Canister Refiller -- WARNING

[hikin_jim]

I'm pretty sure it's 1 degree colder for every 100 metres in altitude. I think I posted a topic here with a reference once. Semantics.

Sent from crap electronic device using dodgy app.

I believe that's the general rule for how much the air temperature changes (in general, all else being equal). What I'm talking about is the lowering of the boiling point which is about 1C per 300 meters (2F per 1000 feet). Those are very approximate "rule of thumb" numbers.

HJ

[hikin_jim]

What hikin' jim meant was that if you go up in altitude 100 meters the air pressure will drop about 10 millibars (for the first several thousand meters). So for a 300 meter change that would be 30 mb. Around 0°C a 1°C change in temperature corresponds to a 38 mb change in the vapor pressure of n-butane, which means you can use the butane stove 0.8°C colder. The colder the butane the smaller the pressure change per unit temperature change so by the time you get up to about 2500 meters a +100 meter change really does allow you to use butane 1°C colder.

My numbers are very approximate. I believe they're fairly accurate up to about 5000m. When you're getting up above 6000m/7000m, odd things start happening, and changes in boiling point are less linear. Next time you're at 8000m, remember that.

But I think hikin_jim is a chicken for not adding a little propane. With a little care and pressure checking it isn't dangerous.

Well, perhaps. The one thing we haven't discussed is internal corrosion. If a bit of moisture gets in as you refill, then you could get some kind of internal corrosion or rust -- something that might not be visible from the outside. I think the chances are small, but if I'm using a canister that is rated for a 30/70 mix but only refilling with 100% butane, I've got a rather large safety margin. I happen to be fond of large safety margins. I keep remembering that those little cheap disposable butane lighters are made of not particularly strong plastic. If flimsy plastic can withstand the pressure of liquefied butane, then I have great confidence in a steel canister.

HJ

[Stew63]

I have both an adapter to run stove burners and a really nice device that I can transfer 220 gm butane into 230gm canisters,
used the Butane with my stove and Brunton Platinum mantle Lantern in reasonably warm conditions and it was very acceptable ,up at Oakleigh View on the weekend the Lantern did not burn as bright on Butane in colder conditions as it normally did on the expensive mix but still provided a good light .
Worth while checking out the Butane transfer gizmo 4 x220g cans at K Mart $4.75 1x 230g canister of mixed gas around $8.00
worth having a go in my opinion
corvus

corvus, if you don't mind me picking your brain for a minute. Which adapter do you have for the stove burner and which brand/type stove are you adapting? The adapter I bought off eBay (which doesn't work) is a small black Kovea branded one (with silver metal internals) - sorry I don't know how to post a picture here. (I'm trying to adapt a Primus Omni Fuel with the small screw in valve into a clamp on setup for 220gm butane canisters)

[corvus]

G'day this is the one I bought http://www.ebay.com.au/itm/310381003646 ... 573wt_1037
Works with all of my stove burners but not for the Lantern (needs a cut and shave) to do that
corvus

[Orion]

My numbers are very approximate. I believe they're fairly accurate up to about 5000m. When you're getting up above 6000m/7000m, odd things start happening, and changes in boiling point are less linear. Next time you're at 8000m, remember that.

The change in the boiling point of butane with altitude is fairly linear between 0 and 8000 meters. Maybe you're thinking of the relationship between air pressure and altitude?

The one thing we haven't discussed is internal corrosion. If a bit of moisture gets in as you refill, then you could get some kind of internal corrosion or rust -- something that might not be visible from the outside. I think the chances are small, but if I'm using a canister that is rated for a 30/70 mix but only refilling with 100% butane, I've got a rather large safety margin. I happen to be fond of large safety margins.

I like safety margins too which is one of the reasons I don't refill canisters at all. But if I did I would add a dose of propane. As long as care is taken to not overfill or overdose with propane the types of leaks one might get from corrosion would most likely be no worse than a leak through the valve. Hissing, it might catch fire, no drama. Nothing like the scenario of a canister filled with 100% propane bursting catastrophically.

[hikin_jim]

Works with all of my stove burners but not for the Lantern (needs a cut and shave) to do that

Unfortunately, the standards for various parts of the connection between canister and stove are not fully defined. There's a bit of gray area there, and not every adapter will work with every stove.

I've never had a problem with any stove not fitting any canister, but I've run into several problems (either people I know or on my own) where adapters haven't fit quite right and cannot be used with a particular stove.

HJ

[hikin_jim]

The change in the boiling point of butane with altitude is fairly linear between 0 and 8000 meters. Maybe you're thinking of the relationship between air pressure and altitude?

