Orifice Plate Flow Calculator
Airflow from an orifice plate differential pressure reading.
Enter your values
ⓘ Live results
Results
- Airflow
- 53 CFM
- Orifice velocity
- 10.2 ft/s
- Orifice area
- 0.0873 sq ft
Quick answer
Flow through an orifice plate is proportional to the discharge coefficient, orifice area and the square root of the differential pressure.
Q = C x A x sqrt(2 x dP / rho)
How to use the Orifice Plate Flow Calculator
- 1Enter the orifice bore diameter, discharge coefficient (typically 0.6-0.62 for sharp-edged plates) and measured differential pressure.
- 2The tool converts pressure to velocity through the orifice and multiplies by area.
- 3Confirm the coefficient against the plate manufacturer's calibration for best accuracy.
Worked example
Using the values the calculator loads with:
Inputs
- Orifice diameter4 in
- Differential pressure2.0 in wc
- Discharge coefficient0.61
- Air density0.075 lb/ft3
Results
- Airflow53 CFM
- Orifice velocity10.2 ft/s
- Orifice area0.0873 sq ft
Frequently asked questions
Where is Cd from?
Sharp-edged concentric orifice plates typically use 0.60-0.62; use the manufacturer's calibrated value if available.
Does beta ratio matter?
Yes for precise metering; this calculator assumes a simple orifice-in-duct approximation.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.