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For further information, please contact:
Raimo Perttunen
+358 20 442 3536
| SMIA total solution consists of a fan unit with integrated smoke hatches, a control panel and a control unit. |
| The aim of pressurisation design is to make it possible to create a positive pressure within the stairwell, 50 Pa higher than the pressure in the adjacent spaces, in the event of a fire in an apartment. |
| If the door of the apartment on fire opens, the system automatically raises the air flow so that air flows through the door to the apartment at a velocity of 0.75 m/s. |
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The amended technical specifications for buildings that came into effect in July 2009 have further increased the smoke prevention requirements in vertical escape routes. The last change of similar scale was the introduction in 2002 of the requirement that door closing be to at least EI 30 (and therefore with self-closing devices) for entrances to stairwells in buildings of medium height, as well as in many low ones. The obligation to use smoke prevention devices in stairwells ensuring the relevant pressurisation has now been extended to all high-rise buildings, and, with the exception of residential buildings and industrial premises, to all taller buildings as well.
In some countries the pressurisation method is used even more extensively. In Finland, where until now the annual number of fatalities per million inhabitants has been half as high as for example Polands, a government programme has been adopted. The Finnish programme aims to reduce the number of fatalities to a quarter within five years, by a number of measures, including applying this method in residential buildings of medium height and in some low-builds as well. Fläkt Woods Smoke Master SMIA and Smoke Master SMPA systems are used to achieve this.
The systems comply with the requirements of Standard EN 12101-6: “Smoke and heat control systems – Part 6: Specification for pressure differential systems – Kits”. Prior to design, it is essential that the class of the system be specified, based on the type of area in use or type of building protected. The basis for classifying buildings is their intended purpose, but application of this criterion on its own leads to over-simplification. The class may be upgraded based on an evacuation plan, or the size of the building, for instance. Using various data, the system designer should specify the class of the building in consultation with a fire safety expert.
A pressurisation installation for limiting the dissipation of smoke should be of system-type and consist of modules (including an aeration/smoke extraction fan and control module) supplied by a single manufacturer and constituting a complete integral system. The following features characterise a good system:
- The system does not merely meet the defined norms and standards, but has also been thoroughly tested, both under laboratory conditions and in the field.
- The system works in stages – it not only prevents smoke entering the stairwell (blower function at the stage where a fire is discovered and evacuation takes place) but also enables its removal (smoke extraction function at the stage where the fire service intervenes).
- The system can be tailored to a specified type and size of building, which not only means that it can be tailored to the design requirements, but also ensures optimisation of costs.
The remaining installation elements (e.g., ducts) should be of the very best quality, so that they can guarantee that the required parameters will be maintained in any situation.
SMPA System (for use in class A, C and E buildings):
For class A buildings (where evacuation is envisaged solely from locations where fire is an immediate hazard), the following criteria must be met:
- Pressure criterion (for closed doors, at the stage of discovery of the fire): the pressure differential between the protected area and the area on fire ΔP = +50 Pa (ΔPmax = +60 Pa – if pressurisation is greater, it may prevent evacuation doors from opening)
- Air speed criterion (for open door(s), at the evacuation stage): the speed of the air exiting through open doors on the level/floor on fire V = 0.75 m/s
For class C buildings (where rapid one-off evacuation of all people present is envisaged), the following criteria must be met:
- Pressure criterion (for closed doors, at the stage of discovery of the fire): the pressure differential between the protected area and the area on fire ΔP = +50 Pa (ΔPmax = +60 Pa – if pressurisation is greater, it may prevent evacuation doors from opening)
- Pressure criterion (evacuation stage): the pressure differential between the protected area and the area on fire ΔP = +10 Pa with closed doors on the level/floor on fire and entrance doors open
- Air speed criterion (for open doors, at the evacuation stage): the speed of the air exiting through open doors on the level/floor on fire V = 0.75 m/s
For class E buildings (where evacuation in stages is envisaged), the following criteria must be met:
- Pressure criterion (for closed doors, at the stage of discovery of the fire): the pressure differential between the protected area and the area on fire ΔP = +50 Pa (ΔPmax = +60 Pa – if pressurisation is greater, it may prevent evacuation doors from opening)
- Pressure criterion (evacuation stage): the pressure differential between the protected area and the area on fire ΔP = +10 Pa with doors closed on the level/floor on fire and entrance doors open and two sets of other doors open
- Air speed criterion (for open doors, at the evacuation stage): the speed of the air exiting through open doors on the level/floor on fire V = 0.75 m/s with entrance doors open and other doors open
A comprehensive solution:
The comprehensive solution represented by the SMPA system consists of an integrated blower hatch, equipped with actuators, a fan module, a control panel and a control module.
