# Hydraulic Machines Questions and Answers – Double Acting Pumps

This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Double Acting Pumps”.

1. When a cylinder has inlet and outlet ports at each end, then it is called as __________
a) Double acting
b) Air lift pumps
c) Reciprocating pumps
d) Centrifugal pumps

Explanation: When a cylinder has inlet and outlet ports at each end, then it is called as double acting pumps. It operates similar to the single acting pump with respect to its motion.

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

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
d) Heat variations

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.

4. When the piston moves forward, liquid is drawn ________
a) Into the cylinder
b) Away from the cylinder
c) Into the draft tube
d) Away from the draft tube

Explanation: When the piston moves forward, liquid is drawn into the cylinder head. When a cylinder has inlet and outlet ports at each end, then it is called as double acting pumps. It operates similar to the single acting pump with respect to its motion.

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

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.
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6. In a reciprocating pump, with the change in discharge pressure, ________
a) The Volume delivered increases
b) The volume delivered decreases
c) Volume delivered remains the same
d) Volume delivered is independent

Explanation: Irrespective of the change in the discharge pressure, the volume of the fluid delivered remains the same in a reciprocating pump. Thus, it does even vary with the slight increase or decrease of the pump.

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

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.

8. The amount of fluid that leaks internally is called ________
b) Slip
c) Tail race
d) Internal friction

Explanation: The amount of fluid that leaks internally is called as slip. The slip indicates the condition of the pump to improve its overall efficiency.

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

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.

10. Centrifugal pumps are used to transport ________
a) Pressure
b) Speed
c) Power
d) Fluid

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. For a good condition, slip should be________
a) Below 1 percent
b) 1 to 2 percent
c) 3 to 4 percent
d) Above 5 percent

Explanation: For a good condition of the pump, the slip should be below 1 percent. The amount of fluid that leaks internally is called as slip. The slip indicates the condition of the pump to improve its overall efficiency.

12. If the slip is above 5 percent, the pumps needs to be ______
a) Dragged
b) Overhauled
c) Retracted
d) Intermittent

Explanation: If the slip is above 5 percent, the pumps needs to be overhauled. The amount of fluid that leaks internally is called as slip. The slip indicates the condition of the pump to improve its overall efficiency.

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

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

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. Slip in a pump depends on which of following parameters?
a) Wear
b) Pressure
c) Temperature
d) Heat

Explanation: The slip on the pump remains a constant most of the time. The slip changes only when the wear is not rapid. The amount of fluid that leaks internally is called as slip. The slip indicates the condition of the pump to improve its overall efficiency.

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