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Chemical Engineering Principles > Flow of Fluids > Flashcards

Flow of Fluids Flashcards

1
Q

A fluid is one which

A. Cannot remain at rest under the action of shear force
B. COntinuously expands till it fills any container
C. Is incompressible
D. Permanently resists distortion

A

A. Cannot remain at rest under the action of shear force

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2
Q

In an incompressible fluid density

A. Is greatly affected by moderate changes in pressure
B. Is greatly affected only by moderate changes in temperature
C. Remains unaffected with moderate change in temperature and pressure
D. Is sensible to changes in both temperature and pressure

A

C. Remains unaffected with moderate change in temperature and pressure

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3
Q

Potential flow is the flow of

A. Compressible fluids with shear
B. Compressible fluids with no shear
C. Incompressible fluids with shear
D. Incompressible flds with no shear

A

D. Incompressible flds with no shear

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4
Q

Potential flow is characterized by

A. Irrotational and frictioless flow
B. Irrotational and frictional flow
C. One in which dissipation of mechanical energy into heat occurs
D. The formation of eddies within the stream

A

A. Irrotational and frictionless flow

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5
Q

Newton’s law of viscosity relates

A. Shear stress and velocity
B. Velocity gradient and pressure intensity
C. Shear stress and rate of angular deformation in a fluid
D. Pressure gradient and rate of angular deformation

A

C. Shear stress and rate of angular deformation in a fluid

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6
Q

Dimension of viscosity is

A. M/LT
B. ML/T
C. MLT/T
D. MLT

A

A. M/LT

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7
Q

Poise is converted into stoke by

A. Multiplying with density (g/cc)
B. Dividing with density (g/cc)
C. Multiplying with specific gravity
D. Dividing with specific gravity

A

B. Dividing with density (g/cc)

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8
Q

Dimension of kinematic viscosity is

A. M/L²
B. L²/T
C. L²T
D. L²T²

A

B. L²/T

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9
Q

With increase in the temperature, viscosity of a liquid

A. Increases
B. Decreases
C. Remains constant
D. First decreases and then increases

A

B. Decreases

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10
Q

For water, when the pressure increases, the viscosity

A. Also increases
B. Decreases
C. Remains constant
D. First decreases and then increases

A

D. First decreases and then increases

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11
Q

The pressure intensity is the same in all direction at a point in a fluid

A. Only when the fluid is frictioless
B. Only when the fluid is at rest having zero velocity
C. When there is no motion of one fluid layer relative to an adjacent layer
D. Regardless of the motion of one fluid layer relative to an adjacent layer

A

C. When there is no motion of one fluid layer relative to an adjacent layer

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12
Q

Choose the set of pressure intensities that are equivalent.

A. 4.33 psi, 10 ft H2O, 8.83 inHg
B. 4.33 psi, 10 ft H2O, 20.7 inHg
C. 10 psi, 19.7 ft H2O, 23.3 inHg
D. 10 psi, 19.7 ft H2O, 5.3 inHg

A

A. 4.33 psi, 10 ft H2O, 8.83 inHg

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13
Q

For a fluid rotating at constant angular velocity about vertical axis as a rigid body, the pressure intensity varies as the

A. Square of the radial distance
B. Radial distance linearly
C.Averse of the radial distance
D. Elevation along vertical direction

A

A. Square of the radial distance

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14
Q

The center of pressure is

A. Always below the centroid of the area
B. Always above the centroid of the arrea
C. A point on the line of action of the resultant force
D. At the centroid of the submerge area

A

C. A point on he line of action of the resultant force

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15
Q

A rectangular surace 3’ x 4’ has the lower 3 edge horizontal and 6’ below a free oil surface (sp. gr. 0.8). The surface inclination is 300 with the horizontal. The force in one side of the surace is (y = specific weight of water):

A. 39.6y
B. 48y
C. 49.2y
D. 58y

A

B. 48y

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16
Q

A stream tube is that which has ______ cross-section entirely bounded by a stream lines.

