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Civil Law > ChECal and Momentra > Flashcards

ChECal and Momentra Flashcards

1
Q

Laminar flow

A

*Re < 2100
*Fluid travels smoothly or in streamlined paths

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2
Q

Turbulent flow

A

*Re > 4000
*Occurs at high velocity and low dynamic viscosity.

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3
Q

Fluid

A

Phase of Matter that can flow and take up the shape of its container

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4
Q

Nozzle

A

Decreases pressure to increase velocity

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5
Q

Nominal diameter

A

*Size of the pipe

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6
Q

Pipe Schedule

A

*Way pipe wall thickness is mentioned
*1000P/S
*P = max allowable stress
*S = max service stress

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7
Q

BFD vs PFD vs P&ID

A

BFD:
*Logical sequence of processes
*Feeds and products

PFD:
*Equipment and Pumps
*Pipes and Fittings
*Material Balance
*Instrumentation
*Operating pressure and temperature
*Callout Sheets

P&ID:
*Equipment and Pumps
*Pipes and Fittings
*Material Balance
*Instrumentation, and Electrical control loops
*Voting and Sparing Philosophy
*More Detailed Callout Sheets (include design pressure, material, insulation, etc)

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8
Q

Unit Operation vs Unit Process

A

Unit Operation:
*Reversible
*Physical transformation of the feed
*Fluid flow, Mechanical operations, Mass transfer

Unit Process:
*Irreversible
*Chemical transformation of the feed
*Chemical reactors

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9
Q

NON NEWTONIAN:
Pseudoplastic
Dilatant
Bingham plastic

A

*Pseudoplastic
-Shear thinning

*Dilatant
-Shear thickening

*Bingham plastic
-Requires shear threshold before thickening

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10
Q

Shear thinning fluids

A

AKA Pseudoplastic fluids

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11
Q

Shear thickening fluids

A

AKA Dilatant fluids

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12
Q

It is a liquid that does not flow at all until a threshold shear stress is attained.

A

Bingham fluids

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13
Q

Fluid whose viscosity is independent of shear rate

A

Newtonian fluids

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14
Q

Fluid whose shear stress is directly proportional to the shear rate

A

Newtonian Fluids

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15
Q

Discipline of fluid mechanics which studies the relationship between fluid deformation and stress.

A

Rheology

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16
Q

Viscosity decreases with increase in
shear rate.

A

Pseudoplastic
e.g. clay, milk and cement

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17
Q

Viscosity increases with increase in shear rate

A

Dilatant
e.g. Quicksand

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18
Q

No-slip condition

A

Velocity of the
fluid must equal that of the adjacent wall

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19
Q

Internal energy

A

All other energy present in a unit mass, such as, rotational and vibrational energy in chemical bonds.

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20
Q

Potential energy

A

Energy present because of the position of the mass in a gravitational field.

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21
Q

Kinetic energy

A

Energy present because of the translational or rotational motion of the mass

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22
Q

Shear stress decreases with time at a constant shear rate.

A

Thixotropic

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23
Q

Shear stress increases with time at a constant shear rate.

A

Rheopectic

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24
Q

Mechanical Energy

A

Type of energy that is work or can be directly converted to work.

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25
Q

The fluid property, due to which, mercury does not wet the glass is

surface tension
viscosity
cohesion
adhesion

A

surface tension

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26
Q

The normal stress is the same in all directions at a point in a fluid, when the fluid is ___

non-viscous.

incompressible.

both (a) and (b).

having no motion of one fluid layer relative to the other.

A

having no motion of one fluid layer relative to the other.

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27
Q

The head loss in turbulent flow in a pipe varies

as velocity

as (velocity)^2

inversely as the square of diameter

inversely as the velocity

A

as (velocity)^2

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28
Q

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 ____

discharge.

suction.

suction minus vapor pressure of the liquid at suction temperature.

discharge minus vapor pressure of the liquid at the discharge temperature.

A

suction minus vapor pressure of the liquid at suction temperature.

