Juggling Fuel Canisters

[nsherry61]

I just got back from a cross-country trip with my brother-in-law that left me with a box of mostly empty large (16 oz) fuel canisters that he could not take back with him on the plane. What to do? I have no use for the large canisters, but I like free fuel . . . so, I ordered a "fuel canister refill adapter" from Amazon for about $14, figuring it might be kinda funky, but I could probably manage, somehow to fill up my empty and partially empty small (4 oz, 110 g) fuel canisters from the partially full large ones.

WOW! It was way easier than I expected. So I thought I'd share what I did in case some others like the idea of reusing canisters, filling small canisters with the much less expensive fuel bought in quantity in the large canisters ($1.75/oz vs $0.75/oz), or people that don't wont to carry any more fuel than necessary, so they can transfer fuel to or from canisters to get the exact amount of fuel they want for a given trip.

The whole process was super easy.
1) Attach the adapter between the two canisters you are moving fuel from and to.
2) Place the canister you want to fill on the bottom in a pan of ice water (see attached picture)
3) Pour boiling water into the bottom of the upside down canister you want to transfer fuel from.
4) Let the canisters sit for a minute or two to cool in the ice water and warm from the hot water.
5) Open the refill adapter to fill (or partially fill) the lower canister.
6) Unscrew the canisters from each other and the adapter.
7) Go backpacking

fuel canister refilling.jpg

A few notes:
1) The 110 g canisters can easily be filled to about 130 g with no apparent issues. (Edit . . . NOTE: Overfilling canisters beyond the original gas weight is surely unwise and may be dangerous, therefore, if your canister is overfilled, reverse the process described above and transfer a little of the gas back out of the overfilled canister to retain a robust safety margin.)

2) The canisters being emptied only emptied down to about the last 10 g of fuel in most cases, since the fuel is transfering via a pressure gradient that requires pressure in the upper canister to be higher than the lower canister. With patience, you may be able to do a little better than I did, but you will never get every last gram of fuel out of the upper canister until you puncture is to let out the last remaining pressure before putting it in the recycling.

3) Having a kitchen diet scale (~$15) is super helpful in knowing how much fuel is in each canister and how much you have transfered. The same type scale is considered mandatory gear for most backpackers to be able to weigh all their other gear. I write the fuel weight on each canister with a sharpie so I know how much fuel I'm taking whenever I grab one to use, and I can grab one with the amount of fuel I want for a given trip. Just subtract the empty canister weight from the total weight to calculate available fuel.
- 110 g canisters weigh about 100 g empty
- 220 g canisters weigh about 150 g empty
- 550 g canisters weigh about 200 g empty

[dcdennis]

This thread's got me all.....gassed up.

[dcdennis]

Your link doesnt go to amazon though. Just to an adventure blog. Whats the device you used?

[FreeGoldRush]

This might earn someone a Darwin Award.

[nsherry61]

This might earn someone a Darwin Award.

Obviously you've never worked at a propane filling station. You'd be hard pressed to get into trouble with these simple devices.

Try this link to the gadget I used, although, it looks like there are several similar options if you search for "fuel canister refill adapter"

[HooKooDooKu]

1) The 110 g canisters can easily be filled to about 130 g with no apparent issues.

And you can light the fuse on a stick of dynamite and hold it in your mouth "with no apparent issues"... until it becomes an issue.

[somers515]

Cool tip - thanks Nsherry61! I use up my old canisters trying out new backpacking recipes but this is a neat idea too.

[nsherry61]

And you can light the fuse on a stick of dynamite and hold it in your mouth "with no apparent issues"... until it becomes an issue.

Yep. That being said, it is the vapor pressure of the gas, determined by the temperature of the gas, not the quantity, that determines the pressure in the canister. That is actually why the canisters work as well and consistently they do even with a huge range of different gas quantities in the canisters.

[Adfischer]

I'm no going to criticize anyone for trying to say money, so do as you see fit. However I personally would never do that because I would be afraid of leaks. Those Lindal valves are cheap and not designed for multiple uses. Last thing I want on the trail is to get to camp and discover all my fuel has leaked out (or worse). I have also heard there is a DOT regulation that prohibits transporting refilled canisters but I dont have anything I can cite on that. I have a pretty healthy respect for highly flammable gasses so I'll stick with purchasing new ones.

[nsherry61]

. . . I have also heard there is a DOT regulation that prohibits transporting refilled canisters but I dont have anything I can cite on that. I have a pretty healthy respect for highly flammable gasses so I'll stick with purchasing new ones.

Good thoughts.

To my knowledge, DOT doesn't have anything to say about refilled vs. new canisters. Transportation of all backpacking stove fuels (except maybe wood) are highly restricted by DOT, esbit tablets less so than gasses. I am not aware of any differences between pressurized canisters, refilled pressurized canisters and/or liquid fuels. They are all dangerous if not handled responsibly. Frankly, not unlike filling your car.

As for reliability of the Lyndal valves, they are clearly simple, designed for single use, and highly effective. Some people may use up a canister by installing and removing their stove 5 to 10 times. Someone else may do so, especially with larger canisters, dozens of times. They are designed to be used safely significantly more than most of us will ever use them for an average 110 g canister. Over many years and much abuse, I've only ever had a Lyndal valve fail in extremely cold conditions whereby it didn't reseal after the stove was removed. Never any real danger, just leaking gas, well away from any potential sparks or open flames. Never leaking except immediately after removing the stove. And frankly, I got it to seal by putting the stove back on and removing it again.

