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ASTM E822-92(2003)

(Practice)

Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls

Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls

SCOPE
1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays.
1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported.
1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice.
1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls.
1.5 The categories of solar collector cover plate materials to which this practice may be applied cover the range of:
1.5.1 Brittle sheet, such as glass,
1.5.2 Semirigid sheet, such as plastic, and
1.5.3 Flexible membrane, such as plastic film.
1.6 Solar collector cover materials should be tested as:
1.6.1 Part of an assembled collector (Type 1 specimen), or
1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen).
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 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
14-Sep-1992
ICS
27.160 - Solar energy engineering
Technical Committee
E44 - Solar, Geothermal and Other Alternative Energy Sources
Current Stage
Ref Project

Relations

Replaces
ASTM E822-92(1996) - Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls
Effective Date
15-Sep-1992
Replaced By
ASTM E822-92(2009) - Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls
Effective Date
01-Apr-2009
Referred By
ASTM E1038-10(2019) - Standard Test Method for Determining Resistance of Photovoltaic Modules to Hail by Impact with Propelled Ice Balls
Effective Date
15-Sep-1992

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ASTM E822-92(2003) - Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice BallsASTM E822-92(2003) - Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls
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ASTM E822-92(2003) - Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact With Propelled Ice Balls
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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:E822–92(Reapproved 2003)
Standard Practice for
Determining Resistance of Solar Collector Covers to Hail by
Impact With Propelled Ice Balls
This standard is issued under the fixed designation E822; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2. Significance and Use
1.1 This practice covers a procedure for determining the 2.1 In many geographic areas there is concern about the
abilityofcoverplatesforflat-platesolarcollectorstowithstand effect of falling hail upon solar collector covers. This practice
impact forces of falling hail. Propelled ice balls are used to maybeusedtodeterminetheabilityofflat-platesolarcollector
simulate falling hailstones. This practice is not intended to covers to withstand the impact forces of hailstones. In this
apply to photovoltaic cells or arrays. practice,theabilityofasolarcollectorcoverplatetowithstand
1.2 This practice defines two types of test specimens, hail impact is related to its tested ability to withstand impact
describes methods for mounting specimens, specifies impact from ice balls. The effects of the impact on the material are
locations on each test specimen, provides an equation for highly variable and dependent upon the material.
determiningthevelocityofanysizeiceball,providesamethod 2.2 This practice describes a standard procedure for mount-
for impacting the test specimens with ice balls, and specifies ingthetestspecimen,conductingtheimpacttest,andreporting
parameters that must be recorded and reported. the effects.
1.3 This practice does not establish pass or fail levels. The 2.2.1 The procedures for mounting cover plate materials
determination of acceptable or unacceptable levels of ice-ball and collectors are provided to ensure that they are tested in a
impact resistance is beyond the scope of this practice. configuration that relates to their use in a solar collector.
1.4 The size of ice ball to be used in conducting this test is 2.2.2 The corner locations of the four impacts are chosen to
not specified in this practice. This practice can be used with represent vulnerable sites on the cover plate. Impacts near
various sizes of ice balls. corner supports are more critical than impacts elsewhere. Only
1.5 Thecategoriesofsolarcollectorcoverplatematerialsto asingleimpactisspecifiedateachoftheimpactlocations.For
which this practice may be applied cover the range of: test control purposes, multiple impacts in a single location are
1.5.1 Brittle sheet, such as glass, not permitted because a subcritical impact may still cause
1.5.2 Semirigid sheet, such as plastic, and damage that would alter the response to subsequent impacts.
1.5.3 Flexible membrane, such as plastic film. 2.2.3 Resultant velocity is used to simulate the velocity that
1.6 Solar collector cover materials should be tested as: may be reached by hail accompanied by wind. The resultant
1.6.1 Part of an assembled collector (Type 1 specimen), or velocity used in this practice is determined by vector addition
1.6.2 Mounted on a separate test frame cover plate holder ofa20m/s(45mph)horizontalvelocitytotheverticalterminal
(Type 2 specimen). velocity.
1.7 The values stated in SI units are to be regarded as the 2.2.4 Iceballsareusedinthispracticetosimulatehailstones
standard. The values given in parentheses are for information because natural hailstones are not readily available to use, and
only. ice balls closely approximate hailstones. However, no direct
1.8 This standard does not purport to address all of the relationship has been established between the effect of impact
safety concerns, if any, associated with its use. It is the of ice balls and hailstones. Hailstones are highly variable in
responsibility of the user of this standard to establish appro- properties such as shape, density, and frangibility. These
priate safety and health practices and determine the applica- properties affect factors such as the kinetic energy delivered to
bility of regulatory limitations prior to use. the cover plate, the period during which energy is delivered,
and the area over which the energy is distributed. Ice balls,
withadensity,frangibility,andterminalvelocityneartherange
ofhailstones,arethenearesthailstoneapproximationknownat
