Propeller pump:
- They are designed principally for low head and large capacities.
- They are two types i.e axile flow and mixed flow.
- They may be single stage or multistage type.
- Heads of 9-12 m length are obtained.
- The smaller sized single stage pump will operate efficiently at low heads of 2-8 m.
- The multistage pumps will handle heads upto above 38 m.
Air lift pump:
- Operates by the injection of compressed air directly into the water inside discharge at a point below the water level of the well.
Advantages
a) Simplicity
b) Tube wells need not to be perfectly straight to vertical
c) Impaired water will not damage the crop
Disadvantages
a) Low efficiency (max. 35% only)
b) The initial cost of pump s high.