Description : Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head. (A) Manometric (B) Total (C) Static (D) Friction
Last Answer : (A) Manometric
Description : Horsepower requirement for given pump capacity depends upon the (A) Specific gravity of the liquid (B) Suction lift (C) Discharge head (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
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
Description : State the difference between Static head & Manometric head in centrifugal pump.
Last Answer : Static head: The sum of suction head & delivery head is known as static head. Manometric head: It is the total head that pump is required to develop. This include all losses. This is equal to difference between pressure head at inlet & outlet of pump.
Description : In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency. (A) Manometric (B) Mechanical (C) Volumetric (D) Overall
Description : Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency) (A) ηma × ηm × ηv = ηo (B) ηm = ηv . ηma (C) ηma = ηm × ηv (D) ηv = ηm × ηma
Last Answer : (B) ηm = ηv . ηma
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
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
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
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
Description : Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases. (A) ... the pump (C) Head of the liquid pumped (D) All (A), (B) and (C)
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
Description : Acceleration head in a reciprocating pump (A) Increases the work done during delivery stroke (B) Decreases the work done during suction stroke (C) Does not change the work requirement of the pump (D) Increases the work done during suction stroke
Last Answer : (C) Does not change the work requirement of the pump
Description : Head developed by a centrifugal pump depends on its (A) Speed (B) Impeller diameter (C) Both (A) and (B) (D) Neither (A) nor (B)
Last Answer : C) Both (A) and (B)
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
Description : Consider the following statements: The total head against which a pump has to work must include, besides any other items, 1. the suction lift. 2. the delivery head. 3. the head lost due to friction at entrance in the rising main. 4. the ... 2 & 3 only (b) 2 & 3 only (c) 1, 2, 3 & 4 (d) 3 & 4 only
Last Answer : (c) 1, 2, 3 & 4
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
Description : Consider the following statements: Air vessels are fitted on the suction and delivery sides of a reciprocating pump to 1. Achieve higher speed without separation. 2. Reduce work in overcoming frictional resistance. 3. Avoid excessive vibration ... 2 & 3 only (c) 2, 3 & 4 only (d) 1, 2, 3 & 4
Last Answer : (d) 1, 2, 3 & 4
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
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)
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
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
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
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
Description : High specific speed of a pump implies that, it is a/an __________ pump. (A) Centrifugal (B) Mixed flow (C) Axial flow (D) None of these
Last Answer : (C) Axial flow
Description : Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type. (A) Axial (B) Radial (C) Mixed (D) None of these
Last Answer : (A) Axial
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
Description : At a constant speed of the centrifugal pump, it’s __________ the impeller diameter. (A) Capacity varies directly with (B) Head varies as the square of (C) Horsepower varies as the cube of (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)
Description : A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, the power consumed now will be __________ hp. (A) 0.5 (B) 2 (C) 4 (D) 1
Last Answer : (A) 0.5
Description : A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, then the new head will be __________ metres. (A) 2 (B) 4 (C) 8 (D) 5.5
Last Answer : (A) 2
Description : A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, the new discharge will be __________ litres/minute. (A) 500 (B) 200 (C) 1000 (D) 750
Last Answer : (A) 500
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
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*
Description : Specific speed of a centrifugal pump relates it with another pump having the (A) Dynamic similarity (B) Same efficiency (C) Same speed (D) Geometrical similaritySpecific speed of a centrifugal ... another pumphaving the(A) Dynamic similarity(B) Same efficiency(C) Same speed(D) Geometrical similarity
Last Answer : (A) Dynamic similarity
Description : With a constant diameter impeller of a centrifugal pump (A) Its capacity varies directly as the square of speed (B) Head varies as the square of speed (C) Horsepower input varies as the square of speed (D) Head varies as the speed
Last Answer : (B) Head varies as the square of speed
Description : Which of the following options will facilitate the achievement of a very high head (say 30 metres) in case of a centrifugal pump? (A) Increasing the impeller speed and the volute area (B) Increasing the number of vanes ... or more impellers in series on a single shaft (D) Either of (A), (B) or (C)
Last Answer : (C) Mounting of two or more impellers in series on a single shaft
Description : Which is the correct relationship for a centrifugal pump? (Where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm) (A) D = 1840 H0.5 /N (B) D = 1840 N/H0.5 (C) H = 1840 D0.5 /N (D) D = 1840 H/N
Last Answer : (A) D = 1840 H0.5 /N
Description : The head developed by a centrifugal pump is largely determined by the (A) Power of the pump (B) Nature of the liquid being pumped (C) Angle of the vanes and the speed of the tip of the impeller (D) Vapour pressure of the liquid
Last Answer : (C) Angle of the vanes and the speed of the tip of the impeller
Description : A centrifugal pump designed for handling water (μ = 1 cp) will deliver __________ when pumping a thicker oil (μ = 30 cp). (A) Less head & capacity (B) More head (C) More capacity (D) Less head & more capacity
Last Answer : (A) Less head & capacity
Description : In case of a, centrifugal pump, the ratio h1/h2is termed as the __________ efficiency (where, h1 = actual measured head & h2 = head imparted to the fluid by impeller). (A) Mechanical (B) Overall (C) Volumetric (D) Impeller
Last Answer : A) Mechanical
Description : While starting a centrifugal pump, its delivery valve should be kept (A) Opened (B) Closed (C) Either opened or closed; it does not make any difference (D) Either opened or closed; depending on the fluid viscosity
Last Answer : (B) Closed
Description : Gear pump (A) Is a positive displacement pump (B) Is a centrifugal pump (C) Is a non-positive displacement pump (D) Can be started with delivery valve closed
Last Answer : (A) Is a positive displacement pump
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
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
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.
Description : Capacity of a rotary gear pump can be varied by (A) Changing the speed of rotation (B) Bleeding air into suction (C) Bypassing liquid from the suction or discharge line (D) All (A), (B) and (C)
Description : Define suction head and delivery head with diagram.
Last Answer : i. Suction head: It is defined as vertical distance between lowest water level in sump well and centre-line of pump. ii Delivery head: It is defined as the vertical distance between centre-line of the pump and highest level in the overhead tank up to which water is lifted. OR
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