159. In the case of isolated buildings, such as country residences, the architect is frequently required, not only to specify fixtures and piping, but also means for procuring water. A slight knowledge of the machinery which is available for that purpose, is therefore necessary.

In city houses, machinery is used for pumping water into tanks on the top floors, when the pressure upon the street mains is insufficient to raise the water high enough to properly supply the upper floors.

For raising water to a moderate height from wells or cisterns, say about 10 feet, chain pumps are to be preferred, because they agitate, and thus to some extent aerate the water. They cannot be used for forcing, however, and when the lift is great, a piston or plunger pump must be used.

160. Pneumatic pressure may be employed to force water to a building by simply forcing the water into a large closed vessel furnished with an inlet and outlet pipe so attached that the air will be locked in the vessel and cannot be forced out with the flow of the water. An arrangement similar to that shown in Fig. 60 will answer the purpose.

An air-tight metal cylinder A, having an inlet pipe a connecting it to the delivery pipe b of the force pump shown, and an outlet pipe c leading to the house to be supplied with water, forms an underground storage tank under pressure.

Fig. 60.

A check-valve d prevents the water in A from flowing back through b into the pump or out of the draw-off cock e above the surface of the ground. It will be seen that the plunger in the pump cylinder, which is under water in the well, is operated by the application of force to the handle of the bent lever f, the fulcrum of which is solidly bolted to a platform over the well. The pump shown is single acting, and it raises water with the up stroke of the plunger. A stuffingbox at g, through which the plunger rod h moves, makes a water-tight joint.

A stop and waste cock on the pipe which supplies e, can be operated by a T-handle key i. This is only for winter use to shut off water from e and drain its supply pipe below frost. This plan of underground storage has the advantage of always keeping the water cool in summer and of storing it away where foul odors cannot contaminate it. It has also two disadvantages: First, the pressure will be irregular, gradually-decreasing as the water flows from the cylinder. Second, unless air be forced into the cylinder, that contained in the cylinder will soon be absorbed by the water.

161. If a small stream of good water, having a fall of 5 feet or more, flows within a reasonable distance of the premises, a hydraulic ram may be used to great advantage to pump a steady supply of water into a suitable house tank. These rams are also made double, so that they may be operated by a stream of dirty or impure water, but take pure water from some other source and elevate it to the point desired.

The drive pipes which are attached to hydraulic rams should be of wrought iron or brass, because the hammering of the water columns will rapidly destroy ordinary lead pipes. They should not be less than 30 or 40 feet long, otherwise the weight of the driving columns will be too small. If two or more rams are used, each must have its own independent driving pipe; but they may all discharge into the same delivery pipe. If angles or bends are necessary in any of the pipes, they should be made by bending the pipes to as large a radius as practicable. Angles should not be made with ordinary pipe fittings, because they seriously impede the movements of the water.

162. When windmills are employed for raising water, it is especially necessary that the pumps, which are single acting, be provided with extra large air chambers, otherwise the mill is liable to hammer itself to pieces, or make an unbearable amount of noise.

163. Hot-air engines are very well adapted for pumping purposes. They require very little attention and use but little fuel. Care must be taken to avoid overheating them, and to keep them properly lubricated. If the engine is of the vertical type, the engine-house roof must be made high enough to permit the removal of the pistons by means of a block and tackle. There should be a hatch in the roof large enough to allow the pump rods and tubes to be lifted out of the well.

When it is necessary for the pump to raise water to a height greater than 100 feet, such as is often the case in country buildings, a double-cylinder hot-air engine is most commonly used. With this class of engine, coal is generally used as the fuel, although furnaces can be had which will burn any kind of fuel.

These engines must be set upon a solid foundation, preferably a concrete floor, and the base should be bolted to the floor. They must also be set perfectly plumb, so that the pistons, which are very heavy, will bear equally all around. Hot-air engines are specially adapted for pumping where unskilled labor is employed to run them.

164. Another type of engine which has been recently perfected is the oil engine. This machine uses a small quantity of oil, varying in kind, from crude petroleum to gasoline, to a gas which is exploded in the cylinder of the engine. For the same power they are much smaller in size than hot-air engines. There is no danger connected with their use, except that which arises from the presence of the oil tank upon the premises. They require a certain amount of cooling water to be circulated through them. Usually the water which is pumped by them can be used for cooling, without objection. They can be used anywhere, and can be operated by almost anybody.

165. In towns where gas or electricity can be obtained, gas engines or electric motors may be employed to good advantage for pumping purposes.

For hotels, and other places which require a large amount of water, the steam pump is probably the best machine that can be employed.