The first oxy-acetylene torch was invented by Mr. Edmond Fouche, who at the time was general manager of the Campagnie Francaise de P Acetylene dissous.

As they were using compressed acetylene in acetone, it was very easy with acetylene under pressure to get the proper mixture when used with oxygen under pressure.

A couple of years later Fouche went with another company, which was controlled by Javal. But as they were not handling compressed acetylene, but only generators using gas under a normal pressure, Fouche went ahead and devised a new oxy-acetylene burner under the principle of an injector, which with the oxygen under pressure coming from a small tube into a larger, would produce a suction, by this absorbing acetylene in enough quantity to produce a very hot flame. So this is where the first two torches originated - high- and low-pressure.

Fig. 33- - Low-pressure torch for oxy-acetylene. Industrial oxygen company.

There is a certain defect in both these torches. The high-pressure torch mixes in the long tube as the two gases are forced together near the handle, and when the tip of the burner gets overheated in case of a flash back, you get a back fire in the whole length of the tube; in which case, if the operator is not quick in cutting off the flow of gases, he runs a chance of melting part of his torch. As for the low-pressure torch, the defect is in depending entirely on the suction made by the injector, which very often does not carry enough acetylene gas, making an oxidizing flame which prevents the metal from uniting properly and making the weld very weak.

The house of A. Boas Rodrigues & Company, of Paris, after looking over both systems, went to work to devise a third torch, which as far as possible would remove some of the objections of the high and low pressure. By making a medium-pressure injector type of torch, having the acetylene under at least 3 pounds' pressure or a little more, they could force in a surplus of acetylene so as to remedy the defect of the low-pressure system, which depended only on the injector.

Moreover, back-firing was not troublesome in this medium-pressure torch, because the gases were mixed an inch from the nozzle. If the torch back-fired, the operator could tell at once by the roaring sound. If he did not turn off the flame at once, the tip would be burned, but not the torch. The tip could be unscrewed and replaced.

Fig. 34. - High-pressure oxy-acetylene torch and replaceable tips (Davis-Bournorr ville Company).

The present low-pressure torch (Fig. 33) also mixes its gases a short distance from the tip of the nozzle.

The nozzles of all oxy-acetylene torches suffer in time from the intense heat of the flame. Constant back-firing, caused by holding the torch too close to the work, will soon burn out the tip. Pieces of melted metal will get in the tip, and should be removed carefully. The burner is a very sensitive tool.

The up-to-date torch is a handy affair with cocks at the handle end to turn the gases on and off and a small detachable tip or burner at the nozzle end. The gases are mixed near the orifice in the low-pressure torch. In the high-pressure torch the gases are mixed in the tip (Fig. 35). In both torches the acetylene is first passed through a packing of asbestos, wire gauze, etc., with handle which prevents a flash back into the generator, on the principle of the Davy lamp. The torches are in several standard sizes, each with five or six graded detachable tips. An extra oxygen tube can be clamped on the burner when used for cutting metals. Special cutting torches (Fig. 36) are now made.

Fig. 35. - Diagram of replaceable tip of high-pressure torch (Davis-Bournonville Company).

A new cutting head is screwed into the torch head. The pure oxygen jet flows through the center and in front, and behind this are two small heating flames, four in all. With this torch it is possible to cut in any direction.

To summarize, there are at present in use in this country three torches:

1. The original Fouche torch, improved, in which the gases are mixed as they enter the haft.

Fig. 36. - Cutting torch attachment (Davis-Bournonville Company).

2. The low-pressure torch (also invented by Fouche) in which the oxygen injected under pressure draws acetylene with it (Fig. 33).

3. The high-pressure torch (French medium pressure) with acetylene up to 15 pounds and oxygen stepped down from 120 atmospheres to one or two atmospheres (Fig. 35).

Each torch claims its advantages, and to number them would be to simply give the talking points of the competing firms, without effect.

The Low-Pressure Torch (The Linde Air Products Co.)

Note - For copper plates larger blowpipes are required than for steel plates of corresponding gauge.

Another authority estimates 25 per cent, additional of each gas for the same thickness of plate. The high-pressure torch uses about the same volume of gas, with the oxygen and acetylene in the proportion of 1.28 to 1.