Plastic Pipes
The friction head loss (feet H 2 O per 100 feet pipe) in straight plastic pipes made of PVC, PP, PE, PEH or similar can be estimated from the table below.. Head losses are calculated for PVC pipe Schedule 40 by using the HazenWilliams equation and the HazenWilliams roughness constant c = 145. Note that minor loss in fittings must be added when calculating total head .