Main Vents

Overview

Engineering reference data for Main Vents in piping systems.

Key Formulas

Continuity

$A_1 v_1 = A_2 v_2$

Mass conservation in pipe flow.

Pressure Drop

$\Delta P = f \frac{L}{D} \frac{\rho v^2}{2}$

Darcy-Weisbach equation.

Pipe Area

$A = \frac{\pi D^2}{4}$

Cross-sectional area of a pipe.

Variables

Symbol	Description	Unit
$D$	Pipe diameter	m
$v$	Flow velocity	m/s
$\Delta P$	Pressure drop	Pa
$f$	Friction factor	—

Important Considerations

• At least one vent should terminate through the roof.
• Air admittance valves within the building may be permitted (check with local authority).
• Terminating vents in a side wall may be permitted (check with local authority).

Interactive Charts

References

• Original Source