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29
Q

The velocity profile for turbulent flow through a closed conduit is ___

logarithmic
parabolic
hyperbolic
linear

A

logarithmic

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30
Q

The velocity profile for laminar flow through a closed conduit is ___

logarithmic
parabolic
hyperbolic
linear

A

parabolic

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31
Q

Water hammer in a pipeline results from the _____

bursting of pipelines due to closure by a valve.

rapid pressure change due to a rapid change in the rate of flow.

pressure increase due to closure of a valve resulting in decrease in rate of flow.

none of these.

A

rapid pressure change due to a rapid change in the rate of flow.

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32
Q

Which of the following denotes the effect of compressibility in fluid flow ?
Weber number
Mach number
Euler number
Reynolds number

A

Mach number

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33
Q

Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.

smaller than
larger than
same as
twice

A

smaller than

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34
Q

If the discharge of a centrifugal pump is throttled, then its suction lift ____

increases
decreases
remains unchanged
data insufficient to predict

A

increases

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35
Q

In fluid flow, cavitation is caused, if the ___

fluid velocity decreases to zero.

total energy decreases.

both (a) and (b).

flow pressure approaches its vapor pressure at the prevailing temperature.

A

flow pressure approaches its vapor pressure at the prevailing temperature.

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36
Q

Cavitation vs Air Entrainment vs Suction Vortex

A

*Cavitation
-Sudden implosion of vapor to cause shockwaves in pump

*Air Entrainment
-simply air in fluid. May not be related to suction pressure level

*Suction Vortex
-Highly unstable and dance around, resulting in radial force.

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37
Q

Why Cavitation happens?

A
  1. Vapor in suction
  2. Air / Vapor entrainment
  3. Recirculation - liquid can’t exit pump
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38
Q

Co-efficient of velocity is __________ the coefficient of discharge.
less than
more than
equal to
not related to

A

more than

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39
Q

All pipes of a particular nominal size have the same ___

inside diameter
outside diameter
thickness
none of these

A

outside diameter

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40
Q

PREVENTING CAVITATION:

A

1.Heights
Increase surface height
2. Temperature
Reduce
3. Pressure
Pressurize tank
4. Line Length and Size
Shorten line, Enlarge pipe

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41
Q

DECREASE NPSHr

A

*Lower RPM pump
*Use oversized pump
*Use parallel pumps

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42
Q

PUMPS IN SERIES/PARALLEL:
1. Head
2. Volume

A
  1. Head
    Series: Additive
    Parallel: Equal
  2. Volume
    Series: Equal
    Parallel: Additive
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43
Q

When Pumps in Series are used?

A

*BOOSTER: To increase NPSHa

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44
Q

Affinity Law:
Q,H,P vs N,D

A

Exponents of N and D:
1. Very
2. Hard
3. Problems

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45
Q

FANS vs BLOWER vs COMPRESSOR

A

Fans: < 1 psig
Blower: 1-50 psig
Compressor: > 50 psig

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46
Q

For a particle settling in water at its terminal settling velocity, which of the following is true ?

Buoyancy = weight + drag
Weight = buoyancy + drag
Drag = buoyancy + weight
Drag = weight

A

Weight = buoyancy + drag
Kasi Buoyancy = weight - drag

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47
Q

Shear stress in a fluid flowing in a round pipe

varies parabolically across the cross-section.

remains constant over the cross-section.

is zero at the centre and varies linearly with the radius.

is zero at the wall and increases linearly to the centre.

A

is zero at the centre and varies linearly with the radius.

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48
Q

What causes cavitation in centrifugal pump ?
High suction pressure
Low barometric pressure
Low suction pressure
High suction velocity

A

Low suction pressure

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49
Q

A hydraulic ram acts as a/an __________ pump.
centrifugal
reciprocating
impulse
parallel cylinder

A

impulse

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50
Q

The friction factor for turbulent flow in a hydraulically smooth pipe ___

depends only on Reynolds number.

does not depend on Reynolds number.

depends on the roughness.

none of these.

A

depends only on Reynolds number.

