Centrifugal Pumps. i o 



D =r Cy/- ^ 



D = Diameter of fan in feet. 



H = Head of water in feet, including head^ corresponding 



with friction of pipes, &c. 

 S = Speed of periphery of fan in feet per second. 

 Q = Quantity of water lifted, feet per minute. 

 C = '12 to -18. 



The great advantage that a centrifugal pump has over all 

 other machines for raising water for the drainage of land 

 where the lift is constantly varying, either from the rise and 

 fall of the tide in the outfall river or the lowering of the water 

 in the inside drains as the pumping proceeds, is that it adapts 

 itself to these variations in the lift without any alteration in 

 the speed of the engine, employment of differential gear, or 

 attention on the part of the engine-driver. If kept working 

 at the ordinary speed, the pump will discharge either more or 

 less water as the lift diminishes or increases. 



Centrifugal pumps of the smaller class are generally kept 

 in motion by a strap running round a pulley on the spindle 

 of the pump and the driving wheel of the engine. Those of 

 the turbine form are worked by a mitre pinion, keyed on to 

 the vertical spindle gearing into a bevel wheel on the crank 

 shaft of the engine. Direct-acting engines and centrifugal 

 pumps are also constructed with engine and pump on the 

 same base plate, the piston-rod being attached by a short 

 connecting-rod to a crank in the spindle of the pump. On 

 Fig. 7, Plate 4, is shown one of a pair of these pumps as fitted 

 up by Messrs. J. and H. Gwynne for the drainage of the 

 Grootslag Polder, near Andyk, the lift being 10 feet 6 inches 

 and the discharge 75 tons per minute for each pump. 



Messrs. Gwynne strongly advocate the use of the pump 

 with horizontal spindle as preferable to the turbine type, 

 being, in their opinion, more effective, occupying only a very 

 small space, and requiring inexpensive foundations, the cost 



