Fans Flashcards

1
Q

List three (3) kinds of pressure found in operating fan ducts?

A
  • Static
  • Velocity
  • Total Pressures
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2
Q

What is a manometer used for?

A

Is a U shape tube connected to the fan for measuring pressures.

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3
Q

How can you remove static electricity generated from a fan?

A

Ground the rotating element with a ground brush and cable assembly.

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4
Q

Name two (2) major type of fans according to flow through the impeller?

A
  • Radial Flow Centrifugal

* Axial Flow Propeller

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5
Q

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

A

The Scroll.

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6
Q

Name two (2) ways of placing bearings on a shaft in relationship to the fan wheel?

A
  • The wheels can be mounted between bearings

* The wheels can be mounted overhung on the shaft

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7
Q

How can control of air through fans be accomplished?

A
  • Inlet Louvre
  • Outlet Dampers
  • Varying The Fan Speed
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8
Q

Why are some fans mounted on a base with the aid of springs?

A

Fan base springs are used to dampen out fan vibrations to the base.

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9
Q

What is the type of inspection that allows periodic checking of fans on a routine basis?

A

Preventative Maintenance.

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10
Q

Troubleshooting of fans is best accomplished by using which type of monitor?

A

A vibration analyzer.

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11
Q

Fan overhaul is best accomplished by following what directions/instructions?

A

Original Equipment Manufacturer’s Overhaul Prints And Procedures.

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12
Q

Why should all parts be inspected and measured during an overhaul?

A

All part need to be inspected for off-specification sizes and fatigue (cracks).

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13
Q

Why would the fan wheel hub be heated before installing it on a shaft?

A

The bore size is increased with heat, allowing easy installation onto a cold shaft?

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14
Q

Explain the purpose of balancing a fan rotor in a dynamic balancer?

A

Dynamic balancing is performed to reduce the vibration of the fan to acceptable levels.

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15
Q

What is the purpose of a cold rollover of the fan rotors?

A

A cold rollover is used to confirm that there are no rubbing metal parts and no cracking noises experienced after a fan overhaul.

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16
Q

What is static pressure?

A

Is the pressure the air exerts on the inside of the duct walls or piping and what overcomes the resistance ducts, fuel beds, filters and grates.

17
Q

The pressure exerted on the vane is pressure due to air velocity is called?

A

Velocity Pressure.

18
Q

How is velocity pressure produced?

A

is produced by the impact of air flowing through a duct and is felt only by the surfaces that the air actually strikes.

19
Q

Velocity pressure is the pressure over and above what pressure?

A

Static Pressure.

20
Q

What is total pressure?

A

Is adding velocity pressure to static pressure.

21
Q

How is static electricity caused?

A

By stripping electrons off ductwork surfaces making the static charges built up to very high levels before they get to discharge and arcing the bearing.

22
Q

As air flow decreases, so does the system pressure (backpressure) and the fan respond by creating more flow, this action is known as?

A

Hunting or Surge

23
Q

Large single suction fans are generally mounted on?

A

Double Row Spherical Roller Bearing.

24
Q

What are the three variations of mechanical draft?

A
  • Induced Draft
  • Forced Draft
  • Balanced Draft