Answer to Question #112530 in Mechanical Engineering for Jayapal Reddy

Question

A pump is delivering 50m3/hr of water with a discharge pressure of 3.5kg/cm2.The water is drawn from a sump where water level is 5 meter below the pump centre line.The power drawn by the motor is 9.5kw at 90% motor efficiency.Find out the efficiency of the pump.

Answer 1

Discharge pressure = $P_2=3.5g \times 10^4 N /m^2$

Suction pressure = $P_1= \rho\times g\times h= 1000\times9.8\times 5=4.9 \times10^4 N/m^2$

Pump delievering at the rate of $50 m^3 /hr$ , Power driven=9.5 kW, $\eta_m=90$ %,

As we know that,

$\eta_p= \frac{(P_2-P_1)Q}{P\times \eta_m}$

$\eta_p= \frac{(34.3-4.9)50\times 10^4}{9.5\times.9\times3600}$

$\eta_p= 47$ %