The system has a compressed air pipe with a nozzle introduced into the sump or the well. The compressed air is introduced into one or more nozzles at the foot of the delivery pipe, which is fixed in the well from which water is to be lifted. In the delivery pipe, which is partly open to the well or sump which contains water, a mixture of air and water is formed. As already discussed, this density of air and water becomes less than the density of pure water. Hence a small column of pure water is sufficient to balance a very long column of air-water mixture. This air-water mixture is discharged through the delivery pipe. The flow will continue as long as the compressed air supply is maintained.
Let us assume
h = height of static water level above the tip of the nozzle,
H = height to which water is lifted above the lip of the nozzle.
Thus (H-h) is known as the useful lift. The results are optimum if the useful lift (H-h) is less than the height of static water (h) above the tip of the nozzle. Hence for best results,
(H-h) < h.
The ratio (h/H-h) generally varies from 4 to 1.
Also when h = 30m, then the ratio (h/H-h) is about 4.
When h = 90m, then the ratio (h/H-h) is about 1.
For h = 30m,
so, 30/H-30 = 4
30 = 4H – 120
4H = 150
H = 37.5 m.
For h = 90, h/H-h = 1.
90/H-90 = 1.
90 = H – 90.
H = 180m.
So it is evident that when h increases H also increases.