AUST Hendry advises under certain conditions, the Building Code of Australia (BCA) requires a stairwell pressurisation system to be installed a in fire isolated stair to ensure in a fire situation the occupants of the building have sufficient time to evacuate before the stairwell becomes untenable due to smoke fumes and heat.
Contractors are required to inspect and report on whether the relief vent is operating satisfactorily as this is part of the essential safety measures reporting system leading to the signing of the Annual Fire Safety Statement.
Hendry has found some relief vents have not operated correctly when the system has been audited. This has caused the fire doors to be extremely difficult to open and therefore possibly exceed the maximum opening door force of 110N allowed by the BCA in the stairwell when the system is activated.
A stairwell pressurisation system must be installed in accordance with AS/NZS 1668.1:2015. The use of ventilation and air-conditioning in buildings – Fire and smoke control in multi-compartment buildings and the building permit. When installed, the stairwell pressurisation system has two operating modes – Normal mode and Fire mode.
In the event of the fire detection system detecting a fire in the buildings, the stairwell pressurisation system will automatically change to Fire mode and activate the system.
AS1851-2012 Routine service of fire protection systems and equipment requires stair pressurisation systems and fire doors to be inspected, tested and maintained (including state specific statutory documents such as Occupancy Permits and Final Certificates) to prescribed levels, including being assessed as part of required System Interface Test under AS1851-2012.
The following illustration depicts stairwell pressurisation relief in Class 2 or 3 buildings.