Compact/light weight propane canisters

[Eugene Hollingsworth]

I’ve been waiting for an update on the Boss Propane Torch fuel canisters Dave Gardner posted about since September. Haven’t been able to locate that canister either.  With colder weather settling in I’m going to try remote canister stoves and invert the canisters, but running a high propane blend would be, IMO, the best solution.  However I don’t really want to carry around 1 lb propane tanks, even if I’m dragging a pulk.

Weight and bulk are the issues – I suppose I could save some weight by using half full propane tanks.  I would love to have 8 oz refillable propane tanks.

It would be really cool if I could refill the lighter canisters with butane (cheap) and up to 20% propane, but since nobody’s doing it the risk of over-pressuring the light isobutane canisters is just great.  Not worth the risk.

 

[Roger Caffin]

The risk is not so much of over-pressurising but of over-filling. You MUST leave empty space in the canister. That is checked by weighing the canister.

Cheers

[David Thomas]

>”However I don’t really want to carry around 1 lb propane tanks, even if I’m dragging a pulk.”

Yeah, I learned that on one snow-camping family trip.  I figured, “it’s all in the pulk, what does weight matter?” and threw in propane cylinders and nice dry wood but you still have the work of hauling any weight up a hill and the more a sled weighs, the more you’re going to compress the snow and that’s all work that you’re doing.   So now I’m only heedless of weight in the sled when the access is all on a frozen lake AND there’s not much snow pack on the lake.

Pro-tip: put a nordic-skiing glide wax all over the bottom of your sled/pulk.  It really helps.  And minimizes the chance of the base icing up if you move in and out of the sun through thawing and then frozen snow.

Why not refill a standard iso-butane  (or butane-propane-mix) canister with 60% butane and 40% propane or even higher by mixing ingredients, mark it as such, and only use it in winter?  Or just use 20% of the original contents and top off with straight propane?

I used to caution against that since, as you connect the propane source to the backpacking canister, the canister will see propane’s full vapor pressure (it won’t instantly mix with the butane and have an intermediate vapor pressure – that would come after the liquids mix completely).  But after re-reading Roger’s 2007 article ( https://backpackinglight.com/exploding_gas_canisters_the_hazard_of_overheating/ ) in which he intentionally took a canister of 30% propane / 70% isobutane up to 98 °C (208 °F) to make it explode.  A seriously DON’T TRY THIS AT HOME, KIDS experiment.

He concludes that standards for the canisters and previous advice to never exceed 50 – 55 °C (122 – 131 °F) still stand, but one can be reassured that there is a considerable safety margin at that temperature with 30/70 or 40/60 mixes.

To get the same margin of safety with pure propane (during refilling from a pure propane source), would require the donor propane never be above about 27°C (80°F) so one should never heat a donor propane cylinder, ever, but rather cool the receiving canister (or not, since the donor propane naturally has a higher pressure).  To actually burst a canister, which Roger did at 98°C, would take about 68°C (154°F) if you had pure propane in a backpacking canister* ** ***.
* But that’s with NO safety margin
** And no allowance for a dent or rust spot or manufacturing flaw in the canister

*** Remember that transport and storage can easily heat a canister up (a car left to warm up, left in the sun, a canister stored near a heater vent, etc, etc).

I’m getting tempted to refill a canister with pure propane and then put it in a water bath far, far from the house and blow it up, recording at what temperature that happens.

There’s a long list of caveats if you’re putting pure propane into backpacking canisters.  One of which is that liquid butane is 1.16x the density of liquid propane, so if you fill to the same weight, you’ll have more liquid volume inside.  That’s bad.  So 100 grams of butane should only be replaced with 86 grams of propane to maintain the same headspace / freeboard inside.

[David Gardner]

Eugene: I obtained a case of the Boss Torch canisters directly from Enviro-Safe and have been using them for home cooking for the past 6 weeks or so with regular butane stoves. They work pretty much just like butane canisters, including similar average boil times. One thing I’ve noticed (due to increased pressure I believe) is that cheap knock off stoves with cheap valves have trouble maintaining a consistent burn rate: they sometimes have to be turned way up to get them to flow at all and then back down to a reasonable setting, they sputter, and sometimes after a few minutes of use they will suddenly accelerate to 2-3X burn rate and have to be turned down. This has been with cheap BRS 3000T clones off Amazon. The real BRS 3000T and Fire Maple clones (and other high quality stoves too I’m sure) have no trouble.

I’ve been using them upright, which is a bit tippy. When the time comes to actually use them in the field I’ll make some kind of stabilizing base/leg structure.

Happy to send you one at cost if you want to PM me.