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51
Q

The simple pitot tube measures the __________ pressure.
static
dynamic
total
none of these

A

total

52
Q

Manometers measure the __________ pressure.

vacuum as well as the atmospheric
difference in
absolute
gage

A

difference in

53
Q

The fluid property which matters for fall-ing rain drops to acquire spherical shape is its ___

pressure
height of descend
viscosity
surface tension

A

surface tension

54
Q

Venturimeter and orificemeter measures the __________ of the fluid.
pressure
maximum velocity
average velocity
point velocity

A

average velocity

55
Q

During ageing of fluid carrying pipes, the ___

pipe becomes smoother with use.

friction factor increases linearly with time.

absolute roughness decreases with time.

absolute roughness increases linearly with time.

A

absolute roughness increases linearly with time.

56
Q

Check in a centrifugal pump is ___

provided in the discharge line.
generally a globe valve.

provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running.

all (a), (b) and (c).

A

all (a), (b) and (c).

57
Q

Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter ‘d’?

At the centre
At d/4 from the wall
At the wall
At d/8 from the wall

A

At the wall

58
Q

In an incompressible fluid, the density is ____

greatly affected by moderate changes in pressure.

greatly affected only by moderate changes in temperature.

not affected with moderate change in temperature & pressure.

sensible to changes in both temperature & pressure.

A

not affected with moderate change in temperature & pressure.

59
Q

Define Priming

A

Preparing the pump by removing the air and filling it up with water.
Prevent cavitation / pump damage

60
Q

What are Self Priming Pumps?

A

Has the ability to use liquid stored in its housing to generate a vacuum on the suction line.

61
Q

WORK OF COMPRESSION:
Adiabatic
Isothermal

A

*Adiabatic - Maximum
*Isothermal - Minimum

62
Q

COOLING OF COMPRESSION:
Isentropic
Polytropic
Isothermal

A

*Isentropic - No Cooling
*Polytropic - Some Cooling
*Isothermal - Maximum Cooling

63
Q

Types of Pumps

A

Centrifugal / Dynamic Pumps:
*Smaller size, Smaller cost
*Impellers pass to the fluid to imparting kinetic energy
*Produces pressure by creating flow

Positive Displacement Pumps:
*Larger size, larger cost
*Requires safety valve
*Self priming
*High viscosity
*Encloses definite amount of fluid and exits the discharge
*Produces flow by creating pressure

64
Q

When to use:
*Gravity Flow
*Centrifugal
*Positive Displacement

A

*Gravity Flow
-< 50 kPag needed to move liquid
*Centrifugal
-Default choice
*Reciprocating
- Low flowrates and high viscosity
*Rotary
-High flowrates and high viscosity

65
Q

Turbine

A

Compresses gas to increase its pressure to transfer in gas plants

66
Q

Types of Positive Displacement Pumps

A

*Rotary
-Achieves pumping through meshing of gears, lobes, etc

*Reciprocating
-Uses valve to traps liquid inside and direct liquid to certain areas

67
Q

Types of Centrifugal Pumps

A
  1. Axial Flow
    *High Flow, Low Pressure
    *Flow PARALLEL to impeller shaft
  2. Mixed Flow
    *Medium Flow, Medium Pressure
    * Greater then 90 deg
  3. Radial Flow
    *Low Flow, High Pressure
    *Flow PERPENDICULAR to impeller shaft
68
Q

What is a Compressor?

A

Device that increases gas pressure by decreasing its volume

69
Q

What is a pump?

A

Device responsible for moving liquids

70
Q

Minimum data required for line sizing

A
  1. v,p,u
  2. Pipe length
  3. Fittings
71
Q

When are pumps not required?

A
  1. Gravity flow
  2. Pressurized storage
72
Q

Implications of below Minimum flow for Pumps

A

*Pitted/worn impeller vanes
*Overheated casing/bearings
*Excessive noise or vibration
*Broken shafts
*Mechanical seal failures
*Poor performance efficiency

73
Q

Based on two pressure measurements how can you estimate gas flow?

