BS ISO 9772:2020 pdf download – Cellular plastics — Determination of horizontal burning characteristics of small specimens subjected to a small flame
5.1 A laboratory fume hood, having an inside volume of at least 0,5 m 3 is used. The chamber shall permit observation of tests in progress and shall provide a draught-free environment whilst allowing normal thermal circulation of air past the test specimen during burning. The inside surfaces of the chamber shall be of a dark colour. When a light meter, facing towards the rear of the chamber, is positioned in place of the test specimen, the recorded light level shall be less than 20 lux. For safety and convenience, this enclosure (which can be completely closed) shall be fitted with an extraction device, such as an exhaust fan, to remove products of combustion that might be toxic. The extraction device shall be turned off during the test and turned on again immediately after the test to remove the fire effluents. A positive closing damper might be needed. NOTE The amount of oxygen available to support combustion is naturally important for the conduct of these flame tests. For tests conducted by this method when burning times are protracted, chamber sizes greater than 0,5 m 3 might be needed to provide reproducible results.
5.2 P/PF2 laboratory burner, as specified in ISO 10093. The burner shall be the diffusion flame burner specified in ISO 10093:2020, 11.3, having a barrel length of (100 ± 10) mm and an internal diameter of (9,5 ± 0,3) mm. The barrel shall not be equipped with an end attachment, such as a stabilizer.
5.3 The burner shall be fitted with a burner wing top, having an opening of internal length (48 ± 1) mm and internal width (1,3 ± 0,05) mm (see Figure 1). To ensure the wing top opening is uniform in width, one option is to slide a (1,3 ± 0,05) mm steel wire or spacer along its length.
5.4 The support gauze shall be a wire cloth of plain weave, approximately 215 mm long by 75 mm wide, as shown in Figure 2. It shall consist of (6,4 ± 0,5) mm mesh gauze constructed of (0,9 ± 0,1) mm diameter stainless steel, plain or low carbon steel wire. The cloth-mesh and wire diameter shall be determined as described in the Standard Specification for Industrial Woven Wire Cloth, ASTM E2016.
5.5 The gauge-support holder shall consist of two laboratory ring stands with clamps adjustable to the desired angles and heights. The gauze-support holder shall be constructed from aluminium or steel and shall satisfy the following conditions:
— the long axis of the gauze shall be maintained to within 1° of the horizontal;
— the nearest end of the specimen shall be (13 ± 1) mm above the burner wing top (see Figure 2);
— the space both above and below the specimen shall not be obstructed;
— a means shall be provided for positioning the burner in the correct location relative to the specimen, preferably with a sliding mechanism and a stop to allow fast movement of the burner flame towards and away from the specimen;
— the gauze shall be equidistant from the front and back, and from both sides, of the test chamber, and shall be (175 ± 25) mm above the cotton indicator base-board (see Figure 2). 5.6 There shall be two timing devices, each of which reads to within 1 s or less.
5.7 A measuring scale graduated in millimetres, shall be used to measure the length, width and thickness of the test specimen.
5.8 The gas supply shall consist of technical-grade methane gas with a purity of at least 98 % and having a heat content of (37 ± 1) MJ⋅m −3 , with regulator and meter to ensure uniform gas flow. Other gas mixtures having a heat content of approximately (37 ± 1) MJ⋅m −3 or propane having a heat content of (94 ± 2) MJ⋅m −3 have been shown to provide similar results when using the procedure of Clause 8. In cases of dispute, however, technical-grade methane shall be used.
5.9 A manometer and gas flow meter, calibrated for the gas used and capable of reading the values shown in Table 1 shall be used.