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.
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.
IMPORTANT PRINCIPLES RELATING TO WATER.
There are some underlying natural laws and other data relating to water which every engineer should thoroughly understand. Heat, water, steam, are the three properties with which he has first to deal.