I found Iso-Butane at REI backpacking stores in Oregon. This fuel is for MSR stoves. MSR stoves are distributed world wide, so I expect most backpacking stores have the 6 oz/ 170g cans. Sulphur Springs markets an adaptor for the fuel cans. I believe, but did not record and do not remember, that I was using butane-propane mix in this tank. I haven't been able to find pure butane in years, and use the mixture in all our locomotives on the FH&PB. So the pressures in my test would have been correspondingly higher than those on the LocoSteam graph.
