UL Propane stove with 300 BAR refillable 0.6L composite fuel bottle?

[Roger Caffin]

Ah so.
A recycled (now free) Coleman Powermax canister weighs 68 g.
A bigger breakthrough might be needed?

Cheers

[David Gardner]

If I get to the production phase I will fill the tanks to 320 PSI For DOT approval. At Fluor we always designed with at least a 2X safety factor. For a consumer product I will design with a safety factor of 3-4X, so going to 320 PSI will not be a problem.

I looked into the embrittlement question. Hydrogen uptake occurs in aluminum alloys upon exposure to aqueous environments, water vapor saturated air, and water vapor mixed with other gases such as nitrogen, argon or dihydrogen. Uptake does not readily occur in the absence of water or water vapor. Regarding titanium, I spent a couple of hours googling but could not find anything regarding propane embrittlement of titanium, but many technical articles regarding titanium embrittlement by hydrogen gas, sea water, very hot water, various gasses and fluids (especially with sulfur compounds). There were a number of articles about embrittlement of titanium in propane refinery components, but only in the presence of the other factors such as hydrogen gas, seawater, etc. Also discovered that there are various coatings that will prevent titanium embrittlement even with exposure to problematic compounds.

It would be great to have a translucent tank! For mass consumption it makes sense to use inexpensive fiberglass, but for my (our) goal of minimizing weight I think we need to go with carbon fiber or titanium :- (

I’m guessing that titanium would be less expensive, but if I can hit the $100 price point or lower with CF that is probably the direction I would go.

Taking a stab at what it would take to amortize the extra $100: a 20 lb. propane tank (typical BBQ type) holds 4.7 lbs. (2132 gm) of propane and, at an average price of $4/gal costs $18.80 to refill = $0.0088/gm. A 230 gm butane canister costs about $5 = $0.0217/gm. The price difference is $0.0129/gm. To make up the cost of a $100 UL propane tank would there require the purchase of 7,752 gm of propane.

I will assume using 1:1 propane vs. butane since I have no accurate data as to how much less propane vs. butane it would take to boil water, and I will also assume that it takes 7 gm to boil 500 ml of water. If you boil 500 ml of water for breakfast and 500 ml for dinner and use 14/gm per day it would take 554 days to make up the difference. If you go camping 3 weeks per year it would take 26.4 years to amortize the extra $100. So it takes a LONG time to amortize the extra cost, so long that the fuel cost savings is not a significant factor in choosing propane vs. butane.

That leaves considerations of convenience, availability, speed, cold weather use, waste and possibly lower pack weight or more days between resupplies on a long trip.

[Roger Caffin]

Yes, you would probably need a safety factor of at least 4 in the consumer market.

As for cost – that is always the limiting factor!
Even a high pressure version of a standard aluminium ‘hair spray’ canister (or Coleman Powermax) would be wonderful, but again, the mfr would need huge volume.

Cheers

[David Thomas]

There’s an error in your cost calculation, ” . . . a 20 lb. propane tank (typical BBQ type) holds 4.7 lbs. (2132 gm)” 4.7 lbs should be 4.7 gallons.  A 20-lb cylinder holds 20 lbs = 9,080 gram.  Refilling it in my town costs $2.79/gallon or $13.11 for the whole thing (pre-filled Blue Rhine cylinders may cost more), so $13.11/9080 gram = $0.00144/gram or basically free compared to the cost of butane mixes.

So to save $100 of $5 butane mix canister, you need to avoid buying just about 20 of them (20.3 of them), versus the 34 canisters that calculation suggests.

[Nick Gatel]

The exchange 20# tanks, such as Blue Rhino, contain 3.55 gallons of LPG, not 4.7.

Here’s an explanation: http://popupbackpacker.com/is-it-a-good-deal-to-exchange-your-propane-tanks/

For more general information about bulk LPG tanks: http://popupbackpacker.com/are-we-out-of-propane-again/

[Roger Caffin]

Thank you Nick and David.

Cheers

[David Thomas]

Good info, Nick. Thanks.

I’ve got a fleet of 4 tanks, locally, there’s no minimum charge, it’s been $2.79/gallon about forever, and my “20-pound” tanks consistently take 4.4 or 4.5 gallons in the overfill protection device era.

When I was working in CA, I was buying 500-2000 gallons of propane a month and got it considerably cheaper than retail refill rates.  60% or so of gasoline/prices.

[Nigel Ward]

These are currently available from Princess Auto in Canada:

https://www.princessauto.com/en/detail/8-oz-propane-gas-cylinder/A-p8734873e

[David Gardner]

Nigel, that’s awesome. Gave them a call. Unfortunately it’s an “in store only” item they won’t ship to the US :-(

I need a friend in Canada!

[David Thomas]

They claim “Approximately 1/10 the weight” (of traditional propane cylinders) which would be fabulous.  1/10 of a pound is 1.6 ounces which would be amazing or holding 8 ounces of propane.  I suspect they’re really optimistic in that claim.

Could these just be horizontal, “Asian grocery-store” 8-ounce butane containers repurposed for propane, relying on the small diameter and giving up a lot of the safety factors with propane in it?

