Part 6: ventilation, air ducts and venting (HVAC

Last updated October 22, 2026

Values this chapter turns on

vented combustion products above walks and drives: 2.15 m; vented combustion products above walks and drives
carbon monoxide limit in an enclosed storage garage: 100 ppm; carbon monoxide limit in an enclosed storage garage
exhaust per water closet, urinal or shower: 24 L/s; exhaust per water closet, urinal or shower
appliance output limit for a Part 9 masonry chimney: 120 kW; appliance output limit for a Part 9 masonry chimney

Section 6.3. is long, but for a house-focused exam the questions cluster on a few points: when a dwelling unit's ventilation must follow Section 9.32. instead, garage ventilation numbers, makeup air, intake separation distances, laundry and bathroom exhaust ducts, and where vented combustion products may discharge. Several Sentences are excluded from the syllabus and are flagged below.

Ventilation requirements

All buildings must be ventilated under Section 6.3., with one key carve-out: a self-contained heating-season mechanical ventilation system serving only one dwelling unit must comply with Subsection 9.32.3. OBC Div. B 6.3.1.1.. Live/work units must be mechanically ventilated. (Sentence 6.3.1.1.(2), the ASHRAE 62.1 outdoor air procedures, is excluded from this exam.)

Natural ventilation. Part 6 ventilation is mechanical by default. Natural ventilation, or a mix, is allowed only for non-residential buildings with not more than one person per 40 m², industrial buildings whose process needs large openings even in winter, and seasonal buildings not used in winter OBC Div. B 6.3.1.1A..

Crawl spaces and attics. Unconditioned, unoccupied crawl spaces and attic or roof spaces are ventilated as Part 5 requires OBC Div. B 6.3.1.2..

Storage garages for five or more motor vehicles, if enclosed, need mechanical ventilation designed to one of these limits OBC Div. B 6.3.1.3.:

Option	Limit
Carbon monoxide control	Not more than 100 parts per million
Nitrogen dioxide control (mostly diesel vehicles)	Not more than 3 parts per million
Continuous outdoor air in operating hours	Not less than 3.9 L/s per m² of floor area

The CO and NO2 options must be controlled automatically by monitors. The garage is kept at a lower pressure than adjoining occupancies. Mechanical parking halves the requirement, and open-air storeys are exempt. Repair garage Sentences (7) to (10) are excluded from this exam.

Heat recovery ventilators rated at not less than 25 L/s and not more than 200 L/s must be installed to Subsection 9.32.3., even in a Part 6 building OBC Div. B 6.3.1.4..

Contaminants. Remove contaminants at source as far as possible, prevent spread from contaminated spaces, and design to minimise biocontaminant growth OBC Div. B 6.3.1.5.. Commercial cooking ventilation follows NFPA 96 OBC Div. B 6.3.1.6..

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Air duct systems

Subsection 6.3.2. covers duct systems other than those in dwelling units covered by Part 9 OBC Div. B 6.3.2.1.. Points that recur:

Condensate drain pans: piped outside the airstream, no stagnant water, and an indirect connection to drainage OBC Div. B 6.3.2.2..
In a residential occupancy, air from one suite must not be circulated to another suite or to a public corridor; garage duct systems are not directly interconnected with other parts of the building OBC Div. B 6.3.2.7..
Makeup air must be admitted for systems that exhaust to outdoors, interlocked with the exhaust devices, and tempered if delivered directly to occupied areas in winter OBC Div. B 6.3.2.8..
Openings less than 2 m above the floor need grilles that stop a 15 mm sphere; outdoor intakes at least 0.3 m above roofs or grade (allowing for snow); exterior screens with openings not larger than 15 mm OBC Div. B 6.3.2.9..

Intake separation distances come from the intake table OBC Div. B Table 6.3.2.9.. Read the row for the contaminant source and take the minimum distance in metres. Three values worth tabbing: a low-traffic driveway or parking space is 1.5 m, a kitchen exhaust outlet is 3.0 m, and a sanitary vent is 3.5 m.

