Thursday, January 19, 2012

Refilling Gas Canisters

I refill my own gas canisters.  This procedure is not recommended by any manufacturer.  There may also be certain legal sanctions against refilled canisters.  I'm not a lawyer, but my understanding is that in the US refilled canisters may not be transported across state lines and that refilled canisters may not be sold.

There are certain dangers that go along with using gas, even if you're using your stove in exactly the manner prescribed by the manufacturer.  Gas is flammable.  Gas can explode.  Know and understand the dangers before working with gas.

If one chooses to refill his or her own canisters, there are certain additional dangers including but not limited to:
  1. Overfilling.  If you fill a gas canister beyond it's stated capacity, the internal pressure may cause the canister to leak, burst, or explode.
  2. Gas leaks.  Gas may escape during refilling with or without equipment failures or malfunctions.  Such gas could ignite or explode.  Leaking gas can also be very very cold, and cold injuries could result.
  3. Damage to valve or threads.  The valve or threads could become damaged or worn during refilling.  No problem may occur during the refilling itself, but the damaged threads or valve could be hazardous later on.
  4. Refilling with gases with too high a vapor pressure.  Canisters come with a specific mix of gases.  If one were to refill with different gases or a different mix of the same gases, the vapor pressure of the resultant mix might exceed the strength of the canister.   Do NOT fill backpacking type canisters with 100% propane under any circumstances.
Clearly, there are dangers to canister refilling.  If you choose to refill gas canisters, you are making a decision to engage in a practice that you know to be dangerous.  If you of your own free will choose to engage in a practice that you know to be dangerous, don't blame me or anyone else for your choices.

That said, I will describe how I refill canisters.  I will also describe what steps I take to partially mitigate the dangers of refilling, but understand that no matter how safe your procedures are, refilling gas canisters is by its very nature dangerous.  You might be able to somewhat reduce the danger, but refilling is dangerous no matter what.

Step one is of course to get an empty canister.  Today, I'm going to refill a Coleman brand standard threaded 220g canister.
A Coleman brand 220g standard threaded gas canister.
The first step in refilling is to weigh the canister.  Why weigh the canister?  I weigh the canister to establish a maxium full weight.  You do NOT want to overfill the canister.  The best practice is to weigh the full canister when you first bring it home from the store.   The weight of the full canister when you bring it home from the store should be considered the maximum full weight.  

What if I forgot to weigh the canister when it was new?  Well, if you weigh the canister when it is empty and then add the capacity of the canister, in this case 220g, then you should also be able to determine the maximum full weight of the canister.
The empty weight of a Coleman 220g canister is approximately 143g 
The empty weight of a Coleman brand 220g canister is 143g.  The capacity is 220g.  Therefore, the maximum full weight is 363g.  Do NOT exceed the maximum full weight when you refill.  If you exceed this weight, the pressure inside the canister may exceed the strength of the canister.  If the canister leaks, bursts, or explodes, very serious injuries could result.  Do NOT exceed the maximum full weight of the canister.

Next, I mark the weights on the canister.  I tend to lose slips of paper, so I mark the canister itself.
The empty and full weights, marked directly on the canister.
Next, I mark the canister as refilled by writing an "R" on the bottom of the canister.  I then put a hash mark next to the "R" every time I refill the canister.  One hash mark indicates one refill, two hash marks indicates two refills, and so on.  
An "R" on the bottom of the canister indicates that the canister has been refilled.  Hash marks indicate the number of refills.  This canister has been refilled one time.
Eventually the valve may become weakened with use.  After I've refilled a canister 12 times, I take the canister to the recycling center.  Twelve is an arbitrary number, but it is a relatively low number.  So far twelve has been a safe number.  I visually inspect the canister and threads/valve before refilling. If it looks bad, it is bad, and it goes in the recycle bin.

Now, after all that, I take out my refiller.
A refiller for standard threaded gas canisters.
I bought this refiller via eBay seller world_wide_2009 who apparently is in Japan.  I believe I paid $37.00 USD for the refiller.  I've had the refiller for at least two years.  With this somewhat expensive but high quality refiller, I feel like there is a) a reduced risk of damaging the threads or valve on a receiving canister, and b) very little gas leaks -- about the same amount as would normally leak when hooking up or unhooking a stove.  Very little in other words.  I've seen lots of scary looking homemade rigs of questionable quality.  I personally would rather pay the extra money and do it right. 

