ASTM G154-12 PDF

These exposures may include a means to introduce moisture to the test specimen. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure. Alternatively, the exposure may simulate the effects of sunlight through window glass. Typically, these exposures would include moisture in the form of condensing humidity. Note 2—Caution: Refer to Practice G for full cautionary guidance applicable to all laboratory weathering devices.

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More G Typically, these exposures would include moisture in the form of condensing humidity. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure.

Alternatively, the exposure may simulate the effects of sunlight through window glass. Warning—Refer to Practice G for full cautionary guidance applicable to all laboratory weathering devices. Therefore, no reference shall be made to results from the use of this practice unless accompanied by a report detailing the specific operating conditions in conformance with Section Generally, two controls are recommended: one known to have poor durability and one known to have good durability.

It is recommended that at least three replicates of each material evaluated be exposed in each test to allow for statistical evaluation of results. Scope 1. This practice is 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. Different types of fluorescent UV lamp sources are described. No other units of measurement are included in this standard. 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.

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ASTM G154-12 PDF

Scope 1. This practice is 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. Note 1: Practice G describes general procedures to be used when exposing nonmetallic materials in accelerated test devices that use laboratory light sources. Note 2: 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.

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ASTM G154 and G155 Explained

When rays of sunlight—particularly UV rays—bombard a surface, they degrade smaller pigment particles, changing the surface color and creating a chalky effect. Cracking, peeling, de-glossing, oxidation, and tensile weakening are additional outcomes of exposure; sometimes such deterioration can even occur through window glass. Moisture takes its own toll on surfaces, and the combination of sunlight and moisture can amplify damage, costing millions of dollars of depreciation each year. The ASTM G and G tests empower manufacturers to design products that can withstand exposure to sunlight and moisture. Ultimately, the most realistic way to test for weathering is to allow the product to degrade in real time, with outdoor testing panels. In the U. Due to time constraints, however, many producers employ the G and G laboratory chamber tests for reliable exposure results in shorter time periods.

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ASTM G154测试标准

Nar Such outcomes cannot be quickly obtained in gg settings; therefore, these weatherization tests are invaluable in timely product development. Annex A1 states how to determine relative spectral irradiance. Following are some representative exposure conditions. These numbers represent the characteristic nominal wavelength in nm of peak emission for each of these lamp types. In the ASTM G test, xenon arc lamps simulate full-spectrum sunlight within a controlled test chamber. 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. As such, the ASTM G and G tests produce comparative, not absolute data, but these comparative evaluations can still prove extremely valuable to designers.

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