Volumetric Efficiency

When a positive displacement pump is operating under a slip condition the pump looses the ability to deliver the volume of fluid it is theoretically capable of pumping.

Volumetric Efficiency = Actual Flow (/) Theoretical Flow

For a given pump and fluid the slip is proportional to the pressure differential from outlet to inlet. If the pump had no slip the volume pumped would be directly proportional to speed (RPM).

• When slip occurs the Actual Flow is reduced.

• IIf a certain flow is required at a given pressure the speed (RPM) must be increased.