I picked one up and it's totally worth it. Now I just buy the large canisters and refill my small and medium ones from those. It definitely saves money since the small canisters are only 1$ less expensive than the medium with twice as much gas. Not having to buy small canisters saves a bundle over time.
Thanks for the review. Greatest little gadget to carry on a thru hike. Never have to buy a new canister as all hostels have half filled canisters left behind in the hiker box from previous hikers.
@@derekhand7904 Definitely, I can't believe there are not 15 different options. It would be amazing if you could go to your local gear store for a refill like you do for your propane for your gas grill.
@@mChrest05 No, as there are plenty of tricks you can do… one is to pre mark your (new, full) can with a magic marker where it floats in the water float test. Then just have a bowl, sink, whatever of water nearby at the hostel when your filling up can with gas and check it out with your water test.
You sir, are concise, straight to the point, not clickbaity and not wasting people's valuable time. For that, you earned a sub and thank you. From one outdoor enthusiast to another.
This device is a game-changer! I'm buying one today. Also, sweet Buffalo River shirt! As an Arkansan, I tell all my out-of-state friends about that beautiful river.
Thanks for the video, it corroborated what other videos have shown. In my case in UK a 100g cost £4, 230g cost £5 and a 450g cost £7. So 100g gas from the 450g costs £1.55, so I saved £2.44 per refill. The adapter cost £9.45 meaning it's paid for itself after 4 refills. I use on average 13g/day so 100g = 7 days. I have 2 100g canisters and if trip is shorter I use the partly-used canister and if longer the refilled canister, then swap between them. Advantages: - saves money (in my case after 4 refill). - always carrying a full canister when I want to - e.g. 5 night trip - I don't need to carry either another 100g to be on the safe side. - less waste. True there is still some waste but an empty 450g canister is 190g, an empty 100g is 106g, so there's 60% less landfill by weight. Obviously there's the cost of the accurate scales, in my case was £7 but I use for multiple uses.
*WARNING* These are great little gadgets and I use them myself, but there is a reason why the manufacturers say NEVER REFILL their bottles and its not what you think. Refilling your bottles isnt dangerous because leakage, damage to the valves or any of the other host of reasons people give (although its not impossible). They fail because of physics: Liquid is essentially incompressible. These gas bottles are filled at a certain temperature, rated for certain pressures, and this is all calculated based on normal temperature variations, and *specifically* the ratio of the volume of the cannister and the amount of liquid gas in it. When the cannister heats up, its ok, because there is enough "headspace" for the gas ... so it does not over pressure. If you refill these cans fully, and they start to get hot, they exert a HUGE pressure on the cannister. But if you fill them up to the top whilst they are cold, then just taking them outside starts to overpressure the can..... and a bit of heat, maybe hot direct sunlight, or having heat radiated from the stove, will make these blow like a pipe bomb. When these cans leave the factory they are rated to all kinds of standards, and this is also buffered by the fact that the action of expanding the gas as you use it should COOL the cannister itself. But if you refill a can until its entirely full, then even a small variation in temperature will create a huge spike in PSI which will rupture the can. Since this usually happens during usage... it will be close to a flame. I personally refill them, but I always weigh every can I get and write the net weight on it when it arrives. I also er massively on the side of caution. I would rather have a half full can than a trip to the burns unit. Just be careful guys. If you over fill these cans its one of those scenarios where "its all working perfectly fine until it doesnt".
While people should do what you say, there is a very huge safety margin on these canisters. The bottom blows outward if it reaches high pressure and this adds volume to lower pressure. Obviously if this happens your stove will tip over because now the base is round and not flat, but the risk of these bursting are extremely low unless you continue to use a bulged canister. A canister is more likely to burst if it is dropped and hits a sharp rock than from the internal pressure.
@@DaveSmith-cp5kj NO! I appreciate your kind response and polite manner. That is rare on the internet and I salute you. You are right that there are huge safety margins built in to the canisters, but that is when they are filled correctly. If you fill any gas canister, container or bottle, to 100%, then increase the temperature by 1-2 degrees, then the incompressibility of liquids results in the container rupturing. Ok here is the useful information ...... refilling is fine.... just make sure you only refill any container yourself to 50% capacity. My best wishes to you, your family and your kind
How do you fill them 'to the top', or overfull? No more gas will go into them when the pressure is equalized. The new tank does not have higher pressure than the small ones. I don't believe it is possible to exceed or even match the original pressure doing this. It would need to have a bleed valve opened to displace the volume required to get them overfull.
@@gizzyguzzi I probably didnt explain it well. Basically when you buy one new in the store, the can is only filled to about 60% capacity with liquid gas. They deliberately leave headspace in the can because liquid is incompressible. The "air gap" or technically "gas gap", allows the liquid to expand and contract as it heats up or cools down. (liquids slightly increase volume as they heat up, plus gasses expand when they heat up too.) They only partially fill these cans so to allow a safe margin for increased pressure due to temperature. The classic cannister explosion happens like this.... Someone gets up on a cold morning, goes to their cold shed, and refills a used cannister all the way to the very top, with nice, cold gas. They throw the cannister in their ruck and then head out camping somewhere warm. Because the cannister is totally full, there is no spare room for thermal expansion. So when either hot weather or simply heating the can via cooking, causes the liquid gas to expand, that force is immediately and directly exerted on the can... because there is no gas volume to compress. This results in a very rapid catastrophic failure of the cannister, usually whilst its being used to cook, so it not only explodes but it ignites too. Its a similar principle as freezing bottles of water for a swamp cooler ..... you only ever fill the bottles to about two thirds full so the ice can expand without bursting the bottle. I hope this helps mate.
@@TheWtfnonamez it's a pressure vessel. They don't work that way, unless they fill them and then install the valve somehow. These refills are by pressure. There is no way to exceed the pressure in the other tank regardless of volume. When you fill a small propane bottle from a large propane tank it will not get full, even though the other tank is much larger. Unless there is a pump on the large tank, or a relief valve on the small bottle is opened to allow the 'air' to escape.
Just did this today, exact same device. Did not warm the output, but did chill the input for 10 min. Turned out even 30 seconds was much too long and I had to bleed the input a couple times to get it within spec. This says to me: practice with your gear in your climate and elevation.
It takes practice. I just chill the input too. I find myself weighing the output multiple times to make sure I don’t over do it. Thanks for the comment, see you outside!
If you’re freezing a canister, make sure to put a hot pad or something for thermal insulation on the scale. If the canister cools down the scale, it throws off the zero weight and you won’t get an accurate reading
How do you 'consolidate'? You can only equalize the pressures between 2 bottles. There is no pressure relief valve to allow filling them all the way, right?
