What is the difference b/w npsh and npshr
How can one calculate it
Its meaning and maximum info. Regarding it

NPSH is net positive suction head , NPSHa & NPSHr are the NPSH available and required for the pump. NPSHr is given by the manufacturer of pump and calculated by precise testing on test rig.NPSHa is actual available suction head at impeller eye of pump at user site.NPSHa is calculated =suction head available-vapor pressure of pumping fluid at pumping temperature- friction losses in suction piping. NPSHr+~2kg/cm2>=NPSHa. If this is not met at site pump will caviate.