Currently in the process of re-design the studio for beadFX - where I teach - as they are moving to a new location - which is one of the reasons I've been very quiet lately. (The other has to do with my mother being ill - but that's another story.)
So - trying to figure out how big a gas line we need. We're going with Natural Gas (again) - and I got the following figures from Peter at Nortel Mfg - so I thought I would publish them here - in case someone else needs them, or I need them at some point in the future.
For Natural Gas
Mega & Minor Torch - at 1/4 psi, uses 3 litres per minute
Midrange Torch - at 1/4 psi, uses 8 litres per minute
Usage increases with psi increase - possibly up to 50% more.
BTUs - calculate at 35 btus/litre.
This is the info I fed to the gasfitter - got it straight from Peter.
Just don't ask me to explain it! ;-)