RBI Grade B officer - Hydraulics & Fluid Machineries 1000+ MCQ [Solved] PDF Download

1. By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. The saving in case of a double acting reciprocating pump is
A. 39.2 %
B. 48.8 %
C. 84.8 %
D. 88.4 %
Answer : A

2. In axial flow fans and turbines, fluid enters and leaves as follows
A. Radially, axially
B. Axially, radially
C. Axially, axially
D. Radially, radially
Answer : C

3. Maximum impulse will be developed in hydraulic ram when
A. Waste valve closes suddenly
B. Supply pipe is long
C. Supply pipe is short
D. Ram chamber is large
Answer : A

4. The ratio of actual work available at the turbine to the energy imparted to the wheel is known as ________ efficiency.
A. Hydraulic
B. Mechanical
C. Overall
D. None of these
Answer : B

5. The Fourneyron turbine is _________ reaction turbine.
A. An axial flow
B. An inward flow
C. An outward flow
D. A mixed flow
Answer : C

6. For small discharge at high pressure, following pump is preferred
A. Centrifugal
B. Axial flow
C. Mixed flow
D. Reciprocating
Answer : D

7. Which of the following pump is generally used to pump highly viscous fluid?
A. Centrifugal pump
B. Reciprocating pump
C. Air lift pump
D. Screw pump
Answer : D

8. Guide angle as per the aerofoil theory of Kaplan turbine blade design is defined as the angle between
A. Lift and resultant force
B. Drag and resultant force
C. Lift and tangential force
D. Lift and drag
Answer : A

9. Which of the following pump is successfully used for lifting water from deep wells?
A. Centrifugal pump
B. Reciprocating pump
C. Jet pump
D. Air lift pump
Answer : D

10. Slip of a reciprocating pump is negative, when
A. Suction pipe is short and pump is running at low speeds
B. Delivery pipe is long and pump is running at high speeds
C. Suction pipe is short and delivery pipe is long and the pump is running at low speeds
D. Suction pipe is long and delivery pipe is short and the pump is running at high speeds
Answer : D

11. A Pelton wheel develops 1750 kW under a head of 100 metres while running at 200 r.p.m. and discharging 2500 litres of water per second. The unit power of the wheel is
A. 0.25 kW
B. 0.75 kW
C. 1.75 kW
D. 3.75 kW
Answer : C

12. A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the
A. Kinetic head
B. Velocity head
C. Manometric head
D. Static head
Answer : C

13. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water would discharge
A. Same quantity of liquid
B. 0.75 Q
C. Q/0.75
D. 1.5 Q
Answer : A

14. The power produced by the reaction turbine is ________ to the head of water.
A. Directly proportional
B. Inversely proportional
C. 4th power
D. None of these
Answer : A

15. A hydraulic press is a device used
A. To store pressure energy which may be supplied to a machine later on
B. To increase the intensity of pressure of water by means of energy available from a large quantity of water at a low pressure
C. To lift larger load by the application of a comparatively much smaller force
D. All of the above
Answer : C

16. Medium specific speed of a pump implies it is
A. Centrifugal pump
B. Mixed flow pump
C. Axial flow pump
D. Any one of the above
Answer : B

17. A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ________ of the jet velocity
A. One-half
B. One-third
C. Two-third
D. Three-fourth
Answer : B

18. Which of the following pump is successfully used for lifting water to the boilers?
A. Centrifugal pump
B. Reciprocating pump
C. Jet pump
D. Airlift pump
Answer : C

19. The jet ratio is defined as the ratio of the
A. Diameter of jet to the diameter of Pelton wheel
B. Velocity of jet to the velocity of Pelton wheel
C. Diameter of Pelton wheel to the diameter of jet
D. Velocity of Pelton wheel to the velocity of jet
Answer : C

20. If a pump is handling water and is discharging a certain flow Q at a constant total dynamic head requiring a definite B.H.P., the same pump when handling a liquid of specific gravity 0.75 and viscosity nearly same as of water, the horse power required will be
A. Same
B. 0.75 B.H.P.
C. B.H.P./0.75
D. 1.5 B.H.P.
Answer : B

21. The ratio of the normal force of jet of water on a plate inclined at an angle of 30° as compared to that when the plate is normal to jet, is
A. 1/?2
B. 1/2
C. 1
D. ?2
Answer : B

22. Which of the following hydraulic unit is used for transmitting increased or decreased torque to the driven shaft?
A. Hydraulic ram
B. Hydraulic intensifier
C. Hydraulic torque converter
D. Hydraulic accumulator
Answer : C

23. A Francis turbine is used when the available head of water is
A. 0 to 25 m
B. 25 m to 250 m
C. Above 250 m
D. None of these
Answer : B

24. The unit speed of the turbine runner is
A. N/?H
B. N/H
C. N/H^3/2
D. N/H²
Answer : A

25. Indicator diagram of a reciprocating pump is a graph between
A. Flow vs. swept volume
B. Pressure in cylinder vs. swept volume
C. Flow vs. speed
D. Pressure vs. speed
Answer : B