Very helpful. Most of my (hammock-)camping is in a local forest, less than twenty miles away, and I ordinarily make a fire and cook on it. On rainy days, I always have an alternate, something I can use under the tarp. To date, it has been an alcohol stove. If you add the weight of the fuel and the stove, a butane stove with fuel is only one ounce heavier, but it is instant heat, rather than the fairly slow rate of alcohol heat. So, for the next year or so, I’ll try the butane, with your suggestion for refills. Thank you for your informative content.
You cannot beat the convenience of a canister. Alcohol will always be lighter. I used to use a MSR Pocketrocket, but now take a weight penalty for a Jetboil.
That is a great little item Mike! Thanks for doing all the numbers and the demo for us. I’ve been sitting on the fence over this but may pull the trigger now. There are some trips that I prefer the quiet of an alcohol stove but these gas stoves are in my arsenal for convenience. Jeff
I usually use canister gas for my JetBoil or Pocketrocket or liquid gas in my Whisperlite. I have a DIY alcohol cat food stove. It works well, but have not relied on it for more than hot chocolate.
thank you, I found a Chinese one online for 5 bucks and it looks exactly the same. I was born and raised in NT near Buffalo. Been out in Utah for 10 years now. Miss Tim Hortons and the Falls! Cheers
Thank you for this informative video. Like you, I am also concern of the environment and budget when hiking/camping. But more importantly peace-of-mind in knowing that I have a full can of fuel left in my cooking repertoire.
Had one of these for a few years now. First time I used it I had watched a video suggesting you put the canisters in the fridge to get the most gas transferred. Mr stupid followed those suggestions and then took stove and canister up a mountain. The bottom of the canister popped out to produce a convex shape., I thought to myself that could have been nasty. Now I transfer the gas in a warm room to avoid this problem. Obviously using scales is a better solution.
That's a great point. Using this device requires knowledge of Boyle's Charles' and Avogadro's Laws. A friend of mine sent me a video of someone who put their canister in boiling water to heat the output. Needless to say, his results were much more extreme than yours. Best is to use weight and stick with that 80% full rule to be safe. See you outside!
@@OutsideChronicles Reminds me of my days training in the Arctic back in the 80s, we had little self priming (no pump) petrol stoves out there and once we had, with great difficulty, got one of them going, we would put the next one on top of the first to get it going. Amazing that we never had a mishap.
That should tell you something. Like perhaps this is not a good idea entirely and there's a reason why they say don't refill these. Use your brain. A new canister only costs a few bucks
Good question, I have only refilled at home. But have heard people on the AT using it to refill. My guess they use the float method as shown on the side of MSR canisters
yeah but there will always be gas left in donor canister once it's going low the pressures equalise so what about all that left over liquid gas each time from the donor canisters? i guess you can put them to use till there empty
Same happens at the end when using it with a burner, right? The pressure is too low to effectively cook. I always pierce them before recycling. There is always some gas left.
@@OutsideChronicles Can you overfill? The stuff going in liquefies, and tops out. Not like say, compressing air into a tank where you could experience "rapid decompression" if you took it too far. Just my theory, don't know for sure. Weighing is to make sure you got enough. Also you can fill empty bottles, BUT, you do not want any air in there. The first step is to remove all air with vac. But since you are refilling a can that is not really empty, it should be OK. However, if you did something whereby you fully emptied the can and it had air in it. Not a good thing to fill it then. Not sure how that would happen, but good to know the principle.
But wouldn’t this just equal out the pressure in both cans? So you could not used two of the same size cans to fill each other? Seems like something that can leave you with a bunch of half full canisters.
Barring the convenience of knowing you have a full canister which enough to but the adaptor. Doesn't this process at some point leave leftover in the larger canister as you get to the end the of the canister, hence wasted, unless you want to go into the woods with a larger canister to use the remainder that cannot be "transferred out to smaller ones? For example: If I buy a larger canister to refill the smaller one, can one ever "empty" the larger canister? Can and should this be used to fill a small fuel canister with household (read BBQ style) propane? Pro/Cons to doing this?
So for the first part, you can get extremely close to empty on the output canister. It gets to a point where even w/o this process, the flame would be unusable. I puncture a hole in the used containers before recycling and there is almost no pressure. As for part 2, I stick with the iso fuel mix. I am not sure how propane differs w/ respect to pressure or performance. Some others have made the same comment.
Great video with detail instructions. Can you refill propane into these isobutane canisters? Camping moon also makes a refill valve allowing you to refill Coleman 1 pound propane canister from a BBQ propane tank which can save lots of money.
Propane only would be a bad idea. You will notice how disposable propane canisters are quite a bit more robust than the isopro ones. That is because propane has a -42C boiling point and butane has a -1C boiling point.
Short answer is no. Long answer the vapor pressure of propane is 122 psi at 70 degrees F. The vapor pressure of Isobutane is 30 psi at 70 degrees F. The vapor pressure of butane is 16 psi at 70 degrees F. MSR uses a 20% Propane 80% Isobutane mix. Cheaper canisters like Coleman use a Propane Butane mix. I could not find what that mix is, my guess is 30% propane, 70% Butane which has a vapor pressure of 45 psi @ 70 degrees F. Propane canisters are constructed out of a thicker gauge steel to withstand the higher pressure. The propane and butane or isobutane mixes have a vapor pressure about half of propane and can be filled into a thinner walled container which is lighter and better suited to backpacking. The problem is that as temperatures drop so does the pressure that is why they don’t perform well at lower temperatures. The other issue is as you use the fuel it has to boil to maintain its vapor pressure this actually lowers the temperature of the fuel which in turn lowers the vapor pressure. You will actually feel the container getting colder. The Isobutane propane mix performs better at lower temps than the butane propane mix but they all have their limits. All of these containers are regulated by the DOT and are not refillable. Meaning it is illegal to transport refilled containers. All the fuels above are classified as liquified gases. When filled in an enclosed container they will liquify when they reach their vapor pressure. White gas is a liquid, it does not create vapor pressure. White gas stoves use a pump in which you pump air into the canister to create pressure. That is why they can be used at low temperatures.
Don't use pure propane as it will burst or explode. Filling the isopro canisters with butane is best as it increases the safety factor of the canister as the vapour pressure of butane much lower. Works great except in cold climates. Butane cans are much cheaper at $1 each where I live in tropics. Use them to fill my isopro canisters.
