## Pumps

### GATE-CH-1993-9-a-fm-2mark

1993-9-a-fm

For a centrifugal pump the net positive suction head is defined as ________

where

$$h_{vs}$$ = velocity head at suction;
$$h_{vd}$$ = velocity head at discharge;
$$h_{ps}$$ = pressure head at suction;
$$h_{pd}$$ = pressure head at discharge;
$$p_{s}$$ = vapor pressure of liquid at suction temperature;
$$p_{d}$$ = vapor pressure of liquid at discharge temperature.

• $$h_{vs} + h_{ps}$$

• $$h_{vd} + h_{pd}$$

• $$h_{vs} + h_{ps} - p_{s}$$

• $$h_{vd} + h_{pd} - p_{d}$$

### GATE-CH-1998-1-10-fm-1mark

1998-1-10-fm

A globe valve is most suitable for applications in which

• the valve is required to be either fully open or fully closed

• flow control is required

• the fluid contains dispersed particles

• one-way flow is required

### GATE-CH-1999-1-10-fm-1mark

1999-1-10-fm

In centrifugal pumps, cavitation occurs when pressure of the impeller eye or vane becomes

• less than atmospheric pressure

• more than liquid vapor pressure

• less than liquid vapor pressure

• more than atmospheric pressure

### GATE-CH-2002-1-5-fm-1mark

2002-1-5-fm

With increasing flow rate, the hydraulic efficiency of a centrifugal pump

• monotonically decreases

• decreases and then increases

• remains constant

• increases and then decreases

### GATE-CH-2006-8-fm-1mark

2006-8-fm

Match the following for a centrifugal pump with impeller speed $$n$$

Group I Group II
(P) Capacity (1) proportional to $$n$$
(Q) Head (2) proportional to $$n^2$$
(3) proportional to $$n^3$$

• P-2, Q-1

• P-1, Q-3

• P-2, Q-3

• P-1, Q-2

[Index]

### GATE-CH-2010-21-fm-1mark

2010-21-fm

A storage vessel exposed to atmosphere (absolute pressure = 10.3 m of water) has a diameter of 3 m and is initially filled with water to a height of 2 m. The pump draws water from the vessel and is located at an elevation of 5 m above the bottom of the vessel. The frictional head loss in the suction pipe is 2 m of water. If the vapor pressure of the liquid at the temperature of operation is 3 m of water, then the available NPSH is

• 2.3 m

• 5.3 m

• 6.3 m

• 8.3 m

### GATE-CH-2011-16-fm-1mark

2011-16-fm

Match the pumps in Group I with the corresponding fluids in Group II.

 (P) Gear pump (I) Highly viscous liquid (Q) Peristaltic pump (II) Aqueous sterile liquid (III) Slurry

• P-III, Q-I

• P-II, Q-I

• P-III, Q-II

• P-I, Q-II

### GATE-CH-2014-18-fm-1mark

2014-18-fm

Slurries are most conveniently pumped by a

• syringe pump

• diaphragm pump

• vacuum pump

• gear pump

### GATE-XE-2016-B-21-fm-2mark

XE-2016-B-21-fm

A pump is used to deliver water to an overhead tank at a flow rate of $$Q=4\times 10^{-3}$$ m3/s. The pump adds 1.6 kW to water. If the density of water is 1000 kg/m3 and acceleration due to gravity is 10 m/s2, the pump head added to the flow is ____________m.

### GATE-CH-2007-38-fm-2mark

2007-38-fm

The figure shows a series-parallel configuration of three identical centrifugal pumps. The head increase $$\Delta H$$ across a single pump varies with flow rate $$Q$$ according to $$\Delta H = a - b Q^2$$. The expression for the total head increase $$\Delta H = H_2-H_1$$ in terms of $$a$$ and $$b$$ and the total flow rate $$Q_1$$ for this configuration is given by

• $$\displaystyle 2a - \frac {5}{4}bQ_1^2$$

• $$2a - bQ_1^2$$

• $$2a-2bQ_1^2$$

• $$a-bQ_1^2$$

[Index]

