Commercial Air Filters and Sound Control Flashcards
By using clean and quiet equipment, what will happen?
Work more efficiently and have a longer life expectancy.
The elimination of noise and air contaminants in a ventilation or air conditioning system is necessary for ?
Satisfactory comfort conditions for a building’s occupant.
What are the options available for noise reductions.
-Silencers.
-Fan isolation mounts.
-Inertia Bases.
-Flexible Connectors.
-Application of acoustical liners.
-Special sound traps.
You can isolate and/ or eliminate vibration and noise caused by fans by using which of the following techniques.
- Mounting fans on spring isolators,
- Hanging fans on isolation hangers.
- Using concrete filled inertia bases installed on rubber mounts and cork pads.
What are inertia bases used for?
Pumps, compressors and large centrifugal fans.
How do you reduce movement or lower the center of gravity on inertia bases?
Concrete reinforcement or weighted steel frames.
What are the four types of isolation bases ?
- 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.
Isolation Mounts consist of the four following types?
-Isolation Rails.
- Isolation Bases.
- Inertia Bases.
- Rooftop Isolation Rail.
What are the four types of isolators available for centrifugal fans
- Free standing
- Restrained Spring.
- Housed Spring.
- Rubber-in shear.
- Neoprene mounts.
What is usually the main generation source of vibrations?
Machinery.
What is the medium through which vibration is transmitted is referred to ?
Sound path.
Flexible duct connectors are used between the?
Machinery and the Ductwork.
Flexible duct connectors are fabricated to be airtight up to?
10” WC
Negative 10” WC
What are flexible duct connectors fabricated of ?
Polyvinyl Chloride (PVC)
Neoprene Coated Fabric.
Sound waves are reflected when they hit hard surface? (t/f)
True.
What is the measurement of the ability of a material to absorb sound waves?
Absorption coefficient (a).
What can you provide to absorb the sound other than direct duct related.
Absorbent ceiling panel.
Carpeting on the floor.
Drapes
Special absorbent.
By providing a single composite treatment to the exterior of the piping or component what can you achieve.
Both Thermal and Acoustical Insulation.
Reactive Silencers provide better noise attenuation at?
Lower Frequencies
Absorptive Silencers provide better noise attenuation at?
Higher Frequencies.
What does reactive silencers consist of?
Several interconnecting pipe segments or chambers.
What does absorptive silencers consist of?
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.
Specific of K27 duct
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.
What does K27 duct control?
Fan noise,
Cross Talk,
High sound transmission loss through wall.
Sound absorbing fibreglass must meet
NFPA 90A and 90B
Type of materials for Acoustical duct lining.
Foams,
Vinyl Barriers,
Sound Damping Products.
Most frequent material used for Acoustical insulation is ?
Fibreglass.
Duct liner should not be used in kitchen ducts or with airstreams conveying solids or corrosive gases.
True
What should be done when velocity exceed 4000FPM (20.3 m/s) in relation to duct liner
Install Metal Nosing
What are the three types of fasteners for duct liners
Adhesively Secured Fasteners
Mechanically Secured Fasteners
Welded Secured Fasteners
What are sound absorbers
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.
How are sound absorbers tested.
Both forward and reversed Airflow.
A sound absorber should not be located directly after a duct elbow or a divided flow fitting.
True
What are the three noise considerations a designer must be aware related to ductwork
Breakout noise.
Break-in noise
Ductwork noise.
What are the three basics element of a noise path
Source
Path
Receiver.
The main consideration when installing air cleaning equipment is the appropriate filtering of air for the purpose of ?
Protecting Health.
Name different air contaminants?
Dust,
Lint,
Pollen,
Bacteria,
Odour.
What is the most important variable in all air cleaning ?
Particle size.
What is one Micron
1/1’000’000 of a meter
Name air cleaning techniques
Filters.
Electronic Air Cleaners.
Electric Filters.
Roll Filters
Air Washers
Describe straining.
Filtrations happen when the particle is too large to fit between the fibre spaces.
Inertial Impingment
Adhesive or Spray-on oily tackifier are added.
Diffusion is the predominant method used in high efficiency air filters (HEPA)
Particle collided with the the air and move on erratic path and attach to the media fibres.
