Page:30 CFR 1993.pdf/26

Mine Safety and Health Admin., Labor (6) Suspension system (for example, metal hooks).

(7) Base material: type, supplier, the supplier’s stock number, and percent of finished product by weight.

(8) Resin: type, supplier, the supplier’s stock number, and percent of finished product by weight.

(9) Flame retardant, if added during manufacturing: type, supplier, the supplier's stock number, and percent of finished product by weight.

(Approved by the Office of Management and Budget under control number 1219-0100)

§ 7.24 Technical requirements.
(a) Brattice cloth shall be flame resistant when tested in accordance with the flame resistance test in § 7.27.

(b) Flexible ventilation tubing shall be manufactured using an MSHA-approved brattice cloth. If a supporting structure is used, it shall be metal or other noncombustible material which will not ignite, burn, support combustion or release flammable vapors when subjected to fire or heat.

(c) Rigid ventilation tubing shall be flame resistant when tested in accordance with the flame resistance test in § 7.28.

§ 7.25 Critical characteristics.
A sample of each batch or lot of brattice cloth and ventilation tubing shall be flame tested or a sample of each batch or lot of the materials that contribute to the flame-resistance characteristic shall be inspected or tested to ensure that the finished product will meet the flame-resistance test.

§ 7.26 Flame test apparatus.
The principal parts of the apparatus used to test for flame-resistance of brattice cloth and ventilation tubing shall be constructed as follows:

(a) A 16-gauge stainless steel gallery lined on the top, bottom and both sides with ⅛ inch thick Marinite or equivalent insulating material yielding inside dimensions approximately 58 inches long, 41 inches high, and 30 inches wide;

(b) Two ⅔-inch diameter steel J hooks and a 3⁄16-inch diameter steel rod to support the sample located approximately 2 3⁄16-inches from the front and back ends of the test gallery, 1½-inches from the ceiling insulation and centrally located in the gallery along its length. Samples shalt be suspended to preclude folds or wrinkles;

(c) A tapered 16-gauge stainless steel duct section tapering from a crass sectional area measuring 2 feet 7 inches wide by 3 feet 6 inches high at the test gallery to a cross-sectional area 1 foot 6 inches square over a length of 3 feet. The tapered duct section must be tightly connected to the test gallery:

(d) A 16-gauge stainless steel fan housing, consisting of a 1 foot 6 inches square section 6 inches long followed by a 10 inch long section which tapers from 1 foot 16 inches square to 12 inches diameter round and concluding with a 12 inch diameter round collar 3 inches long. A variable speed fan capable of producing an air velocity of 125 ft./min. in the test gallery must be secured in the fan housing. The fan housing must be tightly connected to the tapered duct section;

(e) A methane-fueled impinged jet burner igniting source, measuring 12 inches long from the threaded ends of the first and last jets and 4 inches wide with 12 impinged jets, approximately 1⅜-inches long and spaced alternately along the length of the burner tube. The burner jets must be canted so that they point toward each other in pairs and the flame from these pairs impinge upon each other.

§ 7.27 Test for flame resistance of brattice cloth.
(a) Test procedures. (1) Prepare 6 samples of brattice cloth 40 inches wide by 48 inches long.

(2) Prior to testing, condition each sample for a minimum of 24 hours at a temperature of 70±10 °F (21±5.5 °C) and a relative humidity of 55±10%.

(3) For each test, suspend the sample in the gallery by wrapping the brattice cloth around the rod and clamping each end and the center. The brattice cloth must hang 4 inches from the gallery floor.

(4) Use a front exhaust system to remove smoke escaping from the gallery. The exhaust system must remain

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