What causes cavitation in centrifugal pump? (A) High suction pressure (B) Low barometric pressure(C) Low suction pressure(D) High suction velocity

What causes cavitation in centrifugal pump?
(A) High suction pressure
(B) Low barometric pressure
(C) Low suction pressure
(D) High suction velocity
by

1 Answer

Answer :

(C) Low suction pressure
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Related questions

Net positive suction head (NPSH) of a centrifugal pump must be (A) Greater than the vapour pressure of the liquid (B) Less than the vapour pressure of the liquid(C) Equal to the vapour pressure of the liquid(D) Less than barometric pressure

Description : Net positive suction head (NPSH) of a centrifugal pump must be (A) Greater than the vapour pressure of the liquid (B) Less than the vapour pressure of the liquid (C) Equal to the vapour pressure of the liquid (D) Less than barometric pressure

Last Answer : (A) Greater than the vapour pressure of the liquid

Cavitation occurs in a centrifugal pump when the suction pressure is (A) Less than the vapour pressure of the liquid at that temperature (B) Greater than the vapour pressure of the liquid at that temperature (C) Equal to the vapour pressure (D) Equal to the developed head

Description : Cavitation occurs in a centrifugal pump when the suction pressure is (A) Less than the vapour pressure of the liquid at that temperature (B) Greater than the vapour pressure of the liquid at that temperature (C) Equal to the vapour pressure (D) Equal to the developed head

Last Answer : (A) Less than the vapour pressure of the liquid at that temperature

In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature. (A) Lower than (B) Higher than (C) Equal to (D) None of these

Description : In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature. (A) Lower than (B) Higher than (C) Equal to (D) None of these

Last Answer : (B) Higher than

Cavitation in a centrifugal pump can be avoided by keeping the (A) Inlet pressure high (B) Outlet pressure low (C) Inlet pressure low (D) Outlet pressure high

Description : Cavitation in a centrifugal pump can be avoided by keeping the (A) Inlet pressure high (B) Outlet pressure low (C) Inlet pressure low (D) Outlet pressure high

Last Answer : (A) Inlet pressure high

In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow? (A) Discharge of water by a centrifugal pump being run at a constant rpm (B) Water flow in the suction and discharge pipe of a reciprocating pump (C) Water discharge from a vertical vessel in which constant level is maintained (D) Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe

Description : In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow? (A) ... level is maintained (D) Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe

Last Answer : (B) Water flow in the suction and discharge pipe of a reciprocating pump

The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the (A) Discharge (B) Suction (C) Suction minus vapor pressure of the liquid at suction temperature (D) Discharge minus vapor pressure of the liquid at the discharge temperature

Description : The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the (A) Discharge (B) Suction (C) Suction minus vapor ... of the liquid at suction temperature (D) Discharge minus vapor pressure of the liquid at the discharge temperature

Last Answer : (C) Suction minus vapor pressure of the liquid at suction temperature

The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the (A) Discharge (B) Suction (C) Suction minus vapor pressure of the liquid at suction temperature (D) Discharge minus vapor pressure of the liquid at the discharge temperature

Description : The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the (A) Discharge (B) Suction (C) Suction minus vapor ... of the liquid at suction temperature (D) Discharge minus vapor pressure of the liquid at the discharge temperature

Last Answer : (C) Suction minus vapor pressure of the liquid at suction temperature

Cavitation can be prevented by (A) Suitably designing the pump (B) Maintaining the suction head sufficiently greater than the vapour pressure (C) Maintaining suction head = developed head (D) Maintaining suction head lower than the vapour pressure

Description : Cavitation can be prevented by (A) Suitably designing the pump (B) Maintaining the suction head sufficiently greater than the vapour pressure (C) Maintaining suction head = developed head (D) Maintaining suction head lower than the vapour pressure

Last Answer : (B) Maintaining the suction head sufficiently greater than the vapour pressure

Conversion of dynamic velocity head into static pressure head in a centrifugal pump is the result of : (a) Increasing area of flow between adjacent vanes from inlet to outlet (b) Difference in pressure between suction and delivery ends (c) Radial thrust in pumps (d) Stuffing Box

