System NPSH Available (NPSHa)

Pe - Pressure available system inlet liquid level
Pb - Barometric pressure
PD - Vapour pressure of pumped fluid at the pump suction inlet
p - Density of the pumped fluid at the pump suction inlet
g - Local gravitational acceleration (9.81 m/s2)
Ve - Inlet velocity at the system suction inlet
Ze - Static level difference between system inlet liquid level and a reference level, the negative sign becoming applicable if the reference level is above the system inlet liquid.
Hv - Friction loss in suction-side pipework

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