A. A circular
B. Any convenient
C. A small
D. A large

A

B. Any convenient

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17
Q

Mass velocity is independent of temperature and pressure when the flow is

A. Unsteady through uncharged corss-section
B. Steady through changing cross-section
C. Steady and the cross-section is unchanged
D. Usteady and the cross-section is changed

A

C. Steady and the cross-section is unchanged

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18
Q

In turbulent flow,

A. The fluid paricles move in an orderly manner
B. Momentum transfer is on molecular scale only
C. Shear stress is cause more efectively by cohesion than momentum transfer
D. Shear stresses are generally larger than in a similar laminar flow

A

D. Shear stresses are generally larger than in a similar laminar flow

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19
Q

Turbulent flow generally occurs for cases involving

A. Highly viscous fluid
B. Very narrow passages
C. Very slow motion
D. None of these

A

D. None of these

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20
Q

An ideal fluid is

A. Frictionless and incompressible
B. One which obeys Newton’s law of viscosity
C. Highly viscous
D None of these

A

A. Frictionless and incompressible

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21
Q

Steady flow occurs when

A. Conditions change steadily with time
B. Conditios are the same at the adjacent points at any instant
C. Conditions do not change with time at any point
D. Rate of change of velocity is constant

A

C. Conditions do not change with time at any point

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22
Q

Which of the following must be followed by the flw of fluid (real or ideal)?
I. Newton’s law of viscosity
II. Newton’s second law of motion
III. The continuity equation
IV. Velocity of boundary must be zero relative to boundary
V. Fluid cannot penetrate a boundary

A. I, II, III
B. II, III, V
C. I, II, V
D. II, III, V

A

B. II, III, V

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23
Q

Discharge (ft³/sec) from a 24-inch pipe of water at 10 ft/sec will be

A. 7.65
B. 32.36
C. 48.22
D.125.6

A

D. 125.6

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24
Q

The unit velocity head is

A. ft-lb/sec
B. ft-lb/ft³
C. ft-lbf/lbm
D. ft-lbf/sec

A

C. ft-lbf/lbm

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25
Q

Bernoulli’s equation describes

A. Mechanical energy balance in potetial flow
B. Kinetic energy balance in laminar flow
C. Mechanical energy balance in turbulent flow
D. Mechanical energy balance in boundary layer

A

A. Mechanical energy balance in potential flow

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26
Q

The kinetic energy correction factor for velocity distribution of laminar flow is

A. 0.5
B. 1.66
C. 1
D. 2

A

B. 1.66

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27
Q

The momentum correction factor for the velocity distrbution of laminar flow is

A. 1.3
B. 1.66
C. 2.5
D. None of these

A

D. None of these

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28
Q

The loss due to sudden expansion is

A. V1²-V2²/2gc
B. (V1-V2)³/2gc
C. V1-V2/2gc
D. None of these

A

B. (V1-V2)³/2gc

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29
Q

The loss due to sudden contraction is proportional to

A. Velocity
B. Velocity head
C. Turbulence
D. None of these

A

B. Velocity head

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30
Q

The value of critical Reynolds number for pipe flow is

A. 1300
B. 10,000
C. 100,000
D. None of these

A

A. 1300

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31
Q

Reynolds number flow of wate at room temperature through 2 cm diameter pipe at average velocity of 5 cm/s is around

A. 2000
B. 10
C. 100
D. 1000

A

D. 1000

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32
Q

Shear stress in a fluid flowing in a round pipe

A. Varies parabolically across the cross-section
B. Remains constant over the cross-section
C. Is zero at the center and varies linearly with the radius
D. Is zero at the wall and increase linearly to the center

A

C. Is zero at the center and varies linearly with the radius

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33
Q

Discharge in laminar flow through a pipe varies

A. As the square of the radius
B. Inversely as the pressure drop
C. Inversely as the velocity
D. As the square of the diameter

A

A. As the square of the radius

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34
Q

Boundary layer separation is caused by

A. Reduction of pressure below vapor pressure
B. Reduction of pressure gradient to zero
C. An adverse pressure gradient
D. Reduction of boundary layer thickness to zero

A

C. An adverse pressure gradient

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35
Q

The friction factor for turbulent flow in a hydraulically smooth pipe

A. Depends only on Reynolds number
B. Does not depend on Reynolds number
C. Depends on the roughness
D. None of these

A

A. Depends only on Reynolds number

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36
Q

For a given Reynolds number, in hydraulically smooth pipe, further smoothing

A. Brings about no further reduction of friction factor
B. Increases the friction factor
C. Decreases the friction factor
D. None of these

