Canister Refiller -- WARNING

I've been seeing a particular canister refilling device on eBay lately as a "MacCoupler Liquefied Gas Refill Adaptor Gas Charging Valve Inflatable converter" [sic].    This particular device is just downright dangerous and in general should be avoided.  I'll explain why I say "in general" in a minute.

A very dangerous canister refiller.  ** AVOID! **

OK, so what's wrong with this refiller?  Well, in case you don't recognize the fittings, this refiller will refill backpacking type gas canisters from a "bulk" propane tank.

A "bulk" type 100% propane tank

Hey, now doesn't that sound like a great idea?  Hey!  I can take cheap gas out of my bulk propane tank (like for a BBQ) and refill my expensive backpacking canister.  Pennies on the dollar!  Sweet!  What could possibly go wrong?

What could go wrong?  A whole lot, and it could be bad, very bad.  First, backpacking canisters do NOT contain 100% propane.   Standard backpacking type canisters in the US are rated at not more than 20% propane (mixed with 80% isobutane) or 30% propane (mixed with 70% butane).  Propane is a very high pressure gas.  Put 100% propane in a canister rated for only 20 to 30 percent propane and what do you get?  Quite possibly a very nasty explosion.

Oh!  I know!  If my canister is only rated for 20 to 30% propane, I'll just fill it up to 20% of capacity and leave the rest empty!  Duh!  Problem solved.

Uh, not exactly.  When combined with butane or isobutane, propane actually forms a blend.  The resultant blend has a lower vapor pressure than 100% propane.  Odd as it sounds, you'll actually have less vapor pressure in a canister with 20% propane and 80% isobutane than a canister 20% full with propane alone.  Besides, what good is a canister you can only fill to 20% of capacity anyway?

Basically, you should never fill a backpacking type canister with 100% propane.

But what if you filled a canister to  80% of capacity with butane first?  If you filled to 80% of capacity with butane first and were exactingly careful about not exceeding the overall rated capacity, then maybe this adapter would be safe.  I'm not saying that it is safe, I'm saying that there's the possibility that the adapter might be safe -- from the perspective of the mix of gasses.  The adapter might still have other problems in terms of materials, design, and construction.  The very fact that someone put a dangerous refiller like this together suggests that they really don't know about gasses.  I have NO confidence that such a person has the ability to build a refiller that is safe in other respects.  I'm certainly not tempted to buy one.

Putting it into perspective
Now, am I just a "Nervous Nellie?"  Maybe this is actually pretty safe, but you know this is modern society, and we have to protect people from themselves, don't we?

I submit to you that I am no Nervous Nellie.  I refill my backpacking canisters all the time (with butane!!).  I use a windscreen with my upright canister gas stove.  I sometimes use my stove inside a tent.  In other words, I do all sorts of things that manufacturers tell us not to do lest doom and disaster overtake us.  I do things like refill, use a windscreen, and cook inside my tent because I've studied the objective dangers and found them reasonable for a person who is careful and has an understanding of how to mitigate the dangers.  But I will NEVER fill a standard backpacking type canister with 100% propane.  It's just too dangerous.  Period.

This refill adapter is:  NOT recommended (in the strongest possible terms).

I thank you for joining me on another Adventure In Stoving.

HJ

Refilling Coleman PowerMax Canisters

It's no secret that I like Coleman PowerMax gas canisters.  Note:  PowerMax canisters are called just plain "Max" in some locations outside the US.

First, they're aluminum which means they're quite light. The canister weight (tare weight) of a large 300g PowerMax canister is less than the canister weight of a small 110g standard threaded canister.

An aluminum Coleman PowerMax canister connected to an Xtreme stove

Second, at least in the US market, PowerMax canisters have the very best cold weather gas mix available (35% propane/65% butane). Outside the US, I've seen Max canisters labeled 40% propane/60% butane which is better still.  That gas mix when used in liquid feed mode (as designed in other words) can run in temperatures down to -4F/-20C (per Coleman).

Unfortunately, PowerMax/Max didn't make it in the market place. Most people either didn't understand the difference or weren't willing to commit to a proprietary, non-standard canister. Much like superior BetaMax lost out to inferior VHS, PowerMax lost out standard threaded canisters.

For those of us with PowerMax appliances, what to do? Well, of course you can use an adapter, but that's extra weight, extra bulk, and extra fiddle. Wouldn't it be nice if you could simply refill the PowerMax canisters? Of course it would. But how?

Well, I don't have all the answers, but I have a couple of ideas that I thought I'd throw out there and see where they go.

