Orifice Flow Calculator

Orifice Flow Calculator: Flow Rate Through a Sharp-Edged Orifice

Orifice plates are among the most common flow measurement devices in combustion systems, relying on a fixed relationship between the pressure drop across the orifice and the flow rate through it. This calculator applies the standard orifice flow equation directly.

The Formula

Q = Cd × A × √(2 × dP / ρ)

Worked Example

An orifice with area 0.01 m² and discharge coefficient 0.62 has a 5,000 Pa pressure drop across it, with fluid density 1.2 kg/m3.

Q = 0.62 × 0.01 × √(2 × 5000 / 1.2) = 0.566 m3/s

How to Use This Calculator

1. Optionally enter the discharge coefficient (0.62 is a common default for a standard sharp-edged orifice).
2. Enter the orifice area in m².
3. Enter the measured pressure drop across the orifice in Pa.
4. Enter the fluid density in kg/m3.
5. Click Calculate to get the volumetric flow rate.

Related Calculations

Cross-check against the Burner Orifice Size Calculator for burner-specific orifice sizing.