As for refilling canisters, given how simple and well sealed the refill system is, the filling process probably isn't as dangerous as lighting my kitchen gas stove. As for valve reliability, I would probably only refill canisters a few times and not treat them as infinitely refillable. BUT, you are NOT adding extra pressure to the cartridges unless you are using gas mixes different than they originally contained, e.g. filling from a propane bottle instead of another butane/isobutane/propane mix with a max of 20% propane.

[Adfischer]

I found the video below which is talking about refilling DOT39 cylinders. That is where the DOT reg I mentioned came from. I'm not sure camp stoves are considered DOT39 so it may apply, but them seem like they are even thinner and less durable than the 1lb mentioned in the video. You are also (hopefully) not refilling from a 20lb propane tank! I'll stick to the manufacturers cartridge, but I think you are wise to only use them a few times after refilling.

[Adfischer]

I'm not sure camp stoves are considered DOT39 so it may apply....

I meant to say it may NOT apply...

[nsherry61]

I believe the DOT39 refers to relatively high pressure canisters which our backpacking canisters are not. And, in refilling backpacking canisters, we are playing with relatively small pressure differentials compared to propane (slightly less than 1/3 the pressure). There is a reason our canisters are limited to only 20% propane with the rest being butane or isobutane.

You realize that people walk around every day with little plastic butane cartridges in their pants with buttons that accidently release bits of gas now an again and most of us don't think twice about this.

[Kaptainkriz]

I do a lot of refilling of my own canisters with leftovers / butane. Beware, the 110g mass of fuel is referenced against a safe volume and the potential expansion of the liquid when the canister heats up due to weather or use. A canister full when cold, may be overfull when hot. When the expanding liquid (not gas) has nowhere to go, it will deform the canister and possibly rupture. Large propane tanks have a gauge with temp on it to help prevent over filling.
LP_Gas_Gauge134-DFs.jpg

1) The 110 g canisters can easily be filled to about 130 g with no apparent issues.

[4eyedbuzzard]

The reason for only filling a small canister with 110 grams of fuel (or any canister to its designed weight) is to allow for headspace in the canister so that there is room for gas expansion. A small portion of the liquid fuel vaporizes and becomes a gas under pressure in the canister. Headspace is this area, the part which is not filled by the liquid fuel. If overfilled (more than 110 grams) you have exceeded the designed headspace in the canister. If you overfill too much, and don't leave enough headspace for the designed amount of gas, you could get hydrostatic pressurization (because liquids do not compress) and catastrophic failure of the canister. Which could be exactly as it sounds - catastrophic.

[nsherry61]

. . . Beware, the 110g mass of fuel is referenced against a safe volume and the potential expansion of the liquid when the canister heats up due to weather or use. A canister full when cold, may be overfull when hot. . .

I think my previous statement about overfilling a canister was written in a way that can easily be misunderstood. I had no intention to encourage overfilling, but rather just to point out that doing so was possible without any obvious indication of it. MSR claims to fill the canisters with 117 g. I know people that have regularly overfilled their canisters without problem. But, a preponderance of caution would suggest that filling them with more than about 117 g would not be as safe as limiting their fill to 117 g.

[nsherry61]

The Adventures in Stoving web site has a significant write-up about refilling canisters if anyone wants to read even more . . .

[rusane]

My guess is its not 100% effective. Factor in this loss, the energy to make ice and boil water, and the time I could have spent drinking, and it’s a net loser for me.

[cmoulder]

I do a lot of refilling of my own canisters with leftovers / butane. Beware, the 110g mass of fuel is referenced against a safe volume and the potential expansion of the liquid when the canister heats up due to weather or use. A canister full when cold, may be overfull when hot. When the expanding liquid (not gas) has nowhere to go, it will deform the canister and possibly rupture. Large propane tanks have a gauge with temp on it to help prevent over filling.
LP_Gas_Gauge134-DFs.jpg

I think my previous statement about overfilling a canister was written in a way that can easily be misunderstood. I had no intention to encourage overfilling, but rather just to point out that doing so was possible without any obvious indication of it. MSR claims to fill the canisters with 117 g. I know people that have regularly overfilled their canisters without problem. But, a preponderance of caution would suggest that filling them with more than about 117 g would not be as safe as limiting their fill to 117 g.

I agree with Kaptainkriz about NOT overfilling, but the other concerns about transferring fuel from one container to another are indeed vastly overblown. This is, overall, a very safe procedure. The amount of gas released when decoupling is about as much as (or less than!) you'd see when filling a butane cigarette lighter... truly minuscule.

Also, I have a certain Primus canister that I have refilled many dozens of times (using cheap tabletop stove butane cartridge fuel) just to see how many cycles a Lindal valve can stand, and it is far, far more than a few times. I'm still using the darn thing and it just won't quit.

[lonehiker]

My guess is its not 100% effective. Factor in this loss, the energy to make ice and boil water, and the time I could have spent drinking, and it’s a net loser for me.

Drink while making the ice and boiling the water. Then, continue to drink while transferring the gas makes for a net gain...