suction pressure losses in submersible pump?
suction pressure losses in submersible pump?
(OP)
Dumb q. for the assembled cognoscenti:
I'm working through the hydraulic modelling for my first wet well. Despite a reasonable amount of experience with pumping systems I haven't really worked with sub pumps before. Simple question on its face:
Are there any suction friction losses to calculate with a submersible pump? In a conventional application I would look at, e.g., tank exit loss plus suction piping run loss plus maybe an elbow or two and an isolation valve. In the case of a sub pump the suction is flooded and right there in the fluid, no plumbing in the way. Do I simply assume the suction side friction loss is zero?
thanks
leaky
I'm working through the hydraulic modelling for my first wet well. Despite a reasonable amount of experience with pumping systems I haven't really worked with sub pumps before. Simple question on its face:
Are there any suction friction losses to calculate with a submersible pump? In a conventional application I would look at, e.g., tank exit loss plus suction piping run loss plus maybe an elbow or two and an isolation valve. In the case of a sub pump the suction is flooded and right there in the fluid, no plumbing in the way. Do I simply assume the suction side friction loss is zero?
thanks
leaky





RE: suction pressure losses in submersible pump?
RE: suction pressure losses in submersible pump?
http://virtualpipeline.spaces.msn.com
"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain
RE: suction pressure losses in submersible pump?
BigInch, your point is a good one, but I believe I've managed to account for it already. The application is clean(-ish) ambient temperature water so the effects on NPSHa are minimal, and the sump is designed such that the pump suction is flooded well beyond the vendor's recommendations.
RE: suction pressure losses in submersible pump?
I guess what I am saying is that it will be pretty negligible compared to your other losses.
Beware of minimum submergence also.
RE: suction pressure losses in submersible pump?
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"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain
RE: suction pressure losses in submersible pump?
http://www.franklin-electric.com/Manual/AIM_07.htm
http://virtualpipeline.spaces.msn.com
"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain
RE: suction pressure losses in submersible pump?
RE: suction pressure losses in submersible pump?
RE: suction pressure losses in submersible pump?
Likewise the close coupled submersibles power ratings include both pump and motor inefficiencies - this is the reason some units look to be inefficient in terms of power input to hydraulic output.
RE: suction pressure losses in submersible pump?
RE: suction pressure losses in submersible pump?
The only time to worry about the submergence is when you are in a tight well, then you may need to be concerned about the flow up past the motor. I am thinking about pumps with very high head as they need all of the NPSH that they can get.
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Plymouth Tube
RE: suction pressure losses in submersible pump?
The statement about tight wells is inaccurate. I have seen pumps create a vortex in large ponds.
RE: suction pressure losses in submersible pump?
http://virtualpipeline.spaces.msn.com
"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain