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

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
by

1 Answer

Answer :

(A) Inlet pressure high
by

Related questions

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

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

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

Last Answer : (C) Low suction pressure

In centrifugal pump installation, (A) Pump is properly primed before starting (B) The diameter of the pipe at inlet as well as at outlet, is kept smaller than the delivery pipe (C) The motor may burn out if it is started with empty delivery pipe and with open gate valve (D) All the above

Description : In centrifugal pump installation,  (A) Pump is properly primed before starting  (B) The diameter of the pipe at inlet as well as at outlet, is kept smaller than the delivery pipe  (C) The ... out if it is started with empty delivery pipe and with open gate valve  (D) All the above 

Last Answer : (D) All the above 

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

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

The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades. (A) Inlet tip of a blade curves in a direction opposite to that (B) Outlet tip of a blade curves in a direction opposite to that (C) Inlet tip of a blade is towards the direction (D) Outlet tip of a blade is towards the direction

Description : The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades. (A) Inlet tip of a blade curves in a direction opposite to that (B) Outlet tip ... Inlet tip of a blade is towards the direction (D) Outlet tip of a blade is towards the direction

Last Answer : (D) Outlet tip of a blade is towards the direction

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

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

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

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

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

6. In a forward feed multiple effect, the pressure build up will be (A) Least at the inlet of the first effect (B) Least at the outlet of the last effect (C) Highest at the inlet of the last effect (D) Highest at the outlet of the last effect

Description : 6. In a forward feed multiple effect, the pressure build up will be (A) Least at the inlet of the first effect (B) Least at the outlet of the last effect (C) Highest at the inlet of the last effect (D) Highest at the outlet of the last effect

Last Answer : (B) Least at the outlet of the last effect

Momentum correction factor used in fluid flow problems accounts for the (A) Change in direction of flow (B) Change in total energy (C) Change in pressure (D) Non uniform direction of velocities at inlet & outlet sections

Description : Momentum correction factor used in fluid flow problems accounts for the (A) Change in direction of flow (B) Change in total energy (C) Change in pressure (D) Non uniform direction of velocities at inlet & outlet sections

Last Answer : (D) Non uniform direction of velocities at inlet & outlet sections

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

Delivery of insufficient quantity of liquid by a pump may be caused by (A) Air leak in the inlet (B) Low rpm (C) Too high a lift (D) All (A), (B) and (C)

Description : Delivery of insufficient quantity of liquid by a pump may be caused by (A) Air leak in the inlet (B) Low rpm (C) Too high a lift (D) All (A), (B) and (C)

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

The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost is P. Inlet pressure Q. Compressor rpm R. Delivery pressure S. Volumetric flow rate at inlet. (A) P, Q and R (B) P and R (C) R and S (D) P, Rand S

Description : The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost is P. Inlet pressure Q. Compressor rpm R. Delivery pressure S. Volumetric flow rate at inlet. (A) P, Q and R (B) P and R (C) R and S (D) P, Rand S

Last Answer : (A) P, Q and R

A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process? (A) Flow rate of inlet air (B) Relative humidity of outlet air (C) Humidity of inlet air (D) Temperature of the solid

Description : A solid material shows case hardening properties while drying. Which of the following should be controlled to control the drying process? (A) Flow rate of inlet air (B) Relative humidity of outlet air (C) Humidity of inlet air (D) Temperature of the solid

Last Answer : (D) Temperature of the solid

In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is (A) ∞ (B) 0 (C) Equal to the difference between hot and cold fluids inlet temperature (D) Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

Description : In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is (A) ∞ (B) 0 ... temperature (D) Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature

Last Answer : (B) 0

The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt (A) At the inlet (B) At the outlet (C) In the reactor (D) Averaged over the inlet and outlet

Description : The 'E' curve for a non-ideal reactor defines the fraction of fluid having age between t and t + dt (A) At the inlet (B) At the outlet (C) In the reactor (D) Averaged over the inlet and outlet

Last Answer : (B) At the outlet

Which of the statement is “True” for centrifugal compressors? a) The compressor should not be operated at full load b) The compressor should be operated at shut off pressure c) The compressor should not be operated with inlet-guide vane control d) The compressor should not be operated close to the surge point

Description : Which of the statement is True for centrifugal compressors? a) The compressor should not be operated at full load b) The compressor should be operated at shut off pressure c) The ... operated with inlet-guide vane control d) The compressor should not be operated close to the surge point 

Last Answer : d) The compressor should not be operated close to the surge point

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.