Pressurisation:
For the pressurisation system to operate correctly, in the area where the fire started a vent should be installed that opens automatically and which is actuated once the smoke detector is triggered, allowing gases and smoke from the fire to escape outside. The vent may, for instance, be a window or the flap of a smoke extraction duct. Of key importance is the minimum aperture section of the vent (open area), which should not be less than 0.5 m². Vents fitted to the outer shell of a building should always be designed in close cooperation with the architect and fire safety expert, and this issue should be dealt with as early as possible, i.e. no later than the initial meetings relating to design realisation of the building. The control module (i.e. the smoke extraction control box) of the SMPA system requires a control signal received from the protected areas via a floating normally open contact. Comprehensive solutions that take into account the ventilation of the areas, and which include the necessary actuators, smoke detectors and control modules, make the design process and installation of the system easier.
Application:
Thanks to its compact design and modest dimensions, the SMPA module is ideally suited to both new builds and buildings that are in the process of being converted or renovated.
The SMPA is available in 3 sizes. The fan module can be installed in both the top and the bottom half of the stairwell.
Fig. 1. Fan module of the SMPA system from Fläkt Woods
SMIA System (for use in class A buildings):
For class A buildings (where evacuation is envisaged solely from locations where fire is an immediate hazard), the following criteria must be met:
- Pressure criterion (for closed doors, at the stage of discovery of the fire): the pressure differential between the protected area and the area on fire ΔP = +50 Pa (ΔPmax = +60 Pa – if pressurisation is greater, it may prevent evacuation doors from opening)
- Air speed criterion (for open doors, at the evacuation stage): the speed of the air exiting through open doors on the level/floor on fire V = 0.75 m/s
A comprehensive solution:
The comprehensive solution represented by the SMIA system consists of an integrated blower/extractor hatch-door, equipped with actuators, a fan module, a control panel and a control module (smoke extraction control unit).
Pressurisation:
The system is designed to maintain pressurisation in the event of a fire and to remove smoke from stairwells in residential buildings. Pressurisation of the stairwell should already occur in the initial stages of a fire. The SMIA system commences pressurisation within 20 seconds from the moment the smoke detectors are triggered. In urban areas, the time required for the fire service to arrive on the scene of a fire is usually between four and ten minutes. The firemen can then use the SMIA system’s control panel to select the pressurisation/smoke extraction options that are most appropriate for the situation that obtains.
The SMIA system has been designed to fully comply with the requirements specified in Standard EN 12101-6 for class A systems (Finnish RIL 232-2007). In the event of a fire the pressure in a stairwell should be around 50 Pa higher than in its adjacent areas. The blower fan for pressurisation is activated by a smoke detector located in the apartment where the fire started. The same smoke detector should also automatically control opening of a vent in the same apartment. The minimum aperture section of the vent (free area) should be 0.5 m². When the door to the apartment that is on fire opens, the system automatically increases the airflow so that it flows through the door into the area in question at a speed of 0.75 m/s.
Smoke extraction:
The smoke extraction fan is CE-marked with an F400 rating (this rating guarantees that the fan will work continuously for two hours at extracted smoke temperatures up to 400 °C). The SMIA system ensures a constant volume flow rate of 2.0 m³/s for the extracted gases. Smoke extraction is activated by the fire service, using the control panel (smoke extraction control unit). Once the smoke extraction process starts, the pressurisation process is automatically halted. During extinguishing operations, the firemen decide for themselves whether they want to make use of pressurisation or not.
Application:
Thanks to its modest dimensions, the SMIA system fan module is ideally suited for use both in new builds and in buildings that are in the process of being converted or renovated. To simplify the overall system design, one size of fan unit is used, which has fixed air extraction parameters, suitable for use in stairwells of varying heights.
Tests and investigations:
The SMIA system has been subjected to comprehensive technical investigations at the VTT Technical Research Centre in Finland, as well as full-scale tests in the field. Full-scale tests in an actual fire have been conducted in Helsinki in a residential building due for demolition.
The main results of the tests that were carried out are as follows:
- With fire doors closed, overpressure of +50 Pa is obtained after a few seconds throughout the entire height of the stairwell – air speed V = 0 and the smoke does not escape beyond the apartment that is on fire.
- Airflow speed in an open door quickly reaches a level of 0.75 m/s – a small amount of smoke that escapes under the upper edge of the door is returned to the apartment. After ten seconds or so the requisite conditions are obtained.
- A gravitational opening (e.g., a window) with an automatic opening device is needed to allow the gases from the fire to escape, as well as some device for ensuring the door(s) to the area close (automatic closing device, with appropriate training for users, as required).
Fig. 2. Fan module of the SMIA system from Fläkt Woods
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