International standards for operating weathering test apparatuses using Fluorescent UV and Xenon Arc lamps often include requirements for relative spectral power distributions (SPD’s) of the light sources. These SPD’s define ranges for what percentages of a given light source’s irradiance fall within a specified bandpass, e.g. 290-320 nm or 360-400 nm.

Important sets of SPD reference tables are provided in both ASTM and ISO standards. Fluorescent UV spectral tables are provided in ASTM G154 and ISO 4892-3, while xenon arc requirements are found in ASTM G155 and ISO 4892-2. These tables are defined for three different general classifications of lamps and filters: Daylight (outdoor sunlight), Window (behind glass), and Extended UV (UVB-313).

Q-Lab’s UVA-340, UVA-351, and UVB-313EL lamps all meet the specifications of both ASTM G154 and ISO 4892-3 for Daylight, Window, and Extended UV.

The following Q-Lab UV filters used in Q-SUN weathering testers meet the spectral requirements specified in ASTM G155 and ISO 4892-2. The latter standard does not include a specification for Extended-UV.

Table 1 (Daylight filters):                   Daylight-B/B, Daylight-Q, Daylight-F

Table 2 (Window glass filters):        Window-B/SL, Window-Q, Window-IR

Table 3 (Extended-UV filters):         Extended UV-Q/B

The only Q-Lab standard optical filters that fall outside of these SPD requirements are the Extended UV-Quartz and the Window-SF5 filters. The Extended UV-Quartz filter is required only in a few specialty aerospace standards, while the Window-SF5 filter is used only in automotive standards specifying glass with higher cut-on wavelengths than architectural glass.

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