At 7.45 pm., a fire occurred in a plant manufacturing powder milk. At 5:45 pm., the shift manager started up the drying process after changing from milk powder to whey powder. Two hours later, a temperature rise in an exhaust air (gas) filter was reported in the control room computer. The extinguishing system of the exhaust air filter was activated automatically and the plant was shut-down. The extinguishing system could not stop the fire : smoke plumes were emitted by the filter. The manual extinguishing / cooling procedure was started and the fire brigade was alerted and arrived on site 5 min later. The fire was under control after 1 h. No-one was hurt but material damage were significant and amounted to 0.6 M euros.

Smouldering nests of dust deposits (which may have formed in an unfavourable position inside the tube filter) ignited spontaneously during process shut-down / start-up phase associated with product change.

The plant operator added technical measures to control the process and the absence of smouldering fire. Booster pumps were installed on the extinguishing water pipelines (respectively, on the pipe leading to the spry-dryer tower and to the tube filters) in order to raise the necessary extinguishing pressure. The pumps are connected to the emergency power supply. An air compressor, also connected to the emergency power supply, has been installed in order to guarantee the supply of air for the control of the extinguishing water valves. According to the recommendations of the fire department, extinguishing hoses have been installed on every drying plant floor whereas the already existing dry pipe has been connected to the sprinkler system. Additional area drains were installed near the tube filter extraction lock of the tube filter in order to improve the drainage capacity of extinguishing water. Additional detachable manholes covers were installed as measure for preventing the dust depositions in correspondence of the manholes. The inspecting procedure for dust deposits and smouldering fire was reinforced and the employees trained. Checklists, emergency plan, CO-testing system calibration etc. were documented in the updated process documentation system.