Discharge of a centrifugal pump is (where N = Speed of the pump impeller)
Directly proportional to N
Inversely proportional to N
Directly proportional to N²
Inversely proportional to N²
Correct Answer :
A. Directly proportional to N
Related Questions
In a single casing, multistage pump running at constant speed, the capacity rating is to be slightly lowered. It can be done by
Designing new impeller
Trimming the impeller size to the required size by machining
Not possible
Some other alterations in the impeller
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 discharge of wheel is
0.25 m3/s
0.5 m3/s
1.5 m3/s
2.5 m3/s
The centrifugal pump preferred for a specific speed between 80 to 160 r.p.m. is
Slow speed with radial flow at outlet
Medium speed with radial flow at outlet
High speed with radial flow at outlet
High speed with mixed flow at outlet
Francis, Kaplan and propeller turbines fall under the category of
Impulse turbines
Reaction turbines
Axial flow turbines
Mixed flow turbines
Braking jet in an impulse turbine is used
To break the jet of water
To bring the runner to rest in a short time
To change the direction of runner
None of these
The flow ratio in case of Francis turbine varies from
0.15 to 0.3
0.4 to 0.5
0.6 to 0.9
1 to 1.5
The working of which of the following hydraulic units is based on Pascal's law?
Air lift pump
Jet pump
Hydraulic coupling
Hydraulic press
Overall efficiency of a centrifugal pump is the ratio of
Energy available at the impeller to the energy supplied to the pump by the prime mover
Actual workdone by the pump to the energy supplied to the pump by the prime mover
Energy supplied to the pump to the energy available at the impeller
Manometric head to the energy supplied by the impeller per kN of water
The angle of taper on draft tube is
Greater than 15°
Greater than 8°
Greater than 5°
Less than 8°
The Fourneyron turbine is _________ reaction turbine.
An axial flow
An inward flow
An outward flow
A mixed flow
Reciprocating pumps are no more to be seen in industrial applications (in comparison to centrifugal pumps) because of
High initial and maintenance cost
Lower discharge
Lower speed of operation
Necessity of air vessel
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
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
The maximum number of jets generally employed in impulse turbine without jet interference is
4
6
8
12
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
Puck up the wrong statement about centrifugal pump
Discharge a diameter
Head a speed²
Head a diameter
Power a speed⁴
Medium specific speed of a pump implies it is
Centrifugal pump
Mixed flow pump
Axial flow pump
Any one of the above
According to fan laws, for fans having constant wheel diameter, the air or gas capacity varies
Directly as fan speed
Square of fan speed
Cube of fan speed
Square root of fan speed
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
A centrifugal pump will start delivering liquid only when the pressure rise in the impeller is equal to the
Kinetic head
Velocity head
Manometric head
Static head
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
In an inward flow reaction turbine
The water flows parallel to the axis of the wheel
The water enters at the centre of the wheel and then flows towards the outer periphery of the wheel
The water enters the wheel at the outer periphery and then flows towards the centre of the wheel
The flow of water is partly radial and partly axial
The unit power developed by a turbine is (where P = Power developed by the turbine under a head of water (H).
P/ √H
P/ H
P/ H3/2
P/ H²
Head developed by a centrifugal pump is
Proportional to diameter of impeller
Proportional to speed of impeller
Proportional to diameter and speed of impeller
None of the above
Which of the following hydraulic unit is used for transmitting increased or decreased torque to the driven shaft?
Hydraulic ram
Hydraulic intensifier
Hydraulic torque converter
Hydraulic accumulator
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
Mechanical efficiency of a centrifugal pump is the ratio of
Energy available at the impeller to the energy supplied to the pump by the prime mover
Actual workdone by the pump to the energy supplied to the pump by the prime mover
Energy supplied to the pump to the energy available at the impeller
Manometric head to the energy supplied by the impeller per kN of water
By fitting an air vessel to the reciprocating pump, there is always a saving of work done and subsequently saving of power. This saving in case of a single acting reciprocating pump is
39.2 %
48.8 %
84.8 %
88.4 %
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
One-half
One-third
Two-third
Three-fourth
The unit discharge through the turbine is
Q/√H
Q/H
Q/H3/2
Q/H²