In a surface treatment plant, the motor of a filter on a nickel-plating bath had burnt out, and its PVC housing caught fire. Two sprinkler heads were triggered at 7:49 p.m. Only the smoke remained by the time the firefighters and the operator arrived at the scene. The sprinklers’ water supply was shut off at 8:25 p.m., the smoke vents were opened and the fans that had been switched off automatically when the sprinklers started, were restarted. The 4 m³ of water used to put out the fire were directed toward the site’s retaining basin.
Production was stopped for 1 or 2 days, the time necessary to:
- clean up the area;
- check the electrical cabinets that may have been water damaged;
- check that water had not gotten on the bridge of the bath;
- replace the 2 sprinkler heads.
The operator came up with 2 assumptions following analysis of the accident:
- abnormal heating due to bearing wear. However, a significant amount of noise would have been heard, which was not the case;
- nickel salts, sometimes present along the body, may have infiltrated the motor and caused it to overheat.
The operator replaced the filters so that the part surrounding the motor was non-flammable. Seal verification procedures at the start and end of shifts were formalised in writing, and the operator now foresees the formalisation of an overall verification of the installation during filter changes every two weeks.
The alert chain worked well. The weekly exercises and tests performed on the sprinkler system proved advantageous.