I didn't say
I KNEW how to do it, lol. Was wondering if others did.
Seriously, and I may be dead wrong, so hopefully someone like Greg will
step up here. To get butane out of a can requires propellant, usually air.
so when you fill up your tank, you get some air, which does not ignite, per
se. So at the end of a tank, before you add the more butane, take a small
screwdriver or a nail and push in the nib a little and let all the air or whatever
is IN THERE come out. It'll usually go PFFTTttttt......and then nothing. Then
fill as normal. NOT to be confused with the last 1/5 of a tank in which there is
usually still a little in there, but showing a low or weak flame. You should turn
up the flame for the next couple lights to get it all out before actually refilling.
But usually a tank that has not been purged properly gives a bit of a stuttery
flame that won't stay lit, or sometimes even light at all.