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'

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

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

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

Why is an electrical outlet called an outlet when you plug things into it? Shouldn't it be called an inlet?

Description : Why is an electrical outlet called an outlet when you plug things into it? Shouldn't it be called an inlet?

Last Answer : Current flow out from the wall socket when you plug a cord into it. If you want this to be called an inlet and not an outlet, then it would need to be reversed. When you plugged the cord ... flow is by a conductor such as your plug that trips the circuit and allows the electricity to flow freely.

A tank has two inlet pipes, A and B, which can fill the tank in 12 hours and 18 hours respectively, and an outlet C which can empty the tank in 9 hour

Description : A tank has two inlet pipes, A and B, which can fill the tank in 12 hours and 18 hours respectively, and an outlet C which can empty the tank in 9 hour

Last Answer : A tank has two inlet pipes, A and B, which can fill the tank in 12 hours and 18 hours ... time taken right from the start to fill the tank.

Which one of the following statements regarding septic tanks is wrong? A. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided B. The outlet invert level is kept 5 to 7.5 cm below the inlet invert level C. The minimum width of septic level is 90 cm D. The depth of tank is kept equal to its width

Description : Which one of the following statements regarding septic tanks is wrong? A. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided B. The outlet invert level is kept ... . The minimum width of septic level is 90 cm D. The depth of tank is kept equal to its width

Last Answer : ANS: D

State the function of the following parts in a heat engine: a) Crank shaft b) spark plug c) carburettord) kick starter e) inlet valve f) outlet valve

Description : State the function of the following parts in a heat engine: a) Crank shaft b) spark plug c) carburettord) kick starter e) inlet valve f) outlet valve

Last Answer : a) Crankshaft converts the linear movement of piston into circular motion. b) Spark plug is used in petrol engine to ignite the mixture of petrol and air in the cylinder. c) Carburettorhelps to mix ... -air or air into the cylinder. f) Outlet Valve allows the exhaust gases out of the cylinder.

To avoid an interruption in the flow of a siphon, an air vessel is provided (A) At the inlet (B) At the outlet (C) At the summit (D) At any point between inlet and outle

Description : To avoid an interruption in the flow of a siphon, an air vessel is provided (A) At the inlet (B) At the outlet (C) At the summit (D) At any point between inlet and outle

Last Answer : Answer: Option C

Which one of the following is true to estimate the range of cooling tower? a) Range = cooling water inlet temperature – wet bulb temperature b) Range = cooling water outlet temperature – wet bulb temperature c) Range = heat load in kcal per hour / water circulation in lines per hour d) None of the above

Description : Which one of the following is true to estimate the range of cooling tower? a) Range = cooling water inlet temperature - wet bulb temperature b) Range = cooling water outlet temperature - wet bulb temperature ... = heat load in kcal per hour / water circulation in lines per hour d) None of the above

Last Answer : Range = heat load in kcal per hour / water circulation in lines per hour

For attaining maximum efficiency, a Francis turbine runner is so designed as to result in radial discharge at exit. This is done by : a) Providing runner vane angle at inlet as 90o b) Providing guide vane angle at inlet as 90o c) Providing runner vane angle at exit as 90o d) Designing for absolute velocity at outlet to be inclined at 90o to direction of vane there

Description : For attaining maximum efficiency, a Francis turbine runner is so designed as to result in radial discharge at exit. This is done by : a) Providing runner vane angle at inlet as 90o b) Providing ... 90o d) Designing for absolute velocity at outlet to be inclined at 90o to direction of vane there

Last Answer : d) Designing for absolute velocity at outlet to be inclined at 90o to direction of vane there