[Roger Caffin]

Remember that transport and storage can easily heat a canister up (a car left to warm up, left in the sun, a canister stored near a heater vent, etc, etc).
That is the main and big risk. It is why a safety margin is required even over the 50 C threshold.

So 100 grams of butane should only be replaced with 86 grams of propane to maintain the same headspace / freeboard inside.
Remember this folks! YOUR life may depend on it.

cheap knock off stoves with cheap valves have trouble maintaining a consistent burn rate:
Sometimes this is due to a sloppy thread which can jiggle around, and yes, it can be dangerous.

I’m getting tempted to refill a canister with pure propane and then put it in a water bath far, far from the house and blow it up, recording at what temperature that happens.
This is dangerous territory. I have no doubt that DT can handle it safely, but few have his experience in this area. For every one else, don’t try it. (Mine made one hell of a bang! But I was hiding behind a steel wall.)

My 2c.
Cheers

[Tom K]

 

[David Thomas]

Well, there’s that outcome, yeah.

[Jerry Adams]

I saw a documentary that claimed the Hindenburg’s problem was the outer shell was flammable

Hydrogen was not the cause

The fact that hydrogen is so light makes it quickly rise away.  Something like gasoline is worse because it’s fumes will hang near the ground, I think.

Those are good numbers David, thanks, especially the 86 to 100 ratio for weight, that’s surprising it’s so big.  I guess I’ve never considering using straight propane myself because where I go it’s not that cold.

And putting pure propane in a butane canister and keeping it below 80 F isn’t that big a deal in the winter.  Maybe I’d do that if I went below 20 F.

[David Thomas]

Jerry: regarding that 86 grams of propane being the same volume as 100 grams of butane:

The energy difference isn’t quite as bad because there are more BTUs/calories in a gram of propane than butane.  21,640 versus 19,834 BTU/pound gross heating value.  A factor of 1.09

So if you put 86 grams of propane into a 100-gram butane canister, you’d have 94% of the original BTUs.

Also, since propane requires fewer oxygen molecules per propane molecule to burn completely, pre-mixing with a very similar ratio of atmospheric air means higher-propane-fraction mixtures should burn a little leaner and produce less CO at altitude.

[DAN-Y]

Take the easy way out…..purchase BOSS canisters of 70% propane. When empty, refill with propane to the proper level. The containers are made to withstand the pressure. Follow same cautions as per label.

[Eugene Hollingsworth]

Glad to have you folks pitching in. This is a learning experience for me.  Work and life and over-thinking has delayed my responses, though I keep re-reading and following the links.

I get the impression that if I exercise the same caution as I already do when refilling canisters, I should be ok remember this short list:

1) Refill the Enviro-Safe 70% propane canisters with propane to 60% capacity, for temps below 40 deg f, during winter months only. (remembering the 1:16 vol factor) We know by the shape and commercial label on the canister that it’s propane. We can use this canister upright or laying on it’s side w/o issues.

2) Refill or top-off a Isobutane canister with butane only for 40 deg f or higher temperatures, to 90% of capacity. Now I know by canister shape this is not a propane tank, so no cock-up of having a propane laden tank in a warm environment. Works with upright canister stoves.

3 ) Attempting to refill partially used Isobutane canister mix with a combination of butane and propane, or from a pre-mixed commercial donor canister will result in an unknown ratio of Isobutane, propane, butane.

4) Refill a IsoButane canister, 80/20 by weight(butane / propane) to get an actual 80/23 mix. If I did the numbers correctly, stopping at a total of 80% of capacity. (185 gram in a 230 gr canister) That gets trickier if I’m refilling a partial canister and probably not work the effort or risk. (see above)

The reasoning behind my thinking of propane are:

I already refill canisters so that I can take a full canister every time. Now I would like to expand the temp range and reduce the cost without undue complications or danger.

Cold temps for me are 10 – 40 deg f, and propane would be hassle-free at those temps.

Both propane and butane are much cheaper than isobutane canisters.

Particle contaminat clogging of the stove jets isn’t a issue if using gas from upright canisters when possible and propane makes this possible for cold camping. (I keep reading of stoves and heaters malfunctioning from junk in donar tanks, deteriorating hoses, etc)

[Eugene Hollingsworth]

I’m taking the easy way out to purchase BOSS canisters of 70% propane. Thanks Dan for the push.

David Gardner – PM inbound.

