NFPA 921 – 18.12.2 High Explosives
“…The effects produced by diffuse phase (i.e., fuel-air) explosions and solid explosives are very different. In a diffuse phase explosion (usually deflagration), structural damage will tend to be uniform and omnidirectional, and there will be relatively widespread evidence of burning, scorching, and blistering. In contrast, the rate of combustion of a solid explosive is extremely fast in comparison to the speed of sound. Therefore, pressure does not equalize through the explosion volume and extremely high pressures are generated near the explosion. At the location of the explosion, there should be evidence of crushing, splintering, and shattering effects produced by the higher pressures. Away from the source of the explosion, there is usually very little evidence of intense burning or scorching, except where hot shrapnel or firebrands have landed on combustible materials.”
According to 18.12.2 Fuel-air explosions (i.e.- JET FUEL) will be relatively widespread and there will be evidence of burning, scorching, and blistering. If the lobby truly “blew out” from the jet fuel explosion we would see extensive burning, scorching, and blistering.
Do you see any signs of burning, scorching, or blistering? On your size-up pay close attention to the plants and the ceiling…is this what you would expect to see after a “jet-fueled fireball” blew out the lobby?
OR, does this match the damage we would expect to see with solid explosives? (i.e. crushing, splintering, and shattering effects produced by higher pressures).