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centrifugal pumps, (2) power plunger pumps, (3) deep well pumps, (4) 

 air lift pumps, (5) hydraulic rams. 



Deep well pumps and air lift pumps are used for pumping underground 

 water from deep wells. In British Columbia the underground water supply 

 is unknown and need not be considered at present when the water supply 

 is obtainable from the large streams and lakes adjacent to irrigable area. 

 For pumping from these sources -the centrifugal pumps and the power 

 plunger pumps are the best adapted. Hydraulic rams are used for small 

 quantities of water such as for domestic purposes or for irrigation of small 

 pieces of land. They are economical in operation, but require special con- 

 ditions such as a nearby stream with sufficient fall in a short distance. 

 The choice between a centrifugal pump and a power plunger pump will 

 depend on the capacity required and the height of lift. 



Centrifugal pump. 



A centrifugal pump consists of a circular casing with the inlet or suction 

 ^nd connected to the center and the outlet or discharge end formed tangent 

 to the perimeter. Inside the casing is the runner or impeller keyed on the 

 shaft and revolving with it. It is formed of curved vanes closely fitting 

 the casing and corresponds to the piston or plunger of a plunger pump. 

 When in operation the impeller by revolving imparts a velocity to the water 

 between the vanes and forces it away from the center of the casing to- 

 wards the perimeter or rim of the casing through the outlet and up the 

 discharge pipe. This produces a partial vacuum at the center of the im- 

 peller which induces a flow through the suction pipe into the casing. The 

 number of revolutions of the runner or speed of the pump has an exact 

 relation to the head or lift against which the pump is working and for 

 every head there is a speed for which the pump works most efficiently. 

 This speed can be obtained from the pump manufacturers. It is important 

 that the pump be connected to an engine or motor which will give it the 

 proper speed. Overspeeding is preferable to underspeeding but either 

 reduce the pump efficiency. 



Simple centrifugal pumps specially designed and driven at a sufficiently 

 high rate of speed may be used for lifts considerably over 100 feet, but 

 usually the sock pump obtainable from the manufacturers is not suitable 

 for lifts over 75 feet and for the smaller sizes the total lift should not ex- 

 ceed 50 feet. For higher lifts compound or multi-stage centrifugal pumps 

 are used. These consist of two or more pumps connected in series, the 

 discharge of the first pump or stage is delivered into the suction of the 

 next pump and the operation is repeated according to the number of stages. 

 Usually 75 feet to 125 feet is allowed to each stage. 



Where the required capacity of the pump is over 100 or 150 gallons per 

 minute and the total life less than 75 feet, the centrifugal pump is no 

 doubt the best adapted. 



' Centrifugal pumps are usually denoted by a number which represents 

 the diameter of the discharge in inches. The efficient capacity of each size 

 will vary to some extent with the speed of the pump which depends on the 

 total lift pumped against. The pumps can, therefore, not be rated accu- 

 rately. The capacities given in the accompanying table are worked out 

 from the ratings given by a reliable pump manufacturer and are subject 

 o considerable variations either above or below the values given. 



