First of all, these pressure-valves do not drop the pressure "to zero," like the supposed professional-firefighter claimed. Zero pressure would be a vacuum.
Secondly, they don't even release it to equalize with atmospheric pressure.
Thirdly, when it relieves pressure by releasing the gas, where do you think that oxygen goes? If the cylinder is being overheated by a fire, the released oxygen just further intensifies the fire.
Fourth, depending on what happened in the bus, a cylinder landing on its regulator can break the regulator, leading to explosive decompression.
Well excuse me, the pressure is relieved to the point where the value can close if it no longer needed to releive the buildup of pressure.
Yes, the released oxygen will intensify the fire.
NO the cylinder landing on its regulator will not cause EXPLOSIVE decompression. If it were to braeak the fill value area it would take off like a rocket, but not explode.
I have been in very intense fires where cylinders filed with flammable gases were venting into the fire area and burning, and even gas meters on the walls inside of houses.
You cool it down it stops venting, it takes a lot to cause a cynlinder to rupure.
Point is the bus does not appear to hvae blown up, only the reporters reporting it seem to have blown up the story.