operational conditions with fluid flow. Dependent on environmental exposure conditions, the cover plate temperatures obtained with this box may be higher or lower than those obtained und...
SCOPE
1.1 This practice provides a procedure for the exposure of cover materials for flat-plate solar collectors to the natural weather environment at temperatures that are elevated to approximate operating conditions.  
1.2 This practice is suitable for exposure of both glass and plastic solar collector cover materials. Provisions are made for exposure of single and double cover assemblies to accommodate the need for exposure of both inner and outer solar collector cover materials.  
1.3 This practice does not apply to cover materials for evacuated collectors or photovoltaics.  
1.4 The values stated in SI units are to be regarded as the standard.  
1.5 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.

General Information

• Status: Historical
• Publication Date: 28-Feb-2015
• ICS: 27.160 - Solar energy engineering
• Technical Committee: E44 - Solar, Geothermal and Other Alternative Energy Sources
• Drafting Committee: E44.20 - Optical Materials for Solar Applications

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: E782 − 95 (Reapproved 2015)
Standard Practice for
Exposure of Cover Materials for Solar Collectors to Natural
Weathering Under Conditions Simulating Operational Mode
This standard is issued under the fixed designation E782; 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 E881 Practice for Exposure of Solar Collector Cover Mate-
rials to Natural Weathering Under Conditions Simulating
1.1 This practice provides a procedure for the exposure of
Stagnation Mode
cover materials for flat-plate solar collectors to the natural
G7 Practice for Natural Weathering of Materials
weather environment at temperatures that are elevated to
approximate operating conditions.
3. Significance and Use
1.2 This practice is suitable for exposure of both glass and
3.1 This practice describes a weathering box test fixture and
plastic solar collector cover materials. Provisions are made for
provides uniform exposure guidelines to minimize the vari-
exposure of single and double cover assemblies to accommo-
ables encountered during outdoor exposure testing.
date the need for exposure of both inner and outer solar
collector cover materials.
3.2 This practice may be useful in comparing the perfor-
mance of different materials at one site or the performance of
1.3 This practice does not apply to cover materials for
the same material at different sites, or both.
evacuated collectors or photovoltaics.
3.3 Since the combination of elevated temperature and solar
1.4 The values stated in SI units are to be regarded as the
radiation may cause some solar collector cover materials to
standard.
degrade more rapidly than either alone, a weathering box that
1.5 This standard does not purport to address all of the
elevates the temperature of the cover materials is used.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.4 This practice is intended to assist in the evaluation of
priate safety, health, and environmental practices and deter- solar collector cover materials in the operational, not stagna-
mine the applicability of regulatory limitations prior to use. tion mode. Insufficient data exist to obtain exact correlation
1.6 This international standard was developed in accor- between the behavior of materials exposed according to this
dance with internationally recognized principles on standard-
practice and actual in-service performance.
ization established in the Decision on Principles for the
3.5 Means of evaluation of effects of weathering are pro-
Development of International Standards, Guides and Recom-
vided in Practice E781, and in other ASTM test methods that
mendations issued by the World Trade Organization Technical
evaluate material properties.
Barriers to Trade (TBT) Committee.
3.6 Tests of the type described in this practice may be used
2. Referenced Documents to evaluate the stability of solar collector cover materials when
2 exposed outdoors to the varied influences which comprise
2.1 ASTM Standards:
weather. Exposure conditions are complex and changeable.
E781 Practice for Evaluating Absorptive Solar Receiver
Important factors are solar radiation, temperature, moisture,
Materials When Exposed to Conditions Simulating Stag-
time of year, presence of pollutants, etc. These factors vary
nation in Solar Collectors With Cover Plates
from site to site and should be considered in selecting locations
for exposure. Control samples must always be used in weath-
ering tests for comparative analysis. Outdoor exposure for at
These test methods are under the jurisdiction of ASTM Committee E44 on
least two years is required to make evident changes, such as
Solar, Geothermal and Other Alternative Energy Sources and is the direct respon-
sibility of Subcommittee E44.20 on Optical Materials for Solar Applications.
surface degradation without the use of sophisticated analytical
Current edition approved March 1, 2015. Published April 2015. Originally
equipment.
approved in 1981. Last previous edition approved in 2007 as E782 – 95 (2007).
DOI: 10.1520/E0782-95R15.
3.7 Temperature conditions attained with this box may not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
exactly duplicate those that occur under operational conditions
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
with fluid flow. Dependent on environmental exposure
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. conditions, the cover plate temperatures obtained with this box
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E782 − 95 (2015)
may be higher or lower than those obtained under operational
conditions. Additional testing under stagnation conditions,
although not covered by this practice should be conducted.
NOTE 1—Research has shown that exposure outdoors at sites having the
combination of high levels of humidity, solar energy, and ambient
temperature can cause more severe degradation of some polymeric cover
materials, (for example, microcracking and leaching of UV radiation
screening additives) than exposure in arid climates.
NOTE 2—Stagnation conditions are a normal occurrence for solar
collectors, for example, during operation when the storage is fully
charged; when the collectors are initially installed, before system start-up;
or when the system is shut down for maintenance or seasonal consider-
ations such as heating only systems in the summer.
4. Weathering Box Test Fixture
4.1 Weathering Box Test Fixture, consisting of a box, rails,
a box top, a glazing frame, and adhesive tapes. The weathering
box test fixture should be constructed in accordance with Figs.
1-5.