These test methods are under the jurisdiction of ASTM Committee E44 on
Solar, Geothermal and Other Alternative Energy Sources and is the direct respon-
sibility of Subcommittee E44.05 on Solar Heating and Cooling Systems and
Materials.
Current edition approved March 10, 2003. Published June 1993. Originally Gokhale, N. R., Hailstorms and Hailstone Growth, State University of New
approved in 1981. Last previous edition approved in 1996 as E822–92(1996). York Press, Albany, NY, 1975.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E822–92 (2003)
this time. Perhaps the major difference between ice balls and
hailstones is that hailstones are much more variable than ice
balls. However, ice balls can be uniformly and repeatedly
manufactured to ensure a projectile with known properties.
2.2.5 A wide range of observable effects may be produced
by impacting the various types of cover plate materials. The
effects may vary from no effect to total destruction. Some
changes in the cover material may be visible when there is no
apparent functional impairment of the cover plate material.All
effectsofeachimpactmustbedescribedinthereportsothatan
estimate of their significance can be made.
2.3 Data generated using this practice may be used: (1)to
evaluate impact resistance of a single material or collector, (2)
to compare the impact resistance of several materials or
FIG. 1 Frame Dimensions and Location of Test Impact Points
collectors,(3)toprovideacommonbasisforselectionofcover
materials or collectors for use in various geographic areas, or
mounting a solar collector cover plate material (Type 2
(4) to evaluate changes in impact resistance due to environ-
specimen) set in the cover holder.
mental factors such as weather.
3.4 Cover Holder— A rigid edging frame (see Fig. 1 and
2.4 Thispracticedoesnotstatethesize(s)oficeball(s)tobe
Fig.2)designedtoholdanapproximately860by1930-mm(34
usedinmakingtheimpact.Eitherthepersonrequestingthetest
by 76-in.) cover plate.
or the person performing the test must determine ice ball size
to be used in the testing. Choice of ice ball size may relate to
NOTE 2—Hardwood, such as oak, birch, maple, or hickory, is manda-
the intent of the testing. tory if wood is used for the cover holder.
NOTE 3—Cornerstraps,asshowninFig.3andFig.4,havebeenfound
2.4.1 If the testing is being performed to evaluate impact
useful to ensure the cover holder is rigid.
resistance of a single material or collector, or several materials
orcollectors,itmaybedesirabletorepeatthetestusingseveral
3.5 Molds, for casting spherical crack-free ice balls of
sizesoficeballs.Inthis manner the different effectsofvarious
appropriate diameter.
sizes of ice balls may be determined.
NOTE 4—Molds made from room-temperature vulcanizing rubber and
2.4.2 The size and frequency of hail varies significantly
expanded polystyrene have been found suitable.
among various geographic areas. If testing is being performed
3.6 Freezer—Adevice controlled at−12 6 5°C (106 9°F)
toevaluatematerialsorcollectorsintendedforuseinaspecific
for making and storing ice balls.
geographicarea,theiceballsizeshouldcorrespondtothelevel
of hail impact resistance required for that area. Information on
4. Test Specimen
hail size and frequency may be available from local historical
4.1 Type 1—The test specimen shall consist of a complete
weather records or may be determined from the publications
glazing assembly or a complete solar collector panel with
listed in Appendix X1.
necessary mounting brackets or fixtures.
2.5 The hail impact resistance of materials may change as
4.2 Type 2—The test specimen shall consist of a section of
the materials are exposed to various environmental factors.
solar collector cover plate material mounted in the cover
This practice may be used to generate data to evaluate
holder.
degradation by comparison of hail impact resistance data
measured before and after exposure to such aging.
5. Mounting
5.1 Type 1—Position and support the test specimen on a
3. Apparatus
suitable test base using necessary mounting brackets or fix-
3.1 Launcher—A mechanism capable of propelling a se-
tures, or both. Do not obstruct the specified impact points by
lected ice ball at the corresponding resultant velocity. The
the mounting fixtures.
aimingaccuracyofthelaunchermustbesufficienttopropelthe
ice ball to strike the cover plate within 25 mm (61 in.) ofthe
specified impact points. See Fig. 1.
NOTE 1—A launcher that has proven suitable uses a compressed air
supply, an accumulator tank, a large-diameter quick-opening valve and
interchangeable barrels to accommodate the sizes of ice balls to be used.
Barrels should be made from materials with low thermal conductivity to
reducemeltingoftheiceball.Barrelsshouldbesizedsuchthattheiceball
remains intact during loading and launching.
3.2 Velocity Meter, for measuring the ice ball velocity with
an accuracy of 62.0%.
3.3 Test Base—A structurally rigid support for mounting a
complete solar collector panel (Type 1 specimen), or for FIG. 2 Cover Holder, Empty (Section A-A of Fig. 1)
E822–92 (2003)
on the side opposite the impact surface to permit unobstructed
deflection of the cover material.
5.2.1 Lay brittle sheet cover materials, approximately 860
by 1930 mm (34 by 76 in.), on the elastomeric gasket (TypeA
durometer rating 30 to 50) of one member of the cover holder.
Put the shim in place. Lay the other member of the cover
holder on top. Tighten the bolts or C-clamp screws until the
elastomericgasketsarecompressedandtheshimisfirmlyheld,
asshownin
Fig.5.(Note5).Mountthespecimenfirmlyonthe
test base for testing.
NOTE 5—If the cover plate material will be damaged by the procedure
NOTE 1—Slotcornerasindicatedtofitsteelcornerstraps.Strapsshould
specified herein, the bolts or C-clamp screws should be tightened
be flush with surface.
sufficiently to hold the specimen in the frame, but not tightened to the
FIG. 3 Slots for Corner Straps of Cover Holder
extent that permanent deformations are made in the cover plate material.
5.2.2 Clamp semirigid sheet (plastic) cover materials in the
cover holder in the same manner as brittle sheet cover
materials.
5.2.3 Flexible Membrane:
5.2.3.1 Mountthematerialinaccordancewiththemanufac-
turer’s recommendatio
...

