The particulars and instructions on pp. 136 to 139 are due to the Acetylene Corporation, Ltd. Fig. 72 presents a diagrammatic illustration of a complete oxy-acetylene blowpipe equipment with the exception of the acetylene generator and holder, which apparatus may be placed in any suitable position (preferably outside) at any reasonable distance from the blowpipe. A is an ordinary gas tap connecting the hydraulic back pressure valve B with the acetylene supply pipe from the acetylene holder. The blowpipe is connected at valve C by means of a flexible tube with the outlet tap D of the hydraulic back-pressure valve. This forms the acetylene supply pipe to the blowpipe. The blowpipe is connected at valve E by means of a special canvas-covered strong rubber pipe with the outlet tap F of the oxygen pressure regulator, which is fixed, as shown, on the oxygen cylinder. G is a pressure gauge. This pipe conveys the oxygen supply to the blowpipe, and should be securely attached, as it is subject to pressures varying from 5 lb. to 40 lb. per sq. in. The hydraulic back-pressure valve should have been previously charged with water, and the gas regulator screwed into the oxygen cylinder. The blowpipe apparatus is now ready for use, with the taps A and D closed and the taps C, E and F open.
First, slowly open the oxygen cylinder valve (not shown) with the key supplied for that purpose. By means of the thumb-screw H, adjust the gas pressure to the correct working pressure for the blowpipe used. The approximate pressure of oxygen required for each blowpipe is as follows: No. 2, 8 lb. per sq. in.; No. 3, 10 lb.; No. 4, 11 lb.; No. 5, 12 lb.; No. 6, 14 lb.; No. 7, 16 lb.; No. 8, 19 lb.; No. 10, 20 lb.; No. 12, 25 lb.; No. 15, 30 lb. Then open the acetylene taps A and D, and when acetylene is unmistakably smelt at the nozzle of the blowpipe, ignite the gases by means of a gas jet, candle, or taper. Then by means of the tap C slowly throttle down the acetylene until the small white cone of flame at the nozzle of the blowpipe shows a clearly defined outline. As some indication of the correct size of the cone, it may be mentioned that when working with the No. 10 blowpipe this should be about 1/4 in. diameter by 5/8 in. long. This cone in the other blowpipes is greater or less according to the relative size.