Is it safe to use a FlipFuel to keep refilling a 4oz fuel canister?

In addition to that, try having the source directly over the receiver, or at a slight angle either way and see if you can a little more out.

You can not totally empty it.  You can take the almost empties on a car camping trip and get the last little bit

AS Jerry says, there is always a tiny bit left. It is really a canister geometry thing.

Cheers

To get more out of the donor canister, rechill the receiving canister. As the cold donor canister drains into the receiving canister, the temperature and pressure tend to equalize.

When you hear the flow stop, put the receiving canister in the freezer for 15 minutes.  Warm the donor canister gently. Reconnect, and you’ll get more gas out of the donor canister. Do a few repeats until there’s no more flow. As Jerry says, you might not be able to get every last drop out.

At home I use a bowl of very warm tap water to warm up the sending cannister, it helps and (maybe irrationally) seems safer to me than a flame.

Does anyone know if the fuel mixture changes as the donor can is emptied?

I always wondered if there was less propane in the mix at the end of the donor can’s life as at the beginning.  Less propane could result in poor flame when it’s around freezing.

Yes, if you use a canister in upright mide, taking gas out if the canister, the propane evaporates more initially so there is less propane left in the canister, so it’s cold weather performance degrades

If you’re taking liquid out of a canister, there is no preference for propane.  The canister will maintain the same ratio of propane.

xxxxxx said that it’s safe to use a flame on the outside of the canister.

I have used that and so far haven’t blown myself up.

I like the idea of being a fraction of an inch away from an explosion.

Has anyone experienced reduced output(pressure) on their refilled canisters? Gearskeptic mentioned this during his stove videos. Didn’t know if it was wide spread issue.

IIRC, gearskeptic just mentioned how pressure goes down as the cannister gets used so that’s why he redid some tests.  I don’t recall him mentioning refilling lowers pressure, but may have missed it?

If you refilled with just butane, then there’d be less pressure than if you had a butane/propane mix.  Especially if it’s cold

I’ve not seen any performance difference when refilling 100-gram canisters with high-performance mixes from 220- and 450-gram canisters (sourced at Walmart or REI).

Of course there will be lower vapor pressure if you refill from the cheaper, horizontal, “Asian-grocery” many n-butane canisters.  Jerry and I keep saying “Asian grocery store” because they often have 3-, 6- and 12-packs of them for 1/2 the cost of REI or Walmart.  Or less.  Or, in bulk (12, 24, 28 canisters) from Amazon,

they approach $2.20/canister for 8 ounces = 230 grams but they won’t ship to Alaska nor California.  They do, I suspect, to 47/48 of the contiguous states – they did to all the ones I spot checked.

When I checked the local head shops (excuse me, the “cannabis grow-operation equipment suppliers”), their butane was crazy expensive compared to anywhere else.  It promised to be super-duper ultra-pure which I suspect is just printing on the canister.  For their purposes as an organic solvent which evaporates VERY readily, any mix of butanes with or without some propane would work just fine.

There are Asian markets like h mart that sell them fairly cheap

The independent Asian markets are cheaper

I think maybe independent Korean markers are the cheapest.  They don’t speak English very good.

David is the one that told me to use lighter on the side of canister to warm it up, like in cold weather

told me to use lighter on the side of canister to warm it up
Which is fine, as long as there are NO LEAKS!
There often are.
Caution!

Cheers

This can almost went into orbit..https://old.reddit.com/r/Ultralight/comments/1lbkotx/so_i_blew_up_a_fuel_canister/

Not sure if I believe this (or at least the pictures)
1) With that much force, it looks like it must have stripped the threads off of the canister or connector valve. Unless it gave away all at once, it seems like the pressure would start to drop off pretty quickly
2) Why is there drywall in the adapter? Given the picture, it’s on the wrong end of the impact.
3) If the canister hit the glass shade first, that should have absorbed a fair amount of energy. That, and look how deep the canister is embedded into the ceiling
Seems fishy to me.

What struck me was heating the can to 170F. This seems like a recipe for disaster. Not sure ‘warming the source can’ meant to get it that hot.

