Pollution
Humain
Environnement
Economique

In a panel manufacturing plant, at 4 pm a wood dryer technician noticed glowing fibres falling from the wood chip sorting system and raised the alarm with the shift manager. Soon after, a blast in the conveyor activated the opening of the dust collection cyclone vents. The site’s emergency response team, assisted by external firefighters, contained the fire within 30 min. The accident destroyed 2 rubber conveyor belts, the combustion of which generated a substantial amount of black smoke. The activity was shut down for 34 hours for repair, causing operating losses of 20,000 euros; material damage was estimated at 40,000 euros. After 3.17 pm the technician noticed abnormal temperature variations in the dryer but he did not realise that a fire had started and had not been able to implement the measures stipulated for that purpose. Several equipment faults were highlighted. The dryer’s automatic fire extinguishing system was in fact activated, but did not put out the fire completely, then the dryer’s internal alarm was not activated (dryer’s detection box not connected to the alarm central unit). The dryer’s outlet detection system had failed, which prevented activation of the associated audible alarm and automatic deluge extinguishing system. The combustion of wood fibres then restarted on contact with the air in the conveyor belt; this was hooded to improve its isolation from the outside, which also hindered the discovery of the fire. Finally, once the fire had been declared, the technician who had no access to the fire extinguishing system’s programming was unable to activate it manually because it was locked in automatic mode. Following the accident, the operator integrated the revision of faulty alarms into the twice monthly periodic inspections and installed a manual fire extinguishing system in the conveyor circuits.