@@jdhnsn1961 Wow, that was a great post! Thanks for the details. I never quite got the differences between the gasses until now. I refill isobutane with straight butane and just stay aware in fall and winter trips of the limitations and keep it in my sleeping bag during the night. I tend to onky use them at breakfast as in the evening i usualy have a fire. On straight winter trips I go whitegas if not just wood. p.s. I have not tried a stove which holds the canister upsidedown. This suggests its not just a pressure issue but also a vapor vs. liquid fuel issue. I wonder if this is just an issue with separation of gasses in isobutane, i e. so you burn of the butane first thus retaining the 30% propane untill the end and thus better pressure. Or if there are other factors I don't understand. Would be great to find a chart comparing boil times at different temperatures and with inverted canister stoves. I think its time to start digging.
Does it matter if you are filling a Jetboil canister with a Coleman tank? Or should you stick to same brand refills? I'm not sure if the fuel combination from brand to brand differs.
Another thing you can do is weigh a brand new canister and then mark the weight on the bottom with a sharpie. As long as you go under the weight you initially measured it works fine
I believe you actually just fill it up to the gross weight if you canister shows you gross weight. When you don't know the gross weight then you do 80% of net weight, because there will be gas left in you "empty" canister. The gross weight is often not shown or not obvious on canisters.
Not sure if this works for the smaller canisters, but it's a start (just found it, haven't tried it). THere's a link in this video for the adapter. ruclips.net/video/lb0dV-1397c/видео.html
@@sundaymorninghikes6275 don't do it as pure propane has a higher vapour pressure then the original isopro mix in the canister. It could explode. Notice the one pound Coleman propane canister weighs a tonne and is really thick metal? That's why. Butane is the way to go. Notice they come in thin metal cans like hair spray? Going into a isopro canister, butane actually gives you an increased safety factor over isopro 80/20 mix. Drawback is not so great in freezing climates. Works great in warm climates though!
In the UK we can get the cheap canisters that look a bit like the things you used to use to fill gas lighters with, that work in those cheap oblong picnic stoves. It's possible to get the canisters over here with a propane/butane mix. You can find a converter on ebay. This is the cheapest way I have found of refilling screw top canisters. Means you need two converters.
Can I use this method to refill the canister with the bottles of fuel that looks similar to “Spray paint”, I don`t know if I am clear with the description. Thanks
That is where the temperature difference comes into play. I guess there might come a point under some circumstances when it can’t over come 100%. In my experience, it drains the output beyond a usable point.
A pro tip for getting every drop. Put the canister you want to fill in the freezer and put the canister you're trying to fill in the sun (or other mild heat source)
Anyone have success in filing the iso-propane or is it iso-butane? (The ones he shows in this video) canisters (lindal valve) with the 1 lb Coleman propane canisters? I'm familiar with filing my 1 lb propane cans from a 20 lb tank and do it successfully numerous times after cooling the empty and having the big tank in the sun. But I've tried a few times with 2 different lindal valve iso-butane cans and even though everything sounds fine (I hear gas flowing when I open the valve) I get barely any fuel transferred.
I've got the same device. I think it defective. After connecting the canisters and opening the valve - it doesn't transfer anything, it only vents out the port.
@@OutsideChronicles Yep and put the donating canister in hot water too. I also tried this with the butane adapter. The issue is the device itself. I get venting of gas AND fluid from the device's side port without even one drop going into the receiving canister. Its not supposed to vent at all unless you press the side button.
I dunno if it's my altitude or what (3500ft) but after having the empty in the freezer for 30 mins and the full one in the sun for 15 mins (it gets warm) it still takes me 20 seconds to transfer 45g and by then the one getting filled has warmed up, so I toss it back in the freezer and set the other back outside. Then repeat till it weighs full. Can't get it all in one push.
Could be an elevation thing, I am at about 700’. It also depends on the pressure of the output canister. When mine are low, it takes a few cycles to get it all out. Thanks for the comment! See you outside!
@@OutsideChronicles That could have been it too, I didn't weigh the larger cylinder before I grabbed it; could have been a slightly used one. I feel like the people who don't like them don't seem to understand how it uses Dalton's law. By heating/cooling the cylinders you're transferring the most liquid as possible instead of just gas vapor. I have to say I don't understand the advertising picture on amzn that shows the guy in front of the tent with the two same-sized cylinders... it's not that you couldn't use it to transfer some gas in the field, but WHY would you do that??? If you've got a cannister with fuel on it with a tindal thread...screw the dang stove on it and get to cooking! It's really useful to buy larger cylinders at a cheaper price per oz and refill your 100g cannisters with them. I just don't understand people claiming they're for "field" use, I don't see it.
@@syberphish I totally agree, it is not for field use. If you have already carried the canister just use it. Now I did hear of an AT hiker that used it at mail drops to refill his small containers which I thought was pretty smart. I also was sent a video of a canister exploding causing a fire because the guy put the output canister in boiling water. I see this not as a problem with the product but rather a poor grasp of physics.
@@OutsideChronicles In boiling water??? Heck, I get a little spooked just setting it in the sun for 10 mins. 😆 Just pulled out all my iso canisters yesterday. 1 large one, 13 mediums and 5 smalls. Not sure if I thought I was going to wait out the apocalypse with a jetboil or what. Back when Sport Chalet was open out here I'd buy them during sales. That place went out of business years ago but the canisters are still in great shape.
How do you prevent gas from leaking when you separate the canisters from the valve? Mine sprayed a lot of gas each time I separated them to weigh the small one.
Would think you’ll need to close the valve before disconnecting the smaller one. You’ll always have a small bit escape when you disconnect but if it’s spraying out you probably left the valve open.
@@timothyjenkins9247 right, I did close the valve every time before separating the canisters, but still had a lot of gas spray each time I separated them from the valve. It’s as if the valve on the canister doesn’t close fast enough to stop the gas from escaping. I tried to unscrew the valve as fast as I could too.
@@richardlourens1008Sounds like that canister might just be bad. I wouldn’t keep refilling that one. Try another canister and see if you have the same issue.
