Smoke exhaust ductwork

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Enormous smoke exhaust duct used to extract smoke generated during fire testing at National Research Council (Canada)'s National Fire Laboratory in Mississippi Mills, Ontario Mississippi mills nrc irc national fire laboratory smoke exhaust duct.jpg
Enormous smoke exhaust duct used to extract smoke generated during fire testing at National Research Council (Canada)'s National Fire Laboratory in Mississippi Mills, Ontario

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, 3.2.8.8. Mechanical Exhaust System, as well as Sections 909.16.2 and 910 of the 2015 International Building Code.

Contents

Means of construction

Similar to pressurisation ductwork, smoke exhaust can be built using:

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.

Markets

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.

Requirements

Full scale fire testing must include three-dimensional exposures to ductwork as well as the firestop system. Installations must meet the listing.

Rad- und Schwimmsporthalle Berlin, Smoke Exhaust Ductwork made of calcium silicate and plaster fireproofing boards

See also

Related Research Articles

Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and is sometimes formulated as 2CaO·SiO2. It is also referred to by the shortened trade name Cal-Sil or Calsil. It occurs naturally as the mineral larnite.

Kitchen hood Type of home appliance that clears smoke from a stove

A kitchen hood, exhaust hood, or range hood is a device containing a mechanical fan that hangs above the stove or cooktop in the kitchen. It removes airborne grease, combustion products, fumes, smoke, heat, and steam from the air by evacuation of the air and filtration. In commercial kitchens exhaust hoods are often used in combination with fire suppression devices so that fumes from a grease fire are properly vented and the fire is put out quickly. Commercial vent hoods may also be combined with a fresh air fan that draws in exterior air, circulating it with the cooking fumes, which is then drawn out by the hood.

Fireproofing

Fireproofing is rendering something resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a noun, verb or adjective; it may be hyphenated ("fire-proof").

An intumescent is a substance that swells as a result of heat exposure, thus leading to an increase in volume and decrease in density. Intumescents are typically used in passive fire protection and require listing, approval, and compliance in their installed configurations in order to comply with the national building codes and laws.

Fire protection

Fire protection is the study and practice of mitigating the unwanted effects of potentially destructive fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as well as the research and development, production, testing and application of mitigating systems. In structures, be they land-based, offshore or even ships, the owners and operators are responsible to maintain their facilities in accordance with a design-basis that is rooted in laws, including the local building code and fire code, which are enforced by the Authority Having Jurisdiction.

A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fireproofing of a wall or floor assembly allowing it to impede the spread of fire and smoke.

Passive fire protection

Passive fire protection (PFP) is an integral component of the components of structural fire protection and fire safety in a building. PFP attempts to contain fires or slow the spread, such as by fire-resistant walls, floors, and doors. PFP systems must comply with the associated listing and approval use and compliance in order to provide the effectiveness expected by building codes.

Circuit integrity

Circuit integrity refers to the operability of electrical circuits during a fire. It is a form of fire-resistance rating. Circuit integrity is achieved via passive fire protection means, which are subject to stringent listing and approval use and compliance.

Duct (flow) Conduit used in heating, ventilation, and air conditioning

Ducts are conduits or passages used in heating, ventilation, and air conditioning (HVAC) to deliver and remove air. The needed airflows include, for example, supply air, return air, and exhaust air. Ducts commonly also deliver ventilation air as part of the supply air. As such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort.

A fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire resistance test. This can be quantified simply as a measure of time, or it may entail a host of other criteria, involving other evidence of functionality or fitness for purpose.

The Sheet Metal and Air Conditioning Contractors' National Association is an international trade association with more than 4,500 contributing contractor members in 103 chapters throughout the United States, Canada, Australia and Brazil. Its headquarters is in Chantilly, Virginia.

Fire test

A fire test is a means of determining whether fire protection products meet minimum performance criteria as set out in a building code or other applicable legislation. Successful tests in laboratories holding national accreditation for testing and certification result in the issuance of a certification listing. The listing is public domain, whereas the test report itself is proprietary information belonging to the test sponsor.

Area of refuge Location in a building designed to hold occupants during a fire or other emergency

An area of refuge is a location in a building designed to hold occupants during a fire or other emergency, when evacuation may not be safe or possible. Occupants can wait there until rescued or relieved by firefighters. This can apply to the following:

Heat and smoke vents are installed in buildings as an active fire protection measure. They are openings in the roof which are intended to vent the heat and smoke developed by a fire inside the building by the action of buoyancy, such that they are known as "gravity vents".

Pressurisation ductwork

Pressurisation duct work is a passive fire protection system. It is used to supply fresh air to any area of refuge, designated emergency evacuation or egress route.

Grease duct

A grease duct is a duct that is specifically designed to vent grease-laden flammable vapors from commercial cooking equipment such as stoves, deep fryers, and woks to the outside of a building or mobile food preparation trailer. Grease ducts are regulated both in terms of their construction and maintenance, forming part of the building's passive fire protection system. The cleaning schedule is typically dictated by fire code or related safety regulations, and evidence of compliance must be kept on file by the owner.

Kitchen exhaust cleaning

Kitchen exhaust cleaning is the process of removing grease that has accumulated inside the ducts, hoods, fans and vents of exhaust systems of commercial kitchens. Left uncleaned, kitchen exhaust systems eventually accumulate enough grease to become extreme fire hazards. Exhaust systems must be inspected regularly, at intervals consistent with usage, to determine whether cleaning is needed before a dangerous amount of grease has accumulated.

Fire damper

Fire dampers are passive fire protection products used in heating, ventilation, and air conditioning (HVAC) ducts to prevent the spread of fire inside the ductwork through fire-resistance rated walls and floors. Fire/smoke dampers are similar to fire dampers in fire resistance rating, and also prevent the spread of smoke inside the ducts. When a rise in temperature occurs, the fire damper closes, usually activated by a thermal element which melts at temperatures higher than ambient but low enough to indicate the presence of a fire, allowing springs to close the damper blades. Fire dampers can also close following receipt of an electrical signal from a fire alarm system utilising detectors remote from the damper, indicating the sensing of heat or smoke in the building occupied spaces or in the HVAC duct system.

Smoke dampers are passive fire protection products used in air conditioning and ventilation ductwork or installed in physical smoke barriers. This may be done to prevent the spread of smoke from the space of fire origin to other spaces in the same building. A combination of fans and dampers can exhaust smoke from an area while pressurizing the smoke-free areas around the affected area. It may also be used to maintain the required concentration of a fire suppression clean agent in a space, as installed in supply air ducts to restrict the introduction of air into the space, and as installed in return or exhaust air ducts to restrict the depletion of the clean agent from the space. Smoke dampers are usually installed by sheet metal contractors.

Penetrant (mechanical, electrical, or structural)

Penetrants, or penetrating items, are the mechanical, electrical or structural items that pass through an opening in a wall or floor, such as pipes, electrical conduits, ducting, electrical cables and cable trays, or structural steel beams and columns. When these items pierce a wall or floor assembly, they create a space between the penetrant and the surrounding structure, which can become an avenue for the spread of fire between rooms or floors. Modern building codes generally require a service penetration firestop to seal the openings around penetrants, in order to restore the fire-resistance rating of the parent assembly.