No, I have strong reservations about this as well.
How did the glass lampshade get damaged?
The bottom of the canister looks wrong. I have blown up canisters myself, and I have some idea of how the bottom deforms.
The shrapnel marks on the wall do not make sense.
The deformation of the whole canister looks really wrong: apparently compressed?
The Lindal valve looks deformed, but it does not seem to match the deformation of the canister.
Finally, 70 C exceeds the DoT mandated limit of 50 C. Not wise.

I may of course be entirely wrong about this. But after inspecting the photos . . . strange.

Cheers

You’re not supposed to let the butane exceed 120F.

170F is considerably higher.  I’m not surprised something catastrophic happened.

And he had the canister in a pot heating on the stove????

I heat the water to 120F on the stove or wherever and then remove.  Maybe 130F is fine because it will cool down when you put the canister in it.  Let the canister sit in it a minute, then take it out, dry it off, screw the two canisters into the transfer device and transfer.  If needed, may have to repeat a couple times.  And the receiving canister in the freezer.  Sometimes I just do the freezer because that’s easier.

If you’re sitting the canister in the water on the stove at 170 F, the butane inside the canister will also be 170 F.  If it doesn’t blow up before it reaches that temp.

And, the bottom is convex shaped because that’s a mechanically stronger shape, that allows that metal to contain a slightly higher pressure.  Not a risk prevention feature so that it will pop if over pressure.  (Not that I’ve never stated something on the internet that was wrong : )

cool pictures of canister imbedded in the ceiling

are we sure this isn’t just a young adult male blowing things up?  while drinking alcohol?

Adding further to the confusion:
One photo shows a FlipFuel or similar connector. At least one port or maybe the control valve is apparently packed with bits of ceiling material. Meanwhile the photos of the canister in the ceiling show a bare Lindal valve. Just how did the FlipFuel detach from the canister?

Looking at the canister in the ceiling, I now doubt that it has actually exploded. In fact, I would be not at all surprised if it still held fuel.

Reddit. All very dodgy.

Cheers

Fun video, ignore the tittle: refilling canisters are pretty safe.   Roger is going to love this video: physics works!

that is not very useful, in my opinion

for one thing, if there had been an ignition source it would have been much better : )

hard to figure out what was happening.  Two full canisters.  One in freezer, the other heated.  Connect them and open valve with the heated canister on top.

So, butane would go from top to bottom until the bottom one is full to the brim, still cold.  Then, for a while the bottom one would warm up, the butane would expand.  Pretty quickly the expanded butane would put a lot of pressure on the bottom canister which would cause it to rupture.

Except, since the valve was still open, butane would flow from bottom to top canister so the bottom canister would not have excessive pressure causing it to rupture.

And, it appeared that the top canister is the one that ruptured.

Hard to figure out what happened.

He didn’t mention that when you refill a canister, you need to weigh it and make sure you don’t over fill it.  Which is rule one for refilling canisters.

He obviously didn’t understand how this stuff works so was trying random stuff.  Placing a cannister on a car manifold is just plain dumb.  If it blows, bits of the car go with it.

It was fun and I’ve watched him before, seems like a nice guy.  But he should yank the video.  It came across like a backwoods episode of Jackass.  Like that series, I’d hate to see anyone try to reproduce his “experiments”.

I am not sure what all this is about. The video I saw had a lot of talk (audio OFF), then the guy put one (not empty) canister on top of a running stove. It blew up. Also destroyed the stove (MSR PR – no loss).

Duh! Idiot.

Cheers

He was hoping to show that the isobutane gas canister could blow up using 2 new canisters (same size).  He heated one and cooled the other, then used a transfer valve to move the hot liquid into the cold canister hoping for an explosion.  He was hoping that the rapid expansion of the cold gas would cause an explosion.  Of course, this did not happen.  So, he put a bullet through the canister to make it safe to examine.  Then he heated a large canister to dump into a small cold canister.  Nothing happened.  It goes to show that refilling gas canisters can be pretty robust.

Since he could not get anything to blow up, he just put a canister on top of a burning stove; guess what, it exploded.  My 2 cents.