HAND AIR PUMPS.
The use of compressed air has become very general through the use of small hand pumps; the cylinder of these must be smooth, and the plunger is usually packed with a cup leather packing.
Fig. 340.—Gas Fitter’s Proving Pump.
Fig. 340.—Gas Fitter’s Proving Pump.
Fig.340shows agas fitter’s air proving pump. The gauge is attached to any opening into the system of pipes to be tested, with a rubber hose leading to the pump. By working the pump the air is forced into the pipes; upon stopping the pump if the hand upon the gauge remains stationary there are no leaks in the system. If there are leaks the hand of the gauge will gradually return to the zero mark.
Note.—Before putting the pressure on it is customary to put some ether into the small cup—near the gauge as shown—this has a cock which must be opened and closed at the proper time so that the ether will be forced into the pipe system and disclose by the sense of smell the location of the leak.
Note.—Before putting the pressure on it is customary to put some ether into the small cup—near the gauge as shown—this has a cock which must be opened and closed at the proper time so that the ether will be forced into the pipe system and disclose by the sense of smell the location of the leak.
Fig.341shows aPortable Tire Air Pump, which can be used by hand or affixed to a wall or bench; it is of the lever type, with 2 × 8 cylinders, fitted with check valve and extra heavy rubber tubing. As the leverage on the piston-rod increases the resistance on the piston also increases, thereby securing thepowerful leverage of the well-known “toggle-joint” principle as the piston finishes its stroke; thus the best possible results are obtained.
Fig.342illustrates aHand Lever Air Pumpwith cylinder 31⁄4″ × 61⁄4″; its capacity—one stroke—is 36 cubic inches. The greatest pressure it is intended to operate against is 150 lbs. to the square inch. In operation this design has the advantage of the leverage of the toggle-joint indicated above.
Fig.343exhibits a Hand Air Pump which has the same dimensions as that just described, screwed to the floor. Its particular advantage is the fact that the motion of the lever is natural and easy being horizontal and still retaining the advantages of the toggle-joint.
Fig. 341.—Hand Pump.
Fig. 341.—Hand Pump.
Fig. 342.
Fig. 342.
Fig. 343.
Fig. 343.