Is it safe to use a FlipFuel to keep refilling a 4oz fuel canister?

I have an 8 ounce canister I’ve refilled for 3 years now.  Maybe 200 nights.  It has a dent on it and it’s a bit rusty.  I wrote “august 2020” on it.  No reason to throw out yet.

Once I had a canister that failed after a few nights, Lindal valve wouldn’t close.  So I just left the stove screwed on until empty.  They can fail.

I’ve used one of those valves before, but mostly I use a valve that transfers from cartridges to canisters.

The cartridges are maybe $1.25 from Asian grocer for 8 ounces.  But, they’re only good down to about 32 F.  Below that there are easy tricks like I’ll take a lighter and put a flame to the canister to warm it up a little.  (attribution – David’s idea).  Lots of threads for various techniques for cold weather.

“ZYAMY-Adapter-Cylinder-Canister-Accessories” on Amazon – $7.99

I have never seen the same product available for more than a few months.  But it’s just a piece of metal with one o-ring.

I wonder what the vendor intended it for?  Maybe it’s just a generic disclaimer to limit liability.

I have a different brand valve and only use it to refill the smaller 4oz  canisters or consolidate larger 8 oz ones for car camping. Make sure to weigh the new full or an empty canister to know what full really is. Don’t overfill.  The MSR canisters have the total and fuel weights listed on the canisters, but others do not. Other than the rare valve failure I think the only risk would be from overfilling.

the canister makers don’t intend them to be refilled.  Too much opportunity for user error.  They would rather sell new ones.

If you put too much in, and then it warms up the fluid will expand.  It can cause the canister to rupture.  Or the bottom could pop out.  Weigh the canister when new and write that weight on the side of the canister and don’t fill more than that weight.  Or weigh when empty and don’t fill more than 4 ounces above that.

this would apply to either adaptor – canister to canister or cartridge to canister

I’ve refilled a smaller canister quite a bit with larger canisters of isopro and no problems. It weighs 100g empty and comes with 100g of fuel. Some come with 110g of fuel. I’ll weigh the canister so it’s not overfilled. A guy said he did overfill his and the inward domed floor is puffing out the wrong way now. Yikes. Yet I’ve known some that have refilled a single canister for years and zero problems. My method is the Gas Saver +.  This solved the biggest issue of partially empty canisters piling up.

I’ve been doing this for years.  I toss the old cans when they start looking old (“too” rusty), and I’m careful not to overfill as Jerry explains above.  Completely eliminates partial canister anxiety.

“A guy said he did overfill his and the inward domed floor is puffing out the wrong way now. ”

A sane person would discard that canister

On the other hand, an insane person would say that it will now carry more volume : )

Wise advice re. weighing the canister to avoid overfilling. Thanks.

“A sane person would discard that canister”

He did discard it immediately and never overfilled one again. A scale is your best friend here. Lol

I do same as Glen L.

Been re-using 5 different 100g canisters on rotation since 2018.    Must have refilled all of them over a dozen times.

No issues with leaks yet.  Though discarded one for rust issues and another because one of my stoves would no longer depress the valve (others would).

Friend also did the overfill and bottom dome error!  Due to filling in cool condition outside, then stored cartridge in a shed, – when it warmed in spring is when the doming occurred. Luckily he spotted it, and made it safe.

Is there a good tutorial on how to do this safely? I have many huge cans I was gifted. Love to fill up my small cans.

Ventilation.

Connect transfer device to receiving can.

Connect donor can – on top upside down .

Open valve. Wait for noise of fuel transfer to stop .

Disconnect all.

Weigh receiver can.  A 4oz/100g can should weigh no more than 200g when  refilled to spec.  If it does, reverse the process to take some gas out.

It’s that simple.

If you cool the receiving can in a freezer first it speeds up transfer. Can also warm donor can in hot water.

In my experience, “Wait for noise of fuel transfer to stop” will virtually always overfill.  I stop and weigh, sometimes a couple times, as the sound slows down.  I find this less time consuming than reversing the cans after overfilling, as that often leads to yo-yo-ing around full.  Maybe it depends on how good your hearing is and how quiet your environment.

@Todd T  Thanks. What brand valve do you use? Seems to be a ton of them out there.

I think it depends on sending gas mix and ambient temperature too.

I’m in UK.  I actually refilled  a can just yesterday morning with gas from a 500g Coleman mix of 70/30 butane/propane (no iso- butane in the mix).  I use a cartridge top stove every morning for my Bialetti coffe maker.

After noise of gas flow  stopped I weighed the receiver, it was at 167g (⅔ spec capacity).  I reattached and shook the whole setup to get a bit more transfer. I got to 181g. Still not overfilled.

