Hydraulic Pumps MCQ | Centrifugal Pumps MCQ

1. Which of the following types of pump can be used for concreting?

  1. Centrifugally operated with straight blades
  2. Pneumatically operated
  1. ii only
  2. i only
  3. Neither i nor ii
  4. Both i and ii
Answer. d

2. Which of the following statement is correct?

  1. centrifugal pumps convert mechanical energy into hydraulic energy by sucking liquid chamber
  2. reciprocating pumps convert mechanical energy into hydraulic energy by means of centrifugal energy
  3. centrifugal pumps convert mechanical energy into hydraulic energy by means of centrifugal energy
  4. reciprocating pumps convert hydraulic energy into mechanical energy
Answer. c

3. In a centrifugal pump, the inlet angle will be designed to have

  1. absolute velocity vector in the radial direction
  2. zero flow velocity
  3. relative velocity vector in the radial direction
  4. zero peripheral velocity
Answer. a

4. In order to avoid cavitation in centrifugal pumps

  1. the suction pressure should be high
  2. the delivery pressure should be high
  3. the suction pressure should be low
  4. the delivery pressure should be low
Answer. a

5. In a centrifugal pump pressure energy is developed due to

  1. Displacement
  2. Whirling Motion
  3. Both whirling and displacement
  4. None of the above
Answer. b

6. In a centrifugal pump the liquid enters the pump

  1. at the centre
  2. at the top
  3. at the bottom
  4. from sides
Answer. a

7. A centrifugal pump delivers water at the rate of 40 lit/s for a total head of 30 m. If the overall efficiency of set consists of pump and electric motor is 75%, the power required to drive the motor is

  1. 12.4 kW
  2. 13.8 kW
  3. 15.7 kW
  4. 14.3 kW
Answer. c

8. In centrifugal pumps, the relation between power (P) and speed (N) is given by

  1. P ∝ N
  2. P ∝ N2
  3. P ∝ N3
  4. None of these
Answer. c

9. For centrifugal pump impeller, the maximum value of the vane exit angle is

  1. 10° to 15°
  2. 15° to 20°
  3. 20° to 25°
  4. 25° to 30°
Answer. c

10. Multistage centrifugal pumps are used to velocity

  1. give high discharge
  2. pump viscous fluids
  3. produce high heads
  4. both a and c
Answer. d

11. A diffuser blade in the centrifugal pump is used to

  1. convert mechanical energy to kinetic energy
  2. convert kinetic energy to pressure energy
  3. convert pressure energy to kinetic energy
  4. convert potential energy to kinetic energy
Answer. b

12. Which one is not centrifugal pump?

  1. Volute
  2. Diffuser
  3. Reciprocating
  4. Turbine
Answer. c

13. Rotadynamic pump is classified as

  1. Centrifugal pumps
  2. Screw pumps
  3. Propeller pumps

Which of these statements are correct?

  1. Only i and iii
  2. Only i and ii
  3. All three
  4. Only ii and iii
Answer. a

14. The discharge from a centrifugal pump is 100 lpm and the leakage is 11 lpm. Then the volumetric efficiency of the pump is

  1. 89%
  2. 90%
  3. 99%
  4. 80%
Answer. a

15. A centrifugal pump driven by a directly coupled 3 kW motor of 1450 rpm speed is proposed to be connected to another motor of 2900 rpm. The power of the motor should be

  1. 24 kW
  2. 18 kW
  3. 12 kW
  4. 6 kW
Answer. a

16. The size of centrifugal water pump is given by

  1. Horsepower
  2. Impeller diameter
  3. Discharge
  4. Suction and delivery pipe diameter
Answer. a

17. When speed changes in case of centrifugal pump, which of the following points are correct?

  1. The shape of the velocity triangle will remain same
  2. Various angles will remain same
  3. Magnitude of velocity will change proportionately
  1. i and ii only
  2. i and iii only
  3. ii and iii only
  4. i, ii and iii
Answer. d

18. Which one of the following statements is correct regarding centrifugal pumps?

  1. The discharge is fluctuating and pulsating
  2. It is used for large discharge through smaller heads
  3. The efficiency is low
  4. It runs at low speed
Answer. b

19. Of the following statements, pick the correct one.

  1. Centrifugal pumps are used to produce high head
  2. Centrifugal pumps are used to discharge large quantity of water
  1. Statement (ii) alone is correct
  2. Both the statement are wrong
  3. Statement (i) alone is correct
  4. Both the statements are correct
Answer. a

20. A centrifugal pump has an impeller of 30cm diameter and runs at 1000 rpm giving best efficiency. It delivered 1.2 m3/minute against a head of 25m. What is its non-dimensional specific speed (based on flow expressed in l.p.s.)?

  1. 80
  2. 72
  3. 63
  4. 55
Answer. b
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