[MikeK]

Just to clarify "burning", you will get a yellow, sooty flame from propane and mapp as well as acetylene if burned in free air with no added air or oxygen in the mix. The propane and mapp torches use the venturi principle to suck air into the mix. There are lots of acetylene/air torches out there too, and they mix in air the same way, giving an adiabatic mix that produces a nice blue flame, about 4,350F, much hotter than mapp. I have one attached to a prestolite tank, used it for years for brazing work on heavy silver. It will make a steel or wrought iron rivet bright orange quickly and easily. What you will not get from any air/fuel torch is the pinpoint inner flame needed for puddle control in welding. That requires pure oxygen in the mix.