Plastic Pipes - Friction Head Loss

Friction head loss (ft/100 ft) in plastic pipes, PVC, PP, PE, PEH

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The pressure head loss (feet H2O per 100 feet pipe) in straight plastic pipes made of materials as PVC, PP, PE, PEH or similar, can be estimated from the table below.

The friction head loss are calculated for PVC pipes Schedule 40 with the Hazen-Williams equation and a Hazen-Williams roughness constant c = 145. Minor loss in fittings must be added.

Pressure Friction Head Loss (ft H2O/100 ft pipe)
Volume Flow Nominal Pipe Diameter (inches)
Gallons Per Minute
(GPM)1) 		Gallons Per Hour
(GPH)2)
3/8 1/2 3/4 1 1 1/4 1 1/2 2 2 1/2 3 4 6
Nominal Inside Diameter (inches)
0.493 0.622 0.824 1.049 1.380 1.610 2.067 2.469 3.068 4.026 6.065
1 60 3.3 1.1 0.3
2 120 11.8 3.8 1.0 0.3 0.1
4 240 42.5 13.7 3.5 1.1 0.3 0.1
5 300 64.2 20.7 5.3 1.6 0.4 0.2
6 360 29.0 7.4 2.3 0.6 0.3
8 480 49.5 12.6 3.9 1.0 0.5 0.1
10 600 74.7 19.0 5.9 1.6 0.7 0.2 0.1
20 1200 68.6 21.2 5.6 2.6 0.8 0.3 0.1
30 1800 11.8 5.6 1.7 0.7 0.2
40 2400 20.1 9.5 2.8 1.2 0.4 0.1
50 3000 14.4 4.3 1.8 0.6 0.2
60 3600 20.1 6.0 2.5 0.9 0.2
70 4200 7.9 3.3 1.2 0.3
80 4800 10.2 4.3 1.5 0.4
90 5400 12.6 5.3 1.9 0.5
100 6000 6.5 2.3 0.6 0.1
125 7500 9.8 3.4 0.9 0.1
150 9000 4.8 1.3 0.2

1) GPM = gallons per minute

2) GPH = gallons per hour

  • 1 gal (US)/min =6.30888x10-5 m3/s = 0.227 m3/h = 0.0631 dm3(liter)/s = 2.228x10-3 ft3/s = 0.1337 ft3/min = 0.8327 Imperial gal (UK)/min
  • 1 ft H2O = 0.3048 m H2O = 0.4335 psi = 62.43 lbs/ft2

Example of Friction Head Loss in Plastic Pipes

A flow of 10 GPM in a 2" pipe gives a head loss of 0.2 feet water column per 100 feet of pipe.

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