While we’ve heard of DIY methods for transferring fuel from one isobutane canister (the ones typically used in backpacking) to another, we haven’t seen a dedicated valve designed for the purpose marketed to the outdoor world yet. Well, until recently.
Eric Flottman, an Arizona-based backpacker, was tired of the partially filled cans piling up in his garage, so he set out to design a simple, inexpensive device to fix that. It relies on simple physics to work.
When fuel is cold, it condenses. When it gets warm, it expands. To use the Flipfuel, you put the canister you want to fill (the intake) in the freezer to chill the fuel and the one you want to empty (the output) is sitting squarely in sunlight to warm the fuel.
You wait a few minutes for the temperature differential to increase, then pop the intake can out of the freezer, thread on the FlipFuel, attach the output canister, and open the valve. The warm fuel expands into the colder canister, and voila, you now have one empty can and one that’s, well, not empty.
That last bit can be a problem as you really don’t want to overfill a fuel canister. Unfortunately there’s not an easy way to tell how full a canister is. A method we like is floating the canisters in water. Some brands (MSR is one) print a small label on the canisters that show the approximate level of fuel that will be in the can when it floats at a particular level. As long as you conduct something like the float test and ensure the cans you’re filling are less than half full, you should be good to go.
Of course, then you still need to responsibly dispose of the spent canister and here’s a good primer on that.
Would be cooler if there was a way to simply refill the cans somehow, rather than have to buy new ones all the time, but this is a step in the direction of far less waste.
The device costs $35, and, conveniently, weighs 35 grams, though hard to imagine carrying one with you in the backcountry.
Looks promising, hate taking 2 half fuel cans to avoid running out. Here is a table of most brands to make the transfer a little less “exciting” if your math is good and you have a gram scale.
http://troop281.org/wp-content/uploads/2015/08/Fuel-Canister-Weight-Chart.pdf
Awesome. Thank you for sharing that spreadsheet!
What I always wonder about floating an MSR can is that they have a concave bottom that can trap air. So are we supposed to burp the cans when we put them in the water or are we supposed to weigh them with air trapped under the can?
What I have done instead is weigh a full can and an empty can and judge how much gas is left in a third can by weighing it and extrapolating.
Except that it’s dangerous, and while not illegal to refill, it is illegal to subsequently transport refilled single-use cylinders on any public highway.
Rvtravel.com/why-you-should-not-refill-disposable-propane-cylinders
Valves like that have been around for quite a while, I’ve been refilling my cannisters for years using one made by G-Works. There’s quite a selection on Amazon, but the G-Works is one of the only that has machined brass inserts for the threads which makes it more durable than the others which rely on threads just cut into the body which are bound to strip or cross thread sooner or later. They’re also built in Korea so fit and finish are excellent.
As far as refilling canisters, you’re dealing with a highly explosive gas so extreme(!) care needs to be taken during the refilling process and even more to ensure cannisters are not overfilled. Weight is the only way to safely do this, and an accurate digital kitchen scale is necessity. As well as float information, MSR also puts the weight of their cannisters on them which can be used when refilling their cannisters. There’s lots of articles and videos about how to refill cannisters on the net, I’d highly recommend reading/watching those carefully before attempting to do it, or for that matter, deciding if you even want to. I’d never do this in the field, the risks are too great and the monetary gain too small, better to just buy a new canister.
I received one of these as a Christmas present. Genius!
It seems to me that one of those color changing temperature strips or something like that would measure the level, especially if you throw one can in the freezer, you should be able to find the liquid level at the temperature change.
The concave bottom is somewhat of safety feature I believe. Once I did let the receiving canister get too much fuel from the sending canister and got a bulge in its bottom. From then on, I’m sure to never exceed the gross weight listed on a canister (only some brands list that). It means … a) refilling a canister a little bit at a time; b) shutting off and disconnecting from the transfer device; c) weighing (postal scale used) the receiving canister; (d) then repeating process if not yet too close to gross weight listed for the receiving canister. A slower process, but no bulges in the concave bottom.
Article implies Flip Fuel is first to solve the partially filled isobutane canister problem. But G-Works as well as many off-brand clones have been available for some time. In any case, it’s proven to be a very useful tool!
For some reason, I was under the impression G-Works, etc., either weren’t available in all states or were otherwise unreliable. But you’re correct, there are definitely other options.
We do this to refill the green Coleman propane canisters from a five gallon tank, but never bothered with the small backpacking ones. Once they get below about half, they get relegated, (or promoted), to camp coffee duty.