Commercial HVAC TQ Prep Flashcards
What should be the size of the cheeks for a rectangular roof ventilator?
Cheeks should be 25% bigger than the bottom opening.
What is the recommended face velocity for a hood under normal conditions?
100 fpm
What should be the ducting configuration for exhaust ducts entering fans?
Ducting should be straight for at least 2 diameters before it enters the fan.
What are axial fans typically used for?
Commonly used for dilution ventilation.
Why are centrifugal fans preferred for exhausting heavy amounts of dust?
They are less likely to become clogged.
What are heavy material handling wheels designed for?
Used for handling air with small wood block pieces or similar solid materials.
What is the purpose of material handling wheels?
To prevent long fibrous or stringy materials from wrapping around the blades.
What are air handling wheels used for?
Only for clean air, not for handling materials.
What is the recommended distance for exhaust stacks from fresh air intakes in commercial exhaust?
Should not be located closer than 50 feet.
What is the recommended elbow radius for ductwork?
Preferably 2½ times the pipe diameter.
What is the maximum angle for branches entering the main duct?
Not exceeding 45°, with 30° being recommended.
How should transitions in ductwork be designed?
Always be tapered, 1 unit of change for every 5 units of change in length.
What is the recommended clearance between fan and inlet obstruction?
Greater than ½ wheel diameter.
When is forced air mechanical ventilation required?
When workers enter confined spaces with exposure to toxic or flammable vapors, dust, or oxygen deficiency.
What is the air velocity out of an exhaust stack?
Should be 3000 fpm.
What may be required if a stack extends more than 10 feet above a roof?
Guy wire, minimum 3 of them.
What is the minimum air velocity through commercial kitchen exhaust ducts?
500 fpm or 154.2 meters/minute.
What is one of the most important factors in a proper duct collection system?
The hood design.
How should exhaust system dust collection elbows be constructed?
Should be 2 gauges heavier than straight pipe.
What is the kitchen exhaust canopy code material?
18ga mild steel or stainless steel.
What is the recommended cleaning access for duct elbows and transitions?
An opening large enough for cleaning should be at each elbow, change, or transition.
Where should clean outs on ducts be located?
On the sides or top, not on the bottom.
What is the minimum distance for non-listed ductwork openings from outside edges?
Not less than 1½ inches.
What is the recommended size for personal inspection and cleaning access openings?
20”x20”.
What is the recommended interval for cleaning ducts?
12 ft intervals.
What materials should fasteners for duct doors be made of?
Carbon steel or stainless steel.
What clearance should be provided when ducts pass through combustible material?
Not less than 18 inches.
What is the fire rating for buildings less than 4 stories?
No less than 1 hour.
What is the minimum clearance from outlet to adjacent buildings?
10 ft.
What should be the discharge clearance from the outlet to the roof?
Minimum 40 inches.
What is the recommended kitchen air velocity in ducts?
Not below 500 fpm and not exceed 2000 fpm.
How should exhaust in kitchen systems be interlocked?
With a makeup air unit, not to supply more than 10% of their exhaust capacity.
What is the minimum distance between the grease removal device and the cooking surface?
Not less than 18 inches.
What is the minimum vertical distance for charcoal type boilers?
4 feet between the lower edge of the grease removal device and the cooking surface.
What is the minimal angle that grease filters should be installed from the horizontal?
45°.
What are changes to original blueprints called?
Revisions.
What are changes to specifications called?
Addenda.
What supersedes discrepancies between specifications and blueprints?
The written specs always supersede the drawings.
What is the purpose of a maintenance bond?
Guidance against faulty workmanship or materials for a specified period after completion.
What is a bid depository?
A fair process for submitting tenders for a specific project.
What does ACTS mean in submitting a quote?
Alberta Construction Tendering System.
What is the purpose of ACTS?
To provide fair and orderly receipt of bids and protect the tendering process.
What percentage of the tender price is the bid bond?
10%.
What percentage of the tendered price is the performance bond?
50%.
What must a sheet metal worker do before mobilizing on site?
Complete numerous off-site preparation tasks.
Why is it a good idea to maintain good scheduling practices?
It can eliminate problems caused by production bottlenecks.
What are the purposes of scheduling?
To establish a logical sequence and timeline for tasks.
What must you obtain if you vary from the specs on equipment?
Engineer’s permission.
How is an estimate defined?
An accurate project costing of material and labour.
What type of estimating begins three to four years in advance for larger jobs?
Rough order of magnitude (ROM).
How much overhang must a commercial kitchen canopy have?
At least 6 inches.
What does a Type I hood capture that a Type II does not?
Grease.
What are two basic styles of hoods?
Canopy and Non-canopy.
List 4 types of canopy hoods.
Island, Wall, Corner, Slotted.
List two types of non-canopy hoods.
Back shelf and Eye-Brow.
List 4 items that could be part of the grease removal system.
Filters, Baffles, Air washers, UV technology.
What is the minimum clearance required for a commercial kitchen exhaust duct?
