Can anyone help this Pumps & Systems reader with his question on the Pump Chat Forum? Please respond on the forum page so that he will see it. Thanks!

Why would one want to use a PD pump in such a simple application? Joe

Dear Joe,
If you can visualize the pump head curve for a centrifugal pump and that for a PD pump, the answer is obvious. Here, there is pressure variation but flow rem,ains same more or less.

Why not use a centrifugal controlled by a VFD for constant flow operation. Probably half the cost of an equivalent PD pump.

Yes, you can do that too but it all depend upon your site location and also How frequent the pressure change will be. If you are in a remote place, you should have the simplest system. Again if the VFD is not designed for constant changing of head, the speed will rise, fall,fall further rise etc etc. This will shorten the life of your VFD.
I also do not think that there will that much of a price difference. You are not considering the price of the variable speed system. Well, you may save money but the solution is not suited to the problem.