ZIMSEC O Level Combined Science Notes: Pumps: Lift pump
- It has a cylinder
- A piston
- Two valves and
- a spout
- They make use of atmospheric pressure which forces fluid (water) into the pump through valves
- Valves allow fluid to only flow in one direction
- At any given point there is one valve open and another closed

Lift pump diagram.
- During the upstroke the piston moves up
- Atmospheric pressure puts pressure on the water in the well
- The water then pushes against valve B forcing it open
- Water enters the cylinder
- Valve A is closed during this cycle
- During the downstroke the piston moves down
- Valve B is closed by the force of water
- The pressure of the water forces Valve A to open
- Water then enters the area above Valve A
- And flows out through the spout
Advantages
- It is light, cheap and easy to assemble, operate and repair
- No lubrication is required as water is used to lubricate the pump
Disadvantages
- Can only lift water in wells less than 9m deep.
- They only deliver water during the upstroke
- They require priming before use
To access more topics go to the Combined Science Notes page
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