Description : Conversion of dynamic velocity head into static pressure head in a centrifugal pump is the result of : (a) Increasing area of flow between adjacent vanes from inlet to outlet (b) Difference in pressure between suction and delivery ends (c) Radial thrust in pumps (d) Stuffing Box

Last Answer : (b) Difference in pressure between suction and delivery ends

The excess of the sum of pressure & velocity heads over the vaporpressure of the liquid at the suction is called the(A) Static submergence(B) Net positive suction head (NPSH)(C) Cavitation sensitivity(D) Priming

Description : The excess of the sum of pressure & velocity heads over the vaporpressure of the liquid at the suction is called the (A) Static submergence (B) Net positive suction head (NPSH) (C) Cavitation sensitivity (D) Priming

Last Answer : (B) Net positive suction head (NPSH)

In most of the vacuum crystalliser, vacuum is generally produced by means of a (A) Suction pump (B) Compressed air jet (C) Steam jet ejector with a barometric condenser (D) None of these

Description : In most of the vacuum crystalliser, vacuum is generally produced by means of a (A) Suction pump (B) Compressed air jet (C) Steam jet ejector with a barometric condenser (D) None of these

Last Answer : (C) Steam jet ejector with a barometric condenser

Erosion and pits formation on the impeller of a centrifugal pump may be due to (A) Cavitation (B) Low speed of impeller (C) Its operation with delivery valve closed for considerable time after starting the pump (D) Off centering of pump with motor

Description : Erosion and pits formation on the impeller of a centrifugal pump may be due to (A) Cavitation (B) Low speed of impeller (C) Its operation with delivery valve closed for considerable time after starting the pump (D) Off centering of pump with motor

Last Answer : (A) Cavitation

Circulation pump is located below the evaporator to (A) Avoid cavitation (B) Avoid frequent priming (C) Create more suction head (D) None of these

Description : Circulation pump is located below the evaporator to (A) Avoid cavitation (B) Avoid frequent priming (C) Create more suction head (D) None of these

Last Answer : (C) Create more suction head

A centrifugal pump loses prime after starting. The reason of this trouble may be (A) Incomplete priming (B) Too high a suction lift (C) Low available NPSH and air leaks in the suction pipe (D) All (A), (B), and (C)

Description : A centrifugal pump loses prime after starting. The reason of this trouble may be (A) Incomplete priming (B) Too high a suction lift (C) Low available NPSH and air leaks in the suction pipe (D) All (A), (B), and (C)

Last Answer : (D) All (A), (B), and (C)

The main drawback of centrifugal pump is a)necessity of priming b) discharge from pump varies with the load of water c) For high heads efficiency is low up to 50% d) the suction lift is limited to 6 metre e) all of the above*

Description : The main drawback of centrifugal pump is a)necessity of priming b) discharge from pump varies with the load of water c) For high heads efficiency is low up to 50% d) the suction lift is limited to 6 metre e) all of the above*

Last Answer : e) all of the above*

Good design of the casing of a centrifugal pump aims at minimising the (A) Cavitation (B) Frictional losses (C) Kinetic energy loss (D) Static head

Description : Good design of the casing of a centrifugal pump aims at minimising the (A) Cavitation (B) Frictional losses (C) Kinetic energy loss (D) Static head

Last Answer : Option C

Assume that water vaporizes at an absolute pressure of 1.5 m, barometric pressure head is 9.5 m and cavitation coefficient is 0.1 A turbine operates under a head of 40 m. the safe height of the runner above the tail water level, in meters, is : a) 6 b) 4 c) 3 d) 2

Description : Assume that water vaporizes at an absolute pressure of 1.5 m, barometric pressure head is 9.5 m and cavitation coefficient is 0.1 A turbine operates under a head of 40 m. the safe height of the runner above the tail water level, in meters, is : a) 6 b) 4 c) 3 d) 2

Last Answer : b) 4

Specific speed of a centrifugal pump depends upon the __________ head. (A) Suction (B) Delivery (C) Manometric (D) None of these

Description : Specific speed of a centrifugal pump depends upon the __________ head. (A) Suction (B) Delivery (C) Manometric (D) None of these

Last Answer : (D) None of these

Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be __________ ft. (A) 40 (B) 34 (C) 8 (D) 37

Description : Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be __________ ft. (A) 40 (B) 34 (C) 8 (D) 37