A

A. Brings about no further reduction of friction factor

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37
Q

Hydraulic radius is the ratio of

A. Wetted perimeter to flow area
B. Flow area to wetted perimeter
C. Flow area to square of wetted perimeter
D. Square root of flow area to wetted perimeter

A

B. Flow area to wetted perimeter

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38
Q

Hydraulic radius of 6” x 12” c/s is

A. 2”
B. 0.5”
C. 1.5”
D. None of these

A

A. 2”

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39
Q

Reynolds number is the ratio of

A. Viscous forces to gravity forces
B. Inertial forces to viscous forces
C. Viscous force to inertial forces
D. Inertial forces to gravity forces

A

B. Inertial forces to viscous forces

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40
Q

Mach number is the ratio of the speed of the

A. Fluid of that of the light
B. Light to that of the fluid
C. Fluid to that of tthe sound
D. Sound to that of the fluid

A

C. Fluid to that of the sound

41
Q

Power loss in an orifice meter is

A. Less than that in a venturi meter
B. Same as that in a venturi meter
C. More than that in a venturi meter
D. Data insufficient, cannot be predicted

A

C. More than that in a venturi meter

42
Q

The velocity profile for turbulent flow through a close conduit is

A. Logarithmic
B. Parabolic
C. Hyperbolic
D. Linear

A

A. Logarithmic

43
Q

For laminar flow through a closed conduit

A. Vmax = 2V_ave
B. Vmax = V_ave
C. Vmax = 1.5 V_ave
D. V_ave = 2 Vmax

A

A. Vmax = 2 V_ave

44
Q

f = 16/Re is valid for

A. Turbulent flow
B. Laminar flow thorugh an open channel
C. Steady flow
D. None of these

A

B. Laminar flow thorugh an open channel

45
Q

Isotropic turbulence occurs

A. Where there is no velocity gradient
B. At higher temperatures
C. Only in Newtonian fluid
D. None of these

A

A. Where there is no velocity gradient

46
Q

Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement.

A. f1 = f2
B. f1 < f2
C. f1 > f2
D. Data not sufficient to relate f1 and f2

A

C. f1 > f2

47
Q

Bernoulli’s equation for steady frictionless, continuous flow state that

A. total pressure at all sections is same
B. total energy at all section is same
C. velocity head at all section is same
D. none of these

A

B. total energy at all sections is same

48
Q

Drag is define as the force exerted by the

A. Fluid on the solid in a direction opposite to flow
B. The fluid on the solid in the direction of flow
C. The solid on the fluid
D. None of these

A

B. The fluid on the solid in the direction of flow

49
Q

Drag coefficient for flow past immersed body is the ratio of

A. Shear stress to the product of velocity head density
B. Shear force to the product of velocity head and density
C. Average drag per unit projected area to the product of velocity head and density
D. None of these

A

C. Average drag per unit projected area to the product of velocity head and density

50
Q

Stoke’s law is valid when the particle Reynolds number is

A. < 1
B. > 1
C. < 5
D. None of these

51
Q

Drag coefficient CD is given by (in Stoke’s law range)

A. CD = 16/Rep
B. CD = 24/Rep
C. CD = 18.4/Rep
D. CD = 0.079/Rep

A

B. CD = 24/Re*p

52
Q

At low Reynolds number

A. Viscous forces are unimportant
B. Viscous forces control
C. Viscous forces control and inertial forces are unimportant
D. Gravity forces control

A

C. Viscous forces control and inertial forces are unimportant

53
Q

At high Reynolds number

A. Inertial forces control and viscous forces are unimportant
B. Viscous forces predominate
C. Inertial forces are unimportant and viscous forces control
D. None of these

A

A. Inertial forces control and viscous forces are unimportant

54
Q

For flow of fluid through packed bed, the superficial velocity is

A. Less than the average velocity through channels
B. More than the average velocity through channels
C. Dependent on the pressure drop across the bed
D. Same as the average velocity through channels

