Smallest possible butane-stove set-up?

[Jerry Adams]

I think I see where you ground it off.  Your brs 3000 is now lighter.  I wonder what other parts aren’t necessary?

[Roger Caffin]

what other parts aren’t necessary?
Functionally, or legally? Given typical consumer propensities?

Cheers

[Philip Tschersich]

I’ve been mulling over the stove base situation, and kept coming back to the fact that this would just be so much easier if I could use conventional fasteners. So I grabbed a titanium M5 flange nut left over from another project and epoxied that to the base of the canister. I cut a piece of 1 mm thick carbon fiber board to fit the inside of MSR Titan pot and epoxied a trimmed M5 x 0.8 machine screw to it. The base weighs in at 20 g as pictured. Not as impressive as Jan’s printed airhorn base.

The good news is that the base is extremely stiff and the connection to the canister very secure.

[Stefan H]

One important step I believe people have missed in the refilling procedure. HEAT the air horn can (with hair dryer or hot water bath), then purge, then cool. This creates a pretty strong vacuum. This might actually be effective enough to be dangerous. Be careful not to overfill, listen for the ting of metal stretching lol.

[”V” (CzechClown)]

Looking for advice regarding the safe refilling of air horn canisters. Specifically, I want to know how to accurately fill the canister to its maximum safe level without the risk of overfilling.

I am using a net wt. 1.8oz (50g) Air horn canister. While on trail, I will be not have access to a scale.

Any tips or best practices you could share would be greatly appreciated.

[Jerry Adams]

Weigh full canister and write that onto canister.  Never fill more than that weight.

Or, weigh empty container, add 1.8 ounces, write that onto the side…

[”V” (CzechClown)]

Thank you for your great advice! However, I wanted to clarify that, as stated in my post, I will not have access to a scale while on trail.

[Jon Fong / Flat Cat Gear]

Phillip, what do you think about this idea.  Glue a screw on top of a titanium nail (8g).  Thread the canister onto the stake and press the assembly into the ground.  It would have to be pretty level, but it could be very secure.  Just a thought.

[Bill Budney]

V: The lightweight way to “weigh” your canister is to float it in your cooking mug/pot. Float the new canister, mark the water line with a Sharpie or paint or tape. Always refill so that the line is exposed, above the water.

 

[”V” (CzechClown)]

Bill : Thank You, I will certainly give this a try.

[David Thomas]

Jon: for a light (mostly already carried weight), how about three tent stakes driven into the ground, the air horn canister placed between them and secured with one or two of those miniminal Velcro straps like sold for organizing cords?

Although Casey gifted me a pretty fabulous 3-D-printed plastic base last week at GGG that perfectly holds and stabilizes the canister while also fitting perfectly into an aluminium grease pot with his spiffy wind shroud that ups the heat exchange to the pot, especially for a BRS-3000T in the wind.   It makes a single air horn canister of butane viable for a 2-3 day trip.

[”V” (CzechClown)]

David : would you mind posting a picture of your spiffy wind shroud that ups the heat exchange to the pot, especially for a BRS-3000T in the wind.

[David D]

If you use poles and your grips aren’t too long, try this little trick, but adapted for the air horn

https://www.ukclimbing.com/videos/categories/hill_walking/backcountry_magic_trick_measure_your_gas_using_a_trekking_pole-5918

[Casey Bowden]

CzechClown wrote: David : would you mind posting a picture of your spiffy wind shroud that ups the heat exchange to the pot, especially for a BRS-3000T in the wind.

Here’s a link to the post with details. FYI, I’m the one who made it and gave it to David.

https://backpackinglight.com/forums/topic/complete-iso-butane-cook-kit-for-less-than-8-ounces-including-fuel/

[DGoggins]

Does anyone know of a canister brand that consistently has a not so recessed lindal valve? I bought several and all of the lindal valves are a bit too far recessed. I can make a brs-3000 work, but…I really dislike those and would rather use a windmaster or amicus.

[Roger Caffin]

It is not that simple.
As Far As I Know:
The known brands mostly get their canisters filled in China these days: it’s cheaper there you see.
But I dare say the filling companies they use change regularly – the latest or cheapest ‘deal’. The known brands may even run more than one filling company in parallel.
To the best of my knowledge, the gas can be put in the can and then the Lindal valve is crimped on. Much faster filling that way. But the crimping machines which attach the Lindal valve to the can are not always in the best condition: the adjustments change and the shape of the crimp changes with time.
Over the years I have seen variations of up to +/- 2 mm in the height of the nipple with respect to the rim. Yes, specific cases I have seen. The Chinese companies don’t seem to check the adjustments until someone complains.

