Observations on Two Fires in Which the Spill of Flammable Liquids Led to Deflagration and\/or Flash Fire in a Stratified Heavy Vapor\/Air Mixture<\/p>\n
Giovanni Cocchi, P.E., Ph.D.
\nARSON Fire, Safety and Environmental Investigations S.r.l., Italy<\/p>\n
Presented at the International Symposium on Fire Investigation Science and Technology, 2014<\/p>\n
ABSTRACT<\/p>\n
The most common kind of diffuse phase explosions investigated by fire investigators involve methane or LPG,\u00a0either accidentally or willingly allowed to accumulate in the confined volume of the room(s) of a building. Many\u00a0volatile ignitable liquids can form a flammable vapor\/air mixture when spilled on the floor and let evaporate for\u00a0enough time. Upon ignition, flash fire or deflagration will take place, possibly followed by the development of a\u00a0compartment fire. This work reviews the relevant literature about evaporation of volatile ignitable liquids, heavy gas\u00a0dispersion and propagation of flame front in stratified heavy vapor\/air mixtures. Subsequently, two cases in which\u00a0the author was asked to provide its technical opinions will be discussed. The first one is a massive semi-confined\u00a0deflagration in a large storage room that eventually vented through the weakest brick wall of the building. The\u00a0building was not equipped with natural gas lines and no LPG can was retrieved at the scene. Subsequent fire debris\u00a0analysis demonstrated the use of volatile accelerants. The second one is a flash fire that was caught on CCTV\u00a0camera. Around four minutes before, a person was taped while pouring a liquid\u2026After the flash fire, the puddles of\u00a0liquid of what was intended to be a trailer were observed to burn as pool fires, until smoke obscured the camera. The\u00a0flame front of the flash fire shows all the relevant features that other authors have previously shown to be peculiars\u00a0of flash fires in a stratified heavy vapor\/air mixture. Fire investigator should consider that when an explosion or a\u00a0flash fire take place before fire development and natural gas or LPG sources can be legitimately ruled out, use of\u00a0highly volatile accelerants should be regarded as a legitimate hypothesis and tested according to the scientific\u00a0method of NFPA 921-2014 .<\/p>\n
Download the complete paper<\/a> here<\/p>\n","protected":false},"excerpt":{"rendered":" Observations on Two Fires in Which the Spill of Flammable Liquids Led to Deflagration and\/or Flash Fire in a Stratified Heavy Vapor\/Air Mixture Giovanni Cocchi, P.E., Ph.D. ARSON Fire, Safety and Environmental Investigations S.r.l., Italy Presented at the International Symposium on Fire Investigation Science and Technology, 2014 ABSTRACT The most common kind of diffuse phase … Continue reading Observations on Two Fires<\/span>