Pump Decision
Pump Decision
(OP)
I'm having a problem deciding on whether to keep the current centrifugal pump (which periodcally pumps nothing for unknown reasons, a guess is the excessive piping headloss, which is why we're moving the pump location to the bottom of the viscuos liq. column) or to replace it with a pump with half the speed, half the NPSHr and almost twice the impeller size or a PD (moyno) pump. Any suggestions? For any choice we want a 20gpm flow. Sometimes there might be solids in the stream, though rarely.





RE: Pump Decision
You say it could be excessive head-loss, that's fairly easy to check. Is there a suction strainer in the line that could be partially plugged? I'd suggest you stand back and start eliminating causes (which you may have done I realize).
For pump suggestions, you'll need to provide a lot more information than just the flow. What is the head required? What is the fluid? Temperature? Sealing requirements if that's critical wrt emissions? How much NPSHA do you estimate you have? What type of solids? Size range? How much?
RE: Pump Decision
the suggested centrifugal replacement for the current centrifugal is typically the same except for the minimum npshr, impeller diameter and speed.
the moyno was something someone else suggested.
I guess it really just boils down to whether its centrifugals or PD.s
RE: Pump Decision
define the fluid and any solid concentrations,
define the process parameters (pressure, flow, temp, viscosity, etc.),
define any operational requirements or constraints,
then the appropriate pump can be choosen using sound principles.
good luck!
-pmover
RE: Pump Decision
RE: Pump Decision
RE: Pump Decision
- Check the suction line including length, friction loss as you might find much friction loss at the suction line.
- Check the design basis vs. the operating conditions (e.g. solids content, vapor pressure/Temperature/static head..)that might be different and would cause different pump characteristics
- Check the head of the system such as elevation of both destinations, associated fittings and other friction loss piece.
Hope this would help
Cheers
RE: Pump Decision
RE: Pump Decision
What level of viscosity? Like kerosene? Like warm molasses? Like cold molasses? Have you calculated pressure drop in the suction line?