26. The hydraulic efficiency of an impulse turbine is maximum when velocity of wheel is _______ of the jet velocity,
A. One-fourth
B. One-half
C. Three-fourth
D. Double
Answer : B

27. For very high discharge at low pressure such as for flood control and irrigation applications, following type of pump is preferred
A. Centrifugal
B. Axial flow
C. Reciprocating
D. Mixed flow
Answer : B

28. For centrifugal pump impeller, the maximum value of the vane exit angle is
A. 10° to 15°
B. 15° to 20°
C. 20° to 25°
D. 25° to 30°
Answer : C

29. The depth of the bucket for a Pelton wheel is generally ________ the diameter of jet.
A. Equal to
B. 1.2 times
C. 1.8 times
D. Double
Answer : B

30. Which of the following turbine is preferred for 0 to 25 m head of water?
A. Pelton wheel
B. Kaplan turbine
C. Francis turbine
D. None of these
Answer : B

31. Hydraulic accumulator is used for
A. Accumulating oil
B. Supplying large quantities of oil for very short duration
C. Generally high pressures to operate hydraulic machines
D. Supplying energy when main supply fails
Answer : D

32. In centrifugal pumps, maximum efficiency is obtained when the blades are
A. Straight
B. Bent forward
C. Bent backward
D. Radial
Answer : C

33. A double overhung Pelton wheel has
A. Two jets
B. Two runners
C. Four jets
D. Four runners
Answer : B

34. Reaction turbines are used for
A. Low head
B. High head
C. High head and low discharge
D. Low head and high discharge
Answer : D

35. A hydraulic accumulator is a device used to store ________ energy which may be supplied to a machine later on.
A. Strain
B. Pressure
C. Kinetic
D. None of these
Answer : B

36. Which of the following pump is preferred for flood control and irrigation applications?
A. Centrifugal pump
B. Axial flow pump
C. Mixed flow pump
D. Reciprocating pump
Answer : B

37. One horsepower is equal to
A. 102 watts
B. 75 watts
C. 550 watts
D. 735 watts
Answer : D

38. Francis, Kaplan and propeller turbines fall under the category of
A. Impulse turbines
B. Reaction turbines
C. Axial flow turbines
D. Mixed flow turbines
Answer : B

39. The specific speed of a turbine is the speed of an imaginary turbine, identical with the given turbine, which
A. Delivers unit discharge under unit head
B. Delivers unit discharge under unit speed
C. Develops unit power under unit head
D. Develops unit power under unit speed
Answer : C

40. High specific speed of turbine implies it is
A. Propeller turbine
B. Francis turbine
C. Impulse turbine
D. None of the above
Answer : A

41. A hydraulic intensifier normally consists of
A. Two cylinders, two rams and a storage device
B. A cylinder and a ram
C. Two coaxial rams and two cylinders
D. A cylinder, a piston, storage tank and control valve
Answer : C

42. The undershot water wheels are those in which
A. The wheel runs entirely by the weight of water
B. The wheel runs entirely by the impulse of water
C. The wheel runs partly by the weight of water and partly by the impulse of water
D. None of the above
Answer : B

43. The unit discharge through the turbine is
A. Q/?H
B. Q/H
C. Q/H^3/2
D. Q/H²
Answer : A

44. Braking jet in an impulse turbine is used
A. To break the jet of water
B. To bring the runner to rest in a short time
C. To change the direction of runner
D. None of these
Answer : B

45. The maximum hydraulic efficiency of an impulse turbine is (where ? = Angle of blade tip at outlet)
A. (1 + cos ?)/2
B. (1 - cos ?)/2
C. (1 + sin ?)/2
D. (1 - sin ?)/2
Answer : A

46. A turbine develops 10000 kW under a head of 25 metres at 135 r.p.m. Its specific speed is
A. 175.4 r.p.m.
B. 215.5 r.p.m.
C. 241.5 r.p.m.
D. 275.4 r.p.m
Answer : C

47. The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is
A. Slow speed with radial flow at outlet
B. Medium speed with radial flow at outlet
C. High speed with radial flow at outlet
D. High speed with mixed flow at outlet
Answer : D

48. Slip of a reciprocating pump is defined as the
A. Ratio of actual discharge to the theoretical discharge
B. Sum of actual discharge and the theoretical discharge
C. Difference of theoretical discharge and the actual discharge
D. Product of theoretical discharge and the actual discharge
Answer : C

49. The relation between hydraulic efficiency (?_h), mechanical efficiency (?_m) and overall efficiency (?_o) is
A. ?_h = ?_o × ?_m
B. ?_m = ?_m × ?_h
C. ?_o = ?_h × ?_m
D. None of these
Answer : C

50. The cavitation in a hydraulic machine
A. Causes noise and vibration of various parts
B. Reduces the discharge of a turbine
C. Causes sudden drop in power output and efficiency
D. All of the above
Answer : D