Last Answer : (C) 8

If the discharge of a centrifugal pump is throttled, then its suction lift (A) Increases (B) Decreases (C) Remains unchanged (D) Data insufficient to predict

Description : If the discharge of a centrifugal pump is throttled, then its suction lift (A) Increases (B) Decreases (C) Remains unchanged (D) Data insufficient to predict

Last Answer : (A) Increases

Foot valves are provided in the suction line of a centrifugal pump to (A) Avoid priming, every time we start the pump (B) Remove the contaminant present in the liquid (C) Minimise the fluctuation in discharge (D) Control the liquid discharge

Description : Foot valves are provided in the suction line of a centrifugal pump to (A) Avoid priming, every time we start the pump (B) Remove the contaminant present in the liquid (C) Minimise the fluctuation in discharge (D) Control the liquid discharge

Last Answer : (A) Avoid priming, every time we start the pump

In centrifugal pumps, cavitation occurs, when pressure of the impeller eye or vane becomes (A) Less than atmospheric pressure (B) More than liquid vapor pressure (C) Less than liquid vapor pressure (D) More than atmospheric pressure

Description : In centrifugal pumps, cavitation occurs, when pressure of the impeller eye or vane becomes (A) Less than atmospheric pressure (B) More than liquid vapor pressure (C) Less than liquid vapor pressure (D) More than atmospheric pressure

Last Answer : (C) Less than liquid vapor pressure

Suction lift of a pump depends upon (A) Atmospheric pressure (B) Water temperature (C) Velocity of water in suction pipe (D) All the above

Description : Suction lift of a pump depends upon  (A) Atmospheric pressure  (B) Water temperature  (C) Velocity of water in suction pipe  (D) All the above 

Last Answer : (D) All the above 

Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation? (A) Decrease in effect(B) Increase in thrust(C) Develops noise(D) Develops high pressure

Description : Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation? (A) Decrease in effect (B) Increase in thrust (C) Develops noise (D) Develops high pressure

Last Answer : (D) Develops high pressure

Air vessel fitted to a reciprocating pump (A) Increases the work done (B) Decreases the work done (C) Causes cavitation (D) Results in non-uniform discharge

Description : Air vessel fitted to a reciprocating pump (A) Increases the work done (B) Decreases the work done (C) Causes cavitation (D) Results in non-uniform discharge

Last Answer : (B) Decreases the work done

Cavitation is caused by (A) High velocity (B) High pressure (C) Weak material (D) Low pressure

Description : Cavitation is caused by (A) High velocity (B) High pressure (C) Weak material (D) Low pressure

Last Answer : Answer: Option D

The most important factor, which determines the maximum height to which water can be lifted by a pump at standard temperature is the (A) Barometric pressure (B) Speed of the impeller (C) Diameter of the impeller (D) Both (B) and (C)

Description : The most important factor, which determines the maximum height to which water can be lifted by a pump at standard temperature is the (A) Barometric pressure (B) Speed of the impeller (C) Diameter of the impeller (D) Both (B) and (C)

Last Answer : (A) Barometric pressure

Volute type of casing is provided in a centrifugal pump to (A) Convert velocity head to pressure head (B) Convert pressure head to velocity head (C) Reduce the discharge fluctuation (D) Increase the discharge

Description : Volute type of casing is provided in a centrifugal pump to (A) Convert velocity head to pressure head (B) Convert pressure head to velocity head (C) Reduce the discharge fluctuation (D) Increase the discharge

Last Answer : (D) Increase the discharge

What type of pump may be appropriate for a liquid near saturation, a low flow rate, and very limited NPSHa (net positive suction head available)?

Description : What type of pump may be appropriate for a liquid near saturation, a low flow rate, and very limited NPSHa (net positive suction head available)?

Last Answer : This application is nearly perfect for a turbine regenerative type of pump. Factors that immediately identify your application and pump type are the small flowrate, low NPSHa, and high temperature. The ... in pressure. You can visit the site below to learn more about these types of pumps.

