_To find the pressure in pounds per square inch_ of a column of water,
multiply the height of the column in feet by .434, Approximately, we
say that every foot elevation is equal to 1/2 lb. pressure per square
inch; this allows for ordinary friction.
_To find the diameter of a pump cylinder_ to move a given quantity of
water per minute (100 feet of piston being the standard of speed),
divide the number of gallons by 4, then extract the square root, and
the product will be the diameter in inches of the pump cylinder.
_To find quantity of water_ elevated in one minute running at 100 feet
of piston speed per minute. Square the diameter of the water cylinder
in inches and multiply by 4. Example: capacity of a 5 inch cylinder is
desired. The square of the diameter (5 inches) is 25, which, multiplied
by 4, gives 100, the number of gallons per minute (approximately).
_To find the horse power_ necessary to elevate water to a given height,
multiply the weight of the water elevated per minute in lbs. by the
height in feet, and divide the product by 33,000 (an allowance should
be added for water friction, and a further allowance for loss in steam
cylinder, say from 20 to 30 per cent.).
_The area of the steam piston_, multiplied by the steam pressure, gives
the total amount of pressure that can be exerted. _The area of the
water piston_, multiplied by the pressure of water per square inch,
gives the resistance. _A margin_ must be made between the _power_ and
the _resistance_ to _move_ the piston at the required speed—say from 20
to 40 per cent., according to speed and other conditions.
_To find the capacity of a cylinder_ in gallons. Multiplying the area
in inches by the length of stroke in inches will give the total number
of cubic inches; divide this amount by 231 (which is the cubical
contents of a U. S. gallon in inches), and product is the capacity in
gallons.
The temperature 62° F. is the temperature of water used in calculating
the specific gravity of bodies, with respect to the gravity or density
of water as a basis, or as unity.
[Illustration: Fig. 104.]
Important stress has been laid upon keeping all floating objects,
gravel, etc., away from the acting parts of the pump. In Fig. 104 is
presented a cut of an approved strainer which can be removed, freed
from obstruction, and replaced by simply slacking one bolt, the entire
operation occupying one minute. The advantages of this strainer will be
readily apparent.