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In the past, it was possible to refill MSR canisters if you brought them into their repair shop in Seattle. However the repair shop has been closed under the excuse of COVID and still hasn't reopened despite Washington dropping all COVID restrictions on June 30th. I've asked REI employees if they know of an alternative refill location but they weren't able to help me, so it seems like the only remaining option is to keep buying new cans.

With this in mind, I wanted to start refilling my own canisters to avoid creating unnecessary garbage while hiking. But just how dangerous it it? Are the warnings on canisters about refilling just there for "cover your ass"/legal reasons or do I risk having the can explode on me all of a sudden if I refill it too often?

NB: I can afford to buy these cans without issues but feel bad about throwing out perfectly good metal after a few days of camping. So this question is purely environmental rather than financial.

Update: I’m not looking for instructions on how to refill canisters (I already know how that works). Just interested in odds of something going wrong if I do this over a long period of time.

JonathanReez
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  • I’m voting to close this question because it promotes or seems to promote a safety risk. – Willeke Jul 21 '21 at 15:27
  • Question closed on request of a user. – Willeke Jul 21 '21 at 15:28
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    The close vote makes no sense at all to me. The question is clearly on topic, and a safety risk is far better dealt with by answering than pretending the problem doesn't exist – Chris H Jul 21 '21 at 19:07
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    @ChrisH - the question is asking "how to" - which is a safety issue. The real answer is "DON'T!" so it's not a valuable question that is in scope. On various SE sites we close or delete posts that could be seen to be encouraging dangerous or illegal behaviour. This is one of them - there is no way to consider refilling these canisters to be safe. And in many places no legal way to do it either. – Rory Alsop Jul 22 '21 at 11:15
  • Comments are not for extended discussion; this conversation has been moved to chat. – Rory Alsop Jul 22 '21 at 11:15
  • @Rory sometimes the answer the OP needs isn't the one they want. I agree there's no safe way, and plenty of questions here, on bicycles, and on cooking, have attracted answers that boil down to "there's no safe way to do what you want". Maybe the question should be tweaked from "how can I?" to "can I?" but the title is clear - it's dangerous – Chris H Jul 22 '21 at 14:12

4 Answers4

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You almost certainly won't be able to find propane/butane/isobutane mixes for refilling. I'm pretty sure you'll only find pure propane and the backpacking LPG stoves are made to be the most efficient with these mixes. You could have worse boil times and less consistent pressure, unless you're using a regulated stove valve.

Pure propane will actually work to lower temperatures, but there's a good reason you shouldn't fill yourself. On the safety side, the 110/220/450g light canisters are made as light as possible and this works well with the butane derivatives. But propane needs higher pressure to liquify so it needs a much sturdier can. I wouldn't refill the 1lbs steel cans, but those are already safer to refill with propane. Add to this that the light cans are not engineered to be refilled manually and the valve assembly is not very sturdy. If debris gets in there, it might get stuck partially open because it's only spring actuated. The threading can also get worn if it's used over and over, leading to potentially dangerous leaks. The can also lacks any safety overpressure valve so if you overfill it, that will extert stress.

Gabriel
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    @JonathanReez I’m not sure where you got -44°F from, but that’s the temperature at which propane will completely stop vaporizing. Full stop, can not work. Above that temperature, it can vaporize, but takes energy to do so (which will drop the temp of the fuel canister), making them potentially unusable above that temperature. Finally, even at temperatures where propane will still vaporize, they can stop working properly, as they will have worse performance at maintaining pressure even significantly above -44°F ambient. This is especially so as the fuel is depleted. – fyrepenguin Jul 20 '21 at 00:53
  • @JonathanReez The problem is maintaining vapour pressure. At lower temps, internal pressure diminishes greatly, and as the gas vaporises inside, the canister temperature drops even further. This domino effect makes it so for really small canisters, it takes only a couple minutes until the stove starts puttering. I tried it at -25°C, even warming the can in my down parka for 45 minutes beforehand. It lasted about 3 minutes. – Gabriel Jul 20 '21 at 03:09
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    @JonathanReez Dude, just don't refill. It's a bad plan. If I was hiking with someone and learned that they refilled and used that around me, I'd be pretty angry and that'd probably be the last time they saw me. – Gabriel Jul 20 '21 at 03:21
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    @Gabriel You have the boiling points of Propane and Butane the wrong way round. If you have a Butane cylinder below about -5C the gas will not boil off while Propane works at temperatures well below this. This from hard won experience using Butane during a cold UK winter. – uɐɪ Jul 20 '21 at 12:17
  • @JonathanReez A gas canister has the same potential to cause injury as a small incendiary bomb. That's why smart people don't take risks with them. – alephzero Jul 20 '21 at 12:45
  • @uɐɪ You know, you're right. The physics of gas cans was a few years away since I had looked it up. Went and took a look at a few cans and I also remembered the ratio the wrong way around. 80-90% isobutane/butane is a normal range, with propane being the rest. I'll edit. – Gabriel Jul 20 '21 at 17:32
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    At least around here, even the large cylinders use a propane/butane mixture https://www.primagas.cz/10kg I haven't even heard about using pure propane before, although it is also apparently available. So most if this answer is moot, really. – Vladimir F Героям слава Jul 21 '21 at 13:30
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I'll focus on your final statement "So this question is purely environmental". As such my answer will be purely environmental and not on safety which I am unqualified to answer.

