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

• 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 blog.path.org

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 It has since been replaced by the Type B pictured above.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.

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