The discharge through the pump is 200 lit/s when the pump is working against a total head of 20 m. If the manometric efficiency of the pump is 80% determine the outer diameter of the impeller and the width of the impeller at outlet.

Given :

Speed $N=1000r.p.m$

Outlet vane angle $\phi = 45^\circ $

Velocity of flow at outlet $Vf_2=2.5m/s $

Discharge $Q= 200 $ lit/s = $0.2m^2/s $

Head $Hm= 20m$

Manometric efficiency $N_{max}= 80\% = 0.80 $

From outlet velocity triangle we have $\tan\phi = \dfrac {Vf_2}{U_2-Vw_2} \\ or \space \space …