The instructions that came with the refiller were in Japanese but did include helpful pictograms.  Notice that I have the weight written on the refiller itself (88g).  While I'm in the process of refilling, I can weigh the canister without removing the refiller.  I just subtract 88g from the weight displayed on the scale in order to know the weight of the canister I'm in the process of refilling.

Note in the above photo that the connector shown attaches to a standard threaded backpacking type canister.  What does the other side connect to?
This side of the refiller connects to 100% butane canisters.
The opposite side of the refiller connects to the inexpensive 100% butane canisters of the type used in the restaurant industry.  Why butane?  Well, first butane is cheap.  If you're going to do your own refills, then you'd better have a source of gas cheaper than backpacking canisters.  If your refill gas isn't cheaper, why would you refill?  You'd just go buy the regular backpacking gas.  In my area, 227g of butane is $1.25 USD.  Backpacking canisters are about $5.00 for 110g or $6.00 for 220g.  100% butane is far cheaper.  Personally, I use 110g canisters more than any other size.  With refilling, I'm in effect paying $0.63 per 110g canister.  If you saw perfectly good 110g canisters on sale for $0.63, wouldn't you pick a few up?  I bet most people would.  My canisters are always on sale for $0.63.  I never hesitate to take out the gas stove whether on a day hike or a backpacking trip.  You want another cup of coffee?  Sure!  Why not?  How about two?  I rather like having an abundant source of cheap gas.  YMMV.  Each to his or her own.

Second, butane is relatively safe.  Pick up one of those little clear plastic cigarette lighters some time.  Hold it up to the light.  That clear liquid you see in there is butane.  Of the gases commonly used for backpacking canisters, butane has the lowest vapor pressure.  If that little cheap plastic lighter can hold the pressure of butane, your steel backpacking canister certainly can.  No matter what mix originally came in your backpacking canister, butane will have a lower vapor pressure.  Butane is pretty safe to use for refilling.  Do NOT fill backpacking type canisters with 100% propane under any circumstances.

The next step in refilling is to hook everything up.  First I screw the refiller onto the receiving canister.
The refiller screwed on to an empty 220g backpacking type gas canister
Next, I hook up the donating butane canister.  The larger hook on the connector clips onto the collar on the butane canister.
The collar on the butane canister clips on to the larger of the two hooks on the connector of the refiller.
The smaller of the two hooks on the refiller's connector slips through the notch on the collar of the butane canister.
The smaller of the two hooks on the refiller goes through the notch on the butane canister's collar.
The canister is then rotated to the right approximately 1/16th of a turn, locking the canister into the connector on the refiller.
The butane canister turns to the right and locks in place.
When all is said and done, the rig looks like this:
A refiller all hooked up and ready to transfer fuel.
Now, simply open the valve, and gravity will do the work for you.  The liquid butane in the donor canister will flow into the receiving canister.  Recall though that there is one complication:  There is a vapor feed tube inside the canister.
There is a plastic vapor feed tube inside the butane canister.
That tube aligns with the notch in the collar of the butane canister.   For maximum transfer, you want to tilt the canister at a bit of an angle with the notch on the collar of the butane canister pointing down
Prop the canister at a steep angle as shown with the notch pointing down.
The transfer is very slow.  Normally, I set it up and then go about my business.  I check it after a couple of hours.  The vapor feed tube appears to vary slightly brand to brand.  As a purely practical matter, MegaOne gas seems to be the easiest brand to transfer gas from.  GasOne is a bit more tricky.  Sometimes I've had to chill the receiving canister and warm the donating canister to get it to work right.  Each canister brand has a "sweet spot," that is an angle where the transfer works best.  You'll just have to experiment with that.  I've tried three different brands of butane thus far.  I've always been able to get it to work although some brands require more fiddling than others.

