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McqMate
Chapters
1. |
Which of the following types of impeller is used for centrifugal pumps dealing with muds? |
A. | One-side shrouded |
B. | Two -sides shrouded |
C. | Double section |
D. | Open. |
Answer» D. Open. |
2. |
Which of the following statements is correct with reference to an impeller with backward curved vanes? |
A. | It has a falling head - discharge characteristic. |
B. | It has rising head - discharge characteristic |
C. | It is easier to fabricate. |
D. | It cannot run at speeds other than the design speed. |
Answer» A. It has a falling head - discharge characteristic. |
3. |
The head developed by a centrifugal pump may be expressed as |
A. | H = (Vw2 u2 + Vw1 u2)/g |
B. | H = Vw2 u2 /g |
C. | H = Vw1 u1 /g |
D. | None of the above. |
Answer» B. H = Vw2 u2 /g |
4. |
With reference to a centrifugal pump which of the following statements is incorrect? |
A. | The discharge control valve is fitted in the delivery pipe. |
B. | The suction pipe is provided with a foot valve and a strainer. |
C. | The suction pipe has larger diameter as compared to the discharge pipe. |
D. | The discharge control valve is fitted in the suction pipe. |
Answer» D. The discharge control valve is fitted in the suction pipe. |
5. |
A centrifugal pump should be so installed above the water level in the sump such that |
A. | The negative pressures are not allowed to develop in the impeller |
B. | The negative pressures do not reach as low a value as the vapour pressure |
C. | Its height is more than 10·28 m at ordinary temperature of liquid |
D. | None of the above. |
Answer» B. The negative pressures do not reach as low a value as the vapour pressure |
6. |
The specific speed of a pump is defined as the speed of unit of such a size that it |
A. | Produces unit power with unit head available |
B. | Delivers unit discharge at unit head |
C. | Requires unit power to develop unit head |
D. | Delivers unit discharge at unit power. |
Answer» B. Delivers unit discharge at unit head |
7. |
Which of the following statements pertaining to a given centrifugal pump is correct? |
A. | Discharge varies as the square of speed |
B. | Power varies as the square of speed |
C. | Discharge varies directly as speed |
D. | Head varies inversely as speed. |
Answer» C. Discharge varies directly as speed |
8. |
The delivery valve, while starting centrifugal pump, is kept |
A. | Fully closed |
B. | Fully open |
C. | Half open |
D. | In any position. |
Answer» A. Fully closed |
9. |
Which of the following is not a dimensionless parameter? |
A. | Friction factor |
B. | Specific speed |
C. | Thoma’s cavitation parameter |
D. | Pressure co-efficient. |
Answer» B. Specific speed |
10. |
With reference to manometric head which of the following statements is correct? |
A. | It is the head developed by the pump. |
B. | It is the height to which water is lifted by the pump measured above the pump centreline. |
C. | it is the difference in elevation between the water surface in the high level reservoir and the water level in the sump. |
D. | It is the difference in the piezometric heads between the points on the delivery and suction pipes as close to the pump as possible. |
Answer» D. It is the difference in the piezometric heads between the points on the delivery and suction pipes as close to the pump as possible. |
11. |
Higher specific speeds (160 to 500) of centrifugal pump indicate that the pump is of |
A. | Radial flow type |
B. | Axial flow type |
C. | Mixed flow type |
D. | Any of these types. |
Answer» B. Axial flow type |
12. |
What will happen if requirements of net positive suction head (NPSH) for a given pump are not satisfied? |
A. | The pump will get cavitated. |
B. | The pump will consume more power. |
C. | The pump will not develop he |
Answer» A. The pump will get cavitated. |
13. |
In centrifugal pumps, cavitation is reduced by |
A. | Increasing the flow velocity |
B. | Reducing the discharge |
C. | Throttling the discharge |
D. | Reducing the suction head. |
Answer» D. Reducing the suction head. |
14. |
Which of the following statements pertaining to a centrifugal pump is incorrect? |
A. | The suction lift of a pump can be upto 10·3 m or even more. |
B. | The impellers of a multi-stage pump are arranged in parallel to discharge a large quantity of liquid. |
C. | The volute casing of the pump maintains the velocity of flow constant, prevents eddies and converts velocity head to pressure he |
Answer» A. The suction lift of a pump can be upto 10·3 m or even more. |
15. |
Regarding cavitation which of the following statements in incorrect? |
A. | Cavitation affects the performance of a turbine to a lesser degree than that of a pump. |
B. | Thoma’s cavitation parameter has different expressions for turbines and pumps. |
C. | With the increase in pump speed, there is increase in its minimum net positive suction head requirement. |
D. | The leading edge of blades in pumps and the trailing edge of blades in water turbines are more susceptible to cavitation damage |
Answer» B. Thoma’s cavitation parameter has different expressions for turbines and pumps. |
16. |
A centrifugal pump is taking much of power, the probable reason may be |
A. | Liquid being pumped is heavy |
B. | Speed of the pump is low |
C. | There is leakage of air |
D. | Ineffective strainer and foot valve arrangement. |
Answer» A. Liquid being pumped is heavy |
17. |
In rotodynamic pumps, the increase in energy level is due to |
A. | Centrifugal energy only |
B. | Pressure energy only |
C. | Kinetic energy only |
D. | Combination of a, b and c. |
Answer» D. Combination of a, b and c. |
18. |
In a pump there is |
A. | Accelerating flow |
B. | Decelerated flow |
C. | Either of the above |
D. | None of the above. |
Answer» A. Accelerating flow |
19. |
In a centrifugal pump the regulating valve is provided on |
A. | The suction pipe |
B. | Delivery pipe |
C. | The casing |
D. | None of the above. |
Answer» B. Delivery pipe |
20. |
In a centrifugal pump the sum of suction head and delivery head is known as |
A. | Monomeric head |
B. | Total head |
C. | Static head |
D. | None of the above. |
Answer» C. Static head |
21. |
Regarding manometric head (Hmano) which of the following relations is correct? |
A. | Hmano= head imparted by the impeller to the liquid – loss of head in the pump |
B. | Hmano= static head + losses in pipes + Vd2/2g |
C. | Hmano= total head at outlet of the pump - total head at inlet of pump |
D. | All of the above. |
Answer» D. All of the above. |
22. |
The ratio of power outlet of the pump to the power input to the pump is known as |
A. | Mechanical efficiency |
B. | Overall efficiency |
C. | Monomeric efficiency |
D. | None of the above. |
Answer» B. Overall efficiency |
23. |
The flow ratio in case of a centrifugal pump varies from |
A. | 0.1 to 0.25 |
B. | 0.25 to 0.40 |
C. | 0.40 to 0.50 |
D. | 0.50 to 0.65 |
Answer» A. 0.1 to 0.25 |
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