Refilling & Recycling Backpacking Stove Gas Canisters

Backpacking stove gas canisters tend to be replaced when almost empty because the heat from them is no longer enough to be of use. At least that’s what happens to my canisters. Stoves with regulators, low profile stoves with preheat tubes so the canister can be turned upside down, and stove systems with pots with heat exchangers are more efficient at using up gas than simple screw-in canister top stoves but there is always a little gas left when the stove no longer puts out heat.

This presents two problems. How to get the last gas out of a canister and what to do with the growing pile of almost empty canisters, given that they can’t be recycled with gas still in them. There are two different tools for this that actually complement each other.

The first is a gas transfer tool that lets you fill one canister from another. This consists of a two-way valve that screws into both canisters. To ensure the gas flows from one canister to the other there needs to be a heat differential between them with the canister you’re filling colder than the one being emptied. Putting one in the freezer for five minutes and the other in sunshine, or at least a warm room, should be enough.

Once the canisters are screwed in place and the valve is opened you can hear the gas rushing into the bottom canister. Once this stops you can close the valve.

To avoid overfilling a canister, which would be dangerous, I weigh the canisters and ensure that the total amount of gas in both canisters is less than that in a full canister – around 75-85%. Canisters have the amount of gas marked on them – 110g, 230g, 450g are common – so If you know the weight of a full canister (about 380g for a canister with 230g of gas, the size I mostly use, depending on the brand) you can work out how much gas a canister contains.

The tool I use for this is the FlipFuel and it works really well.

 

Now it might seem that this fuel transfer process leaves one canister completely empty, but I haven’t found this to be so, which is where the other tool comes in. To be recycled a canister should be punctured and preferably at least partly flattened (they are tough - try a sledgehammer!). To ensure there is no gas left before puncturing the canister another valve can be attached that vents the very last bit. This valve is part of the Jetboil CrunchIt Butane Canister Recycling Tool which also has a sharp spike for puncturing the canister when fully empty.

I was surprised to discover that when no more fuel would transfer between canisters and I attached the CrunchIt to the apparently empty one gas was still vented, sometimes a surprising amount. Only when the hiss of this has died away and I can’t hear any gas coming out even with my ear close to it do I puncture the canister. The empty canister can then be recycled with other metal cans.

Before I discovered the FlipFuel I was wasting a lot of gas by venting almost empty canisters with the CrunchIt. Now I use the two together.

The valves of both tools are designed for the common Lindahl Valve used on most small gas canisters designed for backpacking stoves. The brand of canister doesn’t matter.

I should point out that I always use both tools outside and nowhere near any open flame.

These are not items I’ve ever carried with me, but I guess on long trips I might do so if I was taking several canisters and thought I might want to transfer fuel between them or puncture and flatten empty ones for carrying. They’re both small and at 36g for the FlipFuel and 32g for the CrunchIt wouldn’t add much to the load.