Refilling butane lighter the physics way

[DaveC426913]

Refilling just involves 'pouring' the liquid Butane in and keeping the supply tank marginally warmer than the torch tank (with my hand). That avoids a build up of excess back pressure in the torch tank and avoids the need for gas to bubble back as the tank fills up.

Should I be doing this when I refill? Should I hold the refill tightly in my hand to warm it up?

It is notoriously difficult to properly refill a lighter that lasts more than a few uses.
You have to drain the lighter of all air pressure, Fill with small amounts frequently so that the lighter has time to warm back up, and sacrifice a chicken over an unmarked virgin's grave. It's a real art.

 

[sophiecentaur]

unmarked virgin's grave

Not a lot of those available where I live.
It's years since I used an actual lighter (last ciggy was in around 1962) and my soldering iron has never completely run out. Once you manage to get any butane into the lighter, it should be possible to purge the air by holding it the correct way up and pressing the button. (Is that upside down or upright? - it would depend whether there is a feed tube to the bottom of the lighter tank.) The air would float on top of the gas in there. . . . i think.
But if you have a problem, you can always throw a cigarette away and the pack would then be a cigarette lighter. (boom boom)

 

[NascentOxygen]

you can always throw a cigarette away and the pack would then be a good cigarette lighter. (boom boom)

better still

 

[NascentOxygen]

It is notoriously difficult to properly refill a lighter that lasts more than a few uses.
You have to drain the lighter of all air pressure, Fill with small amounts frequently so that the lighter has time to warm back up, and sacrifice a chicken over an unmarked virgin's grave. It's a real art.

My experience differs. Every couple of months I refill the gas stove lighter, it's like a cigarette lighter but produces its flame at the end of a long metal barrel. Chance is involved in mating the butane canister to the valve on the lighter, but just occasionally I seem to fluke a perfect match with no gas loss at all, and with the two jammed tightly together I wait for perhaps 20 seconds before separating them, and discover during that period of silence the lighter's tank has filled to around 95% capacity. It has never completely filled that I recall, but perhaps that's because I'm just too impatient to allow adequate time to completely fill?

While I am holding the butane canister during the operation and it must inevitably absorb some heat, the way I hold the lighter I can say I'm confident its tank doesn't get any warmth from my hand.

Next time I shall wrap the canister in a cloth to see whether filling proceeds as normal, I expect it will because I doubt that there is any need for the canister to receive warmth from my hand.

 

[Paul Walsh]

There are still lots of refillable lighters here in Europe - e.g. Cricket , just not Bic who annoyingly incorporate a transverse leak slot to stop you refilling even though there is a valve. Cricket actually used refill-ability, amongst other design features ( wine bottle stopper.. ) as marketing material.

As far as I can see you refill a lighter because the refill canister is at a higher pressure than the lighter. The fact the lighter still has enough pressure to maintain the butane at liquid state is mute. Equilibrium is achieved when there is some, but little, air left in the lighter (by volume, not mass). I cannot see how this idea of a 2 way valve letting air out is correct. A little air may escape but I don't think it is essential to the process.

 

[DaveC426913]

Moot.

I'll see myself out.

 

[jongva]

My experience differs. Every couple of months I refill the gas stove lighter, it's like a cigarette lighter but produces its flame at the end of a long metal barrel. Chance is involved in mating the butane canister to the valve on the lighter, but just occasionally I seem to fluke a perfect match with no gas loss at all, and with the two jammed tightly together I wait for perhaps 20 seconds before separating them, and discover during that period of silence the lighter's tank has filled to around 95% capacity. It has never completely filled that I recall, but perhaps that's because I'm just too impatient to allow adequate time to completely fill?

While I am holding the butane canister during the operation and it must inevitably absorb some heat, the way I hold the lighter I can say I'm confident its tank doesn't get any warmth from my hand.

Next time I shall wrap the canister in a cloth to see whether filling proceeds as normal, I expect it will because I doubt that there is any need for the canister to receive warmth from my hand.

I put the lighter in the fridge for 15mins before refilling. This accelerates the transfer.

 

[sophiecentaur]

It is notoriously difficult to properly refill a lighter that lasts more than a few uses.

I agree.
I did a google search with "filling car autogas tank" and there are many videos available. I gave up on finding a good 'Physics' based discussion but I frequently came across a figure of 80% full as being safe. I also kept reading that decanting PLG involving heating the source bottle is verboten. You have to leave headroom above the liquid fuel so allow for expansion of the liquid without causing unsafe pressure.
I have come away with the idea that the standard, apparently inadequate procedure of pressing your top up bottle against the cigarette lighter has a built in safety feature that won't actually let you have serious accidents (pocket full of fire!). Scaling up to larger bottles is big boys' stuff.