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How is Net Positive Suction Head (NPSH) calculated for a pump?

+1 vote
245 views asked Aug 28, 2014 by Mepanet

2 Answers

0 votes

NPSH = hatm ± hz(s) - hf(s) - hvp


hatm = Atmospheric pressure 14.7 (33.9ft)
hz(s) = Elevation above pump suction (ft), note ithat f pump is located above the water level the hz(s) will be negative
hf(s) = Friction loss in suction pipe (ft)
hvp  = Vapor pressure (from steam table per water temp.) – (ft), note that Vapor pressure in steam table should be converted to feet by multiplying by 2.307.

To prevent captivation in pump’s impeller, the NPSH at pump’s suction pipe should be more than the NPSH pump: NPSHA > NPSHR

NPSHA = Net Positive Suction Head Available (system)
NPSHR = Net Positive Suction Head required (pump)

answered Aug 28, 2014 by Mepanet
0 votes
Thank's a lot.
answered Mar 14, 2015 by M.Safarpoor Khaledi

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