Exhaust ducts OBC Div. B 6.3.2.10.:

Rule	Detail
Discharge	Directly to the outdoors (limited exception into a storage garage)
Back draft	Outlets designed to prevent back draft under wind
Laundry dryers	Independent duct, cleanable along its whole length, smooth corrosion-resistant material, discharge outdoors
Collective dryer venting	One central fan, interlock, makeup air
Washrooms and residential kitchens	Independent of other exhaust ducts, except self-contained systems serving one dwelling unit
Rate	At least 24 L/s per water closet, urinal, shower or slop sink

Return-air rules repeat the Part 9 ideas: the return system must handle the entire air supply, must not affect combustion air or draw combustion products, and a public corridor or exit is never a return-air plenum OBC Div. B 6.3.2.11..

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Chimneys and venting equipment

Products of combustion from oil, gas and solid-fuel appliances are vented under the appliance installation standard named in Article 6.2.1.5. OBC Div. B 6.3.3.1.. Other vented products of combustion must discharge away from the building at least:

From	Minimum
Above sidewalks and driveways	2.15 m
Outdoor air intakes	3 m
Doors and operable windows (horizontal or vertical)	3 m
Occupiable outdoor spaces	3 m

Rectangular masonry or concrete chimneys not more than 12 m high follow Part 9 if they serve appliances totalling 120 kW or less, or fireplaces; others follow NFPA 211 OBC Div. B 6.3.3.2.. Single-wall metal smoke stacks follow NFPA 211 OBC Div. B 6.3.3.3.. External chimney ladder rungs start at least 2.5 m above ground OBC Div. B 6.3.3.4..

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Ventilation for laboratories

Subsection 6.3.4. applies to labs where dangerous goods are used in quantities or ways that create a fire or explosion hazard OBC Div. B 6.3.4.1.. The lab needs continuous mechanical ventilation that exhausts vapours outdoors and never returns them, with monitoring that shows the system is running and alarms on malfunction OBC Div. B 6.3.4.2..

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Common traps

Applying Part 6 duct rules to a single house. Subsection 6.3.2. excludes dwelling units covered by Part 9; use Subsection 9.33.6.
Forgetting the HRV size window (25 to 200 L/s) that pulls even Part 6 buildings back to 9.32.3.
Mixing the 2.15 m (above walks and driveways) with the 3 m distances.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
Ventilation requirements	All buildings must be ventilated under Section 6.3., with one key carve-out: a self-contained heating-season mechanical ventilation system serving only one dwelling unit must…
Air duct systems	Intake separation distances come from the intake table.
Chimneys and venting equipment	Products of combustion from oil, gas and solid-fuel appliances are vented under the appliance installation standard named in Article 6.2.1.5.. Other vented products of combustion…
Ventilation for laboratories	Subsection 6.3.4. applies to labs where dangerous goods are used in quantities or ways that create a fire or explosion hazard.

Ventilation requirements
All buildings must be ventilated under Section 6.3., with one key carve-out: a self-contained heating-season mechanical ventilation system serving only one dwelling unit must…
Air duct systems
Intake separation distances come from the intake table.
Chimneys and venting equipment
Products of combustion from oil, gas and solid-fuel appliances are vented under the appliance installation standard named in Article 6.2.1.5.. Other vented products of combustion…
Ventilation for laboratories
Subsection 6.3.4. applies to labs where dangerous goods are used in quantities or ways that create a fire or explosion hazard.

Usual exam traps

Applying Part 6 duct rules to a single house. Subsection 6.3.2. excludes dwelling units covered by Part 9; use Subsection 9.33.6.
Forgetting the HRV size window (25 to 200 L/s) that pulls even Part 6 buildings back to 9.32.3.
Mixing the 2.15 m (above walks and driveways) with the 3 m distances.

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Questions on Part 6: ventilation, air ducts and venting, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

