Online Net Positive Suction Head Calculator.
Net Positive Suction Head Formulas:
Net Positive Suction Head Formulas In terms of head.
Imperial Units:
NPSH= Ha – Hvpa + Hst – Hfs.
where:
NPSH = net positive suction head at reference point (usually center line of the impeller), ft.
Ha = absolute pressure of the suction vessel, ft.
Hvpa = fluid vapor pressure at pumping temperature, ft.
Hst = static head to suction reference point (usually center line of the impeller), ft.
Hfs = suction line losses, ft.
SI Units:
NPSH= Ha – Hvpa + Hst – Hfs.
where:
NPSH = net positive suction head at reference point (usually center line of the impeller), m.
Ha = absolute pressure of the suction vessel, m.
Hvpa = fluid vapor pressure at pumping temperature, m.
Hst = static head to suction reference line (usually center point of the impeller), m.
Hfs = suction line losses, m.
Net Positive Suction Head Formulas In terms of pressure and head.
Imperial Units:
NPSH= (2.31 (Pa – Pvpa) / SG) + Hst – Hfs.
where:
NPSH = net positive suction head at reference point (usually center line of the impeller), ft.
Pa = absolute pressure of the suction vessel, psia.
Pvpa = fluid vapor pressure at pumping temperature, psia.
Hst = static head at reference point (usually center line of the impeller), ft.
Hfs = suction line losses, ft.
SG = specific gravity.
SI Units:
NPSH= ((Pa – Pvpa) /( g * ρ)) + Hst – Hfs.
where:
NPSH = net positive suction head at reference point (usually center line of the impeller), m.
Pa = absolute pressure of the suction vessel, kPa.
Pvpa = fluid vapor pressure at pumping temperature, kPa absolute.
Hst = static head to suction reference line (usually center point of the impeller), m.
Hfs = suction line losses, m.
ρ = fluid density, kg/m3.
g = gravitational constant, 9.81 m/s2.