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Product description This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 Excerpt: ... oxygen cylinder or to touch the regulating screw of the reducing valve. One closes the oxygen by the conical valve at the outlet of the reducing valve, and the acetylene by the cock on the blowpipe, or by that on the hydraulic valve. We prefer the latter method, because if the blowpipe is changed one is not exposed to a leakage of combustible gas on taking oft' the flexible tube.1 For a definite stopping, the blowpipe is first of all extinguished, then, immediately after, close the valve on the cylinder, then the admission cock to the hydraulic valve. This done, the cocks on the blowpipe are re-opened so as to drive off excess gas stored by the pressure in the various details; finally, the regulating screw of the reducing valve is set free. Notice if the gauge giving the pressure of the gas in the cylinder indicates that the valve has been properly closed. 1 Some types of blowpipe have a cock controlling the two different passages by the same seating--oxygen and acetylene. From certain points of view this arrangement is pprhaps open to criticism; it is none the less very convenient for temporary stopping. GENERAL ADVICE--SAFETY. MAINTENANCE. The welder should always use a blowpipe (or a head-piece in the case of blowpipes of variable delivery) corresponding to the kind and thickness of the metal to be welded. Increasing the power of the blowpipe by increasing the pressure of the oxygen is not good practice, and would not be indulged in by a conscientious welder. Each type of blowpipe and each number of the same type corresponds for normal working to a pressure which cannot be increased without increasing the proportion of oxygen and oxidising the welds. This pressure is generally given by the makers in their catalogues; it should be summari