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Sheet Metal 3rd Period Commercial HVAC AND DRAWINGS > Commercial Air Filters and Sound Control > Flashcards

Commercial Air Filters and Sound Control Flashcards

1
Q

By using clean and quiet equipment, what will happen?

A

Work more efficiently and have a longer life expectancy.

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2
Q

The elimination of noise and air contaminants in a ventilation or air conditioning system is necessary for ?

A

Satisfactory comfort conditions for a building’s occupant.

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3
Q

What are the options available for noise reductions.

A

-Silencers.
-Fan isolation mounts.
-Inertia Bases.
-Flexible Connectors.
-Application of acoustical liners.
-Special sound traps.

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4
Q

You can isolate and/ or eliminate vibration and noise caused by fans by using which of the following techniques.

A
  • Mounting fans on spring isolators,
  • Hanging fans on isolation hangers.
  • Using concrete filled inertia bases installed on rubber mounts and cork pads.
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5
Q

What are inertia bases used for?

A

Pumps, compressors and large centrifugal fans.

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6
Q

How do you reduce movement or lower the center of gravity on inertia bases?

A

Concrete reinforcement or weighted steel frames.

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7
Q

What are the four types of isolation bases ?

A
  • Type A Integral structural steel fan and motor base with motor slide rails.
  • Type B. Slung structural steel base with gusseted brackets.
    -Type C Reinforced concrete inertia base
  • Type D reinforced concrete equipment base with chamfered edges without channel frames.
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8
Q

Isolation Mounts consist of the four following types?

A

-Isolation Rails.
- Isolation Bases.
- Inertia Bases.
- Rooftop Isolation Rail.

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9
Q

What are the four types of isolators available for centrifugal fans

A
  • Free standing
  • Restrained Spring.
  • Housed Spring.
  • Rubber-in shear.
  • Neoprene mounts.
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10
Q

What is usually the main generation source of vibrations?

A

Machinery.

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11
Q

What is the medium through which vibration is transmitted is referred to ?

A

Sound path.

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12
Q

Flexible duct connectors are used between the?

A

Machinery and the Ductwork.

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13
Q

Flexible duct connectors are fabricated to be airtight up to?

A

10” WC
Negative 10” WC

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14
Q

What are flexible duct connectors fabricated of ?

A

Polyvinyl Chloride (PVC)
Neoprene Coated Fabric.

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15
Q

Sound waves are reflected when they hit hard surface? (t/f)

A

True.

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16
Q

What is the measurement of the ability of a material to absorb sound waves?

A

Absorption coefficient (a).

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17
Q

What can you provide to absorb the sound other than direct duct related.

A

Absorbent ceiling panel.
Carpeting on the floor.
Drapes
Special absorbent.

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18
Q

By providing a single composite treatment to the exterior of the piping or component what can you achieve.

A

Both Thermal and Acoustical Insulation.

19
Q

Reactive Silencers provide better noise attenuation at?

A

Lower Frequencies

20
Q

Absorptive Silencers provide better noise attenuation at?

A

Higher Frequencies.

21
Q

What does reactive silencers consist of?

A

Several interconnecting pipe segments or chambers.

22
Q

What does absorptive silencers consist of?

A

Fibrous or Porous sound absorbing materials that reduce the noise by either converting sound energy by reflecting it back to the source in the passages.

23
Q

Specific of K27 duct

A

K27 high pressure duct and fittings.
Pressure tight metal shell,
Fire resistant fiberglass insulation,
Internal perforated liner next to the airflow.
Either rectangular or round.

24
Q

What does K27 duct control?

A

Fan noise,
Cross Talk,
High sound transmission loss through wall.

25
Q

Sound absorbing fibreglass must meet

A

NFPA 90A and 90B

26
Q

Type of materials for Acoustical duct lining.

A

Foams,
Vinyl Barriers,
Sound Damping Products.

27
Q

Most frequent material used for Acoustical insulation is ?

A

Fibreglass.

28
Q

Duct liner should not be used in kitchen ducts or with airstreams conveying solids or corrosive gases.

A

True

29
Q

What should be done when velocity exceed 4000FPM (20.3 m/s) in relation to duct liner

A

Install Metal Nosing

30
Q

What are the three types of fasteners for duct liners

A

Adhesively Secured Fasteners
Mechanically Secured Fasteners
Welded Secured Fasteners

31
Q

What are sound absorbers

A

Another form of sound attenuation in air handling system. A three-foot-long sound absorber provide the same amount of noise control as 250 feet of linear duct.

32
Q

How are sound absorbers tested.

A

Both forward and reversed Airflow.

33
Q

A sound absorber should not be located directly after a duct elbow or a divided flow fitting.

A

True

34
Q

What are the three noise considerations a designer must be aware related to ductwork

A

Breakout noise.
Break-in noise
Ductwork noise.

35
Q

What are the three basics element of a noise path

A

Source
Path
Receiver.

36
Q

The main consideration when installing air cleaning equipment is the appropriate filtering of air for the purpose of ?

A

Protecting Health.

36
Q

Name different air contaminants?

A

Dust,
Lint,
Pollen,
Bacteria,
Odour.

37
Q

What is the most important variable in all air cleaning ?

A

Particle size.

38
Q

What is one Micron

A

1/1’000’000 of a meter

39
Q

Name air cleaning techniques

A

Filters.
Electronic Air Cleaners.
Electric Filters.
Roll Filters
Air Washers

40
Q

Describe straining.

A

Filtrations happen when the particle is too large to fit between the fibre spaces.

41
Q

Inertial Impingment

A

Adhesive or Spray-on oily tackifier are added.

42
Q

Diffusion is the predominant method used in high efficiency air filters (HEPA)

A

Particle collided with the the air and move on erratic path and attach to the media fibres.

43
Q
A

Sheet Metal 3rd Period Commercial HVAC AND DRAWINGS (4 decks)

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