I use a Chinese device that looks exactly the same as a Flip fuel.  Both I believe are cheaper Chinese copies of the original Korean made Gas Saver +.

As I wrote before, I have done this for years many times.  Only rarely have I been able to overfill the receiver, though it has happened.

With a different gas mix I guess YMMV.  Best be safe.

I use G Works Gas Saver

I think any cheap Chinese unbranded version would work equally well.  It’s such a simple device it’s hard to screw it up.  If it did fail, it would be no big deal – hold onto those partly filled canisters until a new valve is delivered.

If a stove failed in the field, that would be worse.  Better get one that’s recommended.

Mole J’s recommendation is good.  I probably know about how much to transfer beforehand so just do it by feel.  I have never overfilled a canister but it would be easy to correct like Mole said.  My problem is the donor cools down (due to evaporative cooling inside) and it stops before it’s emptied.  Then I’ll weigh donee to see how much more I need to transfer.

I always put just enough butane into the canister for the number of days I’ll use it, plus an extra ounce for safety.

I used to be more dilligent about warming up donor and cooling donee, but now I don’t bother.  If the donor stops maybe I’ll put it into my armpit to warm it up.  Maybe I’ll put the donee into the freezer.  I used to put hot water in a container, then put the donor into it.  I like this because it violates all the warnings about not heating butane canister, but it’s easier to omit this step.

When they say “butane” I have found it to be about 50% nbutane and 50% isobutane.  When it gets down to about 22F, the flow goes to zero.  It’s expensive to refine butane to be just nbutane or isobutane.  It’s cheapest to use butane that’s about 50/50 for camping fuel.

There are enumerable threads about all this, but no need to look for them, everything covered here : )

The engineers can weigh in on putting a canister in “hot” water.

This is what I did that worked fine:

I just transferred the remaining contents of six 100 g canisters into another partially-full canister, perfectly topping the latter off. I kept the transfer valve on the recipient canister and placed that in the freezer for about 20 minutes, and then screwed the donor canister to the top and opened the valve. I would occasionally warm the donor canister by holding it in my hands and gently swirling. The final weight of the donor canisters ranged from 99 g to 104 g, indicating that I was really able to get almost all of the fuel out of the donors.

During the cold months I just place the donor on a ccf pad where direct sunlight through a window hits it indoors for a few minutes. When warmed some it’s ready. I do the rest outside. But most of the time  I don’t do anything with the canisters before the process, just try to be mindful.  You’ll just have to see how it goes for you.

This is a great thread. I just bought one of these little transfer valves and I look forward to being much less wasteful with fuel.

What brand valve do you use? Seems to be a ton of them out there.

Mine says “G Works Outdoor Solution GAS SAVER+”.

What Jerry says about the donor can cooling down is probably relevant.  Unlike Jerry, I don’t try to carry as little fuel as possible.  A 4-oz can weighs about 8 oz when full (i.e., 50% is hardware), so trying to minimize the gas (plus one just-in-case ounce) is, for my money, a lot of effort and potential for running out for at most a 1- or 2-oz weight savings.  So I always fill a small can to capacity before a trip and rarely drain one to empty.

That means I’m rarely transferring a full 4 ounces of fuel, so my donor can probably doesn’t cool down very much.  That may be why I experience more overfilling than Mole J.

Regardless, it takes only a few tries to get the feel for things.

A 4 ounce canister would be marginally enough for a 4 or 5 night trip that I usually go on so I use 8 ounce canister.

This has a bit bigger base so less likely to tip over.  I have had my stove/canister tip over causing the contents of the pot to spill.  But, after doing this once I’m more careful, I would probably do fine with a 4 ounce canister.

8 ounce canister weighs 5 ounces empty, 4 ounce container – 3 ounces, so I’m carrying an extra 2 ounces.

These devices work well, but as has been stated it is critical that you weigh the canisters so you do not overfill them.

I have the Korean-made G-Works gas saver plus, and I had the Campingmoon version, which I recently gave to my brother. They both work, the Korean one has brass inserts on the threading so it would last longer.  But it costs more.  By visual inspection the Campingmoon and the flip fuel are made by the same company in China. I don’t have the flip fuel to compare them to confirm this.

I guess I pushed it a little too far, and at 139 g of fuel in the canister, I got a reverse bulge in the bottom dome. This was accomplished by putting the recipient canister along with the attached valve in the freezer for 20 minutes, and then attaching a room temperature partial 8 ounce canister as the donor. I should have stopped and disconnected a few times to halt the fuel flow at around 100 g total. My valve weighs 15 g and so I can leave it attached to the recipient and just do the math to gauge fuel weight.

Ouch

Thanks for posting the exact weight of the overfilled fuel load that caused the canister to fail. That’s a good illustration for never over filling a canister at all and to keep weighing as one goes.