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Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 6.3.1.1. Required Ventilation
(1)Except as provided in Sentence (4), all buildings shall be ventilated in accordance with this Section.
(2)Except in storage garages and repair garages covered by Article 6.3.1.3., outdoor air shall be supplied to buildings for ventilation purposes in accordance with one of the following Sections of ANSI/ASHRAE 62.1, "Ventilation for Acceptable Indoor Air Quality,"
(a)Section 6.2, Ventilation Rate Procedure, excluding the exception stated in Section 6.2.7.1.2 and note H of Table 6.2.2.1.
(b)Section 6.3, Indoor Air Quality Procedure, or
(c)Section 6.4, Natural Ventilation Procedure, excluding residential occupancies.
(3)Except in storage garages and repair garages covered by Article 6.3.1.3., exhaust ventilation shall be provided in accordance with Section 6.5, Exhaust Ventilation, of ANSI/ASHRAE 62.1, "Ventilation for Acceptable Indoor Air Quality," as a minimum.
(4)Self-contained heating-season mechanical ventilation systems serving only one dwelling unit shall comply with Subsection 9.32.3.
(5)Live/work units shall be mechanically ventilated in accordance with the requirements of Sentence (1).
Open OBC Div. B 6.3.1.1. in the code viewer
OBC Div. B 6.3.1.1A. Natural Ventilation
(1)Except as permitted by Sentence (2), the ventilation required by Article 6.3.1.1. shall be provided by mechanical ventilation except that it can be provided by natural ventilation or a combination of natural and mechanical ventilation in
(a)buildings of other than residential occupancy having an occupant load of not more than one person per 40 m² during normal use.
(b)buildings of industrial occupancy where the nature of the process contained in them permits or requires the use of large openings in the building envelope even during the winter, or
(c)seasonal buildings not intended to be occupied during the winter.
(2)Where climatic conditions permit, buildings containing occupancies other than residential occupancies, may be ventilated by natural ventilation methods in lieu of mechanical ventilation where engineering data demonstrates that such a method will provide the required ventilation for the type of occupancy.
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OBC Div. B 6.3.1.2. Crawl Spaces and Attic or Roof Spaces
(1)Unconditioned and unoccupied crawl spaces and attic or roof spaces shall be ventilated by natural or mechanical means as required by Part 5. (See Note A-6.3.1.2.(1))
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OBC Div. B 6.3.1.3. Ventilation of Storage and Repair Garages
(1)Except as provided in Sentences (4) and (6), an enclosed storage garage for five or more motor vehicles shall have a mechanical ventilation system designed to
(a)limit the concentration of carbon monoxide to not more than 100 parts per million parts of air,
(b)limit the concentration of nitrogen dioxide to not more than 3 parts per million parts of air, where the majority of the vehicles stored are powered by diesel-fuelled engines, or
(c)provide, during operating hours, a continuous supply of outdoor air at a rate of not less than 3.9 L/s for each square metre of floor area (see Article 3.3.1.21.).
(See Note A-6.3.1.3.(1)) (See also Sentence 3.3.5.4.(4).)
(2)Mechanical ventilation systems provided in accordance with Clause (1)(a) shall be controlled automatically by carbon monoxide monitoring devices, and systems provided in accordance with Clause (1)(b) shall be controlled by nitrogen dioxide or other acceptable monitoring devices. (See Note A-6.3.1.3.(2))
(3)Mechanical ventilation systems provided in accordance with Sentence (1) shall be designed such that the pressure in the storage garage is less than the pressure in adjoining buildings of other occupancy, or in adjacent portions of the same building having a different occupancy.
(4)In storage garages subject to the requirements of Sentence (1), where motor vehicles are parked by mechanical means, the ventilation requirements may be reduced by one half.
(5)Except as provided in Sentence (6), ticket and attendant booths of storage garages shall be pressurized with a supply of uncontaminated air.
(6)The requirements of Sentences (1) to (5) shall not apply to open-air storeys in a storage garage.
(7)A repair garage shall have a mechanical ventilation system designed to limit the exposure of workers to,
(a)carbon monoxide to below the time weighted average concentration of 25 parts per million for a normal 8 hour workday or 40 hour work week, and
(b)nitrogen dioxide from diesel powered vehicles to below 0.72 parts per million for a normal 8 hour workday or 40 hour work week.
(8)In a repair garage, when a repair bay is not immediately adjacent to an outside garage door opening, a system capable of providing continuous general ventilation of not less than 700 L/s per internal bay shall be provided.
(9)The general ventilation system described in Sentence (8) shall be designed to,
