Hydraulic Machines Questions and Answers – Air Lift Pump and Gear Wheel Pump – 1

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This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Air Lift Pump and Gear Wheel Pump – 1”.

1. A pump that has low suction and moderate discharge is called _______
a) Froth pumps
b) Air lift pumps
c) Reciprocating pumps
d) Centrifugal pumps
View Answer

Answer: b
Explanation: A pump that has low suction and moderate discharge is called air lift pumps. These pumps have a moderate discharge with liquid and entrained solids.

2. Turbomachines work under ________
a) Newtons first law
b) Newtons second law
c) Newtons third law
d) Kepler’s law
View Answer

Answer: b
Explanation: Turbomachines work under Newtons second law. 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.

3. The main function of nozzle is to __________
a) Varying temperatures
b) Pressure variations
c) Load variations
d) Heat variations
View Answer

Answer: b
Explanation: The main function of nozzle is to vary the pressure of fluid passing through the nozzle. It is done by opening and shutting the sets of nozzles. Thus, its main function is to regulate pressure of the fluid.
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4. The main function of centrifugal pumps are to ________
a) Transfer speed
b) Transfer pressure
c) Transfer temperature
d) Transfer energy
View Answer

Answer: d
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 pump injects compressed air at the _________
a) Rotor pipe
b) Bottom of the discharge pipe
c) Top of the discharge pipe
d) Rotor to draft
View Answer

Answer: b
Explanation: An airlift pump injects the compressed air at the bottom of the discharge pipe. A pump that has low suction and moderate discharge is called air lift pumps. These pumps have a moderate discharge with liquid and entrained solids.

6. Which among the following control the flow rate?
a) Valve
b) Pump
c) Head
d) Tank pipe
View Answer

Answer: a
Explanation: Flow rate of the tank is controlled by the valve. The actuation of individual valve closes. This corresponds to the set of nozzle thereby controlling the actual flow rate of the fluid passing through the valve.

7. The compressed air mixes with the liquid casing to become less dense.
a) True
b) False
View Answer

Answer: a
Explanation: The compressed air mixes with the liquid casing to become less denser that the rest of the liquid. This is because it will get displaced upwards through the discharge pipe.
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8. The inlet passage of water entry is controlled by ________
a) Head race
b) Gate
c) Tail race
d) Pump
View Answer

Answer: b
Explanation: The inlet passage of water entry is controlled by the gate opening. The gate opening is an opening that sends only a percentage of fluid through the inlet passages for water to enter to the turbine.

9. Airlift pumps are widely used in aquaculture to pump.
a) True
b) False
View Answer

Answer: a
Explanation: The statement is true. Airlift pumps are widely used in aquaculture to pump. It also circulates and aerates the water in a closed environment. This helps it to recirculate in system and ponds.
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10. Centrifugal pumps are used to transport ________
a) Pressure
b) Speed
c) Power
d) Fluid
View Answer

Answer: d
Explanation: Centrifugal pumps are used to transport fluids. They transport fluids by conversion of energies. Centrifugal pumps are a sub class of dynamic axisymmetric work absorbing turbomachinery.

11. The air lift pump works under the principle of _______
a) Newtons equation
b) Buoyancy
c) Momentum conservation
d) Hydrodynamic energy
View Answer

Answer: b
Explanation: The air lift pump works under the principle of buoyancy force that helps the compressed air to get injected into the lower part of the pipe that transports the liquid.

12. With the increase in load, Energy in the turbine________
a) Decreases
b) Increases
c) Remains same
d) Independent
View Answer

Answer: a
Explanation: When there is an increase in the load, the energy in the turbine is drained off. Thus, to increase the energy, the by pass valve is opened to increase the amount of fresh steam entry. This increases the energy in the turbine.

13. The rotational kinetic energy comes from ______
a) Engine motor
b) Pump
c) Tank
d) Draft tube
View Answer

Answer: a
Explanation: Centrifugal pumps transport fluids by converting rotational Kinetic energy to hydrodynamic energy. The rotational kinetic energy comes from engine or electrical motor.

14. When the balancing of the turbine is disturbed, we use ________
a) Throttle governing
b) Steam governing
c) Nozzle governing
d) Emergency governing
View Answer

Answer: d
Explanation: When the balancing of the turbine is disturbed, we use emergency governing. These governors come into action only when there are emergencies in the turbine.

15. The fluid coming into the airlift pump is accelerated by ________
a) Throttle
b) Impeller
c) Nozzle
d) Governor
View Answer

Answer: b
Explanation: The fluid coming into the airlift pump is accelerated by an impeller. The fluid enters the pump along a radially outward direction into the diffuser or a volute chamber.

Sanfoundry Global Education & Learning Series – Hydraulic Machines.

To practice all areas of Hydraulic Machines, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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