Orifice Flow Calculator
Calculate volumetric flow rate through orifice plates, flow nozzles, and venturi meters
Results
Flow Rate
—
Orifice Velocity
—
Beta Ratio β = d/D
—
Differential Pressure ΔP
—
Formula Reference
Q = Cd × A × √(2ΔP/ρ) / √(1 − β⁴)
where:
A = π × d² / 4 (orifice area)
β = d / D (beta ratio, diameter ratio)
ΔP = P1 − P2 (differential pressure)
ρ = fluid density
Units (Imperial): Q in ft³/s → convert to GPM (× 448.83)
Units (Metric): Q in m³/s → convert to L/min (× 60000)
where:
A = π × d² / 4 (orifice area)
β = d / D (beta ratio, diameter ratio)
ΔP = P1 − P2 (differential pressure)
ρ = fluid density
Units (Imperial): Q in ft³/s → convert to GPM (× 448.83)
Units (Metric): Q in m³/s → convert to L/min (× 60000)
Worked Example
Water (ρ = 8.34 lb/gal = 62.3 lb/ft³) through a 2-inch orifice plate in a 4-inch pipe. P1 = 100 psi, P2 = 85 psi, Cd = 0.61.
| Parameter | Value |
|---|---|
| ΔP | 15 psi = 2,160 lbf/ft² |
| β = d/D | 2/4 = 0.50 |
| A (orifice) | π×(2/12)²/4 = 0.02182 ft² |
| Flow Q | ≈ 106 GPM |
| Orifice velocity | ≈ 10.8 ft/s |