Mike you don"t have to bleed or purge the lighter, after the initial 2 or 3 fills you never have to worry about O2 , remember it is a closed system with higher pressure than the atmosphere so how in the hell is O2,gonna get in, never happen, the trick to refilling Butane lighters is really simple, lower the pressure on the lighter, put it in the referigrator for 4 to 5 mins, raise the pressure on the butane can, run hot water in sink and put can right side up about 1/3 the way up the can , leave for approx 5 minutes, now you have lowered the pressure in the lighter, raised the pressure in the butane can, higher pressure goes into lower pressure, insert can on refilling spigot , press down and count to 8, put it down , take a few puffs then do it again, your lighter will be full, trust me I built gas plants from the ground up for over 30 years. The old cajun