113g Inverted canister stove

[Roger Caffin]

Hi Bob

> I agree that plywood makes a good base material, but most of it is too heavy.
I use a very thin form of 3-ply – a sort of wall-cladding with shallow grooves on the surface. It's not 'structural' stuff by any means, but quite adequate.

Cheers

[DAN-Y]

I’ve completed extensive testing of various remote stoves and found the Volcano to be my 1st choice in putting together 2 winter kits for this coming winter. Everything about the stove fits the requirements.

Canister of 98% Propane will be my fuel of choice. Titanium trivet will maintain canister in upright position to facilitate easy access for gloved flame control.

[Roger Caffin]

Hi Dan

Canister of 98% Propane will be my fuel of choice.
Are you refilling your own canisters then?

[Roger Caffin]

Hi Dan

Canister of 98% Propane will be my fuel of choice.
Are you refilling your own canisters then?

[DAN-Y]

Are you refilling your own canisters then?

 

Yes, absolutely. They are easy to refill. My set-up:

[David Gardner]

Dan: Oh wow, so the Boss Torch canister is compatible with a typical butane stove? Same threads, etc.?

[DAN-Y]

Yes, same threads. The Holy Grail of cold weather canister fuel.

I’ll be refilling them, easy peasy.

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

[Jerry Adams]

according to link, empty canister weighs 3.8 ounces

a regular canister weighs 3 ounces

it says “propane blend” – how much propane and butane are in the new canister?  maybe it’s 75% butane, 25% propane

since the canister weighs about the same, I don’t think it’s any stronger

If you put 4 ounces of 98% propane in it, try gradually increasing the temperature and see at what temperature it bursts.  I think you’d be lucky if it got much above room temperature.  Outside.  Take video.

I’m being facetious – don’t do this – I would be very cautious – definitely don’t go above room temperature

[David Gardner]

Dan, any problems with the Boss Torch canisters that you have refilled with 100% propane, at room temperature or higher?

Jerry, the diameter of the Boss Torch can looks smaller than the smallest isobutane canister, and wall thickness is determined by the square of the radius, so that may be how they pull it off.

[DAN-Y]

I emailed the Enviro-Safe Corp. and this is how they responded:

—–Original Message—–
From: ES-Refrigerants <[email protected]>
Sent: Tuesday, June 30, 2020 12:17 PM
To: ES-Refrigerants <[email protected]>
Subject: New ES-Refrigerants.com Contact Request

NAME
Dan Yeruski

EMAIL
[email protected]

SUBJECT
The Boss Ultimate Propane Blend

MESSAGE
Hello, what is the Propane blend, 100% propane or is there a butane mixed
in?
Thank you
Dan

[email protected]
Tue, Jun 30, 3:11 PM

to me

It is propane. If you need butane, we have that as well.

 

Jeanette Akright
General Manager
Enviro-Safe Refrigerants, Inc.
400 Hanna Drive
Pekin IL 61554
309-346-1110
http://www.es-refrigerants.com

[DAN-Y]

Contents of canister:

Quote:

CAS#% ChemicalName————————————————————–
138-86-3.02% TipCleaner
68476-85-7 99.7% Petroleum gases, liquefied
75-08-1.28% EthylMercaptin

https://www.es-refrigerants.com/docs/43123_62.pdf

[Jerry Adams]

okay, I’m getting convinced : )

try putting it in the freezer and see if there’s still pressure.  0 F would need something like 50% propane to still have pressure.  You’d have to look at the table in one of Roger’s articles.  You’d have to get extremely cold to verify that it’s 98% propane, but you could at least verify it’s not 75% butane 25% propane

does it have a maximum temperature?  like 110 F or 120 F?  That’s the normal max

in it’s regular application would it sometimes get warm?  There must be a lot of people using it and if it bursts at warm temperatures, they would have stopped selling it a long time ago, it must be safe

there are probably no people refilling with 98% propane, so they would have no experience with it possibly bursting

maybe just as an abundance of caution, refill with 98% propane and put in a little warmer place outside than you’d ever experience in normal use just to make sure.  It would be annoying if this happened in your hot car on the way to a trailhead.

[DAN-Y]

Refilling Coleman PowerMax Canisters with 100% propane by Hikin’Jim:

https://adventuresinstoving.blogspot.com/2012/02/refilling-coleman-powermax-canisters.html

[Roger Caffin]

The density of the fuel in the BOSS canisters as quoted in the BOSS docs was well above that of propane. Butane is more dense than propane. My estimate was that the fuel might have been 60% propane/40% butane. That would tally with the heavier BOSS canister: it would be a bit stronger.

However, putting 100% propane in a canister designed for 60% propane is RISKY. I could imagine a hot day, or in a car in the sun, could take 100% propane above the burst strength of the canister. This would not ‘be good’.

If you were to fill and use the BOSS canister with 100% propane in the depths of winter, with the temperature around or below 0 C all (and I mean ALL) the time, you might stay within the pressure rating of the canister. Granted, I do not know what the rating for the BOSS canister might be, but comparing the different fuels on a pressure/temperature graph suggests this.

Of course, there would be no reason to put 100% propane with its attendant risks in any canister in the warmth of mid-summer. Very often you could use 100% butane quite happily. Fly spray cans of butane are not expensive at all.

