Pressure
Drop in Pipe
(head loss in feet of pipe in PVC Class 160 plastic type
pipe)
Note:
For head loss in feet, multiply PSI by 2.31. For instance,
for 20 GPM and 1.5" diameter pipe, multiplying
1.34 PSI by 2.31, you get 3.1 feet. That is, for every
100 feet of 1.5" pipe with 20 GPM flowing through
it, you will lose 3.1 feet of head due to friction.
|
| .
|
Nominal
pipe diameter (inches)
|
| Flow
(GPM) |
1
|
1.25
|
1.5
|
2
|
2.5
|
3
|
4
|
| 1
|
0.05
|
0.02
|
0.00
|
.
|
.
|
.
|
.
|
| 2
|
0.14
|
0.05
|
0.02
|
.
|
.
|
.
|
.
|
| 3
|
0.32
|
0.09
|
0.05
|
.
|
.
|
.
|
.
|
| 4
|
0.53
|
0.16
|
0.09
|
0.02
|
.
|
.
|
.
|
| 5
|
0.81
|
0.25
|
0.12
|
0.05
|
.
|
.
|
.
|
| 6
|
1.13
|
0.35
|
0.18
|
0.07
|
0.02
|
.
|
.
|
| 7
|
1.52
|
0.46
|
0.23
|
0.07
|
0.02
|
.
|
.
|
| 8
|
1.94
|
0.58
|
0.30
|
0.09
|
0.05
|
.
|
.
|
| 9
|
2.42
|
0.72
|
0.37
|
0.12
|
0.05
|
.
|
.
|
| 10
|
2.93
|
0.88
|
0.46
|
0.16
|
0.07
|
0.02
|
.
|
| 12
|
3.51
|
1.04
|
0.53
|
0.18
|
0.07
|
0.02
|
.
|
| 14
|
4.11
|
1.22
|
0.65
|
0.21
|
0.09
|
0.02
|
.
|
| 16
|
5.47
|
1.64
|
0.85
|
0.28
|
0.12
|
0.05
|
.
|
| 18
|
7.02
|
2.10
|
1.09
|
0.37
|
0.14
|
0.05
|
.
|
| 20
|
.
|
2.61
|
1.34
|
0.46
|
0.18
|
0.07
|
0.02
|
| 22
|
.
|
3.16
|
1.64
|
0.55
|
0.21
|
0.09
|
.
|
| 24
|
.
|
3.79
|
1.96
|
0.67
|
0.25
|
0.09
|
0.04
|
| 26
|
.
|
4.43
|
2.31
|
0.79
|
0.30
|
0.12
|
0.05
|
| 28
|
.
|
5.15
|
2.66
|
0.90
|
0.35
|
0.14
|
0.05
|
| 30
|
.
|
5.91
|
3.05
|
1.04
|
0.42
|
0.16
|
0.11
|
| 35
|
.
|
.
|
3.46
|
1.18
|
0.46
|
0.18
|
0.12
|
| 40
|
.
|
.
|
4.62
|
1.57
|
0.62
|
0.23
|
0.13
|
| 45
|
.
|
.
|
.
|
1.99
|
0.79
|
0.30
|
0.15
|
| 50
|
.
|
.
|
.
|
2.49
|
0.79
|
0.30
|
0.20
|
| 55
|
.
|
.
|
.
|
3.03
|
1.20
|
0.46
|
0.25
|
| 60
|
.
|
.
|
.
|
3.60
|
1.43
|
0.55
|
0.30
|
| 65
|
.
|
.
|
.
|
.
|
1.66
|
0.65
|
0.35
|
| 70
|
.
|
.
|
.
|
.
|
1.94
|
0.74
|
0.40
|
| 75
|
.
|
.
|
.
|
.
|
2.22
|
0.85
|
0.45
|
| 80
|
.
|
.
|
.
|
.
|
2.52
|
0.97
|
0.50
|
| 85
|
.
|
.
|
.
|
.
|
2.84
|
1.09
|
0.60
|
| 90
|
.
|
.
|
.
|
.
|
3.19
|
1.22
|
.
|
| 100
|
.
|
.
|
.
|
.
|
.
|
1.36
|
0.80
|
| 150
|
.
|
.
|
.
|
.
|
.
|
1.50
|
1.60
|
| 200
|
.
|
.
|
.
|
.
|
.
|
1.66
|
2.70
|
| 300
|
.
|
.
|
.
|
.
|
.
|
.
|
5.80
|
| 400
|
.
|
.
|
.
|
.
|
.
|
.
|
9.90
|
Pipelines
Important factors:
1 ) Water pressure is the key for power
in a micro-hydro turbine. Power available is directly related
to the pressure at the bottom of the pipe( called 'head' - Multiply
.433 x vertical height in feet for pressure in pounds per square
inch [PSI] ) Plastic is a good choice for feedpipe into a microhydro
system, as the internal wall friction is low and corrosion is
eliminated.
Typical pipe pressure capabilities although
you should always check with a plumbing supply store to ensure
a safety margin.
| Material |
Pressure (PSI) |
| Polyethelene |
up to 100 |
| PVC |
160-350 |
| Steel |
1000 or more |
2) Pipe diameter. Pressure loss through
friction varies with diameter and flow rate. The larger the
diameter or slower the flow, the less loss. To measure the pressure
drop, attach a guage to the pipeline, and a valve at the lower
end of the pipe. With the valve closed, the pressure you measure
is called static pressure ( can be calculated at .433 x height
in feet). With the valve open and water going through the turbine
nozzeles, the pressure measured is the dynamic or working pressure
- this is the real power available. The maximum the pipeline
can deliver occurs with approximately 2/3 of the static pressure.
Past this point the pipeline develops more turbulence thus limiting
the flow. The real flow rate is determined by the turbine nozzle.
As every system is different, we will supply the proper nozzle
or nozzle set for your system based on the information from
head, flow, diameter, and length of pipe.
The product information from the two
manufacturers can help you determine the optimum system.
Let
us help you design the system!
Are you ready to start? We can help
you determine if your site has a good power potential, and design
a suitable system if you wish. Please call (650) 814 5177 for
assistance.
Please have the following information
available when you call:
