Friction Loss in Plumbing

This chart gives friction losses for a given flow rate per 100 feet of pipe.

Example: If you have a 1200 gallon per hour (gph) flow and you are using 1" pipe and you have 30 feet of pipe, your friction loss is 21.75 x 0.3 = 6.52 feet. See the fittings chart below this chart to continue the calculation.

Friction Loss Per 100 Feet of SCH 40 Plastic Pipe
Nominal Pipe Diameter

GPH*

1/2"

3/4"

1 1/4"

1 1/2"

2.08

0.51

120

4.16

1.02

0.55

0.14

0.07

300

23.44

5.73

1.72

0.44

0.22

0.066

0.015

420

43.06

10.52

3.17

0.81

0.38

0.11

0.021

600

82.02

20.04

6.02

1.55

0.72

0.21

0.03

900

42.46

12.77

3.28

1.53

0.45

0.07

1200

72.34

21.75

5.59

2.61

0.76

0.11

0.03

1500

32.88

8.45

3.95

1.15

0.17

0.04

1800

46.08

11.85

5.53

1.62

0.23

0.06

2100

15.76

7.36

2.15

0.31

0.08

2400

20.18

9.43

2.75

0.41

0.11

2700

25.1

11.73

3.43

0.51

0.17

3000

30.51

14.25

4.16

0.61

0.16

3600

19.98

5.84

0.85

0.22

4200

7.76

1.13

0.31

4500

8.82

1.28

0.34

4800

9.94

1.44

0.38

5400

12.37

1.8

0.47

6000

15.03

2.18

0.58

7500

3.31

0.88

9000

4.63

1.22

10500

6.16

1.63

12000

7.88

2.08

15000

11.93

3.15

*Gallons Per Hour

Total the number of fittings and use the chart below to determine the friction loss in the fittings. Add this amount to the pipe total. This section does not apply if you are using flexible PVC.

Friction Loss in PVC Fittings = Equivalent Feet of Straight Pipe
Pipe Size	1/2"	3/4"	1"	1 1/4"	1 1/2"	2"	3"	4"
90 ELBOW	1.5	2	2.25	4	4	6	8	12
45 ELBOW	0.75	1	1.4	1.75	2	2.5	4	5
GATE VALVE	0.3	0.4	0.6	0.8	1	1.5	2	3
TEE-Flow-RUN	1	1.4	1.7	2.3	2.7	4.3	6.3	8.3
TEE-Flow-Branch	4	5	6	7	8	12	16	22


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