Calculate your TDH - windmills,

 

To choose the right pumping system you need to first calculate your "Total Dynamic Head" (T.D.H). Total Head is the actual height to which water is to be pumped - from the water level at the source to the highest delivery point. Total Dynamic Head (T.D.H) takes into account the friction loss created by the movement of water through the delivery pipeline.

T.D.H. is the addition of

Static Lift + Static Height + Friction Loss.

Static Lift - is the height in metres from the low water level to the ground level where the Windmill or Solar Modules will be mounted.

Static Height - is the height in metres from where the Windmill or Solar Modules will be mounted to the highest point along the delivery pipeline.

Friction Loss - the resistance to water flow - is expressed as height in metres per kilometre of pipe.


Step 1: Determine Static Lift.

Using the diagrams below as a guide, measure the height from the low water level to ground level where the Windmill or Solar Modules will be mounted. This is usually done with a tape measure

Static lift diagram

My static lift is: Meters.



Step 2: Determine Static Height.

Using the diagrams below as a guide, measure the height from the ground level where the Windmill or Solar Modules will be mounted to the highest point along the delivery pipeline.
This measurement can be taken by

  • Using an Altimeter
  • Measuring the pressure in an existing (full) Pipeline (see Tech Note - Pressure, Head & Friction Loss)
  • Using a sight level
  • Reading the contours on a map.

Static height diagram

My static height is Meters.


Step 3: Determine the Friction Loss.

The following tables list the Friction Loss for various types and size of pipe. Follow these few steps to determine the friction loss per 1000 Metres of Pipeline.

  • Decide which system you plan to use. Is it a Windmill, or a Solar system - Fixed or Tracking Array?
  • Decide what volume of water is required per day.
  • Using a Litres per Day number that is larger than required, pick out the Friction Loss (Metres of head per every 1000 Metres of Pipeline) for your pipe size. If you don't have an existing pipe, select a pipe size that has a Friction Loss number less than 10. The smaller the Friction Loss number, the better it is.
  • Enter your Friction Loss Number and the length of your pipeline in the boxes provided below the tables.
Friction Loss for Rural "B" Imperial Polyethylene Pipe
Litres per day
Litres
per
Second
Friction Loss Number (Metres per 1000 Metres of Pipeline)
Windmill
Solar Fixed Array
Solar Tracking Array
1/2"
3/4"
1"
1.1/4"
1.1/2"
2"
2160
1296
1728
0.06
34.0
4.9
1.2
2880
1728
2304
0.08
58.0
8.4
2.1
3600
2160
2880
0.10
84.0
12.0
3.2
1.0
7200
4320
5760
0.20
295.0
43.0
10.5
3.5
1.5
10800
6480
8640
0.30
590.0
86.0
20.4
7.5
2.9
14400
8640
11520
0.40
150.0
37.0
12.2
4.8
1.3
18000
10800
14400
0.50
205.0
54.0
18.5
7.1
1.9
21600
12960
17280
0.60
290.0
75.0
20.5
10.0
2.6
25200
15120
20160
0.70
380.0
96.0
32.0
12.8
3.4
28800
17280
23040
0.80
490.0
120.0
42.0
16.5
4.3
32400
19440
25920
0.90
600.0
145.0
51.0
21.0
5.2
36000
21600
28800
1.00
750.0
180.0
62.0
25.0
6.2
43200
25920
34560
1.20
250.0
85.0
34.0
8.5
50400
30240
40320
1.40
340.0
115.0
44.0
11.5


Friction Loss for Metric - Class PN 6.3 - Polyethylene Pipe
Litres per day
Litres
per
Second
Friction Loss Number (Metres per 1000 Metres of Pipeline)
Windmill
Solar Fixed Array
Solar Tracking Array
20mm
25mm
32mm
40mm
50mm
63mm
2160
1296
1728
0.06
7.9
2.2
0.6
2880
1728
2304
0.08
13.5
3.7
1.1
3600
2160
2880
0.10
20.3
5.7
1.6
0.5
7200
4320
5760
0.20
73.5
20.4
5.7
1.9
0.6
10800
6480
8640
0.30
155.7
43.3
12.2
4.1
1.4
14400
8640
11520
0.40
73.8
20.7
6.9
2.3
0.7
18000
10800
14400
0.50
111.6
31.3
10.5
3.5
1.0
21600
12960
17280
0.60
156.4
43.9
14.7
4.9
1.4
25200
15120
20160
0.70
208.1
58.4
19.5
6.6
1.8
28800
17280
23040
0.80
266.4
74.8
25.0
8.4
2.2
32400
19440
25920
0.90
331.4
93.0
31.1
10.5
2.7
36000
21600
28800
1.00
402.8
113.1
37.7
12.7
3.3
43200
25920
34560
1.20
158.5
52.9
17.8
4.5
50400
30240
40320
1.40
210.9
70.4
23.7
5.9

Enter your Friction Loss number here:
Metres per 1000 Metres
Enter the length of your pipeline here: Kilometres



My Total Total Friction Loss is Meters
My Total Dynamic Head is Meters

You now know your Total Dynamic Head (T.D.H) and the volume you require per day. From these two numbers it is easy to determine the best system to suit your need. Visit our contact page and we will send you a detailed quotation.