Anyone whose ever seen the head knocked off an oxyacetylene tank can attest to that first hand....and I've seen it. Well......actually, it was the oxygen tank, or I'd probably be dead. That tank fell over and the valve hit the side of the wrecker in the junkyard where I worked. It knocked the valve head off and when the tank hit the ground, it took off like a torpedo. It bored itself under several cars and finally ended up out in the woods after it went right through a chain link fence. I could only imagine what a hydrogen tank would have done.