Since I'm writing a blog post, I don't want to wait a couple of hours for my results, so I'll just detach the refiller now and weigh it after only a few minutes.  Recall that our receiving canister weighed 143g when empty. 
The canister now weighs 184g
Not the world's clearest photo, but the canister now weighs 184g, a gain of 41g in just a few minutes.  I notice that there's typically a rush of gas when I first open the valve, and then a very very slow bubbling after that.  I can only hear the slow bubbling if I physically press my ear up to the donating canister.  When using a slow gravity feed like this, I haven't had a lot of problems with overfilling, but remember to periodically check the canister, especially with the small 100g class canisters.  When filling a 220g canister from a 227g canister, there is no worry of any significant overfilling.  I often leave 220g canisters hooked up overnight and simply unhook them in the morning.  The transfer is never 100%.  The donating canister almost always has at least a few grams of gas left behind.  Such is life.

NOTE:  These photos were all taken indoors where the light is good.  I typically refill outdoors where vapors cannot build up and there are no sources of ignition.

That's it.  That's how to refill canisters.  Remember, no matter how you go about it, refilling is innately dangerous.  Refill at your own risk.

Thanks for joining me on another Adventure in Stoving,


Appendix -- Advantages and Disadantages of Refilling

1.  Lower cost in the long run.
2.  Custom filling.  If I am going on a trip where I'll need 140g of gas, I fill my canister to 140g and stop.  I do not need to carry a full 230g canister.  Weight savings: 70g.
3.  Topping off.  Say I come back from a trip with a canister with only 25g left.  Before I had a refiller, that gas would just sit on a shelf with no real value to me.  25g is too little to bother with.  Now, I just top off the canister, and the canister is as useful to me as the day I bought it.
4.  Reduced environmental impact.  Reusing anything reduces one's overall impact on the environment.  Yes, canisters can (and should!) be recycled, but recycling has environmental costs.  Yes, recycling is better than the landfill, but there are transport, processing, re-manufacturing, and distribution costs associated with recycling.  Yes of course I have the empty butane canister to deal with after refilling, but I'm primarily refilling the small 110g canisters from the larger 227g butane canisters.  I'm therefore reducing the overall number of waste canisters.  Ideally, I'd like to find an even bigger canister to refill from, but that opportunity has so far failed to materialize.

1.  "Fiddle" factor.  You have to spend some time to refill the canisters.  Of course, any such fiddle is done in advance.  There is zero extra fiddle out on the trail.  I much prefer filling in advance over using an adapter out on the trail.
2.  Butane is only good for warm weather use.  100% butane is only good so long as the fuel stays above about 40F/5C.  If the fuel gets colder than 40F/5C, then your stove will have lackluster performance.  I personally do the majority of my backpacking and hiking in warmer weather, so this is not an inconvenience to me.


  1. I have thought about doing this in the past, but for no other reason than the fact that it annoys me to have all that metal being used for a canister. And while I punch holes in mine after I use them (thank you jetboil for that nifty tool!) and I am able to recycle them, I often wonder if they actually do end up getting recycled.

    But if all I would be doing is moving fuel from one metal container to another metal container, I suppose it somewhat negates the whole plan of mine.

  2. Ah, now that's a good point, although I refill my 100g backpacking canisters from 227g butane canisters. I'm therefore reducing the amount being landfilled by 50%. (two butane = one backpacking canister)

  3. The big danger in refilling disposable containers is moisture. Water entering the receiving container could cause corrosion of the relatively thin wall of the canister. It is easier to refill canisters when you put the receiving canister in the freezer for a while so that it gets cold. The donor canister is left at room temperature. When you mate the two, the donor fluid fills the empty canister rather quickly, due to the difference in vapor pressure between the two canisters. You still want to be careful about moisture, since you can get condensation on the cold canister. You can also do this by putting the receiving canister in a bucket of ice.

  4. The adapters are still listed, but the price has gone up to $53.

  5. Even at $53 it still seems to be very economical. Where do you buy the donor butane from at a good price?

    As to it being dangerous, show me something that inherently isn't, including backpacking itself. Unless of course, one does it correctly. Plans ahead, checks the weather, always carries the ten essentials etc. The point being that if done correctly, responsibly and intelligently, we can mitigate the danger to an acceptable level.

    As to the fiddle factor, looking forward to, and getting ready for a trip and the anticipation is part of the enjoyment. At least for me.

    But the two biggest advantages I see are the potential cost savings, and perhaps most importantly, actually always being able to start a trip with a full can, and not having to worry about if I have enough left over in my many (sometimes) partial cans. That is the very reason why I usually have hiked with just white gas, simply because I can be sure of exactly how much I have at any one time. Even despite it’s drawbacks of always having to prime, possibility of spills while transferring fuel , fussing with a pump etc.