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Standard Practice for Evaluating Absorptive Solar Receiver Materials When Exposed to Conditions Simulating Stagnation in Solar Collectors with Cover Plates

SIGNIFICANCE AND USE
4.1 Although this practice is intended for evaluating solar absorber materials and coatings used in flat-plate collectors, no single procedure can duplicate the wide range of temperatures and environmental conditions to which these materials may be exposed during in-service conditions.  
4.2 This practice is intended as a screening test for absorber materials and coatings. All conditions are chosen to be representative of those encountered in solar collectors with single cover plates and with no added means of limiting the temperature during stagnation conditions.  
4.3 This practice uses exposure in a simulated collector with a single cover plate. Although collectors with additional cover plates will produce higher temperatures at stagnation, this procedure is considered to provide adequate thermal testing for most applications.
Note 1: Mathematical modeling has shown that a selective absorber, single glazed flat-plate solar collector can attain absorber plate stagnation temperatures as high as 226 °C (437 °F) with an ambient temperature of 37.8 °C (100 °F) and zero wind velocity, and a double glazed one as high as 245 °C (482 °F) under these conditions. The same configuration solar collector with a nonselective absorber can attain absorber stagnation temperatures as high as 146 °C (284 °F) if single glazed, and 185 °C (360 °F) if double glazed, with the same environmental conditions (see “Performance Criteria for Solar Heating and Cooling Systems in Commercial Buildings,” NBS Technical Note 1187).4  
4.4 This practice evaluates the thermal stability of absorber materials. It does not evaluate the moisture stability of absorber materials used in actual solar collectors exposed outdoors. Moisture intrusion into solar collectors is a frequent occurrence in addition to condensation caused by diurnal breathing.  
4.5 This practice differentiates between the testing of spectrally selective absorbers and nonselective absorbers.  
4.5.1 Testing Spectrally Selective...
SCOPE
1.1 This practice covers a test procedure for evaluating absorptive solar receiver materials and coatings when exposed to sunlight under cover plate(s) for long durations. This practice is intended to evaluate the exposure resistance of absorber materials and coatings used in flat-plate collectors where maximum non-operational stagnation temperatures will be approximately 200 °C (392 °F).  
1.2 This practice shall not apply to receiver materials used in solar collectors without covers (unglazed) or in evacuated collectors, that is, those that use a vacuum to suppress convective and conductive thermal losses.  
1.3 The values stated in SI units are to be regarded as the standard.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM
ASTM E822-92(2023)(Practice)
Standard Practice for Determining Resistance of Solar Collector Covers to Hail by Impact with Propelled Ice Balls

