Drainage Pipe Pitch

Overview

Engineering reference data for Drainage Pipe Pitch in fluid mechanics.

Key Formulas

Reynolds Number

$Re = \frac{\rho v D}{\mu}$

Ratio of inertial to viscous forces — determines flow regime.

Bernoulli's Equation

$P + \frac{1}{2}\rho v^2 + \rho g h = \text{const}$

Conservation of energy for steady, inviscid, incompressible flow.

Continuity Equation

$A_1 v_1 = A_2 v_2$

Conservation of mass for incompressible flow.

Darcy-Weisbach

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

Pressure drop due to friction in a pipe.

Variables

Drainage Pipe Pitch Standards

The required slope for horizontal drainage pipes depends on the pipe diameter to maintain adequate flow velocity and prevent sediment buildup. The following standards are commonly used:

Key Notes

• Pitch is the vertical drop per unit of horizontal length. A pitch of 1/4 in/ft means the pipe drops 1/4 inch for every foot of horizontal run.
• Gradient is the ratio of vertical drop to horizontal distance. A gradient of 1:50 means 1 unit of drop for every 50 units of horizontal distance.
• Larger diameter pipes require less slope because they have a greater capacity to handle flow at lower velocities.

Interactive Charts

References

• Original Source