Cheers

[DGoggins]

Yeah…I guess I could try and go to local stores and look individually at each horn and hope that their lindal valve variance is high enough where one can sits higher than the others. Fortunately, most of the packaging is transparent on these.

[DGoggins]

Well…I’ll keep trying but all the local stores stock of 1oz and 3.5oz canisters were all too recessed without enough variance to get one that had a lindal valve protuding slightly above the crimped top (which is what I’m looking for). Interestingly, the ozark trail 8oz canisters …there was variance at walmart where one was higher than the other from a stock of 2. This can is taller/narrower than an 8oz MSR can, net weight 226g of fuel, but the can itself weighs half as much of a msr 8oz (75g vs 150g), and…can actually fit inside my evernew 650 (or toaks 550) though sticks out the top, but still way better than an 8oz can that doesn’t fit inside the pot at all.

[DGoggins]

Or to think about it another way, this 8oz (226g) container weighs 25g less than a standard 4oz (110g) container yet holds twice as much.

Dumb question….so, I know when refilling everyone recommends filling to 80% of capacity. Lets say you have a 100g fuel canister of isobutane mix (standard MSR fuel). If I’m putting in the same fuel, why should I only fill to 80g? I know the reason is stated to allow for fuel expansion, but why can the manufacturer fill with 100g safely with the same fuel but I can only fill to 80g?

[Jerry Adams]

That would be 80% of a totally full canister

If the canister was sold with 100g of butane, you can refill with 100g

A way to do it would be to weigh the canister when you buy it, write it on the outside, then when you refill, don’t exceed that weight

Another way to do it is to know that 8 ounce canisters weigh 4.5 ounces, so don’t exceed 12.5 ounces when you refill.

[Dan]

I haven’t read this 80% recommendation. I don’t see why you can’t refill to the same mass as original.

[DGoggins]

Yeah….I’m sure I’m not the only one that got confused (I hope). There is plenty of mentions of only refilling a container to 80% of the “capacity”. Now that I’m rereading through things…its 80% of the volume capacity of the container, which…is a calculation that very few people are going to do (calculate the volume of the container, then calculate the density of the fuel you are putting in, etc).

I had incorrectly assumed that by capacity, it was just 80% of the easy capacity number we have access to (the original amount of fuel used by the manufacturer): So, if manufacturer put in 100g, I should refill with 80g of the same fuel.

A way to do it would be to weigh the canister when you buy it, write it on the outside, then when you refill, don’t exceed that weight

Which is why I love MSR canisters…it lists the net and gross weight on all of their canisters.

However…with the air horns…that are typically filled with 1,1 Difluoroethane, I have to fill with a different amount of the msr isobutane/propane mix.

For the typical small sized ones, that are filled with 40g of 1,1 Difluoroethane, David thomas calculated 27-28g of butane mix. Which…the falcon air horns, of the same size, filled with isobutane are 28g, so…that seems like the correct ratio.  (28/40 = 70%).

So, I have a new ozark trail 8oz (226g) of 1,1 Difluoroethane container, I could put in 158g (70% of 226) of isobutane mix into it.

[Dan]

I’m guessing that the concern about over-filling must be to ensure that some headspace remains even at the highest temperature the canister is likely to experience. But I suspect that there is a significant safety margin as long as you’re not camping in Death Valley (the upper safe limit indicated is 125F).

As long as there is headspace, the pressure will just be determined by the equilibrium vapor pressure of the mixture.

[Jerry Adams]

yeah, if the butane warms up and expands, it’s volume can exceed the available space in the canister, and the canister will rupture

If you don’t put in more butane than what it originally came with, then it’s designed to have enough space for the butane to expand at 125F

Plus a margin of error

[DGoggins]

I was able to find a 28g fuel canister with a less recessed valve! So I went to local stores and ….lots of stores have these types of air horns (boat horns, party horns, bear horns, etc). Most…have the horns disconnected, with clear packaging, or..packaging that is very easy to open so you can directly look at the valve. I looked at…4-5 different brands of the 28g canisters, and all were really recessed with little variance. Probably looked at…25 different canisters. Then went to REI…and they had the “frontiersman bear horn”. Unlike everything else…it was really sealed packaging and the horn was attached so you couldn’t see the valve. Also, it contains trans-1,3,3,3-Tetrafluoropropene, instead of 1,1 Difluoroethane like all the others I saw, so that was another difference.

I decided to take a gamble and bought it even though I couldn’t see the valve. And …first try! This canister had a much higher lindal valve than others that worked great with my windmaster/amicus.

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