In a building at a ball bearing plant, fire broke out at 1:30 am on a grinding machine using straight cutting oil. Personnel intervened with powder and CO2 extinguishers, yet were unable to suppress the flames; emergency services were notified. The 35 fire-fighters deployed contained the blaze using 4 variable flow nozzles at 2:40 am; the fire was completely extinguished at 6 am. The smoke had overcome 9 employees, 2 of whom were hospitalised for testing. Five of the 40 workshop production machines were destroyed or severely damaged; the building roof was perforated at the spot where the fire erupted. The water used to cool the roof flowed into the facility’s stormwater network and extinction water (15-20 m³) sprayed inside the building was collected and confined in a centralized machining fluid unit located beneath the workshop; the cooling and extinction water was treated as waste liquids. The cause of the fire remained unknown.
The hypothesis of a fire outbreak during machining of a part on the grinding machine (i.e. hotspot with oil ignition) as a result of excessive metal removal could not be established. Similarly, the possible malfunction of the autonomous CO2 extinction system equipping production machinery due to fire hazard, device tri triggered by a flame or heat detector or by a pushbutton, was not demonstrated.
The machine supplier who also maintains, conducted an investigation. The Classified Facilities Inspectorate requested the operator to implement monitoring and intervention measures in the event of an incident involving production tools that make use of straight cutting oils and moreover to draft a procedure for activating network plugs so as to confine any eventual fire extinction water onsite.