(a)operate continuously, or
(b)be controlled automatically by carbon monoxide monitoring devices, located so as to provide full protection throughout the repair garage.
(10)The general ventilation system described in Sentence (8) is not required when tail pipes of vehicles are directly connected to local mechanical exhaust systems that terminate outdoors.
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OBC Div. B 6.3.1.4. Heat Recovery Ventilators
(1)Heat recovery ventilators with rated capacities of not less than 25 L/s and not more than 200 L/s shall be installed in accordance with Subsection 9.32.3.
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OBC Div. B 6.3.1.5. Indoor Air Contaminants
(1)Air contaminants of concern within buildings shall
(a)be removed insofar as is possible at their points of origin, and
(b)not be permitted to accumulate in concentrations greater than those permitted by good engineering practice such as that described in the publications listed in Sentence 6.2.1.1.(1), measured using the methodology described therein.
(2)Systems serving spaces that contain sources of contamination and systems serving other occupied parts of the building but located in or running through spaces that contain sources of contamination shall be designed in such a manner as to prevent the spread of such contamination to other occupied parts of the building.
(3)Heating, ventilating and air-conditioning systems shall be designed to minimize the growth and spread of biocontaminants.
(4)Mechanical rooms containing refrigeration equipment shall be ventilated in accordance with CSA B52, "Mechanical refrigeration code".
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OBC Div. B 6.3.1.6. Commercial Cooking Equipment
(1)Except as provided in Article 3.6.3.5., all commercial cooking equipment shall be provided with ventilation systems designed, constructed and installed to conform to NFPA 96, "Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations."
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OBC Div. B 6.3.2.1. Application
(1)This Subsection applies to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems other than those in dwelling units covered by Part 9.
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OBC Div. B 6.3.2.2. Drain Pans
(1)HVAC systems that generate condensate or introduce liquid water into the airstream in the ducts shall be equipped with drain pans that are
(a)designed in accordance with Section 5.10, Drain Pans, of ANSI/ASHRAE 62.1, "Ventilation for Acceptable Indoor Air Quality,"
(b)provided with an outlet that is piped to the outside of the airstream in a location where condensate can be safely disposed of,
(c)installed so that water does not stagnate and drains from the pan, and
(d)provided with a drain line that is indirectly connected to a drainage system in accordance with Article 7.4.2.1.
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OBC Div. B 6.3.2.7. Interconnection of Systems
(1)In a residential occupancy, air from one suite shall not be circulated to any other suite or to a public corridor.
(2)Except as permitted by Sentences (3) and 6.3.2.10.(6), air duct systems serving storage garages shall not be directly interconnected with other parts of the building.
(3)Exhaust ducts referred to in Sentence 6.3.2.10.(10) are permitted to exhaust through an enclosed storage garage prior to exhausting to the outdoors, provided
(a)the storage garage exhaust system runs continuously,
(b)the capacity of the storage garage exhaust system is equal to or exceeds the volume of the exhaust entering the garage, and
(c)a leakage rate 1 smoke/fire damper rated in accordance with CAN/ULC-S112.1, "Standard for Leakage Rated Dampers for Use in Smoke Control Systems," is provided near the duct outlet location in the storage garage to prevent air from the storage garage from entering the exhaust ductwork system in the event the building's exhaust fan is shut down.
(4)Except for corridors conforming to Sentence 3.3.1.4.(4) or as permitted in Sentences and (6), a public corridor or corridor serving the public shall not be used as a portion of a supply, return or exhaust air system serving adjoining areas, other than as part of a supply air system serving toilet rooms, bathrooms, shower rooms and similar auxiliary spaces opening directly to the public corridor or corridor used by the public.(5)
(5)A public corridor may be used as part of an engineered smoke control system.
(6)Infiltration due to corridor pressurization is permitted into a residential occupancy from a public corridor.
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OBC Div. B 6.3.2.8. Makeup Air
(1)In ventilating systems that exhaust air to the outdoors, provision shall be made for the admission of a supply of makeup air in sufficient quantity so that the operation of the exhaust system and other exhaust equipment or combustion equipment is not adversely affected.
(2)Makeup air facilities required by Sentence (1) shall be interlocked with the exhaust devices they serve so that both operate together.
