2023 Online Catalog - Flipbook - Page 489
Pipe Friction Tables 17
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
90° Ell
45° Ell
Long Sweep Ell
Close Return Bend
Tee-Straight Run
Tee-Side Inlet or Outlet
Globe Valve Open
Angle Valve Open
Gate Valve - Fully Open
Check Valve (Swing)
Check Valve (Spring)
1/2"
1.5
0.8
1.0
3.6
1.0
3.3
17.0
8.4
0.4
4.0
4.0
3/4"
2.0
1.0
1.4
5.0
2.0
4.5
22.0
12.0
0.5
5.0
6.0
1"
2.7
1.3
1.7
6.0
2.0
5.7
27.0
15.0
0.6
7.0
8.0
1-1/4"
3.5
1.7
2.3
8.3
3.0
7.6
36.0
18.0
0.8
9.0
12.0
1-1/2"
4.3
2.0
2.7
10.0
3.0
9.0
43.0
22.0
1.0
11.0
14.0
2"
5.5
2.5
3.5
13.0
4.0
12.0
55.0
28.0
1.2
13.0
19.0
2-1/2"
6.5
3.0
4.2
15.0
5.0
14.0
67.0
33.0
1.4
16.0
23.0
3"
8.0
3.8
5.2
18.0
4"
10.0
5.0
7.0
24.0
5"
14.0
6.3
9.0
31.0
6"
15.0
7.1
11.0
37.0
17.0
82.0
42.0
1.7
20.0
32.0
22.0
110.0
58.0
2.3
26.0
43.0
27.0
140.0
70.0
2.9
33.0
58.0
31.0
160.0
83.0
3.5
39.0
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
Figure friction loss for 118.5 ft. of pipe
Technical & Engineering
(B) Assume flow to be 80 GPM through 2" plastic pipe.
1. Friction loss table shows 10.9 ft. loss per 100 ft. of pipe.
2. In step (A) we have determined total feet of pipe to be 118.5 ft.
3. Convert 118.5 ft. to percentage 118.5 ÷ 100 = 1.185.
4. Multiply 10.9 x 1.185 = 12.9165 or 12.92 ft. = Total friction loss in this system
5
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