### GATE-CH-2008-38-fm-2mark

2008-38-fm

A pump draws oil (specific gravity 0.8) from a storage tank and discharges it to an overhead tank. The mechanical energy delivered by the pump to the fluid is 50 J/kg. The velocities at the suction and the discharge points of the pump are 1 m/s and 7 m/s, respectively. Neglecting friction losses and assuming kinetic energy correction factor to be unity, the pressure developed by the pump (in kN/m2) is

• 19.2

• 20.8

• 40

• 80

### GATE-CH-2016-35-fm-2mark

2016-35-fm

Water (density=1000 kg/m3) is pumped at a rate of 36 m3/h, from a tank 2 m below the pump, to an overhead pressurized vessel 10 m above the pump. The pressure values at the point of suction from the bottom tank and at the discharge point to the overhead vessel are 120 kPa and 240 kPa, respectively. All pipes in the system have the same diameter. Take acceleration due to gravity, $$g = 10$$ m/s2. Neglecting frictional losses, what is the power (in kW) required to deliver the fluid?

• 1.2

• 2.4

• 3.6

• 4.8

### GATE-CH-1997-4-fm-5mark

1997-4-fm

In the figure given below, calculate the power (in W) required by the pump to deliver water at 3 m/s from a pond. The inner diameter of the pipe is 25 mm. Neglect all losses in the pipe. Density of water is 1000 kg/m$$^3$$.
____________

### GATE-CH-1999-11-fm-5mark

1999-11-fm

Oil of viscosity 100 cP is to be pumped as shown in the following figure. The pipe used every where is of 7 cm I.D. If the efficiency of the pump is 80%, find the power (in W) required for pumping the oil at 20 m$$^3$$/h. Density of the oil is 800 kg/m$$^3$$.
____________

### GATE-CH-2015-35-fm-2mark

2015-35-fm

A centrifugal pump delivers water at the rate of 0.22 m3/s from a reservoir at ground level to another reservoir at a height $$H$$, through a vertical pipe of 0.2 m diameter. Both the reservoirs are open to atmosphere. The power input to the pump is 90 kW and it operates with an efficiency of 75%.
Data:
Fanning friction factor for the pipe flow is $$f=0.004$$. Neglect other head losses. Take gravitational acceleration, $$g=9.8$$ m/s2 and density of water is 1000 kg/m3.
The height $$H$$, in meters, to which the water can be delivered (up to one decimal place) is ____________

[Index]

### GATE-CH-2016-38-fm-2mark

2016-38-fm

The characteristics curve (Head-Capacity relationship) of a centrifugal pump is represented by the equation $$\Delta H_{\text {pump}}=43.8-0.19Q$$, where $$\Delta H_{\text {pump}}$$ is the head developed by the pump (in m) and $$Q$$ is the flowrate (in m 3/h) through the pump. This pump is to be used for pumping water through a horizontal pipeline. The frictional head loss $$\Delta H_{\text {piping}}$$ (in m) is related to the water flowrate $$Q_L$$ (in m3/h) by the equation $$\Delta H_{\text {piping}}=0.0135 Q_L^2+0.045 Q_L$$. The flowrate (in m3/h, rounded off to the first decimal place) of water pumped through the above pipeline, is ____________

### GATE-CH-1994-12-fm-5mark

1994-12-fm

The following data were obtained on a section of piping through which an incompressible viscous fluid is flowing (See Figure)

Point 1:

Pressure = $$1.25 \times 10^5$$ Pa
Cross-sectional area = $$15 \times 10^{-4} m^{2}$$
Fluid Velocity = 1 m/s

Point 2:
Pressure = $$1.05 \times 10^{5}$$ Pa
Cross-sectional area = $$5 \times 10^{-4}$$ m$$^{2}$$
Elevation above point 1 = 3 m

Other Data:

Density of fluid = 1000 kg/m$$^{3}$$
Power delivered by the pump = 7.5 W
assume efficiency = 100%

Based on the data, we can say that the flow is taking place from point 1 to 2. (True/ False)

• True
• False

[Index]