[DAN-Y]

Canisters are available here:

http://www.woodgaz-stove.com/Propane-Fuel-Canister-With-Lindal-Valve.php

[John K]

I may end up getting one of those canisters just to mess with it. When I look at butane vs propane though, doesn’t butane have like 16% more energy? Other than easier use in extreme cold, is there another reason I’d choose it? Butane works pretty darn good with the moulder strip shunt…

[David Thomas]

Yes, butane works fine, has a bigger safety margin, and can be used to stupid-cold temps with a Moulder Strip.

But propane is cheaper.  Almost free in comparison.  4 ounce of butane = $4.99; 4 ounces of propane = $0.16.

And I have lots of 20-pound propane cylinders laying around (and 1-pounders that I refill), versus butane mixes only coming in 450-gram canisters at the largest.  I looked around a bit at the local head shops (butane is used to concentrate THC and CBD oils) but they had smaller containers at higher prices than in the camping aisle.

[John K]

Wow, that pretty much is free…

[DAN-Y]

I have sent BOSS Torch canisters up into Alaska to be tested. My goal is to have the company Enviro-Safe to make the canisters available thru Walmart. I have to ship the canisters via USPS Ground service, an expensive way to purchase them.  One set of canisters will be in Galena, AK and one set in Fairbanks, AK. There is also a set in Colorado to be tested. Maybe by next winter they will be available thru local hardware stores, have patience ;) It’s nice to have a dependable extreme cold weather fuel in small canisters.

Cold weather is a commin…..stay safe and warm! 

 

[Eugene Hollingsworth]

@Dan Y I have sent BOSS Torch canisters up into Alaska to be tested…Galena, AK and … Fairbanks, AK …..(and) Colorado to be tested.

Do you have any particular testing procedure or suggestions, ect? Just curious. It’s my nature. I’m getting a couple of cans from David Gardner and am going to, with some discipline, try to run them only upright, only in open air away from a heat source,  and only in 10 deg f (-12 c) or lower temperatures.

Here’s where I could use a fact-check: If those canisters contain anything except propane, will my stove stop working once the propane is burned off?  Will this give an indication of how much is propane, and how much is isobutane/butane?

[David Thomas]

Eugene, a common misunderstanding is that all the propane burns off before most/any of the butane.  That’s not the case.

Early on, a propane-butane mix it is more propane-rich.  As the canister empties, it has a lower propane fraction, but a mixture of both is, at all times, coming out (and remaining inside) of the canister.

So if you were some extreme conditions (-20F to -30F without a Moulder Strip), you’d see diminished pressure and flame and have to use any of the cold-weather canister stove tricks (warm water bath, flick your Bic, put in inside your jacket for a while, Moulder Strip, pee on it, use a reflector / wind screen to bounce IR down to the canister, etc).  But it wouldn’t be sudden.

[Eugene Hollingsworth]

Thanks Dave for your outstanding patience, having to explain then re-explain, and all that after the articles you have published.  So my more-or-less uncontrolled field use logging should show decreasing performance by the amount of pressure driving the flame.

 

(Addendum: The reason for pursuing this is that I was  using an upright canister stove last year with some Isobutane blend (don’t remember which) and it almost would not light at somewhere below 30 deg. Very low flame.)

 

The ultimate end goal is to carry light canisters, that will still light in an upright position without prewarming, after sitting out all night at 10 deg F.  To many things can go wrong even at those temps, including caffeine deficit fuzz-braining early in the AM. Hope to find light, safe, easy, cheap. Pick all 4. :-)

‘Sides, this is a fascinating subject.

 

[DAN-Y]

 

@geneh_bpl

I’m getting a couple of cans from David Gardner

What instructions did Gardner give with your purchase?

[DAN-Y]

@davidinkenai

So if you were some extreme conditions (-20F to -30F without a Moulder Strip), you’d see diminished pressure and flame and have to use any of the cold-weather canister stove tricks

What would happen if a full can of off the shelf propane-butane mix were to be used in -20F to -30F without a Moulder Strip, would it light?

 

 

 

[Eugene Hollingsworth]

@zelph2 What instructions did Gardner give with your purchase?

None. The picture of his can is different than those you are offering, so I thought to try that in the conditions I camp in, and compare with reports from your AK tests under the conditions they are in. Might be informative. More likely to be wildly different anecdotal reports with no predictive value. I just have fun and try not to hurt myself.

:-)

[David Gardner]

I’m including Enviro-Safe’s BOSS can SDS with the package to Eugene.

[Roger Caffin]

What would happen if a full can of off the shelf propane-butane mix were to be used in -20F to -30F without a Moulder Strip, would it light?
A new 30/70 canister should work down to about -24 C. That is approximate, because the calculations are done for n-butane, not a mix of n and iso butane. So you would be marginal.

Cheers

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