Heat and smoke vent
Encyclopedia
Heat and Smoke Vents are installed in buildings as an active fire protection
Active fire protection
Active fire protection is an integral part of fire protection. AFP is characterised by items and/or systems, which require a certain amount of motion and response in order to work, contrary to passive fire protection.-Fire suppression:...

 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".

Regulatory requirements

Heat and smoke vents are typically installed in buildings for the following reasons:
  • Storage occupancies - The heat release rate from high piled storage commodities is expected to be very high. In such cases, it is considered by some fire protection professionals desirable to vent the heat from the building if the temperatures in the building reaches sufficiently high levels to endanger the structural stability of the roof system. Smoke venting is also considered to provide a minor benefit to increase the visibility in the interior space to facilitate manual fire fighting
    Fire fighting
    Firefighting is the act of extinguishing fires. A firefighter fights fires to prevent loss of life, and/or destruction of property and the environment...

     efforts for a limited period of time.

The use of vents in sprinklered buildings has been controversial over the last 25 years. Vent technology and sprinkler technology were developed independently of one another. Their interaction as beneficial technologies working together has not been successfully demonstrated. Many fire protection professionals are concerned that vents may cause sprinkler systems to fail to control a fire.
  • Large internal volume spaces – Venting smoke from large spaces which regularly contain large numbers of people, such as malls and atria .

Types

Automatic heat and smoke vents are available commercially in two general categories:
  • Mechanically opened vent, powered by springs, pneumatic actuator, or electric motor.

  • Drop-out vent – constructed of plastic which shrinks in the presence of heat (i.e., drop-out panel).

Interaction with automatic fire sprinklers

The majority of guidance available for design of heat and smoke building vents installed in buildings is restricted to nonsprinklered, single-story buildings. This is partly a historical consequence of the installation of heat and smoke vents following the General Motors, Livonia, MI major fire in a nonsprinklered manufacturing facility which effectively stopped the production of automatic transmissions for all of GM. Vents were also installed in storage buildings prior to the installation of fire sprinklers as a widespread warehousing industry practice. Subsequent to sprinklers being installed in storage buildings as a widespread practice, there has been a lack of consensus regarding the nature of the interaction of sprinklers and automatic heat and smoke vents. This lack of consensus continues to this day.

Automatic heat and smoke vents are required by model building code
Model building code
A model building code is a building code that is developed and maintained by a standards organization independent of the jurisdiction responsible for enacting the building code. A local government can choose to adopt a model building code as their own. This saves local governments the expense and...

s in large, single-story factory and storage facilities in conjunction with control mode fire sprinkler
Fire sprinkler
A fire sprinkler system is an active fire protection measure, consisting of a water supply system, providing adequate pressure and flowrate to a water distribution piping system, onto which fire sprinklers are connected...

s, but are not permitted to be installed in conjunction with suppression mode, e.g., ESFR, fire sprinklers unless the vents are manually operated or have an operating mechanism with a thermal rating of not less than 360°F. due to fear of overwhelming the sprinkler system and destroying the building. .

See also

  • Smoke exhaust ductwork
    Smoke exhaust ductwork
    Smoke Exhaust Ductwork is typically protected via passive fire protection means, subject to fire testing 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.-Means of...

  • Pressurisation ductwork
    Pressurisation ductwork
    Pressurisation ductwork is a passive fire protection system. It is used to supply a steady stream of fresh air to any area of refuge or designated emergency evacuation or egress route.-Purpose:...

  • Grease duct
    Grease duct
    A grease duct is a duct that is specifically designed to vent grease-laden vapors from commercial cooking equipment such as stoves, pizza ovens, 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...

  • Passive fire protection
    Passive fire protection
    Passive fire protection is an integral component of the three components of structural fire protection and fire safety in a building. PFP attempts to contain fires or slow the spread, through use of fire-resistant walls, floors, and doors...

  • Active fire protection
    Active fire protection
    Active fire protection is an integral part of fire protection. AFP is characterised by items and/or systems, which require a certain amount of motion and response in order to work, contrary to passive fire protection.-Fire suppression:...

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