# Hydraulic Machines Questions and Answers – Main Parts and Working

This set of Hydraulic Machines Questions and Answers for Entrance exams focuses on “Main Parts and Working “.

1. How many number of valves are required for the rotary pump?
a) 0
b) 1
c) 2
d) 3

Explanation: There are no valves required for a rotary pump. A rotary pump is the one in which the flow is continuous. Since, the flow is continuous, we do not require any valves.

2. Reciprocating pump is divided into how many types, based on its cylinders?
a) 0
b) 5
c) 2
d) 3

Explanation: Based on the number of cylinders, the reciprocating pump is divided into five types. It is divided on the basis of cylinders as single, double, triple , duplex and quintuplex.

3. At each stage the fluid is directed ________
a) Towards the centre
b) Away the centre
c) Towards the surface
d) Away from the centre

Explanation: At each stage in the centrifugal pump, the fluid is directed to towards the centre. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working.

4. The maximum efficiency of the reciprocating pump is _________
a) 20
b) 50
c) 70
d) 85

Explanation: Reciprocating pump is more favourable for small liquid quantities. As the chamber in the liquid is trapped, it has a stationary cylinder which contains a piston and a plunger. The maximum efficiency of the reciprocating pump is 85 percent.

5. The two opposite motion that comprise a single reciprocation is called _________
a) Turbocharger
b) Stokes
c) Fluid motion
d) Auto motion

Explanation: Degree of reaction is most commonly used in turbomachinery. Degree of reaction is defined as the ratio of the static pressure drop in the rotor to the static pressure drop in the stage. It can also be defined in the same way for enthalpy in different stages. It is denoted by the letter ‘R’.
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6. Reciprocating pumps has ____ efficiency compared to centrifugal pumps
a) Higher
b) Lower
c) Equal
d) Exponential

Explanation: Reciprocating pumps has lower efficiency compared to centrifugal pumps. They are generally just used for discharges at higher heads. Their main purpose is to pump water in hilly areas.

7. Reciprocating pumps works on the principle of __________
a) Drag force
b) Liquid flow push
c) Shock waves
d) Flow speed

Explanation: Reciprocating pumps works on the principle of liquid flow push by a piston that reciprocates in a closed fitting cylinder.

8. Reciprocating pump is a type of ___________
a) Positive displacement pump
b) Bicycle pump
c) Multistage pumps
d) Centrifugal pumps

Explanation: Reciprocating pump is a type of positive displacement pump. The positive displacement pump includes piston pump, diaphragm and plunger pump.

9. During the suction stroke the _______ moves left thus creating vacuum in the Cylinder.
a) Piston
b) Cylinder
c) Valve
d) Pump

Explanation: During the suction stroke the piston moves left. Thus, a vacuum is created in the cylinder. This vacuum causes the suction valve to open and water enters the Cylinder.

10. In reciprocating pumps, the chamber in which the liquid is trapped is a stationary cylinder that contains piston or cylinder
a) True
b) False

Explanation: In reciprocating pumps, the chamber in which the liquid is trapped is a stationary cylinder that contains piston or cylinder.

11. Reciprocating pump works like a positive displacement pump.
a) True
b) False

Explanation: Reciprocating pump works like a positive displacement pump. In reciprocating pumps, the chamber in which the liquid is trapped is a stationary cylinder that contains piston or cylinder.

12. When both the sources are effective it is called as __________
a) Double acting pump
b) Single acting pump
c) Triple acting pump
d) Normal pump

Explanation: When both the sources are effective it is called as double acting centrifugal pump. The pumping unit consists of piston and cylinder.

13. A repetitive variation about the central value of equilibrium is called ________
a) Reciprocation
b) Oscillation
c) Filtration
d) Excavation

Explanation: A repetitive variation about the central value of equilibrium is called as oscillation. It need not be linear.

14. A linear wheel turning motion is called as a ________
a) Reciprocation
b) Rotation
c) Oscillation
d) Bicycle pump

Explanation: A linear wheel turning motion is called as a rotational motion. It is linear motion that takes place along a circular section.

15. A reciprocating pump that has 1200 crank is _________
a) Froth pump
b) Single acting
c) Double acting
d) Triple acting

Explanation: A reciprocating pump that has 1200 crank is triple acting or triple cylinder pump. Each cylinder in a reciprocating pump has it suction and delivery pipes. Thus, has a crank of 1200.

Sanfoundry Global Education & Learning Series – Hydraulic Machines.

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