    It never even occurred to me that this was possible. I think this is great. This has really inspired me!! Thanks for pointing out this idea Jim, You write a great blog!!


  6. Hi, Bill,

    Yes, moisture is definitely a concern. I actually visually inspect the canister and valve before refilling. If it looks bad, it is bad, and it goes in the recycle bin.

    The rig that is currently on eBay is a slightly different set up than the one I got. The one currently on eBay also includes not just the refiller, but also an adapter that will allow one to hook appliances like the gas lantern shown to a cheap butane canister. The rig I purchased is less expensive.

    HOWEVER, the dollar to yen exchange rate has changed unfavorably if one is in the US. I'm sure that my cheaper rig is now more than $37.00.


  7. This comment has been removed by the author.

  8. "The point being that if done correctly, responsibly and intelligently, we can mitigate the danger to an acceptable level."

    Exactly, Larry, exactly.

    These butane canisters are available at restaurant supply stores. I imagine CostCo or WalMart may carry them, although I haven't checked. There's a Dollar Store near me that carries them for a dollar. Cheap!

    I also find them in grocery stores that cater to Asians. There's a Korean market near me that sells a four pack for $5.00.


  9. Bill,

    I've topped off a lot of partial canisters of isobutane/propane. As you say, it works, but sometimes I've had to chill the receiving canister.

    Also, as you say, one could transfer other mixes if one had a different adapter. Be very careful though. 100% butane is the safest to transfer. As soon as you start talking about other gases and mixes, the dangers increase. I'm not saying don't do it. Just be very careful. Mixes are tricky. You cannot predict the vapor pressure by simply knowing the relative percentages of the constituent gasses by weight. The formula and the mathematics are QUITE a bit more complex.


  10. My thinking on mixes had to do with topping off canisters with the same mix in each. After re-reading your post, I realized that you had covered this subject and I really wasn't adding anything to what you had already said.

  11. Hi, Bill,

    No problem. You've given me a lot of good feedback. And this was a pretty meaty post.


  12. On the subject of scary refill adapters, here's another interesting one at DealExtreme. This one seems to go from a standard "bbq-type" LPG cylinder to a Lindal valve. The reading up I have done indicates that, at least in Australia, propane is used to fill LPG cylinders of the type typically used for BBQs - it would then be a vary bad idea to top up a hiking canister that way! In reality, this adapter may be more interesting to cut down into parts.

  13. Hi, Jim!
    I want to add a bit about moisture.

    To get rid of the moisture in receiving canister simlply do the next steps before and after refilling.
    1. Make sure you are in good ventilated area and there is no fire around.
    2. Turn the canister upside down.
    3. Wait 3 min
    4. Open the valve of a canister just for a moment by pressing it with a cuted toothpcik.

    All the moister will be pushed out by gas pressure.

    It works fine for me.

  14. Hi, Geoff,

    Yes, that is scary. It appears to mate with a large propane tank. 100% propane. Put that into a thin-skinned backpacking canister, and you could have a very serious problem. It would be like having a bomb in your backpack. NOT GOOD.


  15. AntonPro,

    Now that's a very interesting idea about purging moisture. I'll have to experiment with that.


  16. I have experimented a little with refilling, and learned by reading and experience.

    The overfilling hazard may be the main reason to not make this legal in all states. Leave approx 20% of the volume for expansion. The lindal valve may leak if dirt enters, don't refill a container if its not "good as new" Pure propane has to high pressure, and may make it to a bomb. The valve contains rubber-like seal, and it may be brittle, so even old, unused canisters may leak after first use.
    Use your oldest canisters first, and refill to the the newest if they are with the valve you need.


  17. Hi, dsk,

    Good comments all. I so far haven't tried to refill with propane at all. With propane, the pressures -- and the risks -- are much higher.

    Good advice to use the older canisters first.


  18. I guess this tells about the pressure and mix of propane butane: http://is.gd/sQ7laW
    (from this page: http://is.gd/bqVUwY )

  19. Ah. Good diagram. And now it can be seen why I think filling with 100% butane is relatively safe. 100% butane has the lowest vapor pressure.


