Leeson Electric Motor

Have you ever wondered how to quickly and accurately size the correct horsepower for an application?  Here is another short lesson in technical applications.  In order to correctly size the horsepower for an application one must perform the following equation in order to calculate by the pressure.  This is accomplished by taking the pressure (psi) x flow rate (gpm) divided by the constant for the particular type of pump, (based on the efficiency of the pump type).

For Piston and Plunger pumps, the constant factor is 1460. Roller pumps 1030. Diaphragm pumps 1370. Centrifugal and Gear pumps can vary greatly and must be engineered to the specific application.

Example 1: Plunger pump rated flow is 4gpm at 2000psi. “EBH” or Electric Brake Horsepower required would be 4×2000 = 8000 divided by 1460 = 5.48 This would require an electric motor with at least 5.48 horsepower output to allow the pump to operate at peak performance. In this instance you would most likely need to use a 7-1/2hp electric motor as most motor brands are generally 2hp, 3hp, 5hp, 7-1/2hp, 10hp, etc.

Example 2: Diaphragm pump rated flow is 12gpm at 500psi. “EBH” would be 12×500 = 6000 divided by 1370 = 4.38 This would require an electric motor with at least 4.38 horsepower output to allow this pump to operate at peak performance.

For calculating gas or diesel engine horsepower requirements, a general rule is to take EBH required x 2.0. Example 1 above would require 5.48 EBH x 2. 0 = 10.96 engine horsepower requirement. Therefore you would need a gas or diesel engine that will develop at least 10.96 horsepower to allow the pump to operate at peak performance.

Depending on specific brands, “engine” horsepower requirement could be reduced slightly in some instances.  We certainly hope that this was useful.  Be good out there.

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