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

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