MCF for Displacement Pumps
MCF for Displacement Pumps
(OP)
Hello;
Minimum continious flow (MCF) is just for centrifugal pumps,
Why does not positive displacement pump operate under this princible?
Is there any another reason except design difference?
Thanks
Minimum continious flow (MCF) is just for centrifugal pumps,
Why does not positive displacement pump operate under this princible?
Is there any another reason except design difference?
Thanks





RE: MCF for Displacement Pumps
Centrifugal pumps can be damaged if operated at excessively high flow rates, even though this is not as harmful as operation below the minimum flow point. Pump operation should be limited so that the discharge pressure is never more than 10% below the design point. Operation at too high a flow rate can result in cavitation damage in the discharge of the pump, seal chattering, and leakage. When a centrifugal pump is operated at a very low flow rate, recirculation occurs within the impeller, and it surges at the natural frequency of the system.
http://www.sundyne.com/StaticFiles/Sundyne_Content...
Positive displacement pumps are of a different design and will different design limitations.
RE: MCF for Displacement Pumps
Is there any another reason except design difference?
You've answered your own question....
In essence centrifugal pumps are constant pressure (within 20%) from zero flow to max rated flow ( though head curves can vary)
positive displacement pumps are constant flow pumps ( +/- 10%) with pressure to match the system requirement from nearly zero up to max pump outlet pressure.
Thus if you don't allow for a full flow bypass / relief in the event of locked outlet flow, the PD pump can create a very high pressure until the motor stalls
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: MCF for Displacement Pumps