The suction chamber is used to prevent pounding when the pump reverses and to enable the pump barrel to fill when the speed is high.
Suction is the unbalanced pressure of the air which is at sea level 147⁄10 per inch, or 2096.8 per square foot.
When a valve is spoken of in connection with a pump it may be understood that there may be several valves dividing and performing the functions of one.
A simple method of obtaining tight pump-valves consists simply in grooving the valve-sheets and inserting a rubber cord in the grooves. As the valves seat themselves the cord is compressed and forms a tight joint. An additional advantage is that it prevents the shock ordinarily produced by rapid closing and prolongs the life of the valve seat. The rubber cord when worn can be easily and quickly replaced.
CALCULATIONS RELATING TO PUMPS.
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.).