Профессиональное развитие будущих инженеров-строителей средствами иностранного языка: Лексический практикум по английскому языку. Трубникова Н.В. - 102 стр.

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102

heating of the hot water in the cylinder, a valve can be inserted on the return

circulator. In no circumstance should two valves, be used otherwise the boiler

and pipes will be enclosed and an explosion might follow.

To determine pipe sizes in larger hot-water installations, calcu-

lations based on the quantity of hot water needed should be made, although

previous experience generally provides satisfactory "rule of thumb" guidance.

Any system providing hot water is known as "domestic", we must limit our

concern to the average small-house installation. In general, the back-boiler

used measures about 250 mm in length, is about 200 mm from back to front,

and 150 or 180 mm deep. With an ordinary fire, a boiler of this size provides

enough heating surface to keep the cylinder supplied with hot water. The pri-

mary circulation pipes are normally 19 mm diameter lead or copper pipes.

They should not be less and, if the cylinder is a large one, 25 mm circulation

pipes should be used. The expansion pipe must be equal in size to the circula-

tion pipes, and is usually 19 mm in diameter. The cold feed-pipe is often speci-

fied as one and a halt times the diameter of the largest draw-off. In practice,

equally sized feed and draw off pipes are found to be efficient. In an ordinary

house system they are usually both 19 mm in diameter. There should be no re-

strictions in the supply pipe to bath, so mat a 19 mm pipe to a 19 mm tap is

needed. The branch drew-off pipes to sinks and lavatory basins are generally

12 mm diameter to 12 mm taps.

Waste pipes

Waste pipes from lavatory basins, baths, and sinks may be executed in

lead (traditional), copper, and cast-iron. Individual waste pipes should take the

shortest path, sharp bends should be avoided, and they should be of such size that

they will generally run fairly full and thereby be self-cleaning. Lead "waste pipes

are joined by means of wiped joints. Whenever lead pipe is used, it should be

property supported to avoid sagging. Copper waste pipes, being more rigid than

lead, require less support. Copper tube can be bent to requirement. Cast-iron,

pipes are sometimes used. They should be of heavy-quality, treated inside and

out with a special, bituminous solution. The joints should be caulked with tow