Should not those two be closely mirroring one another?

I like safety margins too which is one of the reasons I don't refill canisters at all. But if I did I would add a dose of propane. As long as care is taken to not overfill or overdose with propane the types of leaks one might get from corrosion would most likely be no worse than a leak through the valve. Hissing, it might catch fire, no drama. Nothing like the scenario of a canister filled with 100% propane bursting catastrophically.

Well, I keep considering it (adding propane), especially since Coleman Max/PowerMax canisters have gone out of production.

HJ

[Orion]

Should not those two be closely mirroring one another?

The air pressure vs. altitude relationship is exponential. The saturated vapor pressure vs temperature curve for butane is also exponential. When you put them together to look at altitude vs temperature for butane it ends up fairly linear.

The following graph shows altitude vs pressure for the atmosphere. It also shows altitude vs boiling point temperature of butane (right y-axis).
(That's NOT the temperature of the air at that altitude. It is also NOT the pressure of the butane for that temperature.)

[hikin_jim]

That's interesting that you're showing the butane boiling points relationship to elevation being so linear. I was of the understanding based on some tables that I've seen (it's been a while), that things started changing above 7000m and even more so as one ascended.

I still think that 1C per 3m is a good rule of thumb for roughly how much improvement in cold weather performance one can expect with a gas stove.

HJ

[Orion]

That's interesting that you're showing the butane boiling points relationship to elevation being so linear. I was of the understanding based on some tables that I've seen (it's been a while), that things started changing above 7000m and even more so as one ascended.

I still think that 1C per 3m is a good rule of thumb for roughly how much improvement in cold weather performance one can expect with a gas stove.

It's not actually linear. You can take approximate equations for the standard atmosphere and the saturated vapor pressure of butane and solve for the boiling point in terms of altitude. The result is something of the form T = A/(B+C*h) + D, where h is the altitude and A,B,C,D are constants. That isn't the equation for a line, but it can be fairly linear over a given range. The graph I posted used measured values for the butane sat. vapor pressure combined with a forumla to calculate the atmospheric pressure. I think I did it right.

In any case your rule of thumb is close enough, all else being equal. But of course all else is almost never equal. The higher canister gauge pressure is more than offset by the lapse rate, so I'm not sure how often you really get to see that performance improvement.

[hikin_jim]

In any case your rule of thumb is close enough, all else being equal. But of course all else is almost never equal. The higher canister gauge pressure is more than offset by the lapse rate, so I'm not sure how often you really get to see that performance improvement.

If one were thinking, "hey my canister doesn't have enough pressure, I'll just climb higher until my gas stove starts working," then I think you'd get nowhere fast. The lapse rate is generally greater than the increase in gauge pressure.

However, if one were planning a trip, then I think my 1C/300m rule of thumb (combined with a good weather forecast and a topo map) would be of use. If I know (approximately) what the temperature will be, what fuel I'm using, and what the elevation will be at my camp site, then I can decide whether, say, I can bring my little upright gas stove or I need to carry my heavier inverted canister stove.

HJ

[hikin_jim]

You guys are thinking of the lapse rate which goes at an average 3.5°F per 1000 feet, with a seasonal dependency if I remember correctly.

Good clarifiction

What hikin' jim meant was that if you go up in altitude 100 meters the air pressure will drop about 10 millibars (for the first several thousand meters). So for a 300 meter change that would be 30 mb. Around 0°C a 1°C change in temperature corresponds to a 38 mb change in the vapor pressure of n-butane, which means you can use the butane stove 0.8°C colder. The colder the butane the smaller the pressure change per unit temperature change so by the time you get up to about 2500 meters a +100 meter change really does allow you to use butane 1°C colder.

Precisely.

Interestingly, at elevations above something like 8000m, things start to get strange, so don't use my "1°C colder for every 300m elevation" approximation the next time you're above 8000m.

But I think hikin_jim is a chicken for not adding a little propane. With a little care and pressure checking it isn't dangerous.

Well, I prefer the word "judicious," but be that as it may, the means are easily at hand and affordable. All one needs is a bit of fortitude... and a lot of caution.