@@OutsideChronicles For $160 they should include the FUEL BOTTLE for that. You ever check the pressure on a propane tank vs butane? Also, I believe that all metal bottles will handle 120PSI without a problem. a standard 20-pound propane tank at 70 degrees will have 145 psi internal pressure. That same tank on a 100-degree day will have 172 psi of pressure. Isobutane (aka R600a refrigerant) pressue at 70 F is roughly 45psi and at 100F is it roughly 73psi. Aerosol cans (aka isobutane fuel cans) must be rated for 1.5 times the maximum pressure rating for what is inside. Isobutane pressure is roughly 110PSI at 130F. 1.5 times 145 is about 215 at 70F. This is why I said using propane in cold weather would work. Colder it is the lower the pressure. Best probably for when outside temps are below the flashpoint of the isobutane. Or roughly 31F. Which is the dead of winter for many people. I have a bottle top propane stove from Coleman. Single burner. I can use that if necessary. BUT want to keep the option open just in case...
campingmoon is a chinese manufacturer who is making the fake products, you can see their all the products were originally from other brands. of course the quality is not so high. i feel shame about it. for this product, the adapter for lindal valve in order to re-fill by userside, was from the brand g-works. and fyi, from many countries, lpg refilling for one-time-use canisters that is illegal.
The whole reason for the device is to consolidate canisters do you do not take half-full canisters on the trail. It is all in the planning and prep for a trip. Sorry you feel that way.
There is definitely the potential of user error. I have seen this fail with people that do not have a good grasp of physics and that do not follow directions.
@@OutsideChronicles Even if you do it correctly, the tanks are thin-walled and not designed to be refilled. Sure, they might tolerate it a few times (which may be why this recommendation for 80% of capacity) but do a few cycles of filling/emptying and you get metal fatigue which runs the risk of rupture - very bad.
The instructions are in Chinese. There's you sign right there that should tell you if this is a good idea or not. In the words of Michael Jordan, "Stop it! Get some help!"
This is dangeous. Isobutane contains about 20% propane. When a new canister is used in cold weather, most of the isobutane is burnt off leaving mostly propane left. The reason it’s dangerous to then consolidate these 1/4 full canister is because you’re using a temperature differential to force the remaining fuel into a canister. That canister is now filled with mostly propane. Propane has much higher pressures at room temperatures or higher than isobutane. Those canisters are not designed to withstand the pressures of propane in those high percentages. So you risk having a canister burst while using a stove.
So what happens if you don't disconnect until it stops transferring? Seems it will just stop when pressure is equal, and that would be less than original fill. Also, you will never be able to use all the gas from the bigger canister, probably about hlalf of it? So you will need to use it at some point or you are wasting money.
With the temp differential, you can definitely overfill. Also, I have emptied canisters to the point that they are effectively empty. I put a hole in the canister before recycling. You can get to a point where almost nothing comes out.
Doing it this way you will never get an overfull canister. I don't think you'll ever get it back to original fill either. Unless you purge it. There is a valve you can get like the G-Works Gas Saver Plus (R-2) that has a purge valve to let them be filled (or overfilled)
I was able to consolidate all of my gas canisters and now all of my 4oz canisters are FULL. Is this a handy device or too much work?
I picked one up and it's totally worth it. Now I just buy the large canisters and refill my small and medium ones from those. It definitely saves money since the small canisters are only 1$ less expensive than the medium with twice as much gas. Not having to buy small canisters saves a bundle over time.
Thanks for the review. Greatest little gadget to carry on a thru hike. Never have to buy a new canister as all hostels have half filled canisters left behind in the hiker box from previous hikers.
That is cool, I heard this device is popular on thru hikes. That is awesome that there are half full ones you can take advantage of.
That’s genius
@@derekhand7904 Definitely, I can't believe there are not 15 different options. It would be amazing if you could go to your local gear store for a refill like you do for your propane for your gas grill.
So, are you going to carry a little digital scale on the thru hike or just guess the weight? What is the lightest digital scale that would work?
@@mChrest05 No, as there are plenty of tricks you can do… one is to pre mark your (new, full) can with a magic marker where it floats in the water float test.
Then just have a bowl, sink, whatever of water nearby at the hostel when your filling up can with gas and check it out with your water test.
You sir, are concise, straight to the point, not clickbaity and not wasting people's valuable time. For that, you earned a sub and thank you. From one outdoor enthusiast to another.
Thanks for that, see you outside!
This device is a game-changer! I'm buying one today. Also, sweet Buffalo River shirt! As an Arkansan, I tell all my out-of-state friends about that beautiful river.
Love the point about " not filling landfills ", this is important to me..
Thanks, I usually put my used canisters in the recycle bin after hammering a hole in them, but there is no guarantee they actually get recycled.
Thanks for the video, it corroborated what other videos have shown. In my case in UK a 100g cost £4, 230g cost £5 and a 450g cost £7. So 100g gas from the 450g costs £1.55, so I saved £2.44 per refill. The adapter cost £9.45 meaning it's paid for itself after 4 refills. I use on average 13g/day so 100g = 7 days. I have 2 100g canisters and if trip is shorter I use the partly-used canister and if longer the refilled canister, then swap between them.
Advantages:
- saves money (in my case after 4 refill).
- always carrying a full canister when I want to - e.g. 5 night trip
- I don't need to carry either another 100g to be on the safe side.
- less waste. True there is still some waste but an empty 450g canister is 190g, an empty 100g is 106g, so there's 60% less landfill by weight.
Obviously there's the cost of the accurate scales, in my case was £7 but I use for multiple uses.
Thanks for the comment, see you outside!
I do use such a thing for years - even overfilling canisters. Never had a problem. Great vid! Appreciated!
Cool, good to know! See you outside!
CampingMoon sells refillable canisters that are safe to refill also have a minicamister for the lamp...
Thank you for sharing your research
*WARNING*
These are great little gadgets and I use them myself, but there is a reason why the manufacturers say NEVER REFILL their bottles and its not what you think.
Refilling your bottles isnt dangerous because leakage, damage to the valves or any of the other host of reasons people give (although its not impossible).
They fail because of physics: Liquid is essentially incompressible.
These gas bottles are filled at a certain temperature, rated for certain pressures, and this is all calculated based on normal temperature variations, and *specifically* the ratio of the volume of the cannister and the amount of liquid gas in it.
When the cannister heats up, its ok, because there is enough "headspace" for the gas ... so it does not over pressure.
If you refill these cans fully, and they start to get hot, they exert a HUGE pressure on the cannister. But if you fill them up to the top whilst they are cold, then just taking them outside starts to overpressure the can..... and a bit of heat, maybe hot direct sunlight, or having heat radiated from the stove, will make these blow like a pipe bomb.
When these cans leave the factory they are rated to all kinds of standards, and this is also buffered by the fact that the action of expanding the gas as you use it should COOL the cannister itself.
But if you refill a can until its entirely full, then even a small variation in temperature will create a huge spike in PSI which will rupture the can. Since this usually happens during usage... it will be close to a flame.