SIGNIFICANCE AND USE
2.1 In many geographic areas there is concern about the effect of falling hail upon solar collector covers. This practice may be used to determine the ability of flat-plate solar collector covers to withstand the impact forces of hailstones. In this practice, the ability of a solar collector cover plate to withstand hail impact is related to its tested ability to withstand impact from ice balls. The effects of the impact on the material are highly variable and dependent upon the material.  
2.2 This practice describes a standard procedure for mounting the test specimen, conducting the impact test, and reporting the effects.  
2.2.1 The procedures for mounting cover plate materials and collectors are provided to ensure that they are tested in a configuration that relates to their use in a solar collector.  
2.2.2 The corner locations of the four impacts are chosen to represent vulnerable sites on the cover plate. Impacts near corner supports are more critical than impacts elsewhere. Only a single impact is specified at each of the impact locations. For test control purposes, multiple impacts in a single location are not permitted because a subcritical impact may still cause damage that would alter the response to subsequent impacts.  
2.2.3 Resultant velocity is used to simulate the velocity that may be reached by hail accompanied by wind. The resultant velocity used in this practice is determined by vector addition of a 20 m/s (45 mph) horizontal velocity to the vertical terminal velocity.  
2.2.4 Ice balls are used in this practice to simulate hailstones because natural hailstones are not readily available to use, and ice balls closely approximate hailstones. However, no direct relationship has been established between the effect of impact of ice balls and hailstones. Hailstones are highly variable in properties such as shape, density, and frangibility.2 These properties affect factors such as the kinetic energy delivered to the cover plate, the period during ...
SCOPE
1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays.  
1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported.  
1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice.  
1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls.  
1.5 The categories of solar collector cover plate materials to which this practice may be applied cover the range of:  
1.5.1 Brittle sheet, such as glass,  
1.5.2 Semirigid sheet, such as plastic, and  
1.5.3 Flexible membrane, such as plastic film.  
1.6 Solar collector cover materials should be tested as:  
1.6.1 Part of an assembled collector (Type 1 specimen), or  
1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen).  
1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
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 this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.9 This international standard was developed in accordance with internatio...

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ASTM
ASTM E881-92(2022)(Practice)
Standard Practice for Exposure of Solar Collector Cover Materials to Natural Weathering Under Conditions Simulating Stagnation Mode

SIGNIFICANCE AND USE
4.1 This practice describes a weathering box test fixture and establishes limits for the heat loss coefficients. Uniform exposure guidelines are provided to minimize the variables encountered during outdoor exposure testing.  
4.2 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade more rapidly than either exposure alone, a weathering box that elevates the temperature of the cover materials is used.  
4.3 This practice may be used to assist in the evaluation of solar collector cover materials in the stagnation mode. No single temperature or procedure can duplicate the range of temperatures and environmental conditions to which cover materials may be exposed during stagnation conditions. To assist in evaluation of solar collector cover materials in the operational mode, Practice E782 should be used. Insufficient data exist to obtain exact correlation between the behavior of materials exposed in accordance with this practice and actual in-service performance.  
4.4 This practice may also be useful in comparing the performance of different materials at one site or the performance of the same material at different sites, or both.  
4.5 Means of evaluating the effects of weathering are provided in Practice E765, and in other ASTM test methods that evaluate material properties.  
4.6 Exposures 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 that comprise weather. Exposure conditions are complex and changeable. Important factors are material temperature, climate, time of year, presence of industrial pollution, etc. Generally, because it is difficult to define or measure precisely the factors influencing degradation due to weathering, results of outdoor exposure tests must be taken as indicative only. Repeated exposure testing at different seasons over a period of more than one year is req...
SCOPE
1.1 This practice covers a procedure for the exposure of solar collector cover materials to the natural weather environment at elevated temperatures that approximate stagnation conditions in solar collectors having a combined back and edge loss coefficient of less than 1.5 W/(m2·°C).  
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, photovoltaic cells, flat-plate collectors having a combined back and edge loss coefficient greater than 1.5 W/(m2·°C), or flat-plate collectors whose design incorporates means for limiting temperatures during stagnation.  
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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ASTM
ASTM E782-95(2022)(Practice)
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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