A pressurisation system consists of three main components: Supply Air (where air is injected into the area that is to be protected), Pressure Relief (to avoid overpressure when doors are closed) and Air Release (air and smoke is released from the adjoining fire area). Combining these elements creates a positive pressure difference that prevents lobbies and staircases from filling up with smoke.
Accommodation air release for the pressurisation system shall be provided by means of a natural ventilation shaft.
The shaft shall be of fire resistant construction and shall be substantially straight and vertical, terminating in a Colt Seefire ventilator, type LS/.. to provide weatherproof closure when the system is not in use.
The shaft shall have a minimum cross sectional area sized to handle the design flow rate from the pressurisation system onto the fire floor under open door conditions at a maximum velocity of 2m/s.
At each storey of the accommodation an automatically controlled fire rated smoke damper / fire door with a cross sectional area at least equal to that of the shaft shall be connected to the shaft, providing an air flow path from the accommodation to the shaft. A low resistance decorative grille or louvre shall be provided in front of each damper. / The fire doors and any guarding necessary to avoid risk of falls through them will be provided by others. Operation of the doors shall be by the Colt Doorman actuator system.
Power to the system shall be provided from a maintained supply and all cables shall be fire resistant. The maintained supply (by others) shall terminate at a changeover panel close to the accommodation air release control panel location. All wiring from this point shall be the responsibility of the system supplier. / The system shall operate at 24 / 12 Volts and shall incorporate a battery back up system. Mains power (by others) shall be provided close to the accommodation air release control panel location. All wiring from this point shall be the responsibility of the system supplier.
In automatic mode, the system shall be activated by the building fire detection system / a dedicated fire detection system incorporating smoke detectors in the accommodation adjacent to each door into the stairwell protected shaft and supplied as part of the accommodation air release system. The detection system shall have the capability of distinguishing on which storey the fire occurs and providing a dedicated output for each storey.
Under fire conditions the Seefire ventilator and the damper / door on the fire floor shall open. The dampers / doors on all other storeys shall remain closed. The Colt OPV addressable control system shall be used to provide this facility.
The control panel or a mimic panel for fire service use shall be mounted in a position accessible to and agreed with the fire service and shall incorporate status indication and manual override for fire service use. The control panel or mimic panel shall be either combined with the panel for the pressurisation system or shall be mounted adjacent to it.
The design, manufacture, installation,wiring and commissioning of the complete system shall be carried out by one specialist company and their approved sub-contractors. The specialist company shall also provide the pressurisation system and shall be responsible for gaining Building Control approval for the complete pressurisation and accommodation air release system.
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