The articles on the universal method of lead burning having been completed, I desire to call attention to a new method and a new generator recently patented and put on the market by the Kirkwood & Herr Hydrogen Machine Company, 3129 South State street, Chicago, Ill. It is called the Kirkwood generator and a general view of it is given in Fig. 44. This generator is a radical departure from the old style generator, as used for the purpose of lead burning, inasmuch as it dispenses with the air blast and consequently with the mixing fork and tubes. The air required to reduce the hydrogen gas to a working condition is obtained by absorbing the air at the mouth of the burner.
The new generator differs also in the amount of pressure used on the gas. With the old style generator, previously described, a pressure of 1½ to 2 pounds is used, whereas the Kirkwood generator is used under a pressure varying from 8 to 30 pounds. At the higher pressure the maker claims the best results are obtained. The generator is made in a size that enables the operator to take it to a job on a street car or train, and that while containing the full charge of acid and zinc, as it weighs when charged about 50 pounds. This is a very important advantage over the old style machine.
Construction of the Generator.
The generator is constructed, so to speak, just the reverse of the old style generator, inasmuch as the lower chamber contains the charge of acid, while the zinc is placed in the upper chamber. The generator shown in the sectional view, Fig. 45, is cylindrical in shape, 9 inches in diameter and 30 inches high. A horizontal partition, to which is burned a pipe long enough to reach to a point about 1 inch above the bottom of the acid chamber, is burned into the cylinder at a point a little above the middle of the cylinder, making the acid chamber larger than the gas chamber. This arrangement allows the back pressure of gas to force the acid down into the acid chamber, compressing the air in the acid chamber without permitting any gas to find its way into the acid chamber and thus preventing a waste of gas. In this horizontal partition and over the pendent pipe a number of ¼-inch holes are drilled or punched. This enables the acid to pass freely into the gas chamber, and prevents any small particles of zinc from falling into the acid chamber, which would generate gas in the chamber. Connected to the top of this acid chamber is a small pipe which runs up through the gas chamber and terminates above it, as shown. This pipe has an air inlet valve, or small hose end gas cock, connected into the side of the pipe, to which the hose from the force pump is attached when supplying air to the acid chamber to force from the acid chamber to the gas chamber in order to start the generation of gas. A safety or blow off valve is also attached to this pipe at the top, and is set to an ordinary working pressure of 15 pounds, or to any pressure desired. If gas is being generated faster than is required it gets up a pressure in excess of 15 pounds. Then the safety valve opens and allows the air in the acid chamber to escape until the gas goes down to the desired pressure again. This obviously allows a portion of the acid to return to the acid chamber, and later, as the acid becomes weaker, the air in this chamber will have to be renewed by the admission of a little more air.
| Fig. 44.—General View. | Fig. 45.—Sectional View. |
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| The Kirkwood Lead Burning Machine. |
Fig. 46.—The Kirkwood Lead Burner.
A large charging screw is placed directly in the top of the gas chamber. Into this is screwed a tee and short nipple, or it may be a special fitting made for that purpose. On this tee or special fitting a pressure gauge is screwed, and a float valve is attached on the branch. Into the gas chamber or as close to the partition as possible an angle valve is placed.
To Operate.
To charge the apparatus the safety valve is removed and the amount of the charge of acidulated water having been previously ascertained, the charge is poured into the acid chamber through the air pipe. The charge of spelter or zinc is placed in the gas chamber through the charging screw on top of the gas chamber. The pump is now attached to the air inlet cock with a short hose, and a few strokes of the pump will force the acid up into the gas chamber until the zinc is completely submerged. The generation of gas will begin at once.
The cock on the burner is then closed until the necessary working pressure is obtained, when it is ready for use. The pressure of gas can be regulated by setting the safety valve to blow off at a greater or less pressure, as desired. The use of the float valve is to prevent acid from being forced out of the gas chamber and into the tube. If this happens, the valve floats up and instantly closes the outlet, in which condition the valve remains until sufficient gas is generated to force the acid back into the acid chamber. When first charging the machine, acid should be forced up into the gas chamber until this valve closes, as that will force all of the air contained in the gas chamber out through the tube, leaving only pure gas in the generator. When the acid is spent it is easily removed from the generator by attaching the pump to the air inlet cock and forcing the acid up into the gas chamber. The angle valve is then opened, when the spent acid can be drawn off into a pail or other receptacle. This will not drain the acid chamber absolutely dry, but practically so.
When the operator ceases work, as for dinner or for any purpose, all that is necessary is to open the air inlet cock and detach the hose from the gas outlet. The acid will return by gravity to the acid chamber when generation ceases. When the operator is ready to resume work a few strokes of the pump will start generation again.
The Burner.
The burner, shown in Fig. 46, which is the most important part of the apparatus, is also constructed on a principle not heretofore used on a lead burning apparatus. It consists of a small tube, to one end of which is screwed a small cock, similar to a pet cock. To the other end, at a convenient angle, is brazed the burner proper. This consists of a needle point valve. The needle point, being about ½ inch long, is arranged so that the point can pass through the gas outlet about 1-16 inch. This seems to spread the flame in such a manner that it absorbs sufficient air to reduce the flame. It can be regulated by drawing the needle in or out, as the work requires. There is also a tube arranged to act as a by-pass or subflame. By opening the valve on this by-pass a pilot or subflame is maintained, which does away with the annoyance of having the flame pop out or become extinguished, as it is instantly ignited again by the subflame. In operating, the flame is held at such a distance from the work as experience will teach to be proper, or until the lead starts to melt. It should fuse with that well-known and instantly recognized bright appearance which indicates the nonoxidizing flame.
Any one who is used to handling the blow pipe can easily familiarize himself with this blow pipe. The maker claims that 2 quarts of vitriol will serve to operate the apparatus for a day of 8 hours on lead as heavy as 12-pound. I have no doubt that it will do even more than the makers claim for it. The apparatus is made in three sizes, adapted for different classes of work. After the experience I have had with it, I feel sure that any beginner can use this apparatus safely if he uses ordinary judgment and care in handling a gas apparatus that needs common sense treatment.
