UL-569:2013 pdf free download – STANDARD FOR SAFETY Pigtails and Flexible Hose Connectors for LP-Gas.
9 Inside Diameter for Flexible Hose Connectors
9.1 The internal diameter of a hose shall be equal to the nominal diameter ±1/32 inch (0.8 mm) for sizes up to and including 3/4 inch (19.1 mm), and ±1/16 inch (1.6 mm) for larger sizes.
9.2 A tapered plug gauge of wood or metal having a taper of 3/8 in per foot (31.3 mm/rn) marked to indicate variation of 1/64 in (0.4 mm) in diameter, a set of wood or metal plug gauges, straight or ball type, in increments of no greater than 0.01 in (0.3 mm) for hoses of nominal size 1 in (25 mm) and less, and in increments no greater than 0.02 in (0.5 mm) for hose of nominal size greater than 1 in (25 mm), or in some cases (see 8.3), an expanding ball gauge and micrometer or other equivalent means to accurately measure the expanded ball, is to be used.
9.3 The end of the hose is to be cut square. When a tapered plug gauge is used, the plug gauge is to be inserted in the hose sample until a close fit is obtained without forcing. The diameter of the gauge at the end of the sample, to the nearest 1/64 inch (0.4 mm), is to be recorded as the internal diameter of the hose. When a set of straight or ball-type plug gauges is used, the diameter of the gauge, which when inserted in the hose sample gives a close fit without forcing, is to be recorded as the internal diameter of the hose. When the end of a wire-braided hose is constricted or flared, the inside diameter is to be measured far enough from the end to be representative of the inside diameter by means of an expanding ball gauge.
10 Thickness of Flexible Hose Tube or Cover
10.1 The thickness of the inner tube, and of the cover, when one is used, shall not be less than 0.047 inch (1.19 mm) when determined as described in 10.2— 10.6.
10.2 A power-driven buffing machine (grinding wheel) or skiving machine outlined in the Practice for Rubber Preparation of Pieces for Test Purposes from Products, ASTM D31 83-84, is to be used for buffing off irregularities on specimens. The abrasive wheel of a buffing machine is to be No. 30 — 36 grit; and its diameter and rotary velocity are to be such that the wheel will have a peripheral speed of 4000 ±700 feet per minute (20 ±3.6 mIs). The machine is to be provided with a slow feed to avoid overheating of the specimen.
10.3 A dial micrometer that is graduated to 0.00 1 inch (0.025 mm) and exerts a load of 80 —85 grams by means of a weight is to be used. The load is to be applied through a flat contact foot 0.25 ±0.01 inch (6.35 ±0.25 mm) in diameter.
10.4 One piece, 6 — 8 inches in length, taken from the sample selected for physical and detail tests, is to be used in determining the thickness of the lining and cover as specified in 10.5 and 10.6.
10.5 A strip, 6-8 inches (1 50-200 mm) in length and 1 inch (25.4 mm) in width, or as close to a 1 inch width as possible from small diameter hose, is to be cut from the hose, and the rubber part separated from the plies. When the thickness of the part is not uniform around the circumference of the hose, the strip is to be cut from the thinnest portion of the sample.
10.6 The strip specimen is to be buffed or skived to remove the impressions left by the fabric or braid or other surface irregularities using the buffing or skiving machine described in 10.2. Five thickness measurements are to be taken within the area from which the impressions have been removed, and the maximum reading obtained is to be considered as the thickness of the rubber part.