In industrial environments, special ambient conditions are a daily occurrence. Production and processing plants of the heavy industry are frequently characterised by high dust concentrations and extreme air humidity. Moreover, exhaust gases being dispersed into the air are produced by conveyor vehicles and machines. Depending on the processed materials natural gas emissions or aggressive vapours aggravate this situation. These factors also prevail in storehouses, silos and conveying facilities in addition to the building conditions which are already sufficiently difficult.
Up to now, it was almost impossible to ensure reliable fire detection under such adverse conditions: conventional smoke detectors trigger false alarms in case of dust and moisture or stop operating due to faults. If the ambient air contains polluted moisture, classical aspirating smoke detectors get chocked in the course of time even if purge air is used.
Another aspect is the fact that there are different kinds of fire showing different behaviour also in their formation phase, for instance, usually, no visible smoke is generated in case of smouldering of coal dust. The same applies to metal dusts and hidden smouldering in grain or wood pellet accumulations.
An effective monitoring of even such industrial areas is ensured by the detectors of the Advanced Discovery System or, in short form, ADICOS.
In case of smouldering fires, an array of gas sensors which is insensitive to dust and water detects a characteristic pattern of several fire gases. Different detector versions are available for the use in buildings with different degrees of exposure and for different detection tasks.
Depending on the detector type, combinations of durable semiconductor gas sensors for hydrogen, carbon monoxide, phenolic hydrocarbons or nitrogen oxides are used. In case of extraordinary boundary conditions, the alerting settings can be easily adjusted via a Service Bus. The purpose of that is to particularly consider factors like the buildings’ geometry or dilution by airflow.
For example, the requirements for the sensitive detection of fires in large rooms are different from the ones of transported goods monitoring, e.g. in conveyor belt systems.
In storehouses where, amongst others, vehicles with combustion engine are used, a further distinction has to be made between fire gases and combustion exhaust gases. The combination with a special fire alarm control panel allows the processing of further tasks, e.g. a daytime-dependant switching between different detection patterns which, for instance, mask out exhaust gases in the daytime.
In Dust-Ex-Areas up to zone 20, special approved detectors with suitable casings can be used. The required dust-tightness is obtained by using sintered metal filters detaining dust and water but allowing fire gases to pass through.
Typical fields of application are corn mills and grain silos, silos for powders and dusts, biomass storehouses (wood pallets and straw pellets) or production fields in the wood-working industry.