This section is from the book "The Building Trades Pocketbook", by International Correspondence Schools. Also available from Amazon: Building Trades Pocketbook: a Handy Manual of reference on Building Construction.
This machine is employed to raise water to a point higher than the source of supply; it is chiefly used where a large flow of water with a low fall is obtainable, and raises part of the water which operates it. The efficiency varies with the ratio of the rise of the discharge to the fall of the drive pipe, about as follows:
Ratio of lift to fall, 4, 6, 8, 10, 12, 14, 10, 18, 20, 22, 24, 26. Pet cent, efficiency, 72, 61, 52, 44, 37, 31, 25,19,14, 9, 4, 0. To obtain the highest efficiency with any fall, the dash valve should be adjusted to close at the instant the water in the drive pipe has attained its maximum velocity.
A ram having a discharge pipe 80 or 100 ft. long will deliver about 1/7 the quantity supplied to a height about five times the fall; or 1/14 the quantity supplied to a height of ten times the fall.
If the pipes are lead, the drive pipe should be of the A grade, for diameters up to 2 in., and cast or wrought iron for greater diameters. The discharge pipe, if lead, should be of the B grade for rises of 50 ft. or less, and of the A grade for rises between 50 and 100 ft. For falls greater than 10 ft., or rises of more than 100 ft., the pipe must be heavier than just given. The length of drive pipe should be from 25 to 50 ft. If the discharge pipe is very long (say 1/4 mile) a larger size than given in the table should be used. With a given supply of water under a great fall, the ram need not be as large as for the same quantity of water under a less fall. When large quantities of water are to be raised, it is better to increase the number of rams, in preference to having one of capacity. Several rams may be set so as to deliver into one discharge pipe, each having a separate drive pipe.
These are used to store rain water underground, for use in country buildings. For an ordinary house with 8 rooms or less, located in a climate where the rainfall is not less than 30 in. per annum, and where very long droughts do not occur, a brick cistern 5 ft. in diameter and 7 ft. deep will be large enough for a family of 10 people. Larger buildings should be provided with two or more cisterns.
Water Supply to Ram. Gal. per Min.
Size of Pipe.
Cistern filters are essential in all cases. Fig. 14 shows an excellent and simple form, which may be built a few feet away from the cistern, and connected to it by the pipe f. The filter well is built of brick, laid in 1-to-l Portland cement mortar, and is divided into two compartments by a partition slab a of slate or flagstone. The bottom is inclined so that the sediment will collect at d. The chamber B has a perforated bottom b, upon which is placed a course of gravel, then clean sand, and is topped with gravel nearly up to the level of the discharge pipe f. Rain water enters A through the pipe c, and deposits any mud that it may contain, at d. Any overflow in A is discharged through pipe e. The water flows upwards through the sand in chamber B, which clarifies it. The filter may be easily cleaned by stopping up f, pouring water into B, and pumping out the mud and dirty water from A. Renewal of the filtering material is thus seldom necessary.