The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

How To Design And Install Plumbing

Duplex Piston Pump. Duplex pumps deliver water on both strokes of two pistons operating in twin cylinders. Pumps of this variety usually contain eight valves, which are synchronized with the piston stroke.

Air Chamber. Fig. 213 represents an air chamber installed on piston pumps to minimize the pulsating discharge from the pump. Pulsation results in an uneven flow of water.

An air chamber is a vessel provided with an opening on its underside. It contains air under atmospheric pressure. When water is forced into it the pressure is increased in direct proportion to the amount of water admitted. The air in this case acts as a cushion, lessening the fluctuation of water flow at the outlet orifice of the pump.

Centrifugal Pump. The centrifugal pump is the type most commonly used for the elevation of water in modern buildings. This type of pumping unit was formerly constructed for circulation of water rather than for elevation of it. In recent years centrifugal pumps have been developed which will elevate water to great heights. The advantage of a centrifugal pump lies in the fact that its motive power can be supplied easily.

Construction of a Centrifugal Pump. A centrifugal pump consists of a housing made of cast iron. The inside of it is accurately machined, forming a chamber into which is built an impeller or water wheel, Fig. 214.

The impeller of the pump usually is built of brass or bronze to prevent corrosion. The impeller in some instances consists of paddles joined to a central shaft. The more efficient impellers are built of a solid piece of metal provided with a number of small waterways or pockets. These cup-like pockets pick up the water on the inlet side of the pump and expel it on the delivery side.

A pump of the centrifugal type permits a great amount of water to slip past the impeller. This cuts down its efficiency to some extent but is not especially detrimental. The discharge capacity of a centrifugal pump is practically unlimited.