Welder dies in blast

In an incident on 16.12.2011 Friday at visakhapatnam, a welder died and another person was injured due to gas cylinder explosion in a tinkering painting workshop. Police suspect the blast is due broken knob of a gas cylinder. The deceased suffered a fatal blow to his skull in the blast.
In another report on the same incident, it is stated that explosion occurred when the person was trying to open a carbon machine and the cylinder exploded and hit his head.
From the above two reports, it appears that the person while working on some equipment/machine, an unintentional action led to hitting and breaking of the adjacent gas cylinder knob and flying of the knob (like a rocket?) hit his head causing the death.
Normally welding gas cylinders are kept in the trolley and chained. The broken knob should not have caused explosion unless other wise it is not secured and is acetylene cylinder. As acetylene is not stable and is sensitive to pressure/impact/shock, any fall of unsecured acetylene cylinder can lead to such explosion. May be the broken knob dislodging with great force due to cylinder gas pressure could have hit the skull and led to death.

In a similar incident earlier at another place, it is reported that a broken knob lead to gas release at high pressure and the resultant blast killed a person.