The formula for lifting or forcing water either under pressure or head is as follows: P = H A W.
Where H = the distance from the level of the source of supply to the point of discharge. A = area in square feet of surface in contact with the water. W = weight of a cubic foot of water, or 62. 5 lbs.
Example. - What is the pull on a pump rod, when the diameter of a bucket is 6 in. and water is raised 20 ft.?
P = HAW =20 X 6 2 X .7854 / 144 X 62.5 = 245.437 lbs.
From the above solution we find that the pull on the pump rod is 245.437 lbs.; to this must be added the amount of power necessary to overcome friction.