Entrapped air bubbled causing high head?
Entrapped air bubbled causing high head?
(OP)
I have a sump pump discharging at a head 50% higher than the system curve calculated (147' instead of 95'). The sump pump is self priming and tees into a line charged at ~30 psig. There is a 16' elevation change from the pump discharge into the tee. There are no dips in the piping, it is all 90s and straight pipe. However, I was thinking that it could be possible to run the pump dry when priming and introduce an air bubble that would be trapped in the line, causing high dP and low flow. There is a check valve immediately downstream of the pump discharge. Has anyone experienced something like this? Is this correct thinking?
-Mike





RE: Entrapped air bubbled causing high head?
I'd look either at scale in the pipe (reducing the pipe ID and increasing velocity and friction) or a problem with an outlet valve or an increase in the header pressure.
Is there anywhere to put a gauge immediately downstream of the check valve (sometimes there is a plug in the valve body that can be used) to see if maybe the discharge check is jammed partially shut when it should be fully open. If that isn't possible, I'd look at either running a camera or dropping out a section of pipe to inspect it if this is a big enough problem to shut down for.
David
RE: Entrapped air bubbled causing high head?
Johnny Pellin
RE: Entrapped air bubbled causing high head?
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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: Entrapped air bubbled causing high head?
I'll follow up on the post once the work is complete.
-Mike
RE: Entrapped air bubbled causing high head?
RE: Entrapped air bubbled causing high head?
thread161-250230: Excessively High Static Head Reading