First you need the size of the pipe and the volume of water supply. Pressure will vary during usage. Standard well system operates between 2040 psi and city systems operate from
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1. Multiply water horsepower by 3,960. If the pump works at 18 horsepower: 18 x 3960 = 71,280. 2. Multiply your answer by the pump's efficiency. If it runs at 90 percent efficiency:
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The flow rate
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You cannot calculate pressure (psi) from pipe diameter and gpm. You can only calculate flow rate. Pressure is resistance to flow. Maximum pressure cannot be calculated until the flow
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