The cooling effect in a cooling tower cannot be increased by (A) Increasing the air velocity over the wet surfaces (B) Reducing the humidity of entering air (C) Lowering the barometric pressure (D) None of these

Description : The cooling effect in a cooling tower cannot be increased by (A) Increasing the air velocity over the wet surfaces (B) Reducing the humidity of entering air (C) Lowering the barometric pressure (D) None of these

Last Answer : (D) None of these

Pick out the wrong statement: (A) Change in barometric pressure does not affect the relative humidity (B) In case of a packed tower, the operating velocity is about half of the flooding velocity, generally (C) 'Elution' means the desorption of the adsorbed solute by a solvent (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Description : Pick out the wrong statement: (A) Change in barometric pressure does not affect the relative humidity (B) In case of a packed tower, the operating velocity is about half of the ... (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

Last Answer : (D) The equilibrium moisture content of the solid can be reduced by increasing the absolute humidity

The cooling effect in a cooling tower can be speeded up by (A) Increasing the air velocity and area of exposed wet surface (B) Reducing the barometric pressure (C) Reducing the humidity of the air (D) All (A), (B) and (C)

Description : The cooling effect in a cooling tower can be speeded up by (A) Increasing the air velocity and area of exposed wet surface (B) Reducing the barometric pressure (C) Reducing the humidity of the air (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

A compressor that takes suction at a pressure below atmospheric and discharge against atmospheric pressure is called a __________ pump. (A) Sump (B) Volute (C) Vacuum (D) Submerged

Description : A compressor that takes suction at a pressure below atmospheric and discharge against atmospheric pressure is called a __________ pump. (A) Sump (B) Volute (C) Vacuum (D) Submerged

Last Answer : (C) Vacuum

Pick out the wrong statement about cavitation. (A) Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation (B) Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities (C) Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise(D) Large scale cavitation cannot damage pipeline, restrict fluid flow anddamage steam turbine blades

Description : Pick out the wrong statement about cavitation. (A) Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation ... (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

Last Answer : (D) Large scale cavitation cannot damage pipeline, restrict fluid flow and damage steam turbine blades

In fluid flow, cavitation is caused, if the (A) Fluid velocity decreases to zero (B) Total energy decreases (C) Both (A) and (B) (D) Flow pressure approaches its vapor pressure at the prevailing temperature

Description : In fluid flow, cavitation is caused, if the (A) Fluid velocity decreases to zero (B) Total energy decreases (C) Both (A) and (B) (D) Flow pressure approaches its vapor pressure at the prevailing temperature

Last Answer : (D) Flow pressure approaches its vapor pressure at the prevailing temperature

Why Cavitation Will Occur In Centrifugal Pumps And Not In Displacement Pumps?

Description : Why Cavitation Will Occur In Centrifugal Pumps And Not In Displacement Pumps?

Last Answer : The formation of cavities (or bubbles) is induced by flow separation, or non-uniform flow velocities, inside a pump casing. In centrifugal pumps the eye of the pump impeller is smaller than ... to increase in temperature in impeller. This air bubbles are transmitted to pump which forms cavitation.

Mercury is an ideal barometric fluid mainly due to its(A) High density (B) Low compressibility (C) Low capillary action (D) Very low vapor pressure

Description : Mercury is an ideal barometric fluid mainly due to its (A) High density (B) Low compressibility (C) Low capillary action (D) Very low vapor pressure

Last Answer : (D) Very low vapor pressure

Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller. (A) Radius of (B) Speed of (C) Fluid velocity leaving (D) None of these

Description : Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller. (A) Radius of (B) Speed of (C) Fluid velocity leaving (D) None of these

Last Answer : (D) None of these

In case of a centrifugal pump, the theoretical head developed is dependent on the __________ the impeller. (A) Speed of (B) Diameter of (C) Fluid velocity leaving (D) All (A), (B) and (C)

Description : In case of a centrifugal pump, the theoretical head developed is dependent on the __________ the impeller. (A) Speed of (B) Diameter of (C) Fluid velocity leaving (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Volute of a centrifugal pump should be designed in a fashion, such that the (A) Kinetic head gets converted into static head (B) Moving stream gradually reduces velocity (C) Mean velocity remains constant (D) None of these

Description : Volute of a centrifugal pump should be designed in a fashion, such that the (A) Kinetic head gets converted into static head (B) Moving stream gradually reduces velocity (C) Mean velocity remains constant (D) None of these

