submersible centrifugal vs dry pit centrifugal pumps
submersible centrifugal vs dry pit centrifugal pumps
(OP)
Designing wastewater treatment plant for non ferrous metal processing wastewater treatment in China. The Chinese typically prefer submersible pumps vs dry pit pumps. The tanks that submersible pumps will set in will also have large mixers running at over 100 rpm with a high rate of tank turnover. On the face of it the submersible seems to be a better choice, low NPSH, lack of cooling problems. My concern is air intake. Thoughts on this appreciated.





RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
For a similar situation, see thread407-276105: Centrifugal Pump Cavitating on tank changeover .
RE: submersible centrifugal vs dry pit centrifugal pumps
Please see URL for diagram
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
If entrained air looks to be a problem the solution is to ensure the mixer is always submerged - however,this in itself may not be cure, even submerged mixer can entrain a lot of free air from the surface, the second solution is to shut down the mixer at a pre-determined sump level so as not to entrain air - alternately use both, keep the mixer submerged and shut it down when air is starting to be entrained.
I have seem a change of direction of the mixer eleviate an air entrainment problem.
Mixers and pumps can be a very poor combination, especially in small sumps.
RE: submersible centrifugal vs dry pit centrifugal pumps
Thanks for this great tip, I thought as much so I am going to go ahead and make necessary design changes based on your input.
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps
For a similar situation, that was solved, see thread407-276105: Centrifugal Pump Cavitating on tank changeover: Centrifugal Pump Cavitating on tank changeover .
RE: submersible centrifugal vs dry pit centrifugal pumps
A great lesson in troubleshooting pump noise, air entrainment problems from mixers, NPSH and so forth Based on this education, going to use variable speed centrifugal pumps, keep the EQ tank large and deep and also going to use submersible pumps. Going to independent mixer expert to review mixer selection recommended by sales engineer.
RE: submersible centrifugal vs dry pit centrifugal pumps
RE: submersible centrifugal vs dry pit centrifugal pumps