306
MODERN STEAM PRACTICE.
61 cubic feet of water requires to be forced to a height of 178 feet,the length of the piping being 8145 feet and the diameter of thepipe 9 inches, we have—
Cubic feet. Length of piping.
61 X 61 = 3 721 X 814 5 = 3°3°75°5
= 23'2 feet,
22 x (9x9x9x9x91= 1299078
as the additional height to be allowed for the friction, or say 24 feetin round numbers; thus 24 feet added to the height the waterrequires to be pumped equals 202 feet: then calculate the horse-power by the ordinary method, namely:
Cubic
Weight of a
feet. Height. cubic foot.61 X 202 X 62 '5
-- = 23-3 horse-power,
to which add one-fourth for loss, and the product is 29 horse-powernearly, irrespective of the friction of the engine.
Formula to find the extra height to allow for friction accordingto the above:—
TT Q 2 l
22 d 6 ’
where Q is the quantity in cubic feet per minute, l the length ofthe line of piping, and d the diameter of the pipes.
Formula to find the horse-power required to overcome the friction:
P represents the horse-power necessary to overcome the friction,/ the length of the pipe in inches, Q the quantity of water to bedelivered in one second in gallons, and d the diameter of the pipein inches. The formula reads, that the cube of the quantity ingallons per second must be multiplied by the length of the line ofpiping in inches, dividing the product by the constant 140 multi-plied by the diameter of the piping into the fifth power.
Delivery of tvater in pipes .—The formula is:
Vd 5
’l x \v !
D = -538-
W = 472 /L V H
V H
where D equals the diameter of the pipes in inches, H the head ofwater in feet, L the length of pipe in feet, and W the cubic feet ofwater discharged in a minute.
G 2 L
'(15 D) 5 H