4

# Centrifugal pump is started with its delivery valve

Kept fully closed

Kept fully open

Irrespective of any position

Kept 50% open

A. Kept fully closed

4

# Which of the following pump is successfully used for lifting water from deep wells?

Centrifugal pump

Reciprocating pump

Jet pump

Air lift pump

4

# Slip of a reciprocating pump is negative, when

Suction pipe is short and pump is running at low speeds

Delivery pipe is long and pump is running at high speeds

Suction pipe is short and delivery pipe is long and the pump is running at low speeds

Suction pipe is long and delivery pipe is short and the pump is running at high speeds

4

# A ship with jet propulsion draws water through inlet orifices at right angles to the direction of its motion. The propelling force of the jet is (where a = Area of the jet, Vr = Relative velocity of the jet and ship = V + v, v = Velocity of the ship, and V = Velocity of the jet issuing from the ship)

waVr /g × (Vr + v)

waVr /g × (Vr - v)

waVr /g × (Vr + v)²

waVr /g × (Vr - v)²

4

# Which of the following pump is successfully used for lifting water to the turbines?

Centrifugal pump

Reciprocating pump

Jet pump

Air lift pump

4

2 to 4

4 to 8

8 to 16

16 to 24

4

# If the net positive suction head (NPSH) requirement for the pump is not satisfied, then

No flow will take place

Cavitation will be formed

Efficiency will be low

Excessive power will be consumed

4

waV / 2g

waV / g

waV² / 2g

waV² / g

4

# The overall efficiency of a reaction turbine is the ratio of

Power produced by the turbine to the energy actually supplied by the turbine

Actual work available at the turbine to the energy imparted to the wheel

Workdone on the wheel to the energy (or head of water) actually supplied to the turbine

None of the above

4

# When a piping system is made up primarily of friction head and very little of vertical lift, then pump characteristics should be

Horizontal

Nearly horizontal

Steep

First rise and then fall

4

# A turbine pump is basically a centrifugal pump equipped additionally with

Vaned diffusion casing

4

# Power required to drive a centrifugal pump is directly proportional to ________ of its impeller.

Diameter

Square of diameter

Cube of diameter

Fourth power of diameter

4

At the top

At the bottom

At the canter

From sides

4

# Francis turbine is best suited for

Medium head application from 24 to 180 m

Low head installation up to 30 m

High head installation above 180 m

4

4

# Maximum impulse will be developed in hydraulic ram when

Waste valve closes suddenly

Supply pipe is long

Supply pipe is short

Ram chamber is large

4

Normal speed

Unit speed

Specific speed

None of these

4

# The power developed by a turbine is (where H = Head of water under which the turbine is working)

Directly proportional to H1/2

Inversely proportional to H1/2

Directly proportional to H3/2

Inversely proportional to H3/2

4

Greater than 15°

Greater than 8°

Greater than 5°

Less than 8°

4

# The mechanical efficiency of an impulse turbine is

Ratio of the actual power produced by the turbine to the energy actually supplied by the turbine

Ratio of the actual work available at the turbine to the energy imparted to the wheel

Ratio of the Work done on the wheel to the energy of the jet

None of the above

4

# Hydraulic accumulator is used for

Accumulating oil

Supplying large quantities of oil for very short duration

Generally high pressures to operate hydraulic machines

Supplying energy when main supply fails

4

# Power required (in watts) to drive a centrifugal pump is (where Hm = Manometric head in metres, w = Specific weight in N/m3, Q = Discharge of the pump in m3/s, and ηo = Overall efficiency of the pump)

(w Hm) / (Q × ηo)

(w Hm Q) / ηo

(w Q) / (Hm × ηo)

(w Q ηo) / Hm

4

Double

Three times

Four times

Five times

4

# The discharge through a turbine is

Directly proportional to H1/2

Inversely proportional to H1/2

Directly proportional to H3/2

Inversely proportional to H3/2

4

Pelton wheel

Kaplan turbine

Francis turbine

None of these

4

# The cavitation in a hydraulic machine

Causes noise and vibration of various parts

Reduces the discharge of a turbine

Causes sudden drop in power output and efficiency

All of the above

4

10° to 15°

15° to 20°

20° to 25°

25° to 30°

4

# Multistage centrifugal pumps are used to

Give high discharge

Pump viscous fluids

All of these

4

0 to 4.5

10 to 100

80 to 200

250 to 300

4

Two jets

Two runners

Four jets

Four runners

4

# In a reaction turbine, the draft tube is used

To run the turbine full

To prevent air to enter the turbine

To increase the head of water by an amount equal to the height of the runner outlet above the tail race

To transport water to downstream