  20. This was extremely helpful, just what I was looking for—thanks!

    However I cannot find the refill adapter on ebay. Any suggestions?

    I saw the japanese website http://www.alva.ne.jp/ but it seems to be meant for locals. If all else fails I'll try to have friends from Japan acquire it for me.

  21. I have made my adapters from old stove parts.

    1. If one is handy, that is an excellent option. The ones from Japan are good, but they are expensive.


  22. There is a refiller available on eBay right now. This is the same refiller as I have except that this one is a set and includes the additional piece that will allow it to be used as not only a refiller but also an adapter.


  23. Oh thanks HJ, somehow my eBay search didn't find that earlier, I really appreciate it.

  24. Hi Jim... Big fan of your blog and posts on various forums. I recently began refilling cartridges using this: http://store.taiwancamping.net/home/field-kitchen/gas-refill-adapter
    It works OK, especially if I freeze the receiving canister first. Wondering if one is replacing a butane/propane mix with pure butane, can one (theoretically) safely overfill since the pressure is lower? Could you, for example, put 120g of butane in a Jetboil 100g canister without exceeding its pressure rating? I am locate din Puerto Rico right now where isobutane camping canisters are very hard to get, but butane cartridges are $1 at the grocery store.


    1. I would definitely NOT overfill. It's not just a matter of the vapor pressure of the gas (100% butane vs. propane/butane), but also a matter of volume. If the canister does not have sufficient vapor space (in other words the interior of the canister is taken up by liquid), then the pressures could be very high indeed.

      I would be EXTREMELY diligent about not overfilling. A couple of grams won't matter, but significant overfilling could be really dangerous.

      Overall, I think you're a smart man for refilling with plain butane in Puerto Rico. I doubt the temperatures in PR necessitate the use of propane/butane or propane/isobutane mixes.


  25. in my country malaysia we are using 14kg tank for domestic use. anyone has any idea using it as donor tank?

    1. There are two issues here. First, what's in the 14kg tank. If it's "LPG" or propane do NOT use it to refill portable canisters. Portable canisters like those used for backpacking cannot withstand the pressures involved with LPG or propane. If on the other hand the 14kg tank has butane in it, then you should be fine, provided that you can find a safe method of transfer.

      That's where the second issue arises: What kind of connector does your 14kg tank have? You have to find a safe way to connect the 14kg tank to a 100g (or 220g or 450g) portable canister.


  26. There's a Taiwanese store that sells a refill adapter for $10 shipped:


    Downside is, it has no mountings and you need to push down/hold it all the time.

    DX also a has an adapter to use straight butane cartridges:


    This is even cheaper, saves you the hassle of refilling and also converts your stove to a remote can stove.

    Last but not least, DX also has the good old propane-tank-to-lindal adapter:


    You'll blow your eye out, kid!

    1. That first one should work. You might lose some gas during the process, but it should be all right if you do it outdoors and away from any heat sources.

      The second one is a good idea, although I don't know about the quality of the particular item at that link. Kovea has one that is very good quality. It's a bit much to carry for a serious backpacking trip, but for shorter trips, day trips, car camping, etc. they'd be fine.

      That last one is down right dangerous and should be avoided. See Canister Refiller WARNING.


    2. Yeah, I thought the last one was a really bad idea ...

      BTW, a little OT, did you see the stoves that DX has available? They've got a couple interesting ones. Cheap ones for $8. Remote-inverted canister stoves with vaporizing tube for $16. A Pocket Rocket clone for $12. And multi fuel stoves for $50.

    3. Dick,

      I have seen some of the really inexpensive stoves. You might be OK with gas although I'd be afraid of traveling to remote area and relying on a cheapie "no name" stove. I definitely would not want to try pressurized liquid fuel. That just seems too dangerous to me, and I've heard/read too many reports of problems with cheap Chinese liquid fuel stoves.


  27. Jim; First off, Thank you for an A+ site. I have learned alot from you.

    Regarding canister refills; I see you stop short of using propane in the mix, no doubt for safety reasons. I live in Michigan and rely on my Windpro II with the canister inverted during winter months. Is there concern in adding 15% (by maximum fuel weight) of propane to the butane refill? I've heard 30% propane is about the safe limit for these thin-walled canisters. Secondly, how many degrees would I gain by adding 15% propane? In other words, is it worth bothering considering the increased pressure/danger?