I personally refill them, but I always weigh every can I get and write the net weight on it when it arrives. I also er massively on the side of caution. I would rather have a half full can than a trip to the burns unit.
Just be careful guys. If you over fill these cans its one of those scenarios where "its all working perfectly fine until it doesnt".
While people should do what you say, there is a very huge safety margin on these canisters. The bottom blows outward if it reaches high pressure and this adds volume to lower pressure. Obviously if this happens your stove will tip over because now the base is round and not flat, but the risk of these bursting are extremely low unless you continue to use a bulged canister. A canister is more likely to burst if it is dropped and hits a sharp rock than from the internal pressure.
@@DaveSmith-cp5kj NO!
I appreciate your kind response and polite manner. That is rare on the internet and I salute you.
You are right that there are huge safety margins built in to the canisters, but that is when they are filled correctly.
If you fill any gas canister, container or bottle, to 100%, then increase the temperature by 1-2 degrees, then the incompressibility of liquids results in the container rupturing.
Ok here is the useful information ......
refilling is fine.... just make sure you only refill any container yourself to 50% capacity.
My best wishes to you, your family and your kind
How do you fill them 'to the top', or overfull? No more gas will go into them when the pressure is equalized. The new tank does not have higher pressure than the small ones. I don't believe it is possible to exceed or even match the original pressure doing this. It would need to have a bleed valve opened to displace the volume required to get them overfull.
@@gizzyguzzi I probably didnt explain it well.
Basically when you buy one new in the store, the can is only filled to about 60% capacity with liquid gas.
They deliberately leave headspace in the can because liquid is incompressible.
The "air gap" or technically "gas gap", allows the liquid to expand and contract as it heats up or cools down.
(liquids slightly increase volume as they heat up, plus gasses expand when they heat up too.)
They only partially fill these cans so to allow a safe margin for increased pressure due to temperature.
The classic cannister explosion happens like this....
Someone gets up on a cold morning, goes to their cold shed, and refills a used cannister all the way to the very top, with nice, cold gas.
They throw the cannister in their ruck and then head out camping somewhere warm.
Because the cannister is totally full, there is no spare room for thermal expansion.
So when either hot weather or simply heating the can via cooking, causes the liquid gas to expand, that force is immediately and directly exerted on the can... because there is no gas volume to compress.
This results in a very rapid catastrophic failure of the cannister, usually whilst its being used to cook, so it not only explodes but it ignites too.
Its a similar principle as freezing bottles of water for a swamp cooler ..... you only ever fill the bottles to about two thirds full so the ice can expand without bursting the bottle.
I hope this helps mate.
@@TheWtfnonamez it's a pressure vessel. They don't work that way, unless they fill them and then install the valve somehow. These refills are by pressure. There is no way to exceed the pressure in the other tank regardless of volume. When you fill a small propane bottle from a large propane tank it will not get full, even though the other tank is much larger. Unless there is a pump on the large tank, or a relief valve on the small bottle is opened to allow the 'air' to escape.
Just did this today, exact same device. Did not warm the output, but did chill the input for 10 min. Turned out even 30 seconds was much too long and I had to bleed the input a couple times to get it within spec. This says to me: practice with your gear in your climate and elevation.
It takes practice. I just chill the input too. I find myself weighing the output multiple times to make sure I don’t over do it. Thanks for the comment, see you outside!
If you’re freezing a canister, make sure to put a hot pad or something for thermal insulation on the scale. If the canister cools down the scale, it throws off the zero weight and you won’t get an accurate reading
Thanks for the tip!
Nice. Very informative. A good reason to pick up and keep used cylinders.
It comes in handy, my only caution is to only reuse the canisters a few times. They are not indestructible. See you outside!
Saw this on the PCT a few years ago. A hiker was consolidating hiker box fuel. I got home and got me one of these for my next long hike.
It’s works good. I only buy med & large canisters now. See you outside!
How do you 'consolidate'? You can only equalize the pressures between 2 bottles. There is no pressure relief valve to allow filling them all the way, right?
@@gizzyguzzi This person was taking what they could out of the ones left behind. Using the fuel they could.
Thanks Mike for your well illustrated video. My adaptor has an overload valve so I'm confidant to leave the filling unattended.
Glad it helped. I just consolidated containers yesterday and recycled the empties. See you outside!
Do you have a link to the one with an overload valve?
Very helpful. Most of my (hammock-)camping is in a local forest, less than twenty miles away, and I ordinarily make a fire and cook on it. On rainy days, I always have an alternate, something I can use under the tarp. To date, it has been an alcohol stove. If you add the weight of the fuel and the stove, a butane stove with fuel is only one ounce heavier, but it is instant heat, rather than the fairly slow rate of alcohol heat. So, for the next year or so, I’ll try the butane, with your suggestion for refills. Thank you for your informative content.
You cannot beat the convenience of a canister. Alcohol will always be lighter. I used to use a MSR Pocketrocket, but now take a weight penalty for a Jetboil.
That is a great little item Mike! Thanks for doing all the numbers and the demo for us. I’ve been sitting on the fence over this but may pull the trigger now. There are some trips that I prefer the quiet of an alcohol stove but these gas stoves are in my arsenal for convenience. Jeff
I usually use canister gas for my JetBoil or Pocketrocket or liquid gas in my Whisperlite. I have a DIY alcohol cat food stove. It works well, but have not relied on it for more than hot chocolate.
@@OutsideChronicles Canister stoves sure do boil water FAST!!
The Best Benefit of many, to me, as long as you have one small canister you'll never have to carry a BIG one for your shorter adventures!
Agree, it is a great little device.
Thank you very much! Did it for the first time and got 192g with my 4oz canister. It was a breeze!
Glad it helped! It’s a great device.
thank you, I found a Chinese one online for 5 bucks and it looks exactly the same. I was born and raised in NT near Buffalo. Been out in Utah for 10 years now. Miss Tim Hortons and the Falls! Cheers
Go Bills!
This makes the canister a much more useful product.
Yes, I love always having full 8oz canisters. See you outside!
Thank you for this informative video. Like you, I am also concern of the environment and budget when hiking/camping. But more importantly peace-of-mind in knowing that I have a full can of fuel left in my cooking repertoire.
Glad it was helpful! See you outside!
FINALLY had a need to use this thing and worked great. Bought it when you posted the video. Wish i had one of these a few years ago!
Cool!
Had one of these for a few years now. First time I used it I had watched a video suggesting you put the canisters in the fridge to get the most gas transferred. Mr stupid followed those suggestions and then took stove and canister up a mountain. The bottom of the canister popped out to produce a convex shape., I thought to myself that could have been nasty. Now I transfer the gas in a warm room to avoid this problem. Obviously using scales is a better solution.
