An explosion occurred at 2.58 am in a wood panel manufacturing plant in a dry wood chip refiner used in the chip sorting and preparation sector. This unit dries, refines and sorts chips (cyclofilter, sifting screen) to supply two 360 m³ silos (A and B). The explosion in the refiner generated a blast that ripped open the cyclofilter, which was protected by vents, and spread to the silos which were also equipped with vents. The explosion was followed by a fire that spread to the associated installations: redler conveyors, vacuum systems, sorters, the refiner silo (28 m³), and silos A and B (about 1/3 full).Immediately following the accident, the spark detection system began injecting water permanently. The silo sprinkling system was triggered by a manual valve and the drier was secured by the shut down of the burners and chip flow. An alarm indication in the control room allowed the site’s firemen to intervene in 10 minutes and also contacted the public fire department. The emergency crews cooled down the silos and the sorters with 5 fire nozzles, checked all of the equipment using a thermal imaging camera and unloaded the silos while being covered with 4 fire nozzles (including 1 on a turnable ladder). As the site’s fire supply had run out, equipment was set up to draw water from a natural water supply.The firefighting water was recovered in a catchpit, then analysed and treated. The chips burned in the fire were disposed of in the plant’s boiler but property damage (refiner, cyclofilter, sifting screen, vents, and the refiner’s suction system) was estimated at 250K euros and the shutdown of the production line for 36 hours resulted in 750K euros in production losses.The site’s accident procedure manual proved efficient. According to the accident report, a metal part in the refiner had broken, causing sparks which caused the refiner to explode. The operator foresees to uncouple the refiner from the rest of the installations; a third-party expert evaluation of the installations, safety systems and intervention procedures; a thermal imaging camera to check the installations before, during and after an accident and an increase in the surface area of the cyclofilter vents (although already in compliance with current standards). Just five days following this accident, a smouldering fire caused a new fire in silo A.

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