Be safe! No responsibility accepted for what YOU do.
Cheers

[DAN-Y]

Roger, have you filled the PowerMax canisters with propane?

[Roger Caffin]

have you filled the PowerMax canisters with propane?
Never.

I may have refilled one with the standard butane/propane mix out of a Primus screw-thread canister, but I have never ‘fiddled’ with the ratio.

Cheers

[Edward John M]

The plywood I use is 4mm hardwood ply and I have never bothered to weigh it. I have some scraps in the shed. I’ll do that in the next few days

[DAN-Y]

Edward John, I use 3 ply Honduras mahogany. Weight per piece = 29 grams

 

Roger, if a canister has 30 grams of propane in it, the pressure inside is the same as when it has 60 grams in it, correct? We just want to know about pressure at this point.

[Roger Caffin]

Hi Dan

It’s not that simple. When you add butane to the propane the total vapour pressure DROPS. You really should read our article on Exploding Canisters at
https://backpackinglight.com/exploding_gas_canisters_the_hazard_of_overheating/

This explains it all. However, to speed things up, have a look at this graph of pressure vs temperature:

Horizontal axis is degrees Centigrade. Vertical axis is in atmospheres of pressure above ambient. Once it hits 0, boiling stops.

Note that by DoT regulations, ALL canisters MUST handle +50 C without any leaks or damage, so I will use that temperature.

The curves to look at first are the light blue over dark blue ones and the red over teal, in the middle of the pack. The pale blue one is 30%propane/70%isobutane; the red one is 30% propane/70%n-butane. These represent the typical modern screw-thread canisters. At 50 C the blue curve is at 11.7 atm, while the red one is at 9.7 atm.

The khaki one above them would be the BOSS pressures IF I am right about the contents, which were calculated from the quoted density. At 50 C the pressure is 15 atm. The grey one is for straight propane, and the pressure is 22 atm. This is nearly double that for the best commercial blend.

Now, my testing (in the article) showed that a single canister did get up to 100C or >30 atm before exploding, but that is NOT guaranteed for any canister. Yes, they build them a bit over-spec – so they have zero failures at all times. But that was a sample of one, and it was undamaged at the start.

Do you feel lucky?

Cheers

[Mike M]

forget about 100% propane for a minute, but if the BOSS canisters are indeed 60% propane, 40% butane; wouldn’t that be significantly better (better as in better for winter use) than anything that is offered currently?

any possible chance of knowing if they are blended with iso-butane vs butane?

 

[Roger Caffin]

Yes, the increased percentage of propane is theoretically ‘good’, in that it better than the others, but I have to ask whether the benefit is all that great.

The BOSS mix might get you to -30 C, while the more conventional mixes will only get you to about -24 C, but how does this work out in the field? I take some care to not let my canister get below 0 C. It travels in my pack next to my back and next to my water bottle, which does not freeze. Overnight it lives inside the foot of my quilt, where it certainly stays above 0 C.

If you were hauling your gear around in a pulk or sled, then the canisters could get well sub-zero. But under those conditions I would be carrying straight propane (boils at -42 C) in heavier bottles.

No, I have no idea of whether BOSS uses iso or n butane. Commercial reality being what it is, the mix of the two is probably uncontrolled and unknown.

Cheers

[Mike M]

ahhh- I thought with roughly three times more propane (~ 60% vs 20%) than current offerings the difference would be more pronounced

[Roger Caffin]

It did not work out that way. Yes, a pity. The effect is only a few degrees difference.

I wonder: did someone, somewhere, in engineering some 40+ years ag,o look at the data and decide that 30% was ‘good enough’? It may be.

Cheers

[Jerry Adams]

or, did the marketers at some point say a label with 30% looks good? : )

One problem with a propane/butane mix, is that when you use it, the propane is evaporated preferentially.  When you’ve used half the canister, you’re left with mostly butane.

adding propane to the mix helps operation in cold temps for the first part of a canister, but after you use most of the canister, the added propane doesn’t make much difference

you can work with this by, for example, plan on just using half your canister on a cold trip

also, as the canister starts getting emptier, the evaporative cooling is more, so if you plan on just using the first half of your canister it will work better at cold temps

but, the alternatives work pretty good – inverted canister, Mulder strip, shallow dish of water.  Using even cheap butane at cold temps is not difficult.

[Roger Caffin]

or, did the marketers at some point say a label with 30% looks good? : )
Me, I don’t think so. I think, without much evidence, that it was a technical decision. ‘They’ also tried it briefly with the Bleuet canisters.

One problem with a propane/butane mix, is that when you use it, the propane is evaporated preferentially. When you’ve used half the canister, you’re left with mostly butane.
Yes, if you are using an upright stove at sub-zero temperatures. But it is more like when you have used 1/3 of the canister!

But that is a bit of a strawman argument. Upright stoves are not meant for sub-zero conditions. Yes, you can use bowls of water or feedback strips to help things along, but that is ‘technical’ and beyond many users. Remote inverted canister stoves are for sub-zero conditions, and they excel at that.

I really don’t mind either way. HYOH, BYOS. (burn your own stove)

Cheers

[Author]

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