Last Answer : (A) Kinetic head gets converted into static head

The peripheral velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec. (A) 1.8 (B) 12.4 (C) 186.2 (D) 736.4

Description : The peripheral velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec. (A) 1.8 (B) 12.4 (C) 186.2 (D) 736.4

Last Answer : (B) 12.4

Which of the following is not the function of a volute casing provided in a centrifugal pump? (A) To reduce the head loss in discharge (B) To increase the pump efficiency (C) To collect liquid from the periphery of the impeller and to transmit it to the delivery pipe at constant velocity (D) To increase the pump discharge rate

Description : Which of the following is not the function of a volute casing provided in a centrifugal pump? (A) To reduce the head loss in discharge (B) To increase the pump efficiency (C) To collect liquid ... and to transmit it to the delivery pipe at constant velocity (D) To increase the pump discharge rate

Last Answer : Option D

Probability of cavitation occuring becomes very high, when the local __________ resulting in water bubbles formation, which on rupture cause cavitation (A) Pressure falls below the vapour pressure (B) Pressure becomes very high (C) Temperature becomes low (D) All 'a', 'b' & 'c'

Description : Probability of cavitation occuring becomes very high, when the local __________ resulting in water bubbles formation, which on rupture cause cavitation (A) Pressure falls below the vapour pressure (B) Pressure becomes very high (C) Temperature becomes low (D) All 'a', 'b' & 'c'

Last Answer : (D) All 'a', 'b' & 'c'

Air vessel provided in a reciprocating pump (A) Smoothens the flow by avoiding pulsations (B) Increases the volumetric efficiency of the pump (C) Saves the pump from the danger of cavitation (D) None of these

Description : Air vessel provided in a reciprocating pump (A) Smoothens the flow by avoiding pulsations (B) Increases the volumetric efficiency of the pump (C) Saves the pump from the danger of cavitation (D) None of these

Last Answer : (D) None of these

. A special type of liquid transporting device is the diffuser pump, in which __________ are minimised. (A) Bearing losses (B) Disk friction (C) Shock losses (D) Cavitation

Description : . A special type of liquid transporting device is the diffuser pump, in which __________ are minimised. (A) Bearing losses (B) Disk friction (C) Shock losses (D) Cavitation

Last Answer : (C) Shock losses

Function of air vessel provided in a reciprocating pump is to (A) Reduce discharge fluctuation (B) Reduce the danger of cavitation (C) Avoid the necessity of priming (D) Increase the pump efficiency

Description : Function of air vessel provided in a reciprocating pump is to (A) Reduce discharge fluctuation (B) Reduce the danger of cavitation (C) Avoid the necessity of priming (D) Increase the pump efficiency

Last Answer : (A) Reduce discharge fluctuation

Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have (A) Very low speeds (B) Smaller discharge (C) Higher capital &maintenance cost (D) High vibrations

Description : Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have (A) Very low speeds (B) Smaller discharge (C) Higher capital &maintenance cost (D) High vibrations

Last Answer : (C) Higher capital &maintenance cost

How does the high/low temperatures, the barometric pressure, and the relative humidity influence what kinds of clouds are out?

Description : How does the high/low temperatures, the barometric pressure, and the relative humidity influence what kinds of clouds are out?

Last Answer : answer:Yikes. The formation of clouds is an application of the First Law of Thermodynamics. According to the First Law, a change in the internal energy of a system can be due to the ... for air under these conditions is the moist adiabatic lapse rate and is approximately -5oC per kilometer.

How Cavitation Can Be Eliminated In A Pump?

Description : How Cavitation Can Be Eliminated In A Pump?

Last Answer : Cavitation means bubbles are forming in the liquid.  To avoid Cavitation, we have to increase the Pump size to One or Two Inch;  To increase the pressure of the Suction Head, or  Decrease the Pump Speed.

The main draw-back of centrifugal pump, is (A) Necessity of priming (B) Discharge from pump varies with the load of water (C) For high heads, efficiency is low up to 50% (D) All the above

Description : The main draw-back of centrifugal pump, is (A) Necessity of priming (B) Discharge from pump varies with the load of water (C) For high heads, efficiency is low up to 50% (D) All the above

Last Answer : (D) All the above