    1. You're welcome. :)

      Butane is always going to be safer than propane because butane has so much lower vapor pressure. However, I think refilling with propane is reasonable if you're a) really careful and b) you use relatively new canisters in good condition. For propane refilling up to 30% by weight, I would only use canisters that originally came with an 80/20 isobutane/propane mix or a 70/30 regular butane/propane mix. Those two mixes have about the same vapor pressure. If you refill those canisters with a 70/30 regular butane/propane mix, you will never exceed what the canister was designed for, and with reasonable care and canisters in good condition, you will probably be OK. There's always some risk when working with explosive, flammable gasses, a risk that you must be aware of and decide whether or not to bear.

      Now, that said, could you go beyond 30% propane? In order to meet EN417 standards, canisters must be strong enough to not deform at 50C (122F). If you keep the canister colder than 50C, you have more of a margin for error. Significantly colder = significantly safer (in terms of internal pressure). If, as in winter, you kept the canister consistently below 0C, you could fill with mixes with more than 30% propane. Would those mixes be safe? Only if you kept them cold. Would it be worth it? Well, the more propane content, the better cold weather operation you'll get, but it's also true the more propane content, the greater the risk. You'd have to decide if it's worth it.

      The other trick, rather than "overfilling" (going beyond 30%) with propane is to warm the canister. With a stove with a wonderful flexible fuel hose like the Windpro II, you can maneuver the canister so that it is close enough to pick up heat from the flame. THIS IS VERY DANGEROUS, but if you frequently and diligently check the temperature of the canister with your bare hand, you mitigate the risk somewhat. If the canister feels hot, take IMMEDIATE action to cool the canister. Particularly with a stove like the WindPro II that can run with the canister upside down, this technique of warming the canister with the heat of the flame is very effective.


  28. Try googeling : propane butane mix temp pressure and look for pictures. You will find a graphical temperature pressure diagram telling more than words.
    I like this one : http://tinyurl.com/2wke2x

    1. That's an excellent diagram. Now, notice something. The pressure, whether measured in bar or psig, is about the same between 50/50 propane/n-butane as 30/70 propane/butane PROVIDED THAT the 50/50 mix is kept about 20 Fahrenheit or 10 Celcius degrees colder. In other words, a 50/50 mix at 10C has about the same pressure as a 30/70 mix at 20C.

      Given the above, one should be able to use mixes containing higher percentages of propane in cold weather. You MUST however keep the mixture cold. Don't forget and bring the mix into the house and set your backpack next to the fire. That would be bad, very bad.


  29. Hi there.

    Love the site, and love the idea of refilling.

    I am trying to figure out whether I can run this heater: http://www.ebay.co.uk/itm/NEW-PORTABLE-GAS-CAMPING-HEATER-4-BUTANE-GAS-REFILLS-/200990848078?pt=LH_DefaultDomain_3&hash=item2ecbfcf44e

    on a larger 4.5kg propane tank. It takes P220 propane canisters which I find very wastefull, and expensive.

    I suppose I could refill the P220 canisters from a larger gas canister, but I wonder if there is a way that I can use the larger tank directly. The regulator is built into the heater and is connected with a copper pipe to the element.

    1. Alexander,

      The heater in the link is a BUTANE heater. I think you'd do far better to get a PROPANE heater if you want to run it off a 4.5 kg propane tank. I'd switch to a different type of heater.


  30. I've found a cheaper way of doing it: a needle adaptor for inflating footballs with a bicycle pump works as well, if you cut the needle down to about 4mm, and make a small cut with a hacksaw to let the gas flow through the side of the needle. A couple of small o-rings to seal it all, and away you go. The disadvantage is that you have to hold the canisters together to let the gas flow but they could be clamped/strapped. Definitely needs to be done outside away from any sources of ignition as some leakage is inevitable.

  31. I just watched a Youtube video by 'clkindred' called 'Butane Tank Adapter'. Toward the end at 7:00 he spotlights an inexpensive airbrush adapter that fits the canisters and has a 1/4" standard pipe thread outlet, which would be great for connecting canisters to various sources. Also I just dug up one of those needle inflators and I'm off to see what I can do with that.