ASTM C1864-17(2022)

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.
Designation:C1864 −17 (Reapproved 2022)
Standard Test Method for
Determination of Solar Reflectance of Directionally
Reflective Material Using Portable Solar Reflectometer
This standard is issued under the fixed designation C1864; 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 3.2 Definitions of Terms Specific to This Standard:
3.2.1 directionally reflective material (DRM), n—material
1.1 This test method covers a technique for determining the
with solar reflectance that varies with solar incidence angle.
solar reflectance of a directionally reflective material using a
commercial portable solar reflectometer, including but not
3.3 Symbols:
limitedtoroofingmaterialswithgranulesorsurfacedesignthat
3.3.1 ρ —solar reflectance measured by reflectometer in
J,K
results in angularly dependent reflectance. The purpose of the
azimuthal orientation J, within measurement series K.
methodistoevaluatetheseasonalandannualsolarreflectances
3.3.2 ρ —solar reflectance measured by reflectometer in
J
of a directionally reflective roofing product.
azimuthal orientation J, averaged over all measurement repeti-
1.2 The values stated in SI units are to be regarded as
tions.
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 This method uses a hemispherical solar reflectometer to
safety concerns, if any, associated with its use. It is the
determine the solar reflectance of a DRM. The reflectometer is
responsibility of the user of this standard to establish appro-
operated in accordance with Test Method C1549, except that
priate safety, health, and environmental practices and deter-
evaluationofthesurfacefollowstheproceduredescribedin4.2
mine the applicability of regulatory limitations prior to use.
and 4.3.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- 4.2 The solar reflectance of a test specimen is measured 12
ization established in the Decision on Principles for the times by rotating the measurement head of the reflectometer in
Development of International Standards, Guides and Recom- 30° increments about the normal to the test specimen.
mendations issued by the World Trade Organization Technical
4.3 The set of 12 measurements is repeated three times to
Barriers to Trade (TBT) Committee.
calculatethesolarreflectanceineachorientationastheaverage
of the three measurements at the same orientation.
2. Referenced Documents
2.1 ASTM Standards:
5. Significance and Use
C1549 Test Method for Determination of Solar Reflectance
5.1 The solar reflectance of a DRM depends on the solar
NearAmbient Temperature Using a Portable Solar Reflec-
incidence angle. This method is intended to provide solar
tometer
reflectance values for DRM roofing products.
3. Terminology
6. Apparatus
3.1 Definitions—The definitions included in Test Method
C1549 are applicable to this method.
6.1 This test method employs a portable solar reflectometer
that is operated in accordance with Test Method C1549.
This test method is under the jurisdiction ofASTM Committee C16 on Thermal
6.2 The test specimen shall be flat (not curved) and have
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
area sufficient to completely cover the measurement port of the
Measurement.
reflectometer.
Current edition approved Sept. 1, 2022. Published October 2022. Originally
ε1
approved in 2017. Last previous edition approved in 2017 as C1864 – 17 . DOI:
6.3 The test specimen shall be placed at the center of a
10.1520/C1864-17R22.
compass pattern marked in 30° increments as shown in Fig. 1.
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
6.4 A vertical indicator arrow, parallel to the central axis of
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the reflectometer head and affixed to the outer wall of the
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C1864−17 (2022)
FIG. 1Specimen Placed at Center of Compass Pattern
reflectometer head, shall be used to gauge the azimuthal angle
FIG. 2Vertical Indicator Arrow Affixed to Side of Portable Reflec-
of the reflectometer head with respect to the compass mark-
tometer
ings.
7. Procedure
7.2.8 Rest the reflectometer measurement port on the
7.1 Set-Up:
specimen, and record solar reflectance measured in this orien-
7.1.1 Prepare the compass pattern template as shown in
tation as ρ .
2,1
Annex A1 and cut out the square that identifies the measure-
7.2.9 Repeat steps 7.2.7 and 7.2.8 for each remaining 30°
ment area.
intervals, recording these solar reflectances as ρ …ρ .
3,1 12,1
7.1.2 Affix the compass pattern to the test bench and place
7.2.10 Repeat steps 7.2.7 and 7.2.8 two times, recording the
the test specimen on the compass pattern. The compass pattern
additional solar reflectance measurement series as ρ …ρ
1,2 12,2
shall not move during the test.
and ρ . ρ .
1,3 12,3
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