NPSHA vs NPSHR
NPSHA vs NPSHR
(OP)
I am calculating NPSHA for specifying a 4,000 gpm gasoline pump.
I know manufacturer's pump curve prepare NPSHR curve based upon water. Therefore, I assume NPSHA conponents should all be referenced using water. Is this correct?
For example I am proposing that NPSHA would be 33' water (atmospheric head from an vented storage tank, less 17' water (vp of 7.5 psia gasoline converted to water, plus 3' water static suction head less 4' water friction head (suction losses based upon gasoline then converted to water.
I know manufacturer's pump curve prepare NPSHR curve based upon water. Therefore, I assume NPSHA conponents should all be referenced using water. Is this correct?
For example I am proposing that NPSHA would be 33' water (atmospheric head from an vented storage tank, less 17' water (vp of 7.5 psia gasoline converted to water, plus 3' water static suction head less 4' water friction head (suction losses based upon gasoline then converted to water.





RE: NPSHA vs NPSHR
RE: NPSHA vs NPSHR
You dont need to refer to "water". Calculated the NPSH a as your static head (incl ambient pressure) (inch, feet, meter whatever) - pressure loss in piping - vapour pressure and stick to "absolute pressure" even though this may stress some mechanical engineers.
Best regards
Morten
RE: NPSHA vs NPSHR
May be I was not clear. The correction factor to apply is on the NPSHR not NPSHA. In case of gasoline, I think that no correction is needed.
RE: NPSHA vs NPSHR
RE: NPSHA vs NPSHR
RE: NPSHA vs NPSHR
Best regards
Morten