Dynamic Compressors And fans Flashcards

1
Q

Sectional casings of a dynamic compressor are used for what pressures?

A

Low pressures

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2
Q

Horizontally split casings of a dynamic compressor are used for what pressures?

A

Under 1000 psi

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3
Q

Vertically split casings of a dynamic compressor are used for what pressures?

A

High pressure applications

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4
Q

Which centrifugal fan impeller is the most efficient?

A

The air foil blade

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5
Q

Which centrifugal fan wheel discharges air at the highest velocity

A

Forward curved blade

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6
Q

Describe a perfect vacuum in PSIA

A

0 psia

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7
Q

Describe a perfect vacuum in psig

A

-14.7 psig

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8
Q

Describe a perfect vacuum in Inches HG

A

29.92 in/hg

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9
Q

Using a manometer how would you measure static pressure?

A

One end would be at a right angle to the duct wall and the other end would be open to atmospheric pressure

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10
Q

Using a manometer how would you measure velocity pressure?

A

One end would be at a right angle to the duct wall and the other end would be open facing the airflow within the duct.

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11
Q

How would you measure total pressure using a manometer?

A

One end would be open facing the airflow within the duct and the other end would be open to atmospheric pressure.

Total pressure= Velocity pressure+Static pressure.

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12
Q

Large single suction fans are usually mounted on what kind of bearings?

A

Double row spherical roller bearings

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13
Q

What kind of fan has blades shaped like aircraft or boat propellers?

A

Axial flow fans

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14
Q

Where would you mount a fan for induced draft?

A

Between the boiler and the chimney

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15
Q

How is natural draft accomplished?

A

By a differential pressure between the top and bottom of the cooling tower.

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16
Q

What kind of fan blade would be used if there where high speeds that require a stronger wheel structure?

A

Radial blade fan

17
Q

What is the purpose of a fan casing?

A

It is to collect the air leaving the impeller wheel and change the velocity pressure into static pressure

18
Q

What kind of axial fan requires fixed guide vanes?

A

Vane axial fans (tube axial fan)

19
Q

What are the 2 types of mechanical draft?

A

Forced draft

Induced draft

20
Q

What are static arrests on a fan duct system?

A

They ground the static electricity generated while the fan is running

21
Q

What is the name of the circular collection chamber mounted around the fan wheel of a centrifugal fan?

A

It is called a scroll

22
Q

How can control of air through fans be accomplished?

A

Inlet louvre, outlet dampers, varying the fan speed.

23
Q

Surge point of a dynamic compressor happens when?

A

There is high pressure and low flow

24
Q

Stone wall point or choke happens in a dynamic compressor when?

A

There is low pressure and maximum flow

25
Q

In an axial flow compressor what blade part is mounted directly to the housing and does not spin?

A

The stators

26
Q

What part of an axial compressor increases gas pressure? And what part increases velocity?

A

The rotor blades (rotating part) increase the gas velocity, which then converts into pressure as it enters the stator section and slows down.