That's a great point. Using this device requires knowledge of Boyle's Charles' and Avogadro's Laws. A friend of mine sent me a video of someone who put their canister in boiling water to heat the output. Needless to say, his results were much more extreme than yours. Best is to use weight and stick with that 80% full rule to be safe. See you outside!
@@OutsideChronicles Reminds me of my days training in the Arctic back in the 80s, we had little self priming (no pump) petrol stoves out there and once we had, with great difficulty, got one of them going, we would put the next one on top of the first to get it going. Amazing that we never had a mishap.
Yup. I had the bottom bubble out on one of my refills a few years ago.
That should tell you something. Like perhaps this is not a good idea entirely and there's a reason why they say don't refill these. Use your brain. A new canister only costs a few bucks
How are you guesstimating weight when you are doing a long hike? Scales aren’t normally brought on hikes. Very cool gadget though.
Good question, I have only refilled at home. But have heard people on the AT using it to refill. My guess they use the float method as shown on the side of MSR canisters
Great video bud very helpful went and bought myself and does the job just fine.
Glad it was helpful and you are finding use for the valve. Thanks for the comment, see you outside!
Love that you did all the math. Nice review!!
Thanks, I hope the calculations are right, I do have a degree in Mathematics. Sometimes simple operations are the most difficult.
yeah but there will always be gas left in donor canister once it's going low the pressures equalise so what about all that left over liquid gas each time from the donor canisters? i guess you can put them to use till there empty
Same happens at the end when using it with a burner, right? The pressure is too low to effectively cook. I always pierce them before recycling. There is always some gas left.
ok@@OutsideChronicles
Thanks for the great video. Does the canister you are filling have to be empty? Or can you refill canisters that are half-full?
The input canister can be empty or partially full, just make sure you know the net and gross weights so you do not over fill.
@@OutsideChronicles thanks!
@@OutsideChronicles Can you overfill? The stuff going in liquefies, and tops out. Not like say, compressing air into a tank where you could experience "rapid decompression" if you took it too far. Just my theory, don't know for sure. Weighing is to make sure you got enough.
Also you can fill empty bottles, BUT, you do not want any air in there. The first step is to remove all air with vac. But since you are refilling a can that is not really empty, it should be OK. However, if you did something whereby you fully emptied the can and it had air in it. Not a good thing to fill it then. Not sure how that would happen, but good to know the principle.
@@HondoTrailside How would air get into it?
Neat. I came over from MyLifeOutdoors.
Welcome, MyLifeOutdoors is great, I subscribe to his channel. I hope you enjoy my content, see you outside!
Do you ever keep canisters in your vehicle in the summer?
Probably not the best idea, Charles’ Law and all.
Hi Mike. You said 211g - 22g = 189g but the caption at 2:11 reads 211g - 88g = 189g. Really helpful video by the way! 👍
Nuts, I did not notice that. 211-22=189 is the correct math.
Question! you can only equalize the 2 canisters or can you actually more or less empty the bigger one ?
REALLY GOOD info sir!!
But wouldn’t this just equal out the pressure in both cans? So you could not used two of the same size cans to fill each other? Seems like something that can leave you with a bunch of half full canisters.
This is why you need a temp differential between canister, see Charles Law. Gravity also helps.
Barring the convenience of knowing you have a full canister which enough to but the adaptor.
Doesn't this process at some point leave leftover in the larger canister as you get to the end the of the canister, hence wasted, unless you want to go into the woods with a larger canister to use the remainder that cannot be "transferred out to smaller ones?
For example: If I buy a larger canister to refill the smaller one, can one ever "empty" the larger canister?
Can and should this be used to fill a small fuel canister with household (read BBQ style) propane? Pro/Cons to doing this?
So for the first part, you can get extremely close to empty on the output canister. It gets to a point where even w/o this process, the flame would be unusable. I puncture a hole in the used containers before recycling and there is almost no pressure.
As for part 2, I stick with the iso fuel mix. I am not sure how propane differs w/ respect to pressure or performance. Some others have made the same comment.
Great video with detail instructions. Can you refill propane into these isobutane canisters? Camping moon also makes a refill valve allowing you to refill Coleman 1 pound propane canister from a BBQ propane tank which can save lots of money.
I do not have experience using propane only in the isopro canisters. I have always refilled using the isobutane and propane mix.
Propane only would be a bad idea. You will notice how disposable propane canisters are quite a bit more robust than the isopro ones. That is because propane has a -42C boiling point and butane has a -1C boiling point.
Short answer is no.
Long answer the vapor pressure of propane is 122 psi at 70 degrees F. The vapor pressure of Isobutane is 30 psi at 70 degrees F. The vapor pressure of butane is 16 psi at 70 degrees F. MSR uses a 20% Propane 80% Isobutane mix. Cheaper canisters like Coleman use a Propane Butane mix. I could not find what that mix is, my guess is 30% propane, 70% Butane which has a vapor pressure of 45 psi @ 70 degrees F.
Propane canisters are constructed out of a thicker gauge steel to withstand the higher pressure.
The propane and butane or isobutane mixes have a vapor pressure about half of propane and can be filled into a thinner walled container which is lighter and better suited to backpacking.
The problem is that as temperatures drop so does the pressure that is why they don’t perform well at lower temperatures. The other issue is as you use the fuel it has to boil to maintain its vapor pressure this actually lowers the temperature of the fuel which in turn lowers the vapor pressure. You will actually feel the container getting colder. The Isobutane propane mix performs better at lower temps than the butane propane mix but they all have their limits.
All of these containers are regulated by the DOT and are not refillable. Meaning it is illegal to transport refilled containers.
All the fuels above are classified as liquified gases. When filled in an enclosed container they will liquify when they reach their vapor pressure.
White gas is a liquid, it does not create vapor pressure. White gas stoves use a pump in which you pump air into the canister to create pressure. That is why they can be used at low temperatures.
Don't use pure propane as it will burst or explode. Filling the isopro canisters with butane is best as it increases the safety factor of the canister as the vapour pressure of butane much lower. Works great except in cold climates. Butane cans are much cheaper at $1 each where I live in tropics. Use them to fill my isopro canisters.
