Sump pump discharge head
Sump pump discharge head
(OP)
I am new to centrifugal pumps. I have a pump above a sump open to atmosphere by 12'. There is a pressure gauge on the discharge of the pump reading 40 psi. When I look at the pump curve, do I add in the 12' of head to the 40 psi, or just read the 40 psi?
Also, when the level drops in the sump, the discharge pressure drops also. I thought that was strange. It should remain constant, right? Am I deadheading the pump?
Also, when the level drops in the sump, the discharge pressure drops also. I thought that was strange. It should remain constant, right? Am I deadheading the pump?





RE: Sump pump discharge head
To answer your question, you can't tell what the discharge pressure will be, if you only know the suction head and the pump curve.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Sump pump discharge head
So if the discharge pressure reading is 40 psig, and the suction is -5 psig, I am at 35 psig on the pump curve?
RE: Sump pump discharge head
The curve reflects *differential* head.
With your readings, you are seeing 45 psi differential, or about 104 feet of water.
Looking at it another way, 40 psig x 2.31 ft/psi = 92.4 ft
But you are also lifting 12 feet on the suction side...
92.4 + 12 = 104.4 ft; 104.4/2.31 = 45.2 psi differential.
I sure hope I am not wrong. I hate it when I am wrong.
Regards,
SNORGY.
RE: Sump pump discharge head
That is, if there is 12 feet of available suction head.
(by the description so far, I can't really be sure, but it looks like that)
<And neglecting any velocity heads>
Total Discharge Head = 40 psi * 144 / 62.4 = 92.3 ft
Suction Pressure = 12 ft * 62.4/144 = 5.2 psi
Pump Differential Pressure = 40 psi - 5.2
Pump Differential Pressure = 40 - 5.2 = 34.8 psi,
Pump Differential Head = 34.8 * 144/62.4 = 80.3 ft
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Sump pump discharge head
thanks biginch, that makes sense
RE: Sump pump discharge head
RE: Sump pump discharge head
RE: Sump pump discharge head
thanks guys
RE: Sump pump discharge head
Timmy, Next time you must post an accompayning diagram!
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Sump pump discharge head
RE: Sump pump discharge head
If I am wrong...
Maybe I should keep my night job (dog trainer)...
Oh well. Sit happens.
(Sadly, sometimes it doesn't...this isn't boding well for me in either career...)
But seriously...
If it's -5 psi on one side and +40 psi on the other side, the differential is 45 psi. That's the extent to which I looked at it initially.
Thanks JohnGP and timmmyc00.
Star to BigInch for the diagram, a whole other "perspective" on things.
Regards,
SNORGY.
RE: Sump pump discharge head
Sorry for the confusion. Back to the kennel now. Got a spare cage?
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/