An automatic fail-safe device is designed to ensure that doors, particularly those related to exit pathways and evacuation routes, automatically unlock when a fire alarm is triggered. This mechanism is vital to prevent the trapping of occupants inside the building, facilitating the safe and quick evacuation of all individuals.
These devices operate by integrating the door locking systems with the building's fire detection and alarm system. When a fire is detected and the alarm sounds, a signal is sent to the door locks to disengage, thus allowing free passage. This feature is especially critical in buildings with high occupancy rates, such as hospitals, hotels, and office buildings where quick evacuation is paramount.
BCA Part D2 emphasizes that all doorways in the path of required exits or forming part of required exits from any part of a building must be readily openable without a key from the side that faces a person seeking egress, in the direction of egress. An automatic fail-safe device provides this exact functionality, unlocking doors immediately when a fire alarm is triggered.
Furthermore, these devices are typically designed to fail "safe". This means that if there's a power loss or the device malfunctions, the doors will default to an unlocked state, hence the term "fail-safe".
The design and installation of these automatic fail-safe devices need to be in accordance with AS 1670.1 (Australian Standard for Fire Detection, Warning, Control and Intercom Systems - System Design, Installation, and Commissioning), which sets out the specific requirements for fire detection and alarm systems, including interfacing with other systems like door mechanisms.
Overall, automatic fail-safe devices play a significant role in improving the safety and survivability of occupants in a building during fire emergencies. It is crucial that these devices are regularly tested and maintained to ensure they perform as expected when needed and that unexpected issues don't complicate submission of your Annual Fire Safety Statement.
The NCC requires automatic fail-safe devices for doors in required exits that don't meet certain conditions, such as automatic sliding doors. The National Construction Code of Australia outlines the specific requirements for door latches in required exits or paths leading to required exits. These provisions ensure safety by enabling easy egress (exit) in emergencies. Here's a breakdown:
(1) Doors must be easily openable without a key from the inside:(a) By a single downward hand action on a device positioned 900 mm - 1.1 m from the floor, with specific provisions for accessibility:(i) Designed for people who cannot grip.(ii) Clearance between the handle and door of 35-45 mm.(b) By a single pushing action on a device located 900 mm - 1.2 m from the floor.
(2) If the latch operation device is not on the door itself:(a) Manual controls must be a certain size, distance, and location depending on the type of door.(b) Must be identified with Braille and tactile signage.
(3) Exceptions to these rules:
(a) Doors serving vaults, sanitary compartments, etc.
(b) Doors in specific sole-occupancy units.
(c) Doors complying with specific Australian Government Security Zones or secure parts of certain facilities.
(d) Doors fitted with a fail-safe device that unlocks in the presence of smoke or other triggers.
(e) Doors in Class 9a or 9c buildings with certain provisions.
(4) Doors referred to in (3)(c) must be immediately unlockable by specific means.
(5) Additional specific requirements for Class 9b buildings (excluding schools, early childhood centers, or religious buildings) accommodating more than 100 persons.
The detailed specifications ensure that doors are designed in such a way that they can be easily and quickly opened in an emergency, such as a fire, without the need for a key or specialized knowledge. The standards take into account a range of different building classes and uses and make provisions for accessibility. They also make special accommodations for certain types of buildings, such as banks or secure government facilities, where additional security considerations might be necessary.
We provide a general breakdown above to make the somewhat hard-to-read NCC more intuitive, but it can lose context or detail in the process. The specific section of the NCC that applies is D3D26. The full extract follows:
D3D26 Operation of latch [2019: D2.21]
(1) A door in a required exit, forming part of a required exit or in the path of travel to a required exit must be readily openable without a key from the side that faces a person seeking egress, by—
(a) a single hand downward action on a single device which is located between 900 mm and 1.1 m from the floor and if serving an area required to be accessible by Part D4—
(i) be such that the hand of a person who cannot grip will not slip from the handle during the operation of the latch; and
(ii) have a clearance between the handle and the back plate or door face at the centre grip section of the handle of not less than 35 mm and not more than 45 mm; or
(b) a single hand pushing action on a single device which is located between 900 mm and 1.2 m from the floor.
(2) Where the latch operation device referred to in (1)(b) is not located on the door leaf itself—
(a) manual controls to power-operated doors must be at least 25 mm wide, proud of the surrounding surface and located— (i) not less than 500 mm from an internal corner; and
(ii) for a hinged door, between 1 m and 2 m from the door leaf in any position; and
(iii) for a sliding door, within 2 m of the doorway and clear of a surface mounted door in the open position; and
(b) braille and tactile signage complying with S15C3 and S15C6 must identify the latch operation device.
(3) The requirements of (1) and (2) do not apply to a door that—
(a) serves a vault, strong-room, sanitary compartment, or the like; or
(b) serves only, or is within—
(i) a sole-occupancy unit in a Class 2 building or a Class 4 part of a building; or
(ii) a sole-occupancy unit in a Class 3 building (other than an entry door to a sole-occupancy unit of a boarding house, guest house, hostel, lodging house or backpacker accommodation); or a sole-occupancy unit with a floor area not more than 200 m2
(iii) in a Class 5, 6, 7 or 8 building; or
(iv) a space which is otherwise inaccessible to persons at all times when the door is locked; or
(c) complies with (4) and serves—
(i) Australian Government Security Zones 4 or 5; or
(ii) the secure parts of a bank, detention centre, mental health facility, early childhood centre or the like; or
(d) is fitted with a fail-safe device which automatically unlocks the door upon the activation of any sprinkler system (other than a FPAA101D system) complying with Specification 17 or smoke, or any other detector system deemed suitable in accordance with AS 1670.1 installed throughout the building, and is readily openable when unlocked; or
(e) is in a Class 9a or 9c building and—
(i) is one leaf of a two-leaf door complying with D2D9(a) or D2D9(d) provided that it is not held closed by a locking mechanism and is readily openable; and
(ii) the door is not required to be a fire door or smoke door.
(4) A door referred to in (3)(c) must be able to be immediately unlocked—
(a) by operating a fail-safe control switch, not contained within a protective enclosure, to actuate a device to unlock the door; or
(b) by hand by a person or persons, specifically nominated by the owner, properly instructed as to the duties and responsibilities involved and available at all times when the building is lawfully occupied so that persons in the building or part may immediately escape if there is a fire.
(5) The requirements of (1) and (2) do not apply in a Class 9b building (other than a school, an early childhood centre or a building used for religious purposes) to a door in a required exit, forming part of a required exit or in the path of travel to a required exit serving a storey or room accommodating more than 100 persons, determined in accordance with D2D18, in which case it must be readily openable—
(a) without a key from the side that faces a person seeking egress; and
(b) by a single hand pushing action on a single device such as a panic bar located between 900 mm and 1.2 m from the floor; and
(c) where a two-leaf door is fitted, the provisions of (a) and (b) need only apply to one door leaf if the appropriate requirements of D2D9 are satisfied by the opening of that one leaf.