SMOKE ANGEL PRESSURISATION & VENTILATION SYSTEM
INTERACTIVE SPECIAL PROJECTS - FIRE ENGINEERING ASSOCIATES - FLÄKTWOODS
TECHNICAL SUBMISSION
Overview
'It is probable that some smoke will get into the common corridor or lobby from a fire in a flat, if only because the entrance door will be open when the occupants escape. There should therefore be some means of ventilating the common corridors/lobbies to control smoke and to protect the common stairs. This offers additional protection to that provided by the fire doors to the stair. (The ventilation also affords some protection to the corridors/lobbies).'
This paragraph from The Building Regulations, Approved Document B, which was re-worded from previous editions of the Approved Document, due to work undertaken by the Building Research Establishment on behalf of the Department of Communities and Local Government (DCLG), acknowledges that smoke logging of the corridor could occur and that the key criteria is to protect the staircase.
This is covered within BD2410 – 'Smoke Ventilation of Common Access Areas of Flats and Maisonettes.'
AD-B states with regard to the smoke control measures 'This can be achieved by natural means in accordance with paragraph 2.26 or by means of mechanical ventilation as described in paragraph 2.27.'
Section 2.27 states
'As an alternative to the natural ventilation provisions in paragraph 2.26, mechanical ventilation to the stair and/or corridor/lobby may be provided to protect the staircase from smoke.
Guidance on the design of smoke control system using pressure differentials is available in
BS EN 12101-6:2005.’ This standard was previously known as BS5588 Part 4.
Proposals
The most effective form of smoke control is provided by a pressurisation system. This raises the pressure within the staircase which then pressurises the lobbies with air then moving towards the accommodation.
All other forms of smoke control, be it by natural means or mechanical extract leads to smoke spreading into the escape route and stairs or being forced into the escape route or stairs by the action of the system when in operation.
This is not ideal from any perspective.
As stairs are used for means of escape purposes and for fire fighting, the smoke control system must be effective and simple in operation with design principles in accordance with the British Standards. Air would be introduced to the head of the staircase only which would provide a pressure level of 50Pa within the staircase (it should be noted that Fire Research Note No. 958 'Pressurisation of Escape Routes in Buildings' – the predecessor to the BS states that for a building height of less than 25m that a pressure level of 25 Pa is acceptable).
As the lobbies are simple lobbies, air will leak into the lobbies to raise their pressure with respect to the accommodation and then pass to the corridors and to the apartments.
The secondary pressurisation of the lobbies via leakage from the staircase will assist or totally prevent smoke movement to the lobbies as the maximum fire pressure developed by a fully developed fire within a residential situation will only be 8Pa.
Therefore, the principles of the system are far superior to any natural or mechanical extract system which allows direct smoke movement into the lobbies and only try to prevent smoke movement into the staircase, as opposed to preventing it.
SMOKE ANGEL PRESSURISATION & VENTILATION SYSTEM
'the only accepted method of smoke control where the objective is to prevent smoke movement into the escape routes in the first place as opposed to allowing smoke movement into the protected spaces and naturally ventilating or mechanically extracting from them.
The air pressure levels of the spaces are increased over the surrounding fire room area to prevent smoke spread instead of promoting smoke movement.
And if the protected spaces stay clear of smoke for occupants to escape, they also enhance fire service access.
Pressurisation is used worldwide as an active form of smoke control and can be applied all building heights although most commonly used on buildings with over 8 - 10 storeys where natural ventilation systems for many reasons are unreliable.
DUAL PURPOSE
The Smoke Angel pressurisation system is automatically activated with operation normally initiated by smoke detectors located within the common corridors or lobbies.
The staircase is pressurized with secondary pressurisation of the surrounding areas during the means of escape phase.
Upon fire service arrival, if required, the supply fan can be reversed for smoke clearance purposes as the Smoke Angel is temperature rated for operation at 300 degrees C for 2 hours.
The Smoke Angel system is suitable for both existing buildings and new to provide a highly effective form of smoke control.
SYSTEM OVERVIEW
The Smoke Angel system is an all-inclusive solution for the stairwell pressurisation and smoke clearance in residential apartment buildings of various heights and layouts with potential effective secondary pressurisation being provided to lobby areas.
The Smoke Angel Systems have been designed and components manufactured to comply with the European Standard EN 12101-6:2005 which has the status of a British Standard. The fans conform to EN12101 – Part 3 and are CE marked and F300 rated.
The control of the system is provided by a dedicated control panel interlinked to smoke detectors and pressure sensors. One single phase power supply is required to the control panel with the mandatory second power supply provided through the intergrated control panel UPS and inverter unit.
