1.1 This practice covers the basic principles and operating procedures for using fluorescent UV light, and water apparatus intended to reproduce the weathering effects that occur when materials are exposed to sunlight (either direct or through window glass) and moisture as rain or dew in actual usage. This practice is limited to the procedures for obtaining, measuring, and controlling conditions of exposure. A number of exposure procedures are listed in an appendix; however, this practice does not specify the exposure conditions best suited for the material to be tested. Note 1 - Practice G151 describes performance criteria for all exposure devices that use laboratory light sources. This practice replaces Practice G53 , which describes very specific designs for devices used for fluorescent UV exposures. The apparatus described in Practice G53 is covered by this practice. 1.2 Test specimens are exposed to fluorescent UV light under controlled environmental conditions. Different types of fluorescent UV light sources are described. 1.3 Specimen preparation and evaluation of the results are covered in ASTM methods or specifications for specific materials. General guidance is given in Practice G151 and ISO4892-1 . More specific information about methods for determining the change in properties after exposure and reporting these results is described in ISO4582 . 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. 1.6 This standard is technically similar to ISO4892-3 and ISO DIS 11507 .