A

A. Less than the average velocity through channels

55
Q

Pressure drop in a packed bed for laminar flow is given by

A. Kozeny-Carman equation
B. Blake-Plummer equation
C. Leva’s equation
D. None of these

A

A. Kozeny-Carman equation

56
Q

Pressure drop in a packed bed for turbulent flow is given by

A. Kozeny-Carman equation
B. Blake-Plummer equation
C. Leva’s equation
D. None of these

A

B. Blake-Plummer equation

57
Q

Force acting on a particle settling in fluid are

A. Gravitational and buoyant forces
B. Centrifugal and drag forces
C. Gravitational or centrifugal, buoyant and drag forces
D. External, drag and viscous forces

A

C. Gravitational or centrifugal, buoyant and drag forces

58
Q

Terminal velocity is

A. A constant veocity with no acceleration
B. A fluctuating velocity
C. Attained after moving one-half of the total distance
D. None of these

A

A. A constant velocity with no acceleration

59
Q

In hindered settling, particles are

A. Place farther from wall
B. Not affected by other particles and the wal
C. Near each other
D. None of these

A

C. Near each other

60
Q

Drag coefficient in hindered settling is

A. Lesser than in free settling
B. Equal to that in free settling
C. Not necessarily greater than in free settling
D. Greater than free settling

A

D. Greater than free settling

61
Q

For the free settling of a spherical particle through a fluid, the slope of CD - log Re, plot is

A. 1
B. -1
C. 0.5
D. 0.5

62
Q

In continuous fluidization

A. Solids are completely entrained
B. The pressure drop less than that for batch fluidization
C. There is no entrainment of solids
D. Velocity of the fluid is very small

A

A. Solids are completely entrained

63
Q

Pressure drop in fluidized bed reactor is

A. Less than that in a similar packed bed reactor
B. More than that in a similar packed bed reactor
C. Same as that in a similar packed bed reactor
D. None of these

A

B. More than that in a similar packed bed reactor

64
Q

Slugging in a fluidized bed can be avoided by

A. Using tall narrow vessel
B. Using deep bed solids
C. The proper choice of particle size and by using shallow beds of solids
D. Using very large particles

A

C. The proper choice of particle size and by using shallow beds of solids

65
Q

Minimum porosity for fluidization is

A. That corresponding to static bed
B. That corresponding to completely fluidized bed
C. The porosity of the bed when true fluidization begins
D. Less that that of the static bed

A

C. The porosity of the bed when tre fluidization begins

66
Q

In a fluidized bed reactor

A. Temperature gradients are very high
B. Temperature is more or less uniform
C. Hot spot formed
D. Segregation of the solids occurs

A

B. Temperature is more or less uniform

67
Q

Lower BWG means

A. Lower thickness tube
B. Lower cross-section of tube
C. Outer diameter of tube
D. Inner diameter of tube

A

B. Lower cross-section of tube

68
Q

Cavitation occurs in a centrifugal pump when

A. The suction pressure < vapour pressure of the liquid at that temperature
B. The suction pressure pressure > vapour pressure of the liquid at that temperature
C. The suction pressure = vapour pressure
D. The suction pressure = developed head

A

A. The suction pressure < vapour pressure of the liquid at that temperature

69
Q

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

A

B. Maintaining the suction head sufficiently greater than the vapour pressure

70
Q

Priming needed in a

A. Reciprocating pump
B. Gear pump
C. Centrifugal pump
D. Diaphragm pump

A

C. Centrifugal pump

71
Q

The maximum depth from which a centrifugal pump can draw water

A. Dependent on the speed N of the pump
B. Dependednt on the power of the pump
C. 34 feet
D. 150 feet

A

C. 34 feet

72
Q

Boiler feed pump is usually a

A. Reciprocating pump
B. Gear pump
C. Multistage centrifugal pump
D. Diaphragm pump

A

B. Gear pump

73
Q

Plungers pumps are used for

A. Higher pressure
B. Slurries
C. Viscous mass
D. None of these

A

A. Higher pressure

74
Q

Molten soap mass is transported by a

A. Diaphgragm pump
B. Reciprocating pum
C. Gear pump
D. Centrifugal pump

A

C. Gear pump

75
Q

To handle smaller quantity of fluid at high discharge pressure use

A. Reciprocating pump
B. Centrifugal pump
C. Volute pump
D. Rotary vacuum pump

A

A. Reciprocating pump

76
Q

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

A

C. Angle of the vanes and the speed of the tip of the impeller

77
Q

The maximum head that can be developed with a single impeller is

A. 25 ft
B. 1000 ft
C. 250 - 300 ft
D. 100 ft

A

C. 250 - 300 ft

78
Q

A fluid jet discharging from a 2” diameter orifice has a diameter of 1.75” at its vena-contracta. The coefficient of contraction is

