A pump station has been designed to lift water out of a 6 metre deep pit (vented to atmosphere) via a centrifigual pump mounted at ground level.
Liquid conditions 20 OC
Suction pipe work losses 2.0 metres
NPSH safety factor 5.0 kPa
Vapor pressure @ 20oC 0.25 metres
Calculate the Net Positive Suction Head (NPSH available) for the system ?
In summer the liquid temperature rises to 60 oC, this changes the water vapor pressure to 2.05 metres. What is the revised NPSH available for the higher water temperature ?
Pressure loss in the suction pipe work is directly proportional to water veloicty in the pipe work squared, which is inversely proportional to suction pipe work diameter squared. For the NPSHavailable result from part (b) what increase in suction pipework size is required to have a positive NPSH available result as calculated in part (a).