First a simple idea. Take a Brunton Fuel Tool or the like (Snow Peak and Primus sell something similar).

A Brunton Fuel Tool

Attach it by some means to an appropriate fuel source.

A Brunton Fuel Tool attached to a donor 100% butane canister via an angled adapter

Then insert the fuel tool into the PowerMax canister.

A Brunton Fuel Tool inserted into a Coleman PowerMax canister

I've had good success with this technique with refilling Rando 360 cartridges.

CV360 cartridges refilled by a Brunton Fuel Tool

Unfortunately, the aperture on a PowerMax canister is wider than on a Rando 360 cartridge.

The connector on a Coleman PowerMax canister

This technique doesn't work very well with the Brunton Fuel Tool "as is." However, if one were to add some "O" rings and spacers (which I haven't tried yet), I think this technique would work well for refilling.

However, this would be a fairly manually intensive technique. The Fuel Tool requires pressure to release the internal valve. In other words, the valve of the Fuel Tool has to be held in place by hand in order to transfer any fuel. With a 100% butane 50g Rando 360 cartridge, this is no big deal. With a 300g PowerMax canister that requires two different component gasses, this could be a bit of a pain in the neck.

But perhaps there is another way.

Let's take a look at a Coleman "X" stove. They're all fairly similar. In this case, I'll show a Coleman Xpert stove.

A Coleman Xpert Stove

Now note how the fuel line comes in from the right. A nut affixes the fuel line from the canister to the fuel line of the burner.

I think that if one were to unscrew the nut shown in the below photo

The nut shown above attaches the fuel line from the canister to the burner

that one could create an adapter that would affix to the underlying threads. In that way, we could use the connector of the stove itself to attach to a PowerMax canister. This would be a non-destructive use of the components of one's stove.

Now there are other candidate ways to connect to a PowerMax canister. 
1. A Kovea TKA-9504 type butane adapter affixes to a butane canister via a "cam and fingers" system similar to the way a PowerMax stove connector affixes to a PowerMax canister. But alas the connector on a PowerMax canister is too wide to fit into the adapter's opening. Even if it were to fit, the adapter has no pin with which to depress the Lindal valve of a PowerMax Canister.

A butane adapter with a "cam and fingers" connector similar to a PowerMax stove connector

2. The base of an MSR SuperFly stove clamps on to the collar of a canister rather than screwing or otherwide attaching to the canister connector itself. The "clamp" does fit on to the collar of a PowerMax canister, but unfortunately, as on a TKA-9504, the PowerMax canister's connector is too wide to fit into the opening of a SuperFly's connector. You can clamp on, but you can't get any gas to flow.

A SuperFly stove clamped to a PowerMax canister.  Unfortunately the connectors are incompatible and no gas will flow.

Neither of the above two candidates for attaching to a PowerMax canister is really suitable.

It seems to me that the best connector for a PowerMax canister is the one we already have; the one that came with the stove.

The "cam and fingers" connector of a Coleman PowerMax type stove

I don't have the machinery and tooling to construct an adapter that would connect to the end of a PowerMax stove's fuel line, but I think that's where a good solution to the problem of refilling PowerMax canisters lies. I hope someone with the proper skills and equipment can make use of the idea.

Note that PowerMax canisters are NOT designed to be refilled.  Refilling a non-refillable canister like a Coleman PowerMax canister in inherently risky.  If you refill a PowerMax canister, you are doing something that was never intended to be done to that canister, and you do so at your own risk.  I won't try to lay out all of the issues involved, but if you choose to refill non-refillable canisters like a PowerMax canister, you should read up on the issues involved, understand the dangers, and be very methodical and careful.  Please note that my surmise that refilling a PowerMax is possible does not mean it's a good idea.

There you have it; my thoughts at this juncture on refilling PowerMax canisters.

Thanks for joining me on another Adventure in Stoving,

HJ

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.

UPDATE 26 March 2017:  There is a another method of canister refilling, a method using the G-Works Gas Saver.  The G-Works Gas Saver is cheaper and easier to use than the adapter I used in the below post.  The G-Works Gas Saver is also better in that it does not use 100% butane (which is only good for warmer weather).  Please see:  The G-Works R1 Gas Saver – Refilling Backpacking Canisters II.

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.

Caution
The newer orange label Coleman canisters do not work with many brands of stoves. The older green label Coleman canisters seem to work fine.

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,

HJ

Appendix -- Advantages and Disadantages of Refilling

Advantages
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.

Disadvantages
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.