Do you always purge?

[Ropey]

I only purge when my lighters start behaving sh*ttily. I usually fill before the things are empty anyway, especially if I won't be around my can of butane for awhile.

[LAN CERO]

So, the freezer temps get the remaining fuel and air to 'condense' a bit, allowing more room-temp butane to inject?

[Emperor Zurg]

So, the freezer temps get the remaining fuel and air to 'condense' a bit, allowing more room-temp butane to inject?

There's no air in there. There is butane in there; liquid butane on the bottom and butane vapor above it. Lowering the temperature reduces the vapor pressure of the butane. The result is that the butane CAN, which is at room temperature, is at a higher internal pressure than that of the lighter. That means that fuel will flow from the can into the lighter - which is what you want. The fuel entering the lighter will be chilled by coming into contact with the cold fuel tank so the lighter will remain at lower pressure even as it is being filled.

The worst case scenario is probably what all you people have been doing. That would be taking the lighter out of your warm pocket and attempting to fill it with a room temp can of butane. In that case, even if the lighter is basically empty, the instant a little butane enters the tank, it immediately flashes off on the warm surface of the tank and suddenly the lighter is at equal or higher pressure than the can. So fuel transfer stops with a drop or two of butane in the tank. Then you wonder why you can only get a light or two out of it before it's empty. It MUST be because it's full of AIR because I forgot to purge it! No, it's simply empty because you never got any fuel in it in the first place.

[projectsunfire]

I used to purge because everyone told me I had to. But I got lazy a few times and filled up without purging...and now I never do. Havn't in years in any of my lighters and they all work perfectly fine.

I had a drunken adventure last weekend that ended up with me in the ocean around 3am and I had my favorite Bugatti in my pocket. It wouldn't light so I just took it apart and let it air for a few days. Works like new again. I don't baby my lighters. If they stop working I buy a new one

[Deke]

There's no air in there. There is butane in there; liquid butane on the bottom and butane vapor above it. Lowering the temperature reduces the vapor pressure of the butane. The result is that the butane CAN, which is at room temperature is at a higher internal pressure than that of the lighter. That means that fuel will flow from the can into the lighter - which is what you want. The fuel entering the lighter will be chilled by coming into contact with the cold fuel tank so the lighter will remain at lower pressure even as it is being filled.

The worst case scenario is probably what all you people have been doing. That would be taking the lighter out of your warm pocket and attempting to fill it with a room temp can of butane. In that case, even if the lighter is basically empty, the instant a little butane enters the tank, it immediately flashes off on the warm surface of the tank and suddenly the lighter is at equal or higher pressure than the can. So fuel transfer stops with a drop or two of butane in the tank. Then you wonder why you can only get a light or two out of it before it's empty. It MUST be because it's full of AIR because I forgot to purge it! No, it's simply empty because you never got any fuel in it in the first place.

This is spot on. My tailgating grill uses the 1 lb propane cylinders. There is a method of refilling them from a large propane tank through a hose by first putting the one pounder in the freezer. Because of the temperature difference, it makes the propane flow into the smaller tank and end up under pressure.

Same concept here.

[LAN CERO]

All Hail Emperor Zurg!
That ought to be a sticky here.

[Branzig]

I've been know to purge my Zippos at least once a week or so...

[04EDGE40]

I purge to keep my girlish figure. And I only purge as much as I eat.

[jhedrick83]

All Hail Emperor Zurg!
That ought to be a sticky here.

You don't get to be Ruler Of The Galaxy without being able to drop some science!

[LAN CERO]

Followed the freezer method this a/m for my main lighter. It seems as the lighter is much more intensely pressurized now, as the flame is twice the length, and the sound is louder, w/o having touched the flame adjustment. NICE!