In a chemical plant, a fire broke out at around 2:15 p.m. on a single filter cartridge installed on a hose, during the transfer of 400 kg of MTBE (a highly flammable solvent, PE = -28 °C) from a container to a production reactor. The operator noted flames on the single cartridge module while the transfer was only half completed. He was able to put out the flames with a fire extinguisher and increased the flow of nitrogen to the reactor to prevent the flames from spreading. He noted the presence of a puddle of MTBE on the floor and a leak on the single cartridge module. The cartridge and the transfer hose were damaged.

According to the operator, the leak on the single-cartridge module was due to a missing gasket, which resulted in the release of flammable MTBE vapours which would have ignited from an electrostatic discharge. Electrostatic charges would have accumulated on the housing during the leakage of the solvent (electrical insulator), transferred at high speed and filtered by a single cartridge made of polypropylene, which is also insulating. The discharge was likely to have occurred on a conductive stainless steel part of the hose/single cartridge module assembly with the fire being fed by the leak.

The operator plans to systematically check that a gasket is present before using single filter cartridges during transfer operations, and to raise the awareness of the personnel regarding the electrostatic risk through posters and training. Initially, it plans to use single-cartridge modules made of stainless steel (conductive material) for the transfer of insulating solvents, while waiting to find single cartridge modules in which polypropylene would be conductive. This information was sent to the group’s other sites.