Ah, just answered my own question.  A reviewer of the UltraFlame stated, “If any of you remember the UltraBlue torch and can, well this is the return of it! New name but same amazing product! I’ve held onto my torch head for 12 years and my diminishing can supply hoping this would return or I’d be lucky to find it again. ” and googling “UltraBlue” shows a clearly Lindal valve on top:

DavidG: If/when things return to normal enough, I’ve got a car delivery to do down the Alcan and could score a few dozen of these at Princess Auto from those friendly Canadians (or, as I like to call them, unarmed Alaskans) on the way through.

They also claim it can be operated in 360 degrees (very handy for plumbers).  Does that mean it has a floating vapor pick-up inside to avoid flaring up should liquid propane reach the intake?

[David Gardner]

David T: 1.6 oz for the bottle would be awesome – less than 1/2 the weight of a standard butane canister. I need to get some to experiment with, and weigh an empty one.

I hope they are DOT approved but can’t tell from what I’ve been able to find so far. Great to have the Lindal valve for using an adaptor (or two) to refill from inexpensive large tanks or other sources and fine tuning the amount carried for any particular trip.

[Jerry Adams]

I weighed one of those butane cartridges from Korean grocer – 3.9 ounces

Maybe when they say those are propane, they mean butane?

Looking at that picture, it looks a little more robust than my butane cartridge – maybe its stronger (heavier) than my butane cartridge, maybe it really is propane

Regular isobutane canister is 5 ounces (for 8 ounce capacity)

As long as we’re talking Korean grocer butane, they cost $1.25 for 8 ounces.  $5 for the little adapter to transfer to a canister.  That makes sense for cheapskates.  It takes only about 1 canister to pay for the adapter.

At the Asian supermarket they cost $1.50.  If I drive 6 miles further to the Korean grocer it’s $1.25.  I’ll have to figure out if that will save money over-all.  What’s the value of my time…

 

[David Gardner]

Won’t know for sure until I get one, but the package says propane.

[Jerry Adams]

Put it in freezer and let it cool.  If there’s still pressure it’s propane.

[Jon Fong / Flat Cat Gear]

OK, let’s say that you can find a small propane tank.  What stove are you going to use with it.  I happened to order a propane to Lindle valve converter and it seems like the pressure is really too high for the stove.  Just wondering.

[Jon Fong / Flat Cat Gear]

Maybe Roger can chime in on his thought aboute pressure regulated stoves (ha ha).

 

[David Gardner]

Jon, too high in what sense? Do the seals leak? Does the stove not regulate the flames well?

That with an MSR Pocket Rocket 2? High quality stove, which doesn’t bode well for my experiments.

I was thinking I would start with a BRS-3000T since I seem to have gotten lucky and obtained one where the pot supports haven’t melted or deformed under the load of a pot with 500 ml of water in it. If that seems to work then I would try the Fire Maple Wasp/Hornet that I just got.

[Jon Fong / Flat Cat Gear]

David,

Too high like as soon as you crack the valve, the stove is roaring.  Throttle it down and the flame goes out, a little higher and the flames start to leave the surface of the burn.  I’ll have to look again tonight as it is still pretty bright out right now.  It seems like it could benefit from a step down regulator.  Who knows.

[Jerry Adams]

just don’t open the needle valve so much?

[”V” (CzechClown)]

David T.  Sent you a private message

[Roger Caffin]

I have not seen the canister myself, so my comments are unreliable, but anyhow …

The canister is steel (well, they say so), which will be stronger than aluminium as in fly sprays etc.

The specs on the canister say 70 psi, and this worries me a lot. 70 psi is the vapour pressure of propane at about 6 C, and most houses are going to be a lot warmer than that! Typically, the VP of propane will be over 120 psi inside a house at, say, 25 C. So I very much doubt that these canisters would pass any DoT regulations in the USA.

Now, if they are just fibbing a bit and the contents are really butane, then that would be OK – apart from the fraud.

I wonder – does the labeling on the canister mention DoT regulations at all? And does the labeling mention the country of origin at all? Curious minds want to know!

I would NOT use this canister for an upright stove without a really good heat shield. Any radiation from the flames back to the can could be deadly. Used with a suitable remote canister stove in the snow might be OK.

EDIT:
The web site gives links to an MSDS pdf and other details, but the links do not work. Dodgy, very dodgy.

Cheers

[Pierre Descoteaux]

Well, I’m in Canada… Should I try one of those canisters with one of my Caffin stoves… What do you think Roger?

[David Gardner]

Roger, I was able to download the MSDS and SDS (there is a second MSDS but it’s the same as the other but in French). Don’t see anything about DOT there but only scanned them. It seems I can’t send them to you as an attachment to a PM.

Also got a better image of the can from their website, which is different than the can shown in David Thomas’ post above:

I don’t mean to endorse or recommend this item, or the use of propane in stoves designed for butane, in any way. I’m just interested seeing what is possible in terms of using propane for UL/LW camping stoves using state-of-the-art materials and science. Safely. All your concerns are noted and your recommendations will be followed.

[Roger Caffin]

Pierre
Be VERY VERY careful!
If the can has a typical Lindal valve, it may work. Keep the can well clear of the stove.

Cheers

[Roger Caffin]

@David
I would REALLY be interested in reading the MSDS IF you can find any way of attaching it to an email. It should specify the contents.

A photo of the other side of the can would also be of great interest. DOT? Country of Origin?

Cheers
roger at backpackinglight dot com

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