Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the ____________ head?

Related Mcqs:

1. Which is the correct relationship for a centrifugal pump? (Where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm) ?

   A. D = 1840 H0.5/N
   B. D = 1840 N/H0.5
   C. H = 1840 D0.5/N
   D. D = 1840 H/N

2. A centrifugal pump is used to pump water through a horizontal distance of 150 m, and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D of 50 mm. What head (m of water) must the pump generate at its exit E. to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062 ?

   A. 10 m
   B. 11 m
   C. 11.8 m
   D. 30 m

3. The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the_________________?

   A. Discharge
   B. Suction
   C. Suction minus vapor pressure of the liquid at suction temperature
   D. Discharge minus vapor pressure of the liquid at the discharge temperature

4. A centrifugal pump used to pump water is used to pump an oil with specific gravity of 0.8 at the same rate. The power consumption will now_________________?

   A. Increase
   B. Decrease
   C. Remain same
   D. Data insufficient to predict

5. A centrifugal pump designed to pump water is employed to pump a more viscous oil. In the later case, the pump_________________?

   A. Develops a lower head
   B. Capacity is reduced
   C. Requires more power
   D. All A., B. and C.

6. Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the _______________ decreases?

   A. NPSH required
   B. BHP required by the pump
   C. Head of the liquid pumped
   D. All A., B. and C.

7. A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, then the new head will be ______________ metres?

   A. 2
   B. 4
   C. 8
   D. 5.5

8. The head developed by a centrifugal pump is largely determined by the____________________?

   A. Power of the pump
   B. Nature of the liquid being pumped
   C. Angle of the vanes and the speed of the tip of the impeller
   D. Vapour pressure of the liquid

9. Head developed by a centrifugal pump depends on its___________________?

   A. Speed
   B. Impeller diameter
   C. Both A. and B.
   D. Neither A. nor B.

10. Theoretical head developed by a centrifugal pump does not depend upon the _____________ the impeller?

    A. Radius of
    B. Speed of
    C. Fluid velocity leaving
    D. None of these