# Hydraulic Machines Questions and Answers – Minimum Speed for Starting Centrifugal Pump

This set of Hydraulic Machines Questions and Answers for Aptitude test focuses on “Minimum Speed for Starting Centrifugal Pump”.

1. Vertical centrifugal pumps are also called as ________
a) Froth pumps
b) Multistage pumps
c) Cantilever pumps
d) Magnetic pumps

Explanation: Vertical centrifugal pumps are also called as cantilever pumps. They utilize a unique shaft and bearing support for configuration. Thus, it is called as cantilever pumps.

2. Vertical pump uses _______
a) Draft tube
b) Throttle bush
c) Stuffing box
d) Interlining

Explanation: Vertical pumps use throttle bush. They do not use stuffing box. Vertical centrifugal pumps are also called as cantilever pumps. They utilize a unique shaft and bearing support for configuration. Thus, it is called as cantilever pumps.

3. When the casing in a centrifugal pump decelerates the flow, what increases?
a) Pressure
b) Temperature
c) Volume
d) Flow rate

Explanation: When the casing in a centrifugal pump decelerates the flow, pressure in the turbine increases. The diffuser helps this happen. The shape of the diffuser passing present in the centrifugal pump is doughnut shaped.

4. The maximum volumetric efficiency of a pump(100cc) is ________
a) 60%
b) 70%
c) 80%
d) 90%

Explanation: The primary objective of a centrifugal pump is to transfer energy. Centrifugal pump is a turbomachinery. Turbomachines are machines that transfer energy between a rotor and a fluid, including both turbines and compressors. It is a mechanical device.

5. The most common application of vertical centrifugal pump is used in _______
a) Parts washer
b) Mineral industry
c) Paper plating
d) Jukebox

Explanation: The most application of the vertical centrifugal pump is used in parts washer. Vertical pumps use throttle bush. They do not use stuffing box. Vertical centrifugal pumps are also called as cantilever pumps.
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6. What does BEP stand for?
a) Best efficiency point
b) Brake ejection point
c) Break effect point
d) Best effect point

Explanation: BEP stands for Best efficient point. It is a point at which Shut off and Run out point. It helps to identify the pumps performance.

7. The height of a column in a pump is called as _______

Explanation: In a centrifugal pump, the height of the column is called as a static head. Static head corresponds to the pressure depending on the weight.

8. The centrifugal pump has varying flow depending on the _________
a) Pressure
b) Static lift
c) Volume
d) Flow rate

Explanation: Due to pressure variations there are changes that take place in the centrifugal pump. Thus, the flow keeps varying.

9. What is purpose of froth in froth pumps?
a) Separates rich minerals
b) Mixes rich minerals
c) Removes ores
d) Detects oil

Explanation: The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

10. Froth contains air that blocks the pumps.
a) True
b) False

Explanation: Froth contains air that blocks the pumps. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

11. When froth blocks the pump, it leads to _______
a) Separation of rich minerals
b) Mixing of rich minerals
c) Removing of ores
d) Loss of prime

Explanation: When froth blocks the pump, it leads to loss of prime. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

12. What affects volumetric efficiency of the pump?
a) Complex interactions
b) Internal interactions
c) Retain flow
d) Air flow

Explanation: The volumetric efficiency of the centrifugal is affected due to complex interactions. Thus, some engines use two intake manifolds.

13. The Positive Displacement Pump has more or less a constant flow regardless of the system pressure or head.
a) True
b) False

Explanation: The Positive Displacement Pump has more or less a constant flow regardless of the system pressure or head.

14. What is the purpose of inducer in a froth pump?
a) It recirculates air
b) The pressurizes the air
c) Froths are generated
d) It breaks the bubbles

Explanation: The purpose of the inducer in a froth pump is to break the bubbles. The main function of the froth in froth pumps is to separate rich minerals. It is also used to separate bitumen from the sand and the clays.

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