4.1.1 The box and box top should be made in metal that is
suitably resistant to corrosion encountered in the exposure
environment.Aweep hole should be drilled at the lower end of
the bottom of the box to provide drainage and to minimize
moisture accumulation.
NOTE 1—Make: 4 per box.
NOTE 2—Material: metal suitably corrosion-resistant for exposure. A
NOTE 3—The box top is intended to protect the edges of the test
typical material would be 24-gage galvanized steel.
specimen in contact with the box from reaching excessively high
NOTE 3—Dimension tolerance 61mm(6 ⁄16 in.).
temperatures, to minimize exposure of the adhesive to sunlight, and to
FIG. 2 Natural Weathering Box—Rolls
minimize moisture penetration into the exposure test fixture.
NOTE 1—Make: 1 per box.
NOTE 2—Material: metal suitably corrosion-resistant for exposure. A
typical material would be 24-gage galvanized steel.
NOTE 3—Top must fit over box with rails in plac
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E782 − 95 (Reapproved 2007) E782 − 95 (Reapproved 2015)
Standard Practice for
Exposure of Cover Materials for Solar Collectors to Natural
Weathering Under Conditions Simulating Operational Mode
This standard is issued under the fixed designation E782; 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
1.1 This practice provides a procedure for the exposure of cover materials for flat-plate solar collectors to the natural weather
environment at temperatures that are elevated to approximate operating conditions.
1.2 This practice is suitable for exposure of both glass and plastic solar collector cover materials. Provisions are made for
exposure of single and double cover assemblies to accommodate the need for exposure of both inner and outer solar collector cover
materials.
1.3 This practice does not apply to cover materials for evacuated collectors or photovoltaics.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
E781 Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar
Collectors With Cover Plates
E881 Practice for Exposure of Solar Collector Cover Materials to Natural Weathering Under Conditions Simulating Stagnation
Mode
G7 Practice for Atmospheric Environmental Exposure Testing of Nonmetallic Materials
3. Significance and Use
3.1 This practice describes a weathering box test fixture and provides uniform exposure guidelines to minimize the variables
encountered during outdoor exposure testing.
3.2 This practice may be useful in comparing the performance of different materials at one site or the performance of the same
material at different sites, or both.
3.3 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade
more rapidly than either alone, a weathering box that elevates the temperature of the cover materials is used.
3.4 This practice is intended to assist in the evaluation of solar collector cover materials in the operational, not stagnation mode.
Insufficient data exist to obtain exact correlation between the behavior of materials exposed according to this practice and actual
in-service performance.
3.5 Means of evaluation of effects of weathering are provided in Practice E781, and in other ASTM test methods that evaluate
material properties.
3.6 Tests of the type described in this practice may be used to evaluate the stability of solar collector cover materials when
exposed outdoors to the varied influences which comprise weather. Exposure conditions are complex and changeable. Important
These test methods are under the jurisdiction of ASTM Committee E44 on Solar, Geothermal and Other Alternative Energy Sources and is the direct responsibility of
Subcommittee E44.05 on Solar Heating and Cooling Systems and Materials.
Current edition approved March 1, 2007March 1, 2015. Published April 2007April 2015. Originally approved in 1981. Last previous edition approved in 20012007 as
E782 – 95 (2001).(2007). DOI: 10.1520/E0782-95R07.10.1520/E0782-95R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E782 − 95 (2015)
factors are solar radiation, temperature, moisture, time of year, presence of pollutants, etc. These factors vary from site to site and
should be considered in selecting locations for exposure. Control samples must always be used in weathering tests for comparative
analysis. Outdoor exposure for at least two years is required to make evident changes, such as surface degradation without the use
of sophisticated analytical equipment.
3.7 Temperature conditions attained with this box may not exactly duplicate those that occur under operational conditions with
fluid flow. Dependent on environmental exposure conditions, the cover plate temperatures obtained with this box may be higher
or lower than those obtained under operational conditions. Additional testing under stagnation conditions, although not covered
by this practice should be conducted.
NOTE 1—Research has shown that exposure outdoors at sites having the combination of high levels of humidity, solar energy, and ambient temperature
can cause more severe degradation of some polymeric cover materials, (for example, microcracking and leaching of UV radiation screening additives)
than exposure in arid climates.
NOTE 2—Stagnation conditions are a normal occurrence for solar collectors, for example, during operation when the storage is fully charged; when
the collectors are initially installed, before system start-up; or when the system is shut down for maintenance or seasonal considerations such as heating
only systems in the summer.
4. Weathering Box Test Fixture
4.1 Weathering Box Test Fixture, consisting of a box, rails, a box top, a glazing frame, and adhesive tapes. The weathering box
test fixture should be constructed in accordance with Figs. 1-5.
4.1.1 The box and box top should be made in metal that is suitably resistant to corrosion encountered in the exposure
environment. A weep hole should be drilled at the lower end of the bottom of the box to provide drainage and to minimize moisture
accumulation.
NOTE 3—The box top is intended to protect the edges of the test specimen in contact with the box from reaching excessively high temperatures, to
minimize exposure of the adhesive to sunlight, and to minimize moisture penetration into the exposure test fixture.
4.1.2 The box interior shall be a flat black nonselective coating having an absorptance of not less than 0.90 after exposure.
Organic absorber coatings should be heated in an oven at 150°C (302°F) for 24 h before the test fixture is asssembled.assembled.
This should minimize outgassing, which results from deterioration of the organic components exposed to elevated temperatures.
4.1.3 The adhesive tapes should be stable when exposed to moisture and elevated temperatures. They should be compatible with
the speci
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