On October 18th, 2015 at 0750 hours our tower (542) was dispatched to a reported working building fire at Sun Re Cheese Factory on Lenker Avenue in the city. Immediately after dispatch the column was visible from the station and we responded with 4. Upon arrival we found a portion of the plant well involved with fire. We immediately set up to go to the roof, however after finding fire had burned through a portion of the roof already, we transitioned into venting horizontally so that we could set up a master stream from the bucket through the windows. After we started master stream operations through the tower, a smoke explosion occurred (8:22 mark of the video). The force of the smoke explosion caused the exterior wall to buckle outwards and a small portion of the roof to collapse just inside the windows. Initially there were disagreements about whether this was a smoke explosion or if a roof collapse caused this incident. However after careful review of multiple videos as well as eye witness accounts from various angles on scene (including chiefs and line officers), it was decided by all that a true smoke explosion occurred. Immediately after this occurred all units were pulled from the building and operations were turned into a defensive mode until control was marked. The truck operated on scene for close to 7 hours until the fire was called out. There were multiple call backs for reported re-kindles, however all turned out to be just steam from the boilers and other areas of the building. Units on scene: CHIEFS: 501, 502, 503, 504, 505 ENGINES: 561, 721, 531, 572, Snyder County 9-2, Union County 2-3, Snyder County 7-1, 111, 731, Montour County 63, 521 TRUCKS: 542, 734, 32, Union County 15-1 RESCUES: 735, 552, Snyder County 5-1 SQUADS: 533, 581, 723, 563 MICU 91 Just some info for those not familiar with a smoke explosion. Conditions Required for a Smoke Explosion The risk of a smoke explosion is greatest in compartments or void spaces adjacent to, but not yet involved in fire. Infiltration of smoke through void spaces or other conduits can result in a well mixed volume of smoke (fuel) and air. Smoke explosion creates a significant overpressure as the fuel and air are premixed and ignition results in a very large energy release. Several factors influence the violence of this type of explosion: The degree of confinement (more confinement results in increased overpressure) Mass of premixed fuel and air within the flammable range (more premixed fuel results in a larger energy release) How close the mixture is to a stoichiometric concentration (the closer to an ideal mixture the faster the deflagration) Potential Smoke Explosion Indicators It is very difficult to predict a smoke explosion. However, the following indicators point to the potential for this phenomenon to occur: Ventilation controlled fire (inefficient combustion producing substantial amounts of unburned pyrolysis products and flammable products of incomplete combustion) Relatively cool (generally less than 600o C or 1112o F) smoke Presence of void spaces, particularly if they are interconnected Combustible structural elements Infiltration of significant amounts of smoke into uninvolved compartments in the fire building or into exposures A smoke explosion requires a relatively cool mixture of fuel (smoke) and air within its flammable range to come into contact with a source of ignition. On the other hand a backdraft requires introduction of air to an hot, extremely ventilation controlled fire where the concentration of gas phase fuel (smoke) is high and oxygen concentration is low. Both result in an explosion, but the initiating event and indicators that may be observed by firefighters and fire officers are considerably different.

• published: 03 Nov 2015
• views: 256