(3)Where makeup air facilities are intended to introduce air directly from the outdoors to occupied parts of the building in winter, they shall incorporate means of tempering that air to maintain the indoor design temperature.
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OBC Div. B 6.3.2.9. Supply, Return, Intake and Exhaust Air Openings
(1)Supply, return and exhaust air openings located less than 2 m above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diam sphere.
(2)Outdoor air intakes shall be located so that
(a)the quality of the air entering the building complies with Sentence 6.2.1.2.(1), and
(b)they are separated a minimum distance from sources of contaminants in accordance with Table 6.3.2.9.
(3)Outdoor air intakes shall be installed not less than 0.3 m above roofs, landscape grades or other surfaces, taking into account anticipated snow accumulation levels.
(4)Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to prevent the screen openings from icing over.
(5)Screens required in Sentence (4) shall be accessible for maintenance.
(6)Combustible grilles, diffusers and other devices covering supply, return, intake and exhaust openings shall comply with Article 3.6.5.7.
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OBC Div. B Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2)
Table 6.3.2.9. Minimum Distances of Air Intakes from Sources of Contaminants — Forming Part of Sentence 6.3.2.9.(2) Source of Contaminants | Minimum Distance of Outdoor Air Intake, m Garage entry of a garage for 5 or more motor vehicles, automobile loading area and drive-in queue | 4.5 Truck loading area or dock, and bus parking | 7.6 Driveway, parking space, lane, road and similar locations that carry a low volume of traffic | 1.5 Thoroughfare, arterial road, freeway, highway and similar locations that carry a high volume of traffic | 7.6 Garbage storage/pick-up area and dumpsters | 4.5 Discharge from evaporative heat rejection systems | 7.6 Sanitary vent | 3.5 Kitchen exhaust outlet | 3.0 Vent for combustion products from solid fuel-burning appliances | 3.0
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OBC Div. B 6.3.2.10. Exhaust Ducts and Outlets
(1)Except as provided in Sentence (2), exhaust ducts of non-mechanical ventilating systems serving separate rooms or spaces shall not be combined.
(2)Exhaust ducts of non-mechanical ventilating systems serving similar occupancies may be combined immediately below the point of final delivery to the outdoors, such as at the base of a roof ventilator.
(3)Exhaust ducts of ventilating systems shall have provision for the removal of condensation where this may be a problem.
(4)Exhaust outlets shall be designed to prevent back draft under wind conditions.
(5)Except as permitted in Sentence (6), exhaust systems shall discharge directly to the outdoors. (See Note A-6.3.2.10.(5) and (6))
(6)Exhaust systems are permitted to exhaust into a storage garage, provided
(a)they serve rooms that are accessible only from that storage garage,
(b)the exhaust contains no contaminants that would adversely affect the air quality in the storage garage, and (See Note A-6.3.2.10.(6)(b))
(c)they are designed in accordance with Sentence 6.3.2.7.(3). (See Note A-6.3.2.10.(5) and (6))
(7)Exhaust ducts connected to laundry drying equipment shall be,
(a)independent of other exhaust ducts,
(b)designed and installed so that the entire duct can be cleaned, and
(c)constructed of smooth corrosion-resistant material. (See Note A-6.3.2.10.(7) and (8))
(8)Where collective venting of multiple installations of laundry-drying equipment is used, the ventilation system shall
(a)be connected to a common exhaust duct that is vented by one central exhaust fan,
(b)include an interlock to activate the central exhaust fan when laundry-drying equipment is in use, and
(c)be provided with make-up air. (See Note A-6.3.2.10.(7) and (8))
(9)Exhaust ducts or vents connected to laundry-drying equipment shall discharge directly to the outdoors.
(10)Except as provided in Sentence (12) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing water closets, urinals, basins, showers or slop sinks shall be independent of other exhaust ducts.
(11)Except as provided in Sentence (12) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing residential cooking equipment shall be independent of other exhaust ducts.
(12)Two or more exhaust systems described in Sentences (10) and (11) may be interconnected or connected with exhaust ducts serving other areas of the building, provided
(a)the connections are made at the inlet of an exhaust fan, and all interconnected systems are equipped with suitable back pressure devices to prevent the passage of odours from one system to another when the fan is not in operation, or
(b)the exhaust ducts discharge to a shaft that is served by an exhaust fan having a capacity that is equal to or greater than the combined capacity of the exhaust fans discharging to the plenum multiplied by the operation diversity factor, provided that the exhaust fan serving the shaft operates continuously. (See Note A-6.3.2.10.(12)(b))
