UL 94-2013 pdf download – Tests for Flammability of Plastic Materials for Parts in Devices and Appliances.
4 Significance of Tests 4.1 Tests conducted on a material under the conditions specified are intended to provide information when: comparing the relative burning characteristics of different materials, or assessing any change in burning characteristics prior to, or during, use. This method is not intended to provide correlation with performance under actual service conditions. 4.2 Assessment for risk of fire shall take into account such factors as fuel contribution, intensity of burning (rate of heat release), products of combustion and environmental factors such as the intensity of source, orientation of exposed material and ventilation conditions. 4.3 Burning characteristics, as measured by these test procedures, are affected by such factors as: density, color, any anisotropy of the material molding conditions and the thickness of the specimen. 4.4 When a specimen of a thin material shrinks from the flame without igniting, the test results shall be deemed invalid and additional specimens shall be tested. If all test specimens shrink from the applied flame without igniting, these materials cannot be evaluated by the test procedure and an alternate test procedure in this Standard shall be conducted. 5 Apparatus 5.1 Laboratory Fume Hood – The laboratory fume hood chamber shall have an inside volume of at least 0.5 m 3 . The chamber shall permit observation of tests in progress and shall be draft free, while allowing a normal thermal circulation of air past the test specimen during burning. The inside surfaces of the chamber shall be of a dark color. 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 lx. For safety and convenience, it is desirable that the enclosure (which can be completely closed) be fitted with an extraction device, such as an exhaust fan, to remove products of combustion which may be toxic.
5.6 Timing Devices – Accurate to 0.1 second. 5.7 Measuring Scale – Graduated in mm. 5.8 Gas Supply – A supply of technical grade methane gas (min. 98 percent pure) with regulator and meter for uniform gas flow. 5.9 Wire Gauze – Having approximately 20 openings per 25 mm, made with 0.43 ±0.03 mm diameter iron or steel wire and cut to approximately 1 25 mm squares. (Used for the test procedure in Horizontal Burning Test; HB Section 7 only.) 5.1 0 Conditioning Room or Chamber – Capable of being maintained at 23 ±2°C and a relative humidity of 50 ±5 percent. 5.1 1 HB Support Fixture – A metal support fixture for testing specimens that are not self-supporting. See Figure 7.2 (Used for the test procedure in Horizontal Burning Test; HB Section 7 only.) 5.1 2 Micrometer – Capable of being read to 0.01 mm. 5.1 3 Cotton – A supply of absorbent 1 00 percent cotton.