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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