A. 1.3
B. 0.766
C. 0.87
D. None of these

79
Q

The discharge through a V-notch weir varies

A. H^3/2
B. H^1/2
C. H^5/2
D. None of these

80
Q

The discharge throgh a rectangular weir varies as

A. H^1/2
B. H^3/2
C. H^2/5
D. None of these

A

D. None of these

81
Q

Propellers are

A. Axial flow mixers
B. Low speed impeller
C. Used for mixing liquids of high viscosity
D. Radial flow mixers

A

A. Axial flow mixers

82
Q

Turbine impeller

A. Produces only radial current
B. Produces only tangential current
C. Is effective over wide range of viscosities
D. Does not produce tangential current

A

C. Is effective over wide range of viscosities

83
Q

With increase in pump speed, its NPSH requirement

A. Decreases
B. Increases
C. Remans unaltered
D. Can either increase or decrease, depends on other factors

A

D. Can either increase or decrease, depends on other factors

84
Q

One dimensional flow implies

A. Flow in the straight line
B. Steady uniform flow
C. Unsteady uniform flow
D. A flow which does not account changes in transverse direction

A

D. A flow which does not account changes in transverse direction

85
Q

In case of centrifugal fan or blower, the gas capacity varies as

A. Spect speed
B. Speed
C. (Speed)³
D. None of these

A

A. Spect speed

86
Q

The continuity equation

A. Relates mass flow rate along a stream tube
B. Related work and energy
C. Stipulates that Newton’s second law of motion must be satisfied at every point in the fluid
D. None of these

A

A. Relate mass flow rate along a stream tube

87
Q

For a specific centrifugal air blower operating at constant speed and capaity the power requirement and pressure vary

A. Directly as squares of gas density
B. Directly as gas density
C. Directly as square root of density
D. Inversely as gas density

A

D Directly as gas density

88
Q

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. Minimize the fluctuation in discharge
D. Control the liquid discharge

A

A. Avoid priming every time we start the pump

89
Q

Differential manometer measures

A. Atmospheric pressure
B. Sub-atmospheric pressure
C. Pressure difference between two points
D. None of these

A

C. Pressure difference between two points

90
Q

Velocity distribution for flow between the fixed parallel plates

A. Varies parabolically across the section
B. Is constant over the entire cross section
C. Is Zero at the plates and increases linerarly to the midplane
D. None of these

A

A. Varies parabolically across the section

91
Q

While starting a cenrifugal 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

92
Q

Path followed by water jet issuing from the bottom of a water tank will be a

A. Parabola (vertex being at the opening)
B. Hyperbolic
C. Horizontal straight line
D. Zig-zag path (which is geometrically undefined)

A

A. Parabola (vertex being at the opening)

93
Q

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 of the abover

A

D. All of the above

94
Q

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 of the above

A

D. All of the above

95
Q

For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is

A. More
B. Less
C. Equal
D. Independent of porosity

96
Q

Reciprocating pumps compared to centrifugal pumps

A. Deliver liquid at uniform pressure
B. Can handle slurries more efficiently
C. Are not subject to air binding
D. Can be operated with delivery valve close

A

C. Are not subect to air binding

97
Q

A tube is specified by its

A. Thickness only
B. Oute diameter
C. Thickness and outer diamete
D. Inner diameter

A

C. Thickness and outer diameter

98
Q

For pipes that must be broken at intervals for maintenance, the connector used should be a

A. Union
B. Tee
C. Reduce
D. Elbow

99
Q

If more than two branches of pipes are to be connected at the same point, then use

A. Elbow
B. Union
C. Tee
D. None of these

Chemical Engineering Principles (5 decks)

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