Smoke exhaust ductwork
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Smoke exhaust ductwork, in Europe, is typically protected via passive fire protection means, subject to fire testing (typically to NBN EN 1366-8) and listing and approval use and compliance. It is used to remove smoke from buildings, ships or offshore structures to enable emergency evacuation as well as improved firefighting. In North America, fireproofed ductwork may be used for the purpose of smoke exhaust, but it is more common to use unfireproofed return air ductwork, whereby no fire testing or listings are employed to qualify the ductwork for this use. Evidence of this North American practice can be found in the 2010 National Building Code of Canada, 18.104.22.168. Mechanical Exhaust System, as well as Sections 909.16.2 and 910 of the 2015 International Building Code.
Means of construction
Similar to pressurisation ductwork, smoke exhaust can be built using:
- ordinary sheet metal with external fireproofing treatment; or
- a proprietary duct that is inherently fire-resistant; or
- suitably stiff fireproofing materials, such as calcium silicate.
The primary difference between pressurisation and smoke exhaust ducting is that one pressurises an area, while the other reduces the pressure through exhausting smoke.
Some smoke exhaust ductwork requires no fireproofing if the smoke is not expected to be at elevated temperature.
Smoke exhaust ducting systems for land-based use are found in most industrialised nations. In North America, the primary purpose is to comply with building codes. Grease ducting is closely related and highly regulated in North America as well; its main purpose is exhaust of grease-laden vapours from commercial cooking operations, as opposed to smoke exhaust from accidental building fires.
- Passive fire protection
- Pressurisation ductwork
- Heat and smoke vent
- Grease duct
- Calcium silicate
- Listing and approval use and compliance
- Emergency evacuation
- on YouTube
- Smoke Extraction in Buildings Slide Show by Vysakh Manohar
- ISO6944 - 2008 Fire containment -- Elements of building construction -- Part 1: Ventilation ducts
- YouTube Return Air Ductwork Video - Return air can be co-opted for cold smoke exhaust in North America
- "Ask the builder" page on return air ductwork. Return air ductwork can be co-opted for cold smoke exhaust in North America
- "Wisegeek" page on return air ductwork. Return air ductwork can be co-opted for cold smoke exhaust in North America