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# How to Calculate the Power of a Reciprocating Pump

by Chris Daniels

A reciprocating pump is a type of positive displacement pump that uses a piston, plunger or diaphragm to drive pressure into the pumped fluid. The power needed to drive a reciprocating pump depends on the maximum pressure, pump capacity and mechanical efficiency of the pump. You must know these quantities to calculate the reciprocating pump power.

#### Step 1

Determine or calculate the reciprocating pump capacity, normally denoted as Q. If Q is not known, you can calculate it by multiplying the pump's displacement, the amount of fluid displaced per unit time, and the pump's volumetric efficiency, the percentage of the total volume of the pump cylinder that is displaced during each stroke.

#### Step 2

Determine the pressure, denoted as P, at which the reciprocating pump operates. The operating pressure is listed with the pump specifications.

#### Step 3

Determine the mechanical efficiency, ME, of the reciprocating pump. The values normally range between 80 and 95 percent, according to Joe Evans, Ph.D., an expert from PumpTech, Inc.

Calculate the pump power, in brake horsepower or bhp, using the following formula: bhp = (Q X P) / (1714 X ME) 1714 is a conversion factor to produce a result in terms of brake horsepower.