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 @ 20^oC                         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).