18 inches
What is installed to suppress a flare-up prior to having heat damage?
Fire suppression system
In what orientation should commercial kitchen exhaust ducts be installed?
Vertically
What is the minimum air velocity through commercial kitchen exhaust?
500 fpm or 152.4 m/minute
How much make-up air is required in a commercial kitchen?
100%
What is a control interlock panel used for in a commercial kitchen?
To ensure that when the exhaust fan is on, the make-up air unit is also on
What can be added to maintain velocity in a constant volume exhaust?
Bypass dampers
What 4 provisions must be considered when designing/installing?
Cleaning * Maintenance * Fire protection * Drainage
What is the maximum face velocity when exhausting toxic fumes?
60-125 fpm
What is another name for an auxiliary air fume hood?
Makeup air fume hood
What is incorporated to maintain a desired face velocity on a variable system?
A closed loop control system
What is the basic principle on how dilution ventilation works?
Blow clean air in and exhaust dirty air out
What is the result of exhausting large amounts of air without a proper system?
Carbon monoxide
What builds up in a duct that can increase the risk of flash fire or explosion?
Static electricity
What can be used to avoid static buildup in a system?
Aluminum or copper ground wire
What is the purpose of a well-designed industrial exhaust system?
Eliminate undesirable contaminants where protection of workers’ health is a concern
Why do some industrial exhaust systems require special piping or ducting?
There may be the possibility of corrosion or abrasion
In what orientation should branches be installed?
On their side or on the top
For transitions, every 1 unit of change requires how many units?
5
What can be provided for fan outlets if an elbow inlet is necessary?
An inlet box or turning vanes
Is it possible to not include certain types of machines when sizing a blower?
Yes
What type of duct is used for class 5?
Plastic or stainless
Class 5 applications consist of corrosives such as _______.
acid
What is the minimum distance a hanger should be from a duct?
At least 2 duct diameters, 4” minimum
Why are expansion joints used?
To provide stress relief and absorb movement during extreme temperatures
What is a blast gate or slide damper used for?
When a positive seal is desired and to close off or isolate parts of a system
Name 3 types of longitudinal seams.
- Groove seam * Butt weld seam * Spiral seam
Volume is measured in?
Cubic feet per minute (CFM)
What is the minimum distance in inches a draw band joint should have?
4” minimum
Which seam can be used for all five duct classes?
Butt weld seam
What is the maximum Center to Center distance for screws or rivets?
6 inches
How many inches of lap should there be on commercial pipe?
2 inches
Class 1 only and 2 gauges heavier than chart values describe what?
Aluminum duct
Elbows should have a centreline radius of what?
No less than twice but preferably 2.5 times the pipe diameter
All branches should enter the main duct at what angle?
Not to exceed 45 degrees with 30 degrees being preferred
What are explosion doors used for?
To provide instantaneous pressure discharge
What are the two broad categories of Type I hoods?
Standard and Listed
What type of pressure is found in a local exhaust ventilation duct?
Slightly negative pressure
What occurs if face velocity in a hood exceeds 125 fpm?
Turbulence
What is a blast gate also known as?
Slide damper
When is plastic or PVC duct used on an industrial exhaust system?
For corrosive or toxic fumes are to be conveyed
What is the best practice regarding centreline radius and number of gores?
Centreline of 2.5 and 7 gores
What can be added to maintain velocity in a constant volume exhaust system?
Bypass dampers
What takes precedence over original drawings and specifications?
Addenda and Revisions
What gauge of mild steel can be used in the construction of a commercial kitchen?
16 gauge mild steel
This specification is important for ensuring structural integrity.
What gauge of mild steel is specified for other constructions?
18 gauge mild steel
This is typically used for less demanding structural applications.
At what length on a commercial kitchen exhaust canopy is it desirable to have specific design considerations?
When the canopy exceeds 10’
This length may require additional structural or design elements.
Where shall access doors be located for the purpose of cleaning and inspection in commercial kitchens?
Side or top
Access doors are crucial for maintenance and safety.
How much extra weight needs to be accounted for in commercial kitchen exhaust systems?
800 lbs
This weight consideration is critical for proper structural support.
How much clearance must a commercial kitchen exhaust duct have?
18”
What does BIM stand for?
Building Information Management
BIM is a digital representation of physical and functional characteristics of a facility.
What must carefully be studied when compiling a job takeoff?
The plans and specifications
This ensures accuracy in estimating quantities and costs.
What is ACTS?
The Alberta Construction Tendering System
ACTS is used for managing construction tenders in Alberta.
What does a bid bond guarantee?
That if the contractor is the low bidder, they will honor the bid
A bid bond protects the project owner from a contractor’s failure to execute the contract.
What is the purpose of a spec?
To describe the work to be done
Specifications provide detailed information on materials, methods, and quality standards.
What is the purpose of a schedule?
To provide information on what goes where
Schedules outline the timeline and sequence of construction activities.
What is a change to a blueprint called?
A revision
Revisions reflect updates or corrections made to original plans.