(13)Where exhaust ducts containing air from conditioned spaces pass through or are adjacent to unconditioned spaces, the ducts shall be constructed to prevent condensation from forming on the inside or outside of the ducts.
(14)Except as provided in Sentence (15), exhaust air shall be provided at a rate not less than 24 L/s for each water closet, urinal, shower or slop sink.
(15)Except as provided in Sentence 6.3.1.1.(4), exhaust air shall be provided for fixtures in dwelling units in accordance with ANSI/ASHRAE 62.1, "Ventilation for Acceptable Indoor Air Quality."
(16)Except for wash basins (lavatories), sanitary facilities in a food premises shall be mechanically ventilated and shall be capable of exhausting air at the rate of not less than 24 L/s for each sanitary fixture listed in Sentence (17).
(17)The mechanical ventilation described in Sentence (16) applies to rooms containing water closets, urinals, basins, showers or slop sinks.
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OBC Div. B 6.3.2.11. Return-Air System
(1)Return-air systems shall comply with Article 3.6.5.8.
(2)Where a ceiling space is used as a return-air plenum, the requirements of Article 3.6.4.3. shall apply.
(3)A public corridor or exit shall not be used as a return-air plenum.
(4)The return-air system shall be designed to handle the entire air supply.
(5)The return-air system shall be designed so that the negative pressure from the circulating fan cannot affect the furnace combustion air supply nor draw combustion products from joints or openings in the furnace or flue pipe.
(6)Return-air inlets shall not be installed in an enclosed room or crawl space that provides combustion air to a fuel-fired appliance.
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OBC Div. B 6.3.3.1. Requirement for Venting
(1)Except as provided in Articles 6.3.3.2. and 6.3.3.3., the products of combustion from oil-, gas and solid-fuel-burning appliances shall be vented in conformance with the requirements in the applicable appliance installation standard listed in Article 6.2.1.5.
(2)Except as provided in Article 6.2.1.5., vented products of combustion, other than those referred to in Sentence (1), shall be discharged away from the building, so as not to re-enter it, to a distance not less than
(a)2.15 m above sidewalks and driveways,
(b)3 m from outdoor air intakes,
(c)3 m horizontally or vertically from doors and operable windows, and
(d)3 m horizontally or vertically from occupiable outdoor spaces, excluding maintenance spaces. (See Note A-6.3.3.1.(2))
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OBC Div. B 6.3.3.2. Masonry or Concrete Chimneys
(1)Rectangular masonry or concrete chimneys not more than 12 m in height shall conform to Part 9 if they serve
(a)appliances with a combined total rated heat output of 120 kW or less, or
(b)fireplaces.
(2)Masonry or concrete chimneys other than those described in Sentence (1) shall be designed and installed in conformance with the appropriate requirements in NFPA 211, "Standard for Chimneys, Fireplaces, Vents and Solid Fuel-Burning Appliances."
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OBC Div. B 6.3.3.3. Metal Smoke Stacks
(1)Single wall metal smoke stacks shall be designed and installed in conformance with NFPA 211, "Standard for Chimneys, Fireplaces, Vents and Solid Fuel-Burning Appliances."
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OBC Div. B 6.3.3.4. Access Ladders
(1)Access ladders for chimneys, when provided, shall consist of steel or bronze rungs, built into the walls of the chimneys.
(2)Rungs for external ladders shall begin at not less than 2.5 m from ground level.
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OBC Div. B 6.3.4.1. Application
(1)This Subsection applies to laboratories where dangerous goods, including flammable liquids and combustible liquids, are used in normal laboratory operations in quantities or in a manner that creates a fire or explosion hazard.
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OBC Div. B 6.3.4.2. General Ventilation
(1)A laboratory shall be provided with continuous mechanical ventilation designed to ensure that dangerous goods vapours and particles
(a)do not accumulate in the laboratory,
(b)are prevented from migrating to other parts of the building,
(c)do not accumulate in the ventilation system,
(d)are exhausted to the outdoors, and
(e)are not returned to the building.
(2)A ventilation system required by this Subsection shall be provided with monitoring devices to
(a)indicate that the ventilation system is in operation, and
(b)sound an alarm if the ventilation system is malfunctioning.
(3)A ventilation system required by this Subsection shall be maintained in conformance with Section 4.12. of the Fire Code made under the Fire Protection and Prevention Act, 1997.
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