UL 94:2016 pdf free download – STANDARD FOR SAFETY Tests for Flammability of Plastic Materials for Parts in Devices and Appliances.
7.1.3 A material classified HB in the 3.0 +0.2 mm thickness shall automatically be classed HB down to a
1.5 mm minimum thickness without additional testing. A material not exceeding the 75mm/mm burning rate tested at any thickness less than 3.0 mm is to be classed HB at the thickness tested (the minimum thickness) and up to a maximum of 2.99 mm without testing additional specimens within this range.
7.1.4 If only one specimen from a set of three specimens does not comply with the requirements, another set of three specimens is to be tested. All specimens from this second set shall comply with the requirements in order for the material in that thickness to be classified HB.
7.2 Test apparatus
7.2.1 See 5.1, 5.2. 5.5— 5.12, 5.20 and 5.21.
7.3 Test specimens
7.3.1 All specimens shall be cut from sheet material, or shall be cast or injection, compression transfer or pultrusion molded to the necessary form. After any cutting operation. care is to be taken to remove all dust and any particles from the surface: cut edges are to have a smooth finish. Fabrication of test specimens shall be in accordance with current ASTM Practices.
7.3.2 Standard bar specimens are to be 125 ±5 mm long by 13.0 ±0.5 mm wide, and provided in the minimum thickness and 3.0 (-0.0 +0.2) mm thick. The 3.0 mm thick specimens are not necessary if the minimum thickness is greater than 3.0 mm, or the maximum thickness is less than 3.0 mm. The maximum thickness is not to exceed 13 mm. The edges are to be smooth, and the radius on the corners is not to exceed 1.3 mm.
7.3.3 Material Ranges — If a material is to be considered in a range of colors, densities. melt flows, or reinforcement, specimens representing these ranges are also to be provided.
7.3.4 Specimens in the natural and in the most heavily pigmented light color (often white) and dark color (often blackincluding carbon black) are to be provided and considered representative of the color range, if the test results are essentially the same. In addition, a set of specimens is to be provided in the heaviest organic pigment loading (not carbon black). unless the most heavily pigmented light and dark colors include the highest organic pigment level. When certain color pigments (for example, red, yellow, or the like) are known to affect flammability characteristics, they are also to be provided.
7.3.5 Specimens in the extremes of the densities, melt flows and reinforcement contents are to be provided and considered representative of the range, if the test results are essentially the same. If the burning characteristics are not essentially the same for all specimens representing the range. evaluation is to be limited only to the materials in the densities, melt flows, and reinforcement contents tested, or additional specimens in intermediate densities, melt flows, and reinforcement contents are to be provided for tests.
7.4 Conditioning
7.4.1 Two sets of three specimens are to be preconditioned as in 6.1.
7.5 Procedure
7.5.1 Three specimens are to be tested. Each specimen is to be marked with two lines perpendicular to the longitudinal axis of the bar, 25 ±1 mm and 100 ±1 mm from the end that is to be ignited.
7.5.2 Clamp the specimen at the end farthest from the 25 mm mark, with its longitudinal axis horizontal and its transverse axis inclined at 45 ±2 degrees. The wire gauze (see 5.9) is to be clamped horizontally beneath the specimen. with a distance of 10 –1 mm between the lowest edge of the specimen and the gauze with the free end of the specimen even with the edge of the gauze. See Figure 7.1.