WATER OR LIQUID PUMPS 



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air pressure; hence the air is prevented from getting back 

 into the pump, while the air and water below the valve 

 in the pump tube open the valve and fill the space below 



Air tight 



Valve -3^M 



THE COMMON PUMP 



the piston with air and water. In diagram 3 the valve in 

 the pump tube closed to prevent the return of the water 

 to the well, while the valve in the piston opened and 

 allows the water to flow above it as the piston descends. 

 At the next upward stroke of the piston the water will be 