If you are refilling you are still buying other canisters/containers to refill the original canister with. So you aren't going from X material to 0 material but rather from X to Y with the hope that Y is smaller than X. If you really wanted to you could calculate the fuel/material ratio but it seems like Y can't be that much smaller than X. As such I'm not sure how much material it really saves the environment. Also, camping fuel canisters are made by companies that generally care about the environment. One example is MSR (chosen because it happens to be the brand I see in stores the most often and you mention them in your question), which documents their environmental impact in detail on their website. If you are buying a bulk brand fuel to use as refill there is a chance that company doesn't produce their goods with the same environmental standards.

You also need to obtain the fuel. Those canisters are available at many shops, such as REI as you mention, which have relatively efficient transportation methods to get the product in the store. If you are going out of your way to order/find the bulk containers then you just added to your environmental impact.

So while you might be using slightly less material as an end user, you might not necessarily be having a smaller environmental impact. So it isn't clear that what you are attempting is really any better environmentally. What was the original question again? :)

noah
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What this post is NOT: This post is not promotion or propagation of cartridge refilling. I do NOT promote cartridge refilling and I do not do it myself. I do NOT claim it is a safe practice.

Safety warning! Cartridge refilling is not safe even when you are careful.

It used to be quite common around here in the past decades (say 1990s and 2000s) because the canisters were more expensive relative to the salaries. Therefore it was mainly done to save money. You can find tutorials in quite mainstream outdoor magazines in Czech Republic.

I never did it myself, nor did I ever knowingly use refilled canisters. With the exception of canisters bought in Leh in India which were probably refilled as half of them performed really bad and emptied very quickly.

Those who say it won't work are clearly wrong. Yes, there is more propane in those big canisters, but the mixture sold here will still work fine.

The key I always heard is to measure the weight of the refilled canister carefully and tu put in somewhat less gas than originally. The concave bottom of the canister is a safety measure. If it changes its shape or even buckles out, you clearly overfilled. Be extremely careful, empty the canister and throw it away.

I have not heard of a serious injury that would happen to a person doing such refilling, but I chose not to try it myself. The biggest risk is probably an explosion caused by over-pressurisizng the cartridge or explosion cased by a cartridge with a defect, no longer holding firmly together... That would probably be without fire, but the expanded gas could be ignited by some other means around. As spikey_richie correctly added, in the right concentration the ignited gas could explode at once possibly with catastrophic consequences, so it can only be done outdoors.

Vladimir F Героям слава
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    In 1990s I was refilling my cartridges the same way as shown on the pictures. I have a much better adapter (between the gas tank adapter and the cooker piece) - a single aluminium piece made by a friend. Yes, it is certainly important to measure the weight of the filled cartridge to be sure to not overfill it. I always filled the cartridges outdoors so that the leaked gas would quickly go away. Using soapy water I also checked that the filled can is not leaking. --- The refilled cartridges worked well (in non-extreme conditions like -5 to +35 °C) they were just sooting the pots a little bit. – pabouk - Ukraine stay strong Jul 20 '21 at 13:45
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    Safety notice. IF anyone reading this proceeds to refilling their own canister, PLEASE do it outside. Hydrocarbons in a gaseous state have an LEL (lower explosive limit) and a UEL (upper explosive limit). This is a %'age of volume of product in air, with an example of Methane having an LEL of 5% and a UEL of 15%. If you do this outside, your volume of air is significantly larger than indoors, and you're much less likely to find yourself inside an explosive range (between LEL and UEL). Keep away from any potential ignition sources, and have a fire extinguisher on-hand incase things go wrong. – spikey_richie Jul 21 '21 at 07:56
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    @JonathanReez So basically, you accepted the answer that didn't explain WHY it is risky, like the question asked, but rather that explained HOW to refill? I have to strongly disagree, this is terrible to have on TOS. – Gabriel Jul 21 '21 at 13:15
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    @Gabriel This answer does NOT explain how to refill at all. Not in the slightest. It merely links to one example of such a direction, and only for illustration. That's all. Your answer also mostly discusses that pure propane won't work well, which is also off-topic as one simply buys propane-butane, not pure propane. – Vladimir F Героям слава Jul 21 '21 at 13:32
  • Just as a strong warning: Certainly do not refill the cartridges the way shown here on pictures: https://www.horydoly.cz/horolezci/prepousteci-ventil-na-plyn.html?akce=100023#prispevek-100023 (the discussion under the article linked from the answer). I just hope no other person was in the building and nearby during the refill. So many things could happen to produce an explosive mix of the gas and air in the room! I was instinctively moving away from the screen when I realized what is going on there! – pabouk - Ukraine stay strong Jul 21 '21 at 13:56
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The basic problem with refilling such fuel containers is that they absolutely must not actually be filled. A "full" cylinder is not full, there's a certain amount of unused volume. Remember, most things expand as they get warmer--and that includes the fuel in those cylinders. If there isn't space for it to expand the best possible outcome is for a blowout to fail, very quickly venting all the fuel in a freezing but highly flammable jet.

Loren Pechtel
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    @JonathanReez If you do it correctly, the risk is none. It's the same as with a nuclear power plant or building a atomic bomb. The question is, can you guarantee that you do it correctly always, every time? This of course also includes checking the canister for any damage or faults before refilling... – Josef Jul 20 '21 at 11:17
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    @JosefsaysReinstateMonica - ...and for valve wear which is best assessed from inside the canister. – Jirka Hanika Jul 20 '21 at 18:20