@@jdhnsn1961 Wow, that was a great post! Thanks for the details. I never quite got the differences between the gasses until now. I refill isobutane with straight butane and just stay aware in fall and winter trips of the limitations and keep it in my sleeping bag during the night. I tend to onky use them at breakfast as in the evening i usualy have a fire. On straight winter trips I go whitegas if not just wood.
p.s. I have not tried a stove which holds the canister upsidedown. This suggests its not just a pressure issue but also a vapor vs. liquid fuel issue. I wonder if this is just an issue with separation of gasses in isobutane, i e. so you burn of the butane first thus retaining the 30% propane untill the end and thus better pressure. Or if there are other factors I don't understand. Would be great to find a chart comparing boil times at different temperatures and with inverted canister stoves. I think its time to start digging.
Great video. NEVER EVER REFILL THESE CANISTERS WITH PROPANE. Propane has a lot more pressure, that’s why propane bottles are ALOT THICKER.
Thanks, several people suggested that. I stick to iso-butane. I fill like with like. See you outside!
Does it matter if you are filling a Jetboil canister with a Coleman tank? Or should you stick to same brand refills? I'm not sure if the fuel combination from brand to brand differs.
Just make sure you are using the same type of fuel, isobutane with isobutane. I have mixed MSR and Olicamp without issue.
Same factory, different label. Not too different from so much of what we purchase.
Excellent video! Thanks for the info!
Thanks and my pleasure, see you outside!
Thank you for this info! Picking one up today!
Outstanding, glad the video helped! Thanks for watching!
How long does it take to transfer?
It depends, you may have to do two or three freezer cycles if your input is empty. But the actual gas transfer is only a minute.
often, the 227g "spraycan" are the cheapest. grab an adapter for these
Another thing you can do is weigh a brand new canister and then mark the weight on the bottom with a sharpie. As long as you go under the weight you initially measured it works fine
Great suggestion, I have several canisters with sharpie marks on them with grams. I wish they all had net and gross like MSR.
Most helpful... Thanks for posting.. liked and subscribed....I look forward to further videos you may do...
Thanks for the sub! Glad the video helped out, just do't overfill (or overheat) and it works great. See you outside!
Can I use this plus 2 propane adaptors to consolidate my 1lb propane canisters?
Does anyone out there know if you can top off your fuei canister w/ butane? Not planning on using it in cold weather.
Awesome! Thank you so much for this!
My pleasure, see you outside!
great tip. thanks for sharing
It works awesome.
is it too difficult to find a gas canister in your place so it has to be refilled? Manufacturers usually ask not to refill
I suggest actually listening to what he says in the video.
Thanks for the video!
I believe you actually just fill it up to the gross weight if you canister shows you gross weight.
When you don't know the gross weight then you do 80% of net weight, because there will be gas left in you "empty" canister.
The gross weight is often not shown or not obvious on canisters.
Yeah, each manufacturer labels it slightly different. It would be smart to weigh them before even using them.
great video, however, I paid 4 x amount for my msr fuel , then shipping...would love to be able to refill thru my propane tank?
I’m not sure, there are adaptors to go from a grill propane tank to the green Coleman camping propane tanks. There might be a way to step it down.
Not sure if this works for the smaller canisters, but it's a start (just found it, haven't tried it). THere's a link in this video for the adapter.
ruclips.net/video/lb0dV-1397c/видео.html
@@sundaymorninghikes6275 don't do it as pure propane has a higher vapour pressure then the original isopro mix in the canister. It could explode. Notice the one pound Coleman propane canister weighs a tonne and is really thick metal? That's why. Butane is the way to go. Notice they come in thin metal cans like hair spray? Going into a isopro canister, butane actually gives you an increased safety factor over isopro 80/20 mix. Drawback is not so great in freezing climates. Works great in warm climates though!
@@ebikecnx7239 Good to know. Thank you!
In the UK we can get the cheap canisters that look a bit like the things you used to use to fill gas lighters with, that work in those cheap oblong picnic stoves. It's possible to get the canisters over here with a propane/butane mix. You can find a converter on ebay. This is the cheapest way I have found of refilling screw top canisters. Means you need two converters.
Worth it just to clear up part filled canisters
You bet, just do not overfill! Thanks for watching!
Can I use this method to refill the canister with the bottles of fuel that looks similar to “Spray paint”, I don`t know if I am clear with the description. Thanks
They make adapters for other types of canisters, like the Coleman propane ones.
money savings - meh. pack weight savings and convenience - yes please. great video!
Thank you! See you outside!
Can also be bought on Ali for 6 bucks.
What happens when the top tank doesn't have more pressure than the bottom tank? Just a question
That is where the temperature difference comes into play. I guess there might come a point under some circumstances when it can’t over come 100%. In my experience, it drains the output beyond a usable point.
A pro tip for getting every drop.
Put the canister you want to fill in the freezer and put the canister you're trying to fill in the sun (or other mild heat source)
That works, do not overheat the canister. One guy did not have a good grasp of physics, boiled it and it exploded. He gave a negative review.
@OutsideChronicles
I'd doesn't take much a temperature difference to make it work very well.
I love seeing the Footstuff sticker
Love those guys and love the Adirondacks. Thanks for noticing. I will feel like I made it when I am invited to be their guest. See you outside!
Anyone have success in filing the iso-propane or is it iso-butane? (The ones he shows in this video) canisters (lindal valve) with the 1 lb Coleman propane canisters? I'm familiar with filing my 1 lb propane cans from a 20 lb tank and do it successfully numerous times after cooling the empty and having the big tank in the sun.
But I've tried a few times with 2 different lindal valve iso-butane cans and even though everything sounds fine (I hear gas flowing when I open the valve) I get barely any fuel transferred.
Super cool! Took two partial canisters last weekend. You have a new fan 💕
Awesome! Thank you! See you outside!
I've got the same device. I think it defective. After connecting the canisters and opening the valve - it doesn't transfer anything, it only vents out the port.
Did you cool the input canister in the freezer for 30 mins?
@@OutsideChronicles Yep and put the donating canister in hot water too. I also tried this with the butane adapter. The issue is the device itself. I get venting of gas AND fluid from the device's side port without even one drop going into the receiving canister. Its not supposed to vent at all unless you press the side button.
@@Roarmeister2 Send it back. The device works as expected. Sounds like you got a defected one.
@@OutsideChronicles $5 from China. It would cost me more in postage than its worth! 🤣😁
I purchased another one (different brand and design). This one worked like a charm.
I dunno if it's my altitude or what (3500ft) but after having the empty in the freezer for 30 mins and the full one in the sun for 15 mins (it gets warm) it still takes me 20 seconds to transfer 45g and by then the one getting filled has warmed up, so I toss it back in the freezer and set the other back outside. Then repeat till it weighs full. Can't get it all in one push.
