Forgotten parts of a building
Roof structures are repeatedly the scene of the outbreaks of fires: Dust and moisture encourage the formation of leakage currents on poorly executed electrical installations which can kindle a smouldering fire.
Flying sparks during a stormy wind find their way into the roof structure, a stroke of lightning can start a fire in the roof timbers. Unfortunately, these parts of a building are often not included in the fire protection concept so that any fire breaking out will not be discovered until it has already spread to protected areas.
Point detectors at their physical limits
However, as these parts of buildings are unheated, difficulties occur with fire protection. The use of conventional point detectors here reach their physical limits. High wind speeds set off false alarms in ionisation smoke detectors.
Dust and insects impair the optical smoke detector.
The greatest problem, however, is moisture and the formation of condensation
on the detector as a result
of the fluctuating temperatures. The function of the detector is impaired.
Heated detectors are one approach towards finding a solution, but not
a satisfactory one as the cushion of warmth formed by the heating keeps
any possible smoke away from the smoke detector, thus switching of the
detector itself, quite apart from the other problems with point detectors
already mentioned above.
Aspiration smoke detection system as a solution
The ASD aspiration smoke detection system is the best possible solution here, as in many other cases. By separating the monitored area from the place of detection, the evaluation unit can be installed in adry, protected location. In addition, particularly in the case of inaccessible roof structures, for example in churches, a further positive effect is achieved: The monitored area no longer has to be made accessible for maintenance works as these tasks are all carried out on the readily accessible evaluation unit.
In any installation in practice, it must be borne in mind that condensation can form in the suction tube as a result of the differences in temperature between the suction holes and the evaluation unit and this must be allowed to drain away in an appropriate manner. This is generally implemented by using a «water bag».
In sectors which are much exposed to weather conditions (snow, fog, ice) and, for example, on timber bridges, the linear heat differential detector SecuriSens® TRANSAFE ADW 511 is used instead of the aspiration smoke detection system, it being ideal for such applications thanks to its extremely robust design.
«Franziskanerkirche» Solothurn
Example of an unheated section of a roof structure
References (extract)
– Church on the «Staufberg», AG/CH
– Ludwigsburg Palace/D
– «Franziskanerkirche», Solothurn/CH
– Reformed church Küsnacht, ZH/CH
Exemplos de aplicações para o sistema de aspiração de fumaça ASD:
Installation monitoring in EDP systems and control cabinets
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