orifice nozzle venturi

Overview

Orifice plates, nozzles, and Venturi meters are differential pressure flow meters. They create a constriction that increases velocity and decreases pressure, allowing flow rate calculation from the pressure differential.

Key Formulas

Flow Rate

$Q = C_d A_2 \sqrt{\frac{2 \Delta P}{\rho (1 - \beta^4)}}$

Discharge through a differential pressure meter.

Beta Ratio

$\beta = \frac{d}{D}$

Ratio of throat diameter to pipe diameter.

Variables

Symbol	Description	Unit
$Q$	Volume flow rate	m³/s
$C_d$	Discharge coefficient	—
$A_2$	Throat area	m²
$\Delta P$	Pressure differential	Pa
$\rho$	Fluid density	kg/m³
$\beta$	Diameter ratio	—

Reference Data

Orifice Flow Calculator

References

• Original Source