Net Positive Suction head NPSH
Net Positive Suction head NPSH
(OP)
I'm going to design a water pipe system onsite fire hydrants for our project site and it requires a booster pump to meet a minimum 20 psi on the pipe system. I'm using waterCAD for analyzing the pipe system. Everytime I run it, it gives me a warning that -20 psi gage pressure on the suction side of the pump and pipe junction upstream or on the side of the pump. The same junction has a positive available pressure, although not enough, when the system is analyzed without the pump. Is the -20 psi gage pressure theoretically caused by the impeller? Is the positive pressure analyzed without the pump (which is gage pressure minus pressure loss due to friction) what I should account for the Net Positive Suction Head Available NPSH (A)? Or Is it the -20 psi gage pressure? Thanks in advance.





RE: Net Positive Suction head NPSH
RE: Net Positive Suction head NPSH
If no then nothing should change. If yes then your friction losses will increase and hence inlet pressure might fall.
Look up NPSH and there are many good explainatons of what this is and how to calculate.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Net Positive Suction head NPSH
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Net Positive Suction head NPSH
RE: Net Positive Suction head NPSH
RE: Net Positive Suction head NPSH
NPSH required is published by Pump Manufacturer
NPSH available must exceed NPSH required.