A

v = 2*dP/density

74
Q

Difference of Newtonian vs Non-Newtonian fluids

A

*Newtonian - viscosity independent of shear rate
*Non-Newtonian - viscosity dependent of shear rate

75
Q

Exothermic vs Endothermic Process

A

Exothermic - releases heat
Endothermic -absorbs heat

76
Q

Valve Types:
Gate Valves

A

*Linear
*On-Off
+Most economical on/off
-Prone to leaks and breakage vs ball valves
-Cause water hammer

77
Q

Valve Types:
Glove Valves

A

*Flow Regulating
+Versatile in different fluids and temperature
+Low chance of leakage
-Creates large pressure drop

78
Q

Valve Types:
Knife Valve

A

*Small diameter
*Flow Regulating

79
Q

Valve Types:
Ball Valve

A

*Quick Acting
*On-Off Control
+Most secure against leaks
+Most durable
+Quarter-turn valve (No water hammer)
-Most expensive

80
Q

Valve Types:
Butterfly Valve

A

*For D>12 inch
*Quick Acting
*On-Off Control
*Flow Regulating

81
Q

Valve Types:
Pressure Relief Valve

A

Relieves pressure from equipment operating LIQUIDS

82
Q

Valve Types:
Pressure Safety Valve

A

Relieves pressure from equipment operating GASES

83
Q

Valve Types:
Check Valve

A

*Non-Return Valve

84
Q

PUMP CURVE:
Run Out

A

*Head produced at maximum flow
*Cavitation, vibration and overloading of the driver.

85
Q

PUMP CURVE:
Shut-off Head

A

Head produced when the pump operates with fluid but with no flow rate.

86
Q

PUMP CURVE:
BEP

A

*Best Efficiency Point
*Flow rate and head at which the pump efficiency is the maximum

87
Q

PUMP CURVE:
Carry Out

A

Operates in the far right of its curve with poor efficiency.

88
Q

PUMP CURVE:
Sweet Area

A

Area near the BEP

89
Q

Importance of Pump Curve

A

*Graphical representation of head and efficiency given flowrate
*Pump selection

90
Q

System Curve

A

*Curve representing the head of pump given flow rate

91
Q

Break Horsepower

A

external power supplied to the pump

92
Q

Water Horsepower

A

useful power actually delivered to the fluid

93
Q

Criteria for Line Sizing

A

*Operating Parameters
-Velocity
-Pressure Drop

*Pump Efficiency

*Liquid Transported

*Transport Equipment Used

*NPSHa/NPSHr Ratio

94
Q

Minimum Flow Rate

A

*Flow rate reported by pump manufacturer
*Below this, pump will start vibrating, heating up and fail prematurely

95
Q

When NOT to use Recirculation Line?

A

*Closed circulating systems
*Pumps in Batch services
*Small pumps
*Pumps with control valve

96
Q

Choked Flow
*Liquids
*Gases

A

*Liquids
-Liquid pressure is lower than vapor pressure –> Cavitation

*Gases
-Choked pressure = below which NO FURTHER INCREASE in mass flow

97
Q

Connect pipes of ___ diameter:
a. Same
b. Different

A

a. Same
Coupling - permanent
Union - removable
b. Different
Reducer or Expander

98
Q

Solvent

A

Substance that dissolves solutes

99
Q

Octane Number

A

*Anti-Knocking Number
*Ability of fuel to resist knocking when ignited
*Volume i-octane/ Total Volume
*i-Octane and n-Heptane

100
Q

Cetane Number

A

*Diesel Performance Number
*Measure delay to ignite diesel fuel (higher number = lower delay)
*Cetane (C16H34) and Methyl Naphthalene

101
Q

Newtonian vs Non-Newtonian Fluids

A

*Newtonian
- Viscosity INDEPENDENT of shear rate

*Non-Newtonian
- Viscosity DEPENDENT of shear rate

102
Q

Fluidization

A

Process of passing through gas to a bed of solids to exhibit fluid-like properties

103
Q

Pyrolysis vs Combustion

A

*Pyrolysis
-Thermal decomposition of organic matter with an absence of oxygen into shorter hydrocarbon chains

*Combustion
-Decomposition of organic matter with presence of oxygen into CO2, CO and H2O

104
Q

COMPRESSORS:
*Surge Point
*Stonewall Point

A

Surge Point
*Reversal of flow when capacity is reduced to a point where insufficient pressure to maintain flow.

