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Wednesday, February 15, 2012

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

4 comments:

  1. Here's an idea... Begin by buying one of these little stoves:

    http://thriftygearreview.blogspot.com/2012/07/stove-review-ultralight-backpacking.html

    They are available from several vendors for as little at $9. Disassemble this stove to remove the burner and the piezo igniter. Also its remove the gas nozzle. Doing this, you are left with an "adapter" which fits to a standard screw-on canister on one end and a little female thread on the other end. Let's call this little thread "Thread #1".

    Now disassemble the canister connector that's at the end of the flexible gas line on the Coleman PowerMax stove. Unscrew the flexible gas line from the guts of the canister connector. You now have the Coleman stove with the flexible gas line attached but without the screw-on adapter that originally connected to the PowerMax canister. At the end of the flexible gas line is another little thread. Let's call this "Thread #2".

    Go to you local hardware store and buy a brass fitting that accepts Thread #1 on one end and Thread #2 on the other end. Back at home, assemble the gas line from the Coleman stove onto this brass fitting on the Thread #2 end. Then from the Thread #1 end of the brass fitting, screw it into the UltraLite stove where its gas nozzle once was.

    What you end up with is a connection between the Coleman stove's input line and the UltraLite stoves output point.

    Buy a standard screw-on butane/propane canister. Attach it to the base of the UltraLite body. Now INVERT the canister and UltraLite combination. The UltraLite will be standing upside-down on the feet that were intended to support the cooking pot. But now these feet sit on the ground and act as the base of the canister holder, which is going to be used upside-down. The Coleman stove will draw liquid fuel just like it did when Coleman Powermax canisters were used. The valve on the UltraLite stove body will control the flow of gas and thus the flame.

    I haven't tried this yet because I still have enough PowerMax fuel to use my coleman stove for three more backpack trips. But I did buy the UltraLite stove today. It comes from China and cost $8.48 including shipping.

    Comments?

    George

    ReplyDelete
    Replies
    1. George,
      Interesting idea. I think I follow what you're saying. However, have you verified that such a connector exists? I would be surprised if it did. I think it would have to be custom made. Worth thinking about though.
      HJ

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  2. Last post was almost a year ago. Have y'all perfected the process? I don't want to trash my almost brand new stove just because Coleman decided to quit producing the canisters.
    thanks
    John

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  3. This is not just propane, it is a blend of isobutane and propane, known as A-46, with a pressure of 46 PSI at room temp. The can valve on PowerMaxx is a female aerosol valve. The key is to measure the stove valve, get the correct female can valve and have an aerosol filler make some new cans.

    ReplyDelete