Faucet A basically used as inlet pipe and Faucet B is used as outlet pipe. Faucet A and B both are opened simultaneously, all the time. When Faucet A fills the tank and Faucet B empty the tank, it will take thrice the time than when both the pipes fill the tank. When Faucet B is used for filling the tank, its efficiency remains constant. What is the ratio of efficiency of Faucet A and Faucet B respectively? a) 1:2 b) 2:1 c) 1:3 d) 3:1

Description : Faucet A basically used as inlet pipe and Faucet B is used as outlet pipe. Faucet A and B both are opened simultaneously, all the time. When Faucet A fills the tank and Faucet B empty the tank, it will take thrice the ... efficiency of Faucet A and Faucet B respectively? a) 1:2 b) 2:1 c) 1:3 d) 3:1

Last Answer : B Efficiency when both pipes used to fill = A + B And efficiency when Faucet A is used to fill and Faucet B is used to empty the tank = A-B So (A+B)/(A-B)=3/1 A/B+1/(A/B-1)=3/1 A/B+1=3(A/B-1) 3A/B-A/B=4 2A/B=4 A/B=2 Thus, the ratio of efficiency of Faucet A and B =2:1

24 pumps are connected to a tank. Some of them are inlet pumps and the others are outlet pumps. Each of the inlet pumps an fill the tank in 16hours and each of the outlet pumps can empty the tank completely in 12hours. If all the pumps are kept open, the empty tank gets filled in 48 hours. How many inlet pumps are there? A) 16 B) 18 C) 17 D) 14

Description : 24 pumps are connected to a tank. Some of them are inlet pumps and the others are outlet pumps. Each of the inlet pumps an fill the tank in 16hours and each of the outlet pumps can empty the tank completely in ... gets filled in 48 hours. How many inlet pumps are there? A) 16 B) 18 C) 17 D) 14

Last Answer : D (x/16)-[(24-x)/12] = 1/48 x/16-24/48+x/12=1/48 (3+4)x/48=97/48 7x/48=97/48 7x=97 X=14

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)

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

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

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

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*

In centrifugal compressor terminology, vaneless space refers to the space between A. The inlet and blade inlet edge B. Blades in the impeller C. Diffuser exit and volute casing D. Impeller tip and diffuser inlet edge

Description : In centrifugal compressor terminology, vaneless space refers to the space between A. The inlet and blade inlet edge B. Blades in the impeller C. Diffuser exit and volute casing D. Impeller tip and diffuser inlet edge

Last Answer : ANSWER : D

Low specific speed of a pump implies that, it is a/an __________ pump. (A) Axial flow (B) Centrifugal (C) Mixed flow (D) None of these

Description : Low specific speed of a pump implies that, it is a/an __________ pump. (A) Axial flow (B) Centrifugal (C) Mixed flow (D) None of these

Last Answer : (B) Centrifugal

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

Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe. (A) Smaller than (B) Larger than (C) Same as (D) Twice

Description : Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe. (A) Smaller than (B) Larger than (C) Same as (D) Twice

Last Answer : (A) Smaller than

A pump operating under specific conditions delivers insufficient quantity of liquid. This may be set right by (A) Decreasing the size of the inlet pipe (B) Increasing the size of the inlet pipe (C) Lowering the pump position (D) Both (B) and (C)

Description : A pump operating under specific conditions delivers insufficient quantity of liquid. This may be set right by (A) Decreasing the size of the inlet pipe (B) Increasing the size of the inlet pipe (C) Lowering the pump position (D) Both (B) and (C)

Last Answer : (D) Both (B) and (C)

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

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

Priming of a centrifugal pump is done to (A) Increase the mass flow rate of fluid (B) Develop effective pressure rise by the pump (C) Avoid chances of separation inside the impeller (D) None of these

Description : Priming of a centrifugal pump is done to (A) Increase the mass flow rate of fluid (B) Develop effective pressure rise by the pump (C) Avoid chances of separation inside the impeller (D) None of these

Last Answer : (C) Avoid chances of separation inside the impeller