18.65—Flame test of hose.
(b) Flame-test apparatus.
The principal parts of the apparatus within and/or appended to a 21-inch cubical test gallery are:
(2)
A Pittsburgh-Universal Bunsen-type burner (inside diameter of burner tube 11 mm.), or equivalent, mounted in a burner placement guide in such a manner that the burner may be placed beneath the test specimen, or pulled away from it by an external knob on the front panel of the test gallery.
(3)
A variable-speed electric fan and an ASME flow nozzle (16-8 1/2 inches reduction) to attain constant air velocities at any speed between 50-500 feet a minute.
(5)
A mirror mounted inside the test gallery to permit a rear view of the test specimen through the viewing door.
(c) Mounting of test specimen.
The specimen shall be clamped in a support with its free end centered 1 inch above the burner top. The longitudinal axis shall be horizontal and the transverse axis inclined at 45° to the horizontal. Under the test specimen shall be clamped a piece of 20-mesh iron-wire gauze, 5 inches square, in a horizontal position 1/4 -inch below the pulley cover edge of the specimen and with about 1/2 -inch of the specimen extending beyond the edge of the gauze.
(d) Procedure for flame tests.
(1)
The Bunsen burner, retracted from the test position, shall be adjusted to give a blue flame 3 inches in height with natural gas.
(4)
At the end of 1 minute the burner flame shall be removed, the ventilating fan turned on to give an air current having a velocity of 300 feet per minute, and the duration of flame measured.
(5)
After the test specimen ceases to flame, it shall remain in the air current for at least 3 minutes to determine the presence and duration of afterglow. If a glowing specimen exhibits flame within 3 minutes the duration of flame shall be added to the duration of flame obtained according to paragraph (d) (4) of this section.
(e) Test requirements.
The tests of the four specimens cut from any sample shall not result in either duration of flame exceeding an average of 1 minute after removal of the applied flame or afterglow exceeding an average of 3 minutes duration.
(2)
Hose—hose conduit accepted by MSHA as flame-resistant shall be marked as follows: Impressed letters, raised letters on depressed background, or printed letters with the words “Flame-Resistant, USMSHA No. __” at intervals not exceeding 3 feet. This number will be assigned to the manufacturer after the sample has passed the tests. The letters and numbers shall be at least 1/4 -inch high.