As generally considered, the water lift finds its principal application in city work, but may also be used to great advantage in the country, and in connection with institutions, manufacturing plants, etc., that have their own private systems of water supply. In Fig. 322 is to be seen a sectional view of a successful type of water lift, and of its auxiliary valve. Owing to the position of the auxiliary valve, it is impossible to show it in a sectional view of the water lift, and therefore it is shown in a separate view.
Fig. 322. - Sectional View of Water Lift and Auxiliary Valve.
Fig. 323 shows the connections for the water lift more clearly than the sectional view does. The water lift is operated by water pressure, and its action may be compared to that of the steam engine, water pressure taking the place of steam. Fig. 323 shows that there are four pipes connecting with the water lift, including the connection with the water supply, the suction pipe into the body of water to be lifted, the discharge pipe from the lift to supply the fixtures, and the waste. The latter should never be connected directly into the drainage system, but may be indirectly connected. The water pressure which operates the lift, first passes into the auxiliary valve chamber, and into the space marked b, at either end of which is a leather cup. The main and auxiliary valves are separated by a wall, and connecting them are two openings c, c, cut through this wall. These passages connecting between the two valves are never closed, and consequently water always fills the chambers b and d, d. The chamber g is always in exhaust through the waste connection on the driving cylinder of the lift. As shown in Fig. 322, the pressure of the water on the piston head g has forced it to the left end of the driving cylinder. This pressure has been exerted by water entering on the rear of the piston-head from the chamber d, through the port, as shown by the arrows. Chamber g is now exhausting into the exhaust chamber connecting with the waste, through the port in front of the piston head, which is connected to that chamber by the chamber e in the main valve. The construction and arrangement of valves is such that this exhaust takes place alternately, at either end of the driving piston. Having thus shown the manner in which pressure water is admitted to the driving cylinder, and exhausted from it, the operation of the valves should be considered. The two valves, main and auxiliary, are set parallel to each other. A small opening is made into the driving cylinder from the auxiliary valve chamber, and at each end of it, as shown by f and f. In the chamber b of the auxiliary valve, are two passages, c, c, which connect into the space in the cylinder of the main valve, which is between the valve head and the cylinder head. The arrangement is such that one of the passages c, is alternately connected with the chamber b, the water of which is under pressure, while the other passage c is alternately connected with the exhaust passage a. In traveling to the left, the driving piston has uncovered the passageway f, and the pressure water enters the chamber of the auxiliary valve at its right end, thereby forcing the auxiliary valve to the left end of its cylinder. The other end of the cylinder is exhausting through f into the exhaust chamber g in the driving cylinder. When the auxiliary valve has traveled to the left, water under pressure passes from b through c into the space formed between the main valve and cylinder heads.
Fig. 323. - Connections for Water Lift.
The pressure exerted on the main valve at its left end shifts it over to the right, and water under pressure from the chamber d at the left, passes into the driving cylinder at its left end, by way of the port leading into it. The driving piston is then forced to the right, uncovering f, and producing a series of operations similar to those just described. When the auxiliary valve shifts the pressure to either end of the main valve, the opposite end will be exhausting, and when the main piston brings the pressure on either end of the auxiliary valve, the other end will be exhaust-ing. Because of this action, neither of the two valves meets with any resistance, and pressure water is against the main valve throughout its stroke. This makes it impossible for the lift to become centered. In the illustration Fig. 323, the cylinder at the right is known as the driving cylinder, and that at the left as the suction cylinder. There is no connection whatever, between the two cylinders. Rigidly connected to the same piston rod, are the driving piston and the suction piston, each working in its own cylinder. The suction pipe is connected at the center of the suction cylinder, and as the piston passes its entrance, a vacuum is created, which draws the water to be lifted, into the suction cylinder, from which, on the next stroke of the piston, it is forced up into the discharge pipe, two check valves holding the water as it is forced up. The air chamber prevents any shock due to the pumping.
Fig. 324. - Water Lift Used on Direct Pressure System.
There are various ways and various systems in which the water lift may be applied. Perhaps the simplest and most common system on which it is used, is the one shown in Fig. 324. This is called the direct-pressure system. It may be operated in city or town work by means of the public water supply, and in country work by means of attic or windmill storage tanks. In this system, the water lift under street pressure, pumps filtered water or soft water, as the case may be, directly into the pipes supplying the fixtures.
An important part of this system is the compression tank. When water is pumped into the tank, it compresses the air in it, and whenever water is drawn at any fixture, the compressed air forces it out under pressure. Whenever the air in the tank becomes exhausted, it may be renewed by opening slightly the bibb on the suction pipe. Owing to the vacuum produced by the piston in the suction chamber, air will be drawn in and be delivered into the tank. In order that air may not be carried out more than possible when the tank is drawn upon, the supply to the fixtures from the tank is taken out of the latter at the bottom. The discharge from the lift into the compression tank is connected into the top of the latter. The use of the tank gives a steady stream and reduces the shock and hammering of pumping. By operating the valves on the cross-connection between lift and compression tank, water from the city mains may be delivered to the fixtures direct in the event that the soft or filtered water supply becomes exhausted. The water lift is now extensively used in connection with the automatic storage-tank system, which is often made use of in supplying soft or filtered water in large quantity. This system is shown in Fig. 324, and in Fig. 325 a sectional view of the automatic storage tank, the action of the latter being as follows:
Fig. 325. - Automatic Storage Tank.
Fig. 326. - Water Lift Used on Automatic Storage Tank System.
This tank is supplied by the water lift through a ball cock whose float works in a cylinder A, of small size, placed inside the storage tank. Two other floats, X and Y are connected by a lever seating arrangement to two openings into the top and bottom of the cylinder F. Whenever the water falls below the level slightly above C, the float Y falls and opens the lower opening, through which the water in A escapes, causing the float F to drop, this action causing the ball cock to open, and also relieving the pressure on the cut-off shown in Fig. 326. The lift then starts into operation, forcing water up into the tank until the water reaches the level B. When this level is reached the float X is raised, thus opening the upper inlet into A, filling the latter with water, and raising the float F, which shuts off the ball cock,
The pressure of the water in the pipe between the lift and the tank is sufficient when the ball cock closes to close the automatic cut-off, which results in cutting off the water pressure from the lift. The water lift remains inactive until enough water has been drawn from the tank to bring the water level down to C again. By the use of the valves A and B, water from the city mains may be delivered to the fixtures when the regular supply is for any reason cut off. A modification of this system is often found in high city buildings in which the public water supply is not of sufficiently high pressure to supply the upper floors. In this system the lower floors are supplied by city pressure in the ordinary manner, while the upper floors are supplied from the automatic storage tank in connection with the water lift. It will be seen that under these conditions, the city pressure being the operating power and also the supply that is to be pumped, the supply to the lift and the suction must each be connected to the public water supply system. There are several other systems of supply, to which the water lift may be applied, which might be illustrated and described, if space permitted.
The advantages of the water lift are many, among them being the fact that its operation is automatic, requiring no attendant and little attention; it uses comparatively little water in operating; the action of the lift is comparatively noiseless, and there is little wear and tear on the working parts.