Pipe Friction Tables - by Nelsen Corporation
Friction loss
Pipe friction is the resistance to flow created by the interior surface of the pipe through which a liquid is moving. The smaller the diameter of the pipe, or greater the rate of flow, the greater the amount of friction (friction loss).
Friction loss is expressed as feet of head in 100 feet of pipe and will vary depending upon the material of which the pipe is made. The following charts show friction losses in steel, copper, and plastic pipe, Pipe size should be sufficiently large so that not more than 10% of the total dynamic head is in friction loss.
| Equivalent Number of Feet Straight Pipe for Different Fittings | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Size of fittings, Inches | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 4" | 5" | 6" |
| 90° EII | 1.5 | 2 | 2.7 | 3.5 | 4.3 | 5.5 | 6.5 | 8 | 10 | 14 | 15 |
| 45° EII | 0.8 | 1 | 1.3 | 1.7 | 2 | 2.5 | 3 | 3.8 | 5 | 6.3 | 7.1 |
| Long sweep EII | 1 | 1.4 | 1.7 | 2.3 | 2.7 | 3.5 | 4.2 | 5.2 | 7 | 9 | 11 |
| Close return bend | 3.6 | 5 | 6 | 8.3 | 10 | 13 | 15 | 18 | 24 | 31 | 37 |
| Tee-straight run | 1 | 2 | 2 | 3 | 3 | 4 | 5 | ||||
| Tee-side inlet or outlet | 3.3 | 4.5 | 5.7 | 7.6 | 9 | 12 | 14 | 17 | 22 | 27 | 31 |
| Globe valve open | 17 | 22 | 27 | 36 | 43 | 55 | 67 | 82 | 110 | 140 | 160 |
| Angle valve open | 8.4 | 12 | 15 | 18 | 22 | 28 | 33 | 42 | 58 | 70 | 83 |
| Gate valve - fully open | 0.4 | 0.5 | 0.6 | 0.8 | 1 | 1.2 | 1.4 | 1.7 | 2.3 | 2.9 | 3.5 |
| Check valve (Swing) | 4 | 5 | 7 | 9 | 11 | 13 | 16 | 20 | 26 | 33 | 39 |
| Chcek valve (Spring) | 4 | 6 | 8 | 12 | 14 | 19 | 23 | 32 | 43 | 58 | |
Figure friction loss for 118.5 ft. of pipe
(B) Assume flow to be 80 GPM through 2" plastic pipe.
Friction loss table shows 10.9 ft. loss per 100 ft. of pipe.
- In step (A) we have determined total feet of pipe to be 118.5 ft.
- Convert 118.5 ft. to percentage 118.5 ÷ 100 = 1.185.
- Multiply 10.9 x 1.185 = 12.9165 or 12.92 ft. = Total friction loss in this system
Example
(A) 100 ft. of 2" plastic pipe with one (1) 90° elbow and one
(1) swing check valve.
| 90° elbow — Equivalent to | 5.5 ft. of straight pipe |
|---|---|
| Swing Check — Equivalent to | 13.0 ft. of straight pipe |
| 100 ft. of pipe — Equivalent to | 100.0 ft. of straight pipe |
| 118.5 ft. = Total equivalent pipe |
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Figure friction loss for 118.5 ft. of pipe
(B) Assume flow to be 80 GPM through 2" plastic pipe.
- Friction loss table shows 10.9 ft. loss per 100 ft. of pipe.
- In step (A) we have determined total feet of pipe to be 118.5 ft.
- Convert 118.5 ft. to percentage 118.5 ÷ 100 = 1.185.
- Multiply 10.9 x 1.185 = 12.9165 or 12.92 ft. = Total friction loss in this system
Example
(A) 100 ft. of 2" plastic pipe with one (1) 90° elbow and one
(1) swing check valve.