Friction Factors for Corrugated Plastic Tubing

Abstract

Hydraulic tests on corrugated plastic drain tubing were conducted at the Southwestern Irrigation Field Station of the Agricultural Research Service, Brawley, CA. Manning&s n and Darcy-Weisback f were determined for commercially available tubing from 1.375 to 4-in. nominal diameter. An average design value of Manning's n of 0.016 is recommended for 2-in. through 3-in. diam. corrugated plastic tubing for grades over 0.001. For lower grades with these diameters an average design value of Manning's n of 0.017 is recommended. For corrugated plastic tubing less than 2 inches in diameter and average design value of Manning's n of 0.018 is recommended. Humps and depressional variations up to two diameters fro ma uniform grade do not increase head losses in full-flowing lines.