Hydraulic Calculator for Nonpressure Pipe

This calculator determines velocity, flow rate, or slope in PVC gravity sewer pipe using the Manning’s Equation (in U.S. Customary units):

where:

• V = mean flow velocity, ft/s
• n = coefficient of roughness, dimensionless
• R_H = hydraulic radius, ft
• s = hydraulic slope for nonpressure pipe, ft/ft

The user can select to solve for:

• velocity and flow rate
• slope and flow rate
• slope and velocity

Laboratory testing of new pipe and field testing of in-service pipe have both confirmed that a Manning’s “n” value of 0.009 is conservative for solid-wall PVC sewer pipe. This value is recommended for hydraulic design. Click here for more information.