Been pondering on this one all day and there are too many missing pieces in the report. I'm wondering if AMR is using composite cylinders which would more easily explain the rupture.
Initial cause of the fire is of little import to the overall event/explosion.
I've been hands on with oxygen cylinders that went through a damn hot fire in a blacksmith shop, and acetylene bottles as well, and each and every one of them the safety ruptured preventing rupture.
At this point, and until I talk to some AMR people, I just can't account for the rupture of an Qxygen bottle. Best speculation I can do at this point is an initial electrical fire lit off something in the compartment getting the area of the cylinder to above 165°f which would melt the alloy of the CGA 3 or 4 over pressure fitting on the valve and allow decompression of the cylinder.
That would definitely lead to an Oxygen rich atmosphere in the compartment rapidly, leading to very high temperatures which probably converted the compartment itself to fuel to combine with available Oxygen. This could have happened within seconds.
We pretty well know the compartment lost all structural integrity early in the event because a cylinder took flight for want of a better term. We also know the ruptured cylinder was found away from the ambulance residue.
Condition of the cab post fire strongly says the cylinder didn't rupture within the vehicle, or left the vehicle in the process of rupturing. My thinking is the vehicle carried 2 cylinders, 1 in service and 1 spare, not connected, and the spare is the one that ruptured and flew. I'm still stuck on why the CGA Safety on that cylinder failed to depressure the cylinder prior to rupture or flight. If the ruptured cylinder was steel, the burst strength should have been over 10,000psi and I question if that happened during the short fire duration before the cylinder flew.
Too many possibles and not enough information. Pretty much my usual starting point.
Denny I doubt Junior ever did more with a cylinder than lean on it, or tap his stupid pen on it. His mother raised him to be an executive. He did once pick up a 10 pound bag of crushed ice all by himself to take to a party, and needed a couple days off to recover.