Let’s face it, most of us use canister stoves.
They’re easy and convenient – a ‘no-fuss, no-muss’ way to cook! (what is muss anyway?)
However, one of the little situations we all take for granted, is that little bit of fuel left in the can when we return from our latest hike.
No, this isn’t an article about alcohol or twig stoves.
What are you going to do with that almost empty can?
Do you grudgingly haul it, along with a full can, on your next trip, in hopes of using it up?
Do you put it on the shelf and watch them turn into a little collection?
Sometimes we just close our eyes and toss them in the trash, rationalizing that, ‘well, there’s probably worse stuff in that landfill.’
Recently my hiking buddy, Gunny, told me about a little thing he saw on YOUTUBE, which for the first time in a long time actually has that WOW! factor.
This little gadget, safely and easily, allows me to transfer unused fuel, from one can to another!
This led me to do some extensive research (no one wants to blow themselves up), I guess it’s in the nature of being a retired engineer to explore this.
Here’s how you do it.
Get the valve.
Have two cans, both partially or almost empty (doesn’t matter).
I recommend chilling for just a bit, the can that is going to RECEIVE the fuel (call this the New Can). This lowers the vapor pressure in the can compared to the can you want to empty (Old Can) (which you want at room temperature). This just makes the fuel transfer a little easier.
Make sure the valve is closed.
Attach both cans to valve. The valve is ONE WAY, the direction is marked by bubbles, going from larger to smaller – this is the flow direction. You want the fuel to go from the Old Can to the New Can.
The Old Can you want to empty (at room temperature) is on the valve side with the larger bubble.
Open the valve. Wait a couple of minutes.
Close the valve. Remove the cans.
Shake the Old Can, it should have less fuel, preferably it will be empty.
You have just emptied out your old canister and can now safely dispose of it.
A Little Safety and Technical Stuff
If you have a scale for your smaller backpacking items (you should be weighing all your gear anyway!!), I suggest weighing and recording the before and after weights of both cans.
This is the best way to ensure that your fuel is going in the right direction and that you don’t overfill the new can.
PLEASE DON’T LEAVE, BUT WE NEED TO DO A TEENSY BIT OF MATH.
JUST ADDITION, I PROMISE.
I’LL MAKE IT EASY.
PLUS YOU’LL BE THE SMARTEST PERSON AROUND THE NEXT CAMPFIRE!
A very short discussion about the smaller versions of the canisters
When you buy it off the shelf the label will read something like:
3.53 oz/100g – This is content gas weight or how much gas is in the can. This IS NOT the total weight of the CAN + GAS.
CAN + GAS = 7 oz or 198 gr
GAS (alone) = 3.53 or 100 gr.
(let’s round this stuff off and only use grams)
FULL CAN = 200
EMPTY CAN = 100
If you weigh your can before a hike, and it reads 150, that means you have 50 gr of fuel or about half a can.
The closer you get to 200, the fuller the can.
The closer the can is to 100, the closer to being empty.
By the way, if you read my stove article, my jetboil uses 5 gr to boil two cups of water. So a new, small can, with 100 gr of fuel, should give me 20 burns (100 divided by 5), sorry, division used there.
Ok, back to transferring the gas.
IMPORTANT SAFETY TIP
Don’t do this around open flames!
Make sure the area is well ventilated, like outside, in the backyard.
When are you filling the NEW CAN, you just don’t want it to exceed 200 – OK? Keep it safe and maybe only fill it to 190 (gr).
Again, I demonstrate the process here. video.
When you finally do it, it is sooo easy!
To get comfortable with this process, try doing just a little bit at a time and weighing the cans to make sure one is getting lighter and one is getting heavier.
A note on any concerns about the valves. This adapter is the EXACT SAME connection as your canister stove and should have no more or less effect on the valve properties.
Where do get this valve?
I got mine on Amazon.
Next Post: Going beyond simply emptying old cans: refilling cans with ‘off the shelf’ fuel (as in butane cans you didn’t know were sold at your local Ace Hardware) and saving a lot of money.