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.
Stairwell pressurisation system, to class A/B/C/D/E to BS 5588-4:1998 as amended or BS EN 12101-6:2005.
The system shall provide pressurisation to the stairwell only / and lobbies / and lift shaft / , lobbies and lift shaft. Air flow rates shall be calculated assuming tight / average / loose construction of the protected shaft.
The system shall incorporate duty and standby fans with automatic change over, mounted on the roof / in a separate plant room / in a general plant room / at ground level. The fans shall supply air through a duct system to the stairs and lobbies / and lift shaft / , lobbies and lift shaft. Separate duct risers shall be provided for each. Air supply grilles shall be provided every 3 storeys in the stairwell and to every lobby / and to the top / bottom of the lift shaft. Ducts shall be fire resistant where they pass within the building but outside the protected shaft or through a general plant room. Ducts shall otherwise comply with the requirements of DW/144.
Sufficient volume control dampers shall be provided to allow correct balancing and control of overall air flow rate on commissioning.
If the supply air intake is at roof level then two air intakes shall be provided, at least 5m apart and facing onto different elevations. Smoke detection in the duct shall close one intake if it becomes affected by smoke.
Air intakes shall be provided with Colt Seefire ventilators, type LS/ to provide weatherproof closure when the system is not in use.
Overpressure relief in the stairwell shall be provided by a wall or roof mounted pressure relief damper behind a Colt Seefire ventilator, type LS/, to provide weatherproof closure when the system is not in use.
Power to the system shall be provided from a maintained supply and cables shall be fire resistant where they pass outside the protected shaft. The maintained supply (by others) shall terminate at a changeover panel close to the pressurisation system control panel location / terminate at the pressurisation system control panel. All wiring from this point shall be the responsibility of the pressurisation 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 protected shaft and supplied as part of the pressurisation system.
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 design shall take account of the available accommodation air release to be provided by:
A full design report including all calculations shall be provided for submission to Building Control prior to installation.
The design, manufacture, installation, wiring and commissioning of the complete system, including associated ductwork, shall be carried out by one specialist company and their approved sub-contractors. The specialist company shall be responsible for demonstrating and gaining Building Control approval for the pressurisation system. The specialist company shall also provide the accommodation air release system.
The specialist company shall be a BSI registered firm for the design, manufacture, installation and commissioning of smoke control systems in accordance with ISO 9000. Proof of certification shall be provided with tender submission.
The system will require annual maintenance and testing. The supplier shall include in the tender for a service visit and system test to be carried out one year after system hand over.
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