632 



HYDEAULICS AND ITS APPLICATIONS 



ART. 173. TYPES AND CONSTRUCTION OF CENTRIFUGAL PUMPS. 



The whole object of a centrifugal pump, as indeed of any pump, is to 

 increase the pressure of the water which it handles, and where, as in the 

 case of a centrifugal pump, the water is delivered from the impeller with a 

 considerable velocity, the degree of efficiency to which the machine may 

 attain depends very largely on the extent to which the kinetic energy of 



FIG. 301. 



discharge from the impeller may be converted into pressure energy in the 

 pump casing. 



Any device having this end in view should be designed so as to reduce 

 the velocity of discharge from the impeller gradually and without shock 

 or eddy formation, to that of flow along the discharge pipe. 



In some pumps no attempt is made to do this, and the water is simply 

 allowed to discharge into a small chamber surrounding, and concentric 

 with the wheel, out of which chamber the discharge pipe is led (Fig. 301). 

 Since each of the vanes is continuously discharging, the quantity passing 

 a section of the collecting chamber will increase continuously from a 

 section at A just past the discharge pipe, to be a maximum at the section 



