ACETYLENE GENERATOR (Fr., Generateur d' acetylene ; Ger., Acetylengasentwickler) An apparatus for generating acetylene by the action of water on calcium carbide. Of the two types of generators, that is probably the better in which the carbide is immersed in or dropped into the water, as when water is permitted to fall on the carbide great heat is created, tending to the production of inferior gas, and the evolu tion of oily products which are liable to accu mulate in the pipes. However, many generators in which the water drips very slowly on the carbide, as in the majority of acetylene lamps for cycle use, have a high reputation. Carbide to water generators are illustrated herewith. In the apparatus shown at A the water is contained in the tank E, in which slides the gas bell or reservoir F. The receptacle G, filled with lump carbide, is suspended from the top of the reservoir, which falls by its own weight, acetylene beginning to generate directly the carbide comes in contact with the water. The gas, filling the reservoir, causes it to rise and lifts the carbide receptacle,. thus stopping further generation until by the consumption of the gas the reservoir again falls. The carbide receptacle is introduced or removed by extracting the tightly-fitting plug H. In the generator shown at B granulated carbide is contained in the hopper G, in which is a small opening or valve closed by the conical plug j. The plug is attached to a rod having a weight K as its lower end. The reservoir falls when empty, until the weight strikes the bottom of the water tank, this causing the rod to push up the plug j, allowing a small quantity of carbide to fall through the opening. The ascent of the reservoir as gas is generated raises the weight, which pulls down the plug and again closes the aperture. B is better in principle than A, as the carbide is acted upon in smaller quantities at a time.
In all the earlier generators the carbide re ceptacle was attached to the reservoir, causing an unnecessary pressure, and one also that varied as the carbide was consumed. Another dis advantage was the fact that the waterseal was furnished from the same water as that used for generation. In the devices shown at C and D these objections are obviated. In the former of these the plug j is weighted to keep it normally closed, and its rod is connected at its upper end to a T-piece, this being in turn pivoted at each side to angle irons, which carry wheels at their outer ends. The reservoir r, in falling, depresses the angle irons, and these raise the plug rod by means of the T-piece, thus liberating a small charge of carbide. The plug is re-closed by the
weight as the gas-laden reservoir rises. In the device shown at D the hopper G containing the carbide has an upward-closing plug j fixed to a rod. The reservoir r in falling presses on the top of the rod and opens the plug, while the spring r, serves to return the rod and close the opening when the reservoir rises.
Except when the carbide is dropped in small quantities into a sufficient excess of water, ci washing apparatus of some kind is called for. If any quantity of acetylene is made, it is better also to remove the remaining impurities by passing the gas through calcium chloride with which is mixed a little unslaked lime, the mixture being contained in muslin bags arranged on perforated shelves, one over the other, in the purifier. A similar mixture is sold ready-pre pared, and with this no bags or shelves are required, the lumps being merely packed in the receptacle.
The pressure should not rise above two or three inches of water in the generator, and the pipes should not be less than in. diameter. All taps must be well ground in, and should be lubricated with vaseline to prevent the corrosive action exerted by acetylene on brasswork. Since the gas leaks more easily than ordinary house gas, greater care must be taken with all joints. Tar and paint are quickly affected, and should not be used for this purpose ; red lead or white-lead, applied sparingly, is best. To detect a leak, a solution of soap and water may be applied, noticing if bubbles appear. In starting, the first gas coming off should be allowed to escape, as it contains an admixture of air. The generator should be kept at least 8 ft. or io ft. distant from any light, and no light should be at hand when emptying it after use. Copper should not be employed in acetylene generators, as under certain conditions a deton ating explosive compound is formed. The best material for the body is tinned or galvanised sheet-iron, brass being used only for taps.
Special burners are required for acetylene. The best are of steatite, on the air-injector principle. For photographic use, Bray's 00000 (acetylene) burners are perhaps most suitable. Fifteen of these, mounted in a white reflector, can be employed for studio portraiture, but a slightly larger number is better. Two-, three-, and four-burner jets are made for optical lantern and enlarging purposes. The soot that soon collects on the burners may be removed with a toothbrush or anything similar, while the holes may be cleared with a fine needle or wire.