Stonewall Point (Choking)
*Discharge pressure falls, but airflow no longer increases due to physical limitations

105
Q

Valve Types:
Diaphragm Valve

A

*Regulating Flow
*Corrosive Fluids

106
Q

Pipes with same nominal diameter but different schedule have the same ____

A

inner diameter

107
Q

Shear rate

A

Rate at which one layer of fluid slides over another layer

108
Q

Pitot Tube

A
  • Measures local velocity only
    +Negligible pressure drop
109
Q

Orifice Meter

A

*Measure LIQUID flow through pressure difference
- Higher pressure drop than venturi meter
- Cannot be used for dirty fluids
+ CHEAPER and REMOVABLE

110
Q

Venturi Meter

A

*Measure LIQUID AND GAS flow through pressure difference
+ Lower pressure drop than orifice meter
+ Can handle higher flowrates than orifice meter
- EXPENSIVE and PERMANENT

111
Q

Ultrasonic Meters

A

*Ideal for CORROSIVE and DIRTY fluids
*Uses Doppler effect (calculate how fast radiation is reflected back)
+CHEAP

112
Q

Positive Displacement Meters

A

*Used to accurately measure fluid flow (for recipes)
- For CLEAN and VISCOUS fluids only

113
Q

Variable Area Meters

A

+CHEAP
+NO POWER DEMAND
+Low pressure drop
- Low accuracy
-Glass prone to breakage

114
Q

Oscillation Meters

A

*Measure oscillation of tubes (sine waves)
*For CLEAN and NON-VISCOUS fluids
*High accuracy, repeatability and low maintenance

115
Q

Turbine Meters and Paddlewheel Meters

A

*Turbine Meters
+More accurate
-More expensive
-More pressure drop (though very small)
-More susceptible to fouling

*Paddlewheel Meters
+Cheaper
+Less pressure drop
-Less accuracy

116
Q

Why Acceleration Head for Centrifugal pump is NOT ZERO while Positive Displacement pump is ZERO?

A

Acceleration head: Head required to accelerate velocity from zero to some value

*Centrifugal pump: Flow is assumed constant
*PD pump: Flow is fluctuating

117
Q

Lift vs Head

A

*Lift
-Liquid level power than pump.
-Pump creates vacuum to force liquid to flow.

*Head
-Liquid level higher than pump

118
Q

COMPRESSORS:
*Centrifugal
*Axial Flow
*Positive Displacement

A

*Centrifugal
+Most common
+High flowrate

*Axial Flow
+Compressors for turbines

*Positive Displacement
+High pressure head and low flowrate
+Used for air
-Prone to leaking

119
Q

Assumptions of Bernoulli Equation

A

*Steady flow
*Incompressible
No shaft work and heat transferNegligible viscous effects (friction) compared to pressure, elevation and kinetic heads

120
Q

Subsonic and Supersonic Flow:
P, V, T, Ma Relation to Nozzles and Diffusers

A

*Subsonic NOZZLE and Supersonic DIFFUSER
-Decrease P and T
+Increase V and Ma

*Supersonic NOZZLE and Subsonic DIFFUSER
-Decrease V and Ma
+Increase P and T

121
Q

Why fuel is sweetened?

A
  • Higher heating values
  • Better odor, oxygen stability and color
122
Q

Explain Dalton’s, Henry’s and Raoult’s Laws

A

Dalton
Pi = sum yi*Pt

Henry (non ideal)
Pi = H * xi
Amount dissolved gas proportional to its partial pressure

Raoult’s (ideal)
Pi = Psat * xi
Partial pressure of gas proportional to both vapor pressure and dissolved gas

123
Q

Vertical vs Horizontal Separators

A

*Vertical Separator
-For high liquid/gas ratio
-Space limitations
-High amounts of solids

*Horizontal Separator
-For low liquid/gas ratio
-For three-phase separation
-Separating foaming crude oil

124
Q

Pipes with nominal size of above ___ is equal to its ___ diameter

A

14”
Outside diameter

125
Q

COMPRESSORS in:
*Parallel
*Series

A

*Series
-Flow: Constant
-Pressure: Additive

*Parallel
-Flow: Additive
-Pressure: Greater than lower-pressure compressor

126
Q

Compressor Surging

A
  • Pressure high enough such that there is reversal of flow / unsustainable flow
  • Equivalent to deadheading in pumps

Civil Law (31 decks)

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