

The head loss for 100 ft pipe can be calculated as The roughness coefficient for PEH pipe is 140 and the length of the pipe is 30 ft. Example - Friction Head Loss in Water PipeĢ00 gal/min of water flows in a 3 inch PEH pipe DR 15 with inside diameter 3.048 inches.

Be aware that the roughness constants are based on "normal" conditions with approximately 1 m/s (3 ft/sec). Note that the Hazen-Williams formula is empirical and lacks a theoretical basis. H 100ft = friction head loss in feet of water per 100 feet of pipe (ft h20/100 ft pipe) Since the Darcy-Weisbach equation requires iterative calculation an alternative empirical head loss calculation like the Hazen-Williams equation may be preferred: The Darcy-Weisbach equation with the Moody diagram is considered to be the most accurate model for estimating frictional head loss for a steady pipe flow.
