| 6.3.4. |
Ventilation for Laboratories |
| 6.3.4.1. |
Application
- 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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| 6.3.4.2. |
General Ventilation
- A laboratory shall be provided with continuous mechanical ventilation designed to ensure that dangerous goods vapours and particles
- do not accumulate in the laboratory,
- are prevented from migrating to other parts of the building,
- do not accumulate in the ventilation system,
- are exhausted to the outdoors, and
- are not returned to the building.
- A ventilation system required by this Subsection shall be provided with monitoring devices to
- indicate that the ventilation system is in operation, and
- sound an alarm if the ventilation system is malfunctioning.
- A ventilation system required by this Subsection shall be maintained in conformance with Article 5.5.4.1. of Division B of the NFC.
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| 6.3.4.3. |
Enclosure Exhaust Ventilation
- The ventilation system for a power-ventilated enclosure required by Sentence 5.5.4.2.(1) of Division B of the NFC shall
- conform to NFPA 91, "Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Noncombustible Particulate Solids,"
- provide continuous exhaust ventilation at an air velocity sufficient to prevent the accumulation of combustible or reactive deposits in the power-ventilated enclosure and its exhaust duct system,
- confine dangerous goods vapours and particles to the area where they are generated and exhaust them to the outdoors,
- not return the exhausted air to the building, and
- be provided with well identified control switches that are
- located outside of the power-ventilated enclosure, and
- readily accessible in case of an emergency.
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| 6.3.4.4. |
Enclosure Construction
- The power-ventilated enclosure required by Sentence 5.5.4.2.(1) of Division B of the NFC and its exhaust duct system shall
- except as provided in Sentences (2) and (3), be constructed of noncombustible materials compatible with and chemically resistant to the dangerous goods vapours and particles being exhausted, and
- be provided with access doors to permit inspection and maintenance of the fan assembly and exhaust ducts.
- Combustible materials are permitted in systems described in Clause (1)(a) if
- such materials are required by the corrosive or reactive properties of the dangerous goods being used, and
- their flame-spread rating is not more than 25.
- The flame-spread rating required by Sentence (2) is permitted to be greater than 25 if an automatic fire suppression system is provided inside the power-ventilated enclosure and its exhaust duct system.
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