BS ISO 22197-4:2021 pdf download – Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for air-purification performance of semiconducting photocatalytic materials Part 4: Removal of formaldehyde 6.3 Photoreactor The photoreactor holds a planar test piece within a 50‑mm‑wide trough, with its surface parallel to an optical window for photoirradiation. The reactor shall be fabricated from materials that adsorb little test gas and withstand irradiation of near‑UV light. The test piece shall be separated from the window by an air layer 5,0 mm ± 0,5 mm thick. The test gas shall pass only through the space between the test piece and the window. This gap shall be accurately set up according to the thickness of the test piece, for example by using height‑adjusting plates with different thicknesses, as shown in Figure 2 a). When a filter-type material is tested, an alternative type of test-piece holder shall be used, which holds the test piece while allowing the test gas to pass through the cells of the filter under irradiation [Figure 2 b)]. Quartz or borosilicate glass that absorbs minimal light at wavelengths longer than 300 nm shall be used for the window. 6.4 Light source The light source shall provide UV irradiation within a wavelength range of 300 nm to 400 nm. Suitable sources include the so-called black light (BL) and black light blue (BLB) fluorescent lamps, with a maximum at 351 nm, as specified in ISO 10677. The test piece shall be irradiated uniformly through the window by the light source. If testing filter-type photocatalysts, the light source shall irradiate one face of the test piece. A light source that requires warming up shall be equipped with a shutter. The distance between the light source and the reactor shall be adjusted so that the UV irradiance (300 nm to 400 nm) at the sample surface is 10 W/m 2 ± 0,5 W/m 2 . The irradiance along the length of the test piece shall also be constant within ±5 %. The UV irradiance shall be measured with a radiometer which conforms to ISO 10677. The reactor shall be shielded from external light if necessary. 6.5 Analytical system The test gas shall be sampled using a sampling cartridge, pump and flow controller, as specified in ISO 16000‑3. The concentration of formaldehyde shall be determined by 2,4‑dinitorphenylhydrazine‑ derivatised high‑performance liquid chromatography (DNPH‑HPLC). The reagents, equipment and procedure as specified in ISO...
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