Could be an elevation thing, I am at about 700’. It also depends on the pressure of the output canister. When mine are low, it takes a few cycles to get it all out. Thanks for the comment! See you outside!
@@OutsideChronicles That could have been it too, I didn't weigh the larger cylinder before I grabbed it; could have been a slightly used one.
I feel like the people who don't like them don't seem to understand how it uses Dalton's law. By heating/cooling the cylinders you're transferring the most liquid as possible instead of just gas vapor.
I have to say I don't understand the advertising picture on amzn that shows the guy in front of the tent with the two same-sized cylinders... it's not that you couldn't use it to transfer some gas in the field, but WHY would you do that??? If you've got a cannister with fuel on it with a tindal thread...screw the dang stove on it and get to cooking!
It's really useful to buy larger cylinders at a cheaper price per oz and refill your 100g cannisters with them. I just don't understand people claiming they're for "field" use, I don't see it.
@@syberphish I totally agree, it is not for field use. If you have already carried the canister just use it. Now I did hear of an AT hiker that used it at mail drops to refill his small containers which I thought was pretty smart. I also was sent a video of a canister exploding causing a fire because the guy put the output canister in boiling water. I see this not as a problem with the product but rather a poor grasp of physics.
@@OutsideChronicles In boiling water??? Heck, I get a little spooked just setting it in the sun for 10 mins. 😆
Just pulled out all my iso canisters yesterday. 1 large one, 13 mediums and 5 smalls. Not sure if I thought I was going to wait out the apocalypse with a jetboil or what. Back when Sport Chalet was open out here I'd buy them during sales. That place went out of business years ago but the canisters are still in great shape.
@@syberphish Enjoy! genxbackpacker.com/penny-wise-and-pound-foolish
Good job 👍
Thanks! And thank you for watching.
How do you prevent gas from leaking when you separate the canisters from the valve? Mine sprayed a lot of gas each time I separated them to weigh the small one.
Would think you’ll need to close the valve before disconnecting the smaller one. You’ll always have a small bit escape when you disconnect but if it’s spraying out you probably left the valve open.
Yes, there is always a little. You even get some just screwing it on.
@@timothyjenkins9247 right, I did close the valve every time before separating the canisters, but still had a lot of gas spray each time I separated them from the valve. It’s as if the valve on the canister doesn’t close fast enough to stop the gas from escaping. I tried to unscrew the valve as fast as I could too.
@@richardlourens1008Sounds like that canister might just be bad. I wouldn’t keep refilling that one. Try another canister and see if you have the same issue.
bought it for 6 in aliexpress
I would just want to refill with propane. Or actually top off with propane.
Don't know any place that sells 20 pound bottles of butane/isobutane.
It is not advisable to refill with propane. Propane canisters are usually thicker walled…for a reason.
@@OutsideChronicles In cold temperatures the pressure would be lower.
@@crazysquirrel9425 agreed, I not willing to chance it. I prefer to move to white gas in winter with a Whisperlite.
@@OutsideChronicles For $160 they should include the FUEL BOTTLE for that.
You ever check the pressure on a propane tank vs butane?
Also, I believe that all metal bottles will handle 120PSI without a problem.
a standard 20-pound propane tank at 70 degrees will have 145 psi internal pressure. That same tank on a 100-degree day will have 172 psi of pressure.
Isobutane (aka R600a refrigerant) pressue at 70 F is roughly 45psi and at 100F is it roughly 73psi.
Aerosol cans (aka isobutane fuel cans) must be rated for 1.5 times the maximum pressure rating for what is inside.
Isobutane pressure is roughly 110PSI at 130F.
1.5 times 145 is about 215 at 70F.
This is why I said using propane in cold weather would work.
Colder it is the lower the pressure.
Best probably for when outside temps are below the flashpoint of the isobutane.
Or roughly 31F.
Which is the dead of winter for many people.
I have a bottle top propane stove from Coleman. Single burner.
I can use that if necessary.
BUT want to keep the option open just in case...
nice video
Thanks, see you outside!
campingmoon is a chinese manufacturer who is making the fake products, you can see their all the products were originally from other brands. of course the quality is not so high. i feel shame about it.
for this product, the adapter for lindal valve in order to re-fill by userside, was from the brand g-works.
and fyi, from many countries, lpg refilling for one-time-use canisters that is illegal.
Thanks for the great information. This is exactly what I wanted to find!
Glad it was helpful! See you outside!
211-88=189? 🤔
Yeeesssssss
This video is not practical. What do you do when you are on the trail?
The whole reason for the device is to consolidate canisters do you do not take half-full canisters on the trail. It is all in the planning and prep for a trip. Sorry you feel that way.
I hope you don’t have a job in logistics!
This is potentially SO risky. Not worth it. Just bring the extra can with you and use it up.
There is definitely the potential of user error. I have seen this fail with people that do not have a good grasp of physics and that do not follow directions.
@@OutsideChronicles Even if you do it correctly, the tanks are thin-walled and not designed to be refilled. Sure, they might tolerate it a few times (which may be why this recommendation for 80% of capacity) but do a few cycles of filling/emptying and you get metal fatigue which runs the risk of rupture - very bad.
The instructions are in Chinese. There's you sign right there that should tell you if this is a good idea or not.
In the words of Michael Jordan, "Stop it! Get some help!"
This is dangeous. Isobutane contains about 20% propane. When a new canister is used in cold weather, most of the isobutane is burnt off leaving mostly propane left. The reason it’s dangerous to then consolidate these 1/4 full canister is because you’re using a temperature differential to force the remaining fuel into a canister. That canister is now filled with mostly propane. Propane has much higher pressures at room temperatures or higher than isobutane. Those canisters are not designed to withstand the pressures of propane in those high percentages. So you risk having a canister burst while using a stove.
Been doing this for a couple of years. You should watch the video because bro explains it at 2:05
Never had an issue.
Refill with cheap Butane 👍
So what happens if you don't disconnect until it stops transferring? Seems it will just stop when pressure is equal, and that would be less than original fill.
Also, you will never be able to use all the gas from the bigger canister, probably about hlalf of it? So you will need to use it at some point or you are wasting money.
With the temp differential, you can definitely overfill. Also, I have emptied canisters to the point that they are effectively empty. I put a hole in the canister before recycling. You can get to a point where almost nothing comes out.
Doing it this way you will never get an overfull canister. I don't think you'll ever get it back to original fill either. Unless you purge it. There is a valve you can get like the G-Works Gas Saver Plus (R-2) that has a purge valve to let them be filled (or overfilled)