NCC 2022 Volume One - Building Code of Australia Class 2 to 9 buildings

22

Specification 22 Smoke-and-heat vents

Specification 22 Smoke-and-heat vents

This Specification contains requirements for automatic smoke-and-heat vents.

To specify requirements for automatic smoke-and-heat vents.

Automaticsmoke-and-heat vents must be installed as a system complying with AS 2665 except that permanently open vents may form part of the smoke/heat venting system provided they comply with the relevant criteria for automatic smoke-and-heat vents in AS 2665.

To nominate AS 2665 as the basis for the installation of automatic smoke-and-heat vents, and specify its limitations.

AS 2665 AS 2665 is adopted as the requirement for the installation of a system of automatic smoke-and-heat vents.

Smoke-and-heat vents 
Smoke-and-heat vents are dependent on the temperature of the hot smoke layer or the presence of smoke for effective operation. The area of the smoke reservoirs is, therefore, limited by AS 2665 to 1500 m2, which is smaller in size than that for mechanical smoke exhaust systems.

It is important to note that the maximum length of a smoke reservoir in a shopping mall is limited to 60 metres due to the distance people travel below a smoke layer while evacuating, having regard to the potential for smoke from a fire in a mall or adjacent specialty shop to flow into more than one reservoir.

AS 2665 requires all smoke-and-heat vents within the same reservoir to operate simultaneously to prevent the formation of stagnant regions leading to excessive cooling and downward mixing of smoke with the clear air below.

In the event of loss of power to operating mechanisms (such as actuators or solenoids), AS 2665 requires smoke-and- heat vents to fail-safe open.

Permanently open vents may be used to replace all or part of the total number of smoke-and-heat vents provided they comply with the relevant parts of AS 2665.

Where a smoke-and-heat vent system is installed to comply with E2D14 to E2D20, then, in addition to thermally released link operation, smoke-and-heat vents must also be initiated by smoke detection complying with S20C6 and S20C8 and arranged in zones to match the smoke reservoirs.

To specify the controls for automatic smoke-and-heat vents.

Smoke-and-heat vents 
Smoke-and-heat vents installed for smoke hazard management purposes in accordance with Part E2 must primarily be initiated on the detection of smoke to enable early operation of the vents.

The smoke detection requirements for smoke exhaust systems are addressed in S20C6 and S20C8. Such smoke detection systems designed to operate smoke-and-heat vents must also activate an occupant warning system.

Override control 
It is important to note that to allow manual control of the smoke exhaust system by the fire brigade, AS 2665 requires an override control to be located in a location compatible with the operating procedures of attending firefighters, such as adjacent to the fire indicator panel.