ASTM G90-98 - 10.12.1998
 
1. Scope

1.1 Fresnel-reflecting concentrators employing the sun as source are utilized in the accelerated outdoor exposure testing of nonmetallic materials.

1.2 This practice covers a procedure for performing accelerated outdoor exposure testing of nonmetallic materials using a Fresnel-reflector accelerated outdoor weathering test machine. The apparatus (see Figs. 1a and 1b) and guidelines are described herein to minimize the variables encountered during outdoor accelerated exposure testing.

1.3 This practice does not specify the exposure conditions best suited for the materials to be tested but is limited to the method of obtaining, measuring, and controlling the procedures and certain conditions of the exposure. Sample preparation, test conditions, and evaluation of results are covered in existing methods or specifications for specific materials.

1.4 The Fresnel-reflector accelerated outdoor exposure test machines described may be suitable for the determination of the relative durability of materials exposed to sunlight, heat, and moisture, provided the mechanisms of chemical or physical change, or both, which control the rates of acceleration factors for the materials do not differ significantly.

1.5 This practice establishes uniform sample mounting and in-test maintenance procedures. Also included in the practice are standard provisions for maintenance of the machine and Fresnel-reflector mirrors to ensure cleanliness and durability.

1.6 This practice shall apply to specimens whose size meets the dimensions of the target board as described in 8.2.

1.7 For test machines currently in use, this practice may not apply to specimens exceeding 13 mm ( 1/2 in.) in thickness because cooling may be questionable.

1.8 Values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are provided for information only.

1.9 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

E816-15(2023)

Standard Test Method for Calibration of Pyrheliometers by Comparison to Reference Pyrheliometers

E824-10(2018)e1

Standard Test Method for Transfer of Calibration From Reference to Field Radiometers (Includes all amendments and changes 6/6/2018).

E903-20

Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres

G7-05

Standard Practice for Atmospheric Environmental Exposure Testing of Nonmetallic Materials

G24-21

Standard Practice for Conducting Exposures to Daylight Filtered Through Glass

G113-22

Standard Terminology Relating to Natural and Artificial Weathering Tests of Nonmetallic Materials

G167-15(2023)

Standard Test Method for Calibration of a Pyranometer Using a Pyrheliometer

G169-01(2021)

Standard Guide for Application of Basic Statistical Methods to Weathering Tests

G173-23

Standard Tables for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37? Tilted Surface

WMO

Guide to Meteorological Instruments and Methods of Observation WMO No. 8, Fifth Edition Available from World Meteorological Organization, Geneva, Switzerland.

D859-16(2021)e1

Standard Test Method for Silica in Water (Includes all amendments and changes 12/6/2021).

D1014-18

Standard Practice for Conducting Exterior Exposure Tests of Paints and Coatings on Metal Substrates

D1435-20

Standard Practice for Outdoor Weathering of Plastics

D1898-68(1989)

Standard Practice for Sampling of Plastics (Withdrawn 1998)

D4141-07

Standard Practice for Conducting Black Box and Solar Concentrating Exposures of Coatings

D4517-15(2023)

Standard Test Method for Low-Level Total Silica in High-Purity Water by Flameless Atomic Absorption Spectroscopy