VFD on Pumps

[engrkate]

Does anyone know of a reliable resource or relationship for estimating power savings for a VFD pump if the original pump curve is known? The application is a glycol pump in a constant pressure system. It seems to me that direct application of the affinity laws would predict overly optimistic savings. Is that correct?

[Andy]

It seems to me that direct application of the affinity laws would predict overly optimistic savings. Is that correct?

Yes but you have to equate this to how long the pump runs at the reduced speedsa and at full speed.

Savings can be quite favourable on this type of application.

Kind Regards Andy

[US Iceman]

It seems to me that direct application of the affinity laws would predict overly optimistic savings.

The pump curve is what you are working off of. The variation in speed generates the power savings, but I think what you are looking for is the impact of the VFD pump operation as it affects the system curve, not the pump curve.