Fluid Mechanics
Flow Through Orifice / Nozzle
Calculate flow rate through an orifice plate, nozzle or sharp-edged hole based on upstream pressure and geometry.
Units:
The discharge coefficient Cd depends on the orifice type: sharp-edged orifice ≈ 0.61, rounded nozzle ≈ 0.98, Venturi ≈ 0.98. For pneumatic quick-exhaust valves and throttle valves, use Cd = 0.60–0.65.
Q = Cd × A × √(2 × ΔP / ρ) [m³/s]
Input
Orifice diameter d iDiameter of the orifice or nozzle opening in mm.
mm
Upstream pressure P1 iGauge pressure upstream of the orifice in bar.
bar
Downstream pressure P2 iGauge pressure downstream of the orifice in bar.
bar
Discharge coefficient Cd iDischarge coefficient. Sharp-edged orifice: 0.61. Rounded nozzle: 0.97. Venturi: 0.98.
Fluid density ρ iFluid density in kg/m³. Water: 1000, Hydraulic oil: 870.
kg/m³
Result
Orifice area A [mm²]
—
Pressure differential ΔP [bar]
—
Flow rate Q [m³/s]
—
Flow rate Q [l/min]
—
Flow rate Q [m³/h]
—