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Dynamic Compressors and Fans > Assignment Review > Flashcards

Assignment Review Flashcards

1
Q

Two Classifications of Dynamic Compressors

A

Centrifugal and Axial

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2
Q

How do Dynamic Compressors create pressure?

A

Converting gas velocity energy into pressure

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3
Q

How is gas directed from one stage to the next in a single-shaft multi-staged design?

A

Through a diffuser

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4
Q

Which centrifugal compressor casing has the lowest pressure capabilities?

A

Sectional Casing

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5
Q

Which centrifugal compressor impeller design used extensively for multi-stage designs is capable of higher pressure ratios?

A

Closed impeller

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6
Q

What causes axial thrust in a dynamic compressor?

A

Pressure differential acting on the impeller’s surfaces

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7
Q

What is used to control axial thrust in a dynamic compressor?

A

Thrust bearings

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8
Q

What is the name of the cast sections that form the diffusers or volutes in single- shaft machines?

A

Diaphragms

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9
Q

Which type of seal used on centrifugal compressors has rotating speed limitations?

A

Mechanical seals

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10
Q

What is the simplest method of controlling axial compressor output?

A

Variable Speed

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11
Q

Where does fouling primarily occur in Axial compressors?

A

Stator blades

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12
Q

What is the name for the condition where high discharge pressures and corresponding low flow rates result in flow reversal?

A

Surging

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13
Q

What is the name for the condition where maximum flow has been reached at low discharge pressures?

A

Stonewalling

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14
Q

How is surging prevented in single-speed dynamic compressors?

A

Opening the recycle valve

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15
Q

How are vibration levels monitored in dynamic compressors?

A

Measuring rotor position continually with proximity probes

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16
Q

What units of measurement do manometers use to indicate relative pressures?

A

inches of water

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17
Q

What pressure is measured when one end of a manometer is inserted perpendicular (90°) to duct air flow and the other end is open to atmosphere?

A

Static Pressure

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18
Q

What pressure is measured when one end of a manometer is facing into the duct air flow and the other end is perpendicular (90°) to the air flow?

A

Velocity Pressure

19
Q

Which of these describes ‘Total pressure’ ?

A

Velocity pressure plus static pressure

20
Q

What is used to prevent static electrical charges from causing harm to equipment or personnel?

A

Installation of grounding straps, brushes and holders

21
Q

What is the name of the draft arrangement in which a fan is located between the boiler and chimney?

A

induced draft

22
Q

Which centrifugal fan wheel is suited for handling high particulates or materials in the air stream?

A

Straight Radial

23
Q

Which centrifugal fan wheel is suited for residential heating systems because of the low operating speeds and noise levels?

A

forward curved

24
Q

Whose principle indicates that converging ducting will increase velocity pressure, while diverging ducting will increase static pressure?

A

Bernoullis

25
Q

How is the capacity of a fan controlled?

A

Inlet guide vanes, inlet/outlet dampers, Variable operating speeds

26
Q

If a fan is located at the top of a cooling tower and draws air upward through the tower, it is known as a(n):

A

Induced draft fan

27
Q

Under what conditions will a dynamic compressor reach its stonewall or choke point?

A

High flow, low pressure

28
Q

__________blades in some _________compressors can be used to control flow through the machine:

A

Stator / Axial

29
Q

Which of the following is used to prevent compressor surging?

A

Recycle / Bypass Valve

30
Q

Fans are:

A

Low pressure / high volume machines

31
Q

Centrifugal blowers operate on the same principle as:

A

Centrifugal compressors

32
Q

What is used to control axial compressor capacity?

A

Adjust operating speed or stator blade pitch

33
Q

A fan drawing flue gas from a boiler furnace would:

A

Require high maintenance because of heat, moisture and contaminants

34
Q

The correct order of installation for the following air-line accessories is:

A

FRL!
Filter, regulator, lubricator

35
Q

Pressure in a confined, static fluid acts the same and equally in every direction, and always acts at right angles to the surface. This statement is known as:

A

Pascals Law

36
Q

What is necessary in order for fluids to flow from one area to another?

A

A Pressure Differential

37
Q

Why would it be advantageous to use a two-stage inter-cooled compressor over a single-stage if both put out 100 CFM?

A

Inter-cooled compressors are more efficient

38
Q

How are dynamic compressors classified?

A

Direction of air or gas through rotating components

39
Q

Which of the following is a tool used to inspect internal components without disassembling a compressor?

A

Borescope

40
Q

What can be used to reduce thrust in a dynamic compressor?

A

Balance drum or piston

41
Q

Which compressor can be cleaned by feeding crushed walnut shells into an operating unit?

A

Axial Compressor

42
Q

Which of the following methods is not used to control the flow through centrifugal fans?

A

Varying the blade pitch

43
Q

Which style of centrifugal compressor housing would be used for extremely high pressure applications?

A

Barrel type (vertically split)

44
Q

The wet seals used on some dynamic compressors require that seal oil enters the seal:

A

At a pressure higher than the gas pressure to be sealed

Dynamic Compressors and Fans (1 decks)

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