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Friction Loss Charts
  To help determine friction loss, from pipe, fittings and linear runs.


As water flows through pipe and fittings there is a resistance. The higher the flow and
the smaller the pipe, the higher the resistance. In addition to calculating for head loss
you also need to consider friction loss. Determine size of the pipe and the number and
type of fittings used along with the distance of the run.

  • Use pipe size guidelines to determine the appropriate size tubing to use
  • Use the simple water flow chart, to determine the linear friction loss
  • Use fitting loss chart to determine friction loss for number and type of fittings
  • See hypothetical system ending this article for help on how to use these charts


Pump Size Guidelines Chart
Use Large Enough Pipe To Minimize Friction Loss.

Maximum Achievable Flow in GPH

Minimum Inside Diameter of Pipe

300 GPH

1/2”

720 GPH

3/4”

1,200 GPH

1,,600 GPH

1 -1/4”

2,600 GPH

1 -1/2”

4,800 GPH

6,000 GPH

2 -1/2”

9,000 GPH

12,000 GPH


Determine your overall pipe length, inc. equivalent length for your fittings. Consult the friction loss charts. Find the column for your pipe diameter and the intersecting row of your flow rate to determine the friction lost per ft. of pipe. Try to limit curves and fittings.


How to use this chart:

If your water feature has a lift of  5 feet, (vertical lift from water level to discharge point) and you want
300 GPH flowing from the discharge located 10 feet away from the pump, you must add the linear
friction loss to the head as follows:
Based on a hypothetical pipe size 1/2”, with a Lift  of  5 ft. and a run of  10 ft. we calculate as follows:
5 ‘ + 2.5’ = 7.5 ft. The required pump therefore, should produce 300 GPH @ 7.5’ not 300 GPH.

GPH

Size Pipe

Friction @10 ‘

Friction @ 25’

Friction @ 50’

Friction @ 100’

300

1/2”

2.5 ft.

6.5 ft.

13 ft.

25.76 ft.

600

3/4”

2.6 ft.

6.5 ft.

13 ft.

25.98 ft.

1200

2.5 ft.

6.2 ft.

12.53 ft.

25.07 ft.

2400

1 1/4”

2.3 ft.

5.8 ft.

11.7 ft.

23.55 ft.

3600

1 1/2”

2.3 ft.

5.8 ft.

11.7 ft.

23.48 ft.

5400

1.4 ft.

3.5 ft.

7.3 ft.

14.26 ft.

12,000

.89 ft.

2.2 ft.

4.4 ft.

8.90 ft.

Friction = amount of work needed to push water through diameter of a pipe based on distance traveled, converted to vertical feet. Chart helps you to convert horizontal runs to vertical lift. You can safely pass amounts shown in chart without much friction loss.

Note:
You may have heard that the general rule that for  2” pipe each 10 linear feet is equivalent
 to 1 foot head, however as you can see from the chart -- 100 ft. is actually 14.26’ not 10’.



Friction Loss in PVC fittings in Equivalent Feet of Straight Pipe

Straight Pipe Size (IN.)

1/2”

3/4”

1 1/2”

 4”

90 Elbow, Standard

1.5

2.0

2.25

4.0

6.0

8.0

12.0

45 Elbow, Standard

0.75

1.0

1.4

2.0

2.5

4.0

5.0

Insert Coupling

0.5

0.75

1.0

1.5

2.0

3.0

4.0

Gate Valve

.3

.4

.6

1.0

1.5

2.0

3.0

Male/Female Adapters

1.0

1.5

2.0

3.5

4.5

6.5

9.0

Tee, Flow Thru Run

1.0

1.4

1.7

2.7

4.3

6.3

8.3

Tee, Flow Thru Branch

4.0

5.0

6.0

8.0

12.0

16.0

22.0

Note:
 Did you notice the 45 degree fittings reduce significantly less than 90 degree fittings.


Using a hypothetical setup  with the friction loss charts let’s figure out your friction head loss.

Using 50’ of 2: pipe will give us a friction head loss of approximately 1 1/2 ft. at a desired flow rate of 2700 GPH

1 -1/2 ft.

Number and type of fittings = (3) 2” 90 elbows, (4) 2” 45 elbows, and (2) 2” Y’s = aproximately 40 ft. of pipe at close to 1 1/2 ft. of friction head loss

1 -1/2 ft.

Miscellaneous other fittings such as reducers, couplings, valves, and fittings add the equivalent of another 40 ft. at close to 1 1/2 ft. friction head loss ie:

  • 90 & 45 elbows and strainer baskets used in out of pond pump installations
  • Bulkhead fittings and swing check valves used with in pond skimmers

1 -1/2 ft.

This totals to to 4 1/2 ft. of friction head loss for the pipe and all the fittings. Add this to the height of the waterfall at 5 ft.

5 ft.

The total friction head loss for this hypothetical system is approximately 9 1/2 ft.


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