The blair pump

The blair pump

ZIMSEC O Level Combined Science Notes: Pumps: Blair pump

  • The pumped was first developed in 1976
  • The design was further refined at the Blair Research Laboratory in Harare
  • Various models have been subsequently designed and made
  • Cumulating in the famous Type B bush pump
  • It is popularly known simply as chibhorani  in rural areas
  • This pump provides essential and clean water to rural communities
  • It is simple to erect and cheap to maintain
  • This is because it is built using easily obtainable off-the shelf parts
  • It combines elements of both the force pump and the lift pump
  • Blair pumps are commonly used to lift water from covered wells
  • They can lift water up to 12 m
Blair Pump in action

Blair Pump in action

  • The pump handle is connected to a piston which moves
  • In a cylinder that is fixed below the water level in a well
  • There are valves in the bottom cylinder and the bottom of the piston
  • During the downward stroke
  • The inlet valve in the piston opens
  • Water passes into the pump rising main (the pipe above the cylinder at the bottom)
  • On the upstroke the piston valve closes trapping air in the pump rising main
  • The valve at the base of the cylinder opens allowing more water into the cylinder
  • When the pump rising in the main is full
  • Water rushes out of the spout on each down stroke
The popular Type B bush pump. Image credit

The popular Type B bush pump. Image credit

NB The pump shown in Focus on Science Books is now rarely if ever encountered in real life. It has since been replaced by the Type B pictured above. This is more powerful. It delivers water on the upstroke.

To access more topics go to the Combined Science Notes page