HJ

[Onestepmore]

I thank HJ for converting his native deg F and feet into deg C and meters for us here.
I wish more overseas manufacturers and cottage producers would list dual measurements for the rest of the world.
My conversion app on my phone gets a good workout when I'm reasearching stuff or reading boooks like Andrew Skurka's

Good point made about the theoretical possibility in the future about not being able to work on your own car unless 'qualified'
When I worked overseas, I found it interesting that in the UK it's not legal to shoe your own horses or do any farriery work - only a qualified farrier is allowed to do that. Very different from here and the US, where anyone can trim and shoe their own horse (obviously you have to know what you're doing, have the right gear etc)
I'm trying to get a canister stand to hold a canister in the inverted positon. I'm not allowed to order a spare parts Helios canister stand in Australia because I have been told the whole Jetboil Helios system is banned in Australia, as is the MSR Universal system. I also can't get the liittle stand that goes with the MSR Universal. More cash for the reshippers /sigh.

I guess with all these adaptors and converters, it's caveat emptor

Last edited by Onestepmore on Wed 13 Mar, 2013 8:11 am, edited 2 times in total.

[wander]

This is all way too complicated.

Will stick with our liquid fuel stove.

[hikin_jim]

I thank HJ for converting his native deg F and feet into deg C and meters for us here.
I wish more overseas manufacturers and cottage producers would list dual measurements for the rest of the world.
My conversion app on my phone gets a good workout when I'm reasearching stuff or reading boooks like Andrew Skurka's

On my blog, I do it for that very reason. If the author does it, it's done once, and all can read without the interruption of having to go and look up the conversion. If the author doesn't do it, then every single reader must do it each and every time.

I'm trying to get a canister stand to hold a canister in the inverted positon. I'm not allowed to order a spare parts Helios canister stand in Australia because I have been told the whole Jetboil Helios system is banned in Australia, as is the MSR Universal system. I also can't get the liittle stand that goes with the MSR Universal. More cash for the reshippers /sigh.

The Universal is banned in Australia? I wonder why? Or is it that it just hasn't been approved yet? The Universal's stand is the same as that of the Windpro by the way. However, the stand is fits onto the stove's valve and not the canister, so I'm not sure an MSR canister stand would be of any help. I just usually lean my canister against a rock or something and that works well enough although it's a bit trickier with a 450g canister (which I rarely use).

I guess with all these adaptors and converters, it's caveat emptor

Definitely.

HJ

[Solohike74]

Alcohol or shellite/white gas stoves are far more economical to operate. They both work well in winter too, even in the snow. Shellite wins for winter alpine expeditions.

They come with bottles where there's no refueling dangers & you can always know how much fuel is left.

IMO that propane refilling system seems dangerous....why put yourself in great danger just to save a few dollars.

[hikin_jim]

IMO that propane refilling system seems dangerous....why put yourself in great danger just to save a few dollars.

Uh, yes, which is why the post has the word "WARNING" in all capital letters.

Was I not clear? This refiller should not be used under any circumstances. "Seems" dangerous? No, it is dangerous. Avoid.

HJ

[Mark F]

On a theoretical point only - if you plan to refill a canister with a butane/propane blend from a pure butane source and a pure propane source then you need to partly fill the canister with butane before topping it up with propane otherwise the vapour pressure difference between butane and propane is likely to cause problems with the refilling. With an inverted canister stove there only needs to be a small amount of propane in the canister to provide the pressure at low temperatures to force the butane into the heated vaporisation section of the stove so you can most probably get by with only 5 or 10% propane in the canister as long as you switch to inverted mode asap each time you run the stove.

[Mark F]

To solohike 74 - Shellite stoves APPEAR more cost efficient to run - and they are over a 5 or 10 year time frame but the difference is not worth considering in terms of the other costs of going walking. I can buy the latest and greatest gas stoves (inverters or canister top) for under $60. For a shellite stove (MSR Whisperlite from the US) I am going to pay about $100 more. Assuming a 230g gas cartridge costs $10 (I can usually buy them a bit cheaper) and it lasts 7 days (over time I use 30g/day for 2 people) then I can buy 10 weeks worth of gas with the $100 I saved buying the gas stove. A shellite stove uses about 50g per day and a litre of Shellite costs about $8 (I think my figures here a adequately conservative). Thus the cost of Shellite per week is around $3. So the fuel price differential is about $1 per day - not even the cost of a muesli bar - and this needs to be split between 2 people. So I can actually walk for 100 days before the Shellite stove becomes cheaper than the gas stove. For most, this is 3 to 4 years of activity. What I haven't considered is the increased cost of maintenance of a Shellite stove compared to a gas stove and while the accountant in me wants to discuss the time value of money I will resist!

[corvus]

To solohike 74 - Shellite stoves APPEAR more cost efficient to run - and they are over a 5 or 10 year time frame but the difference is not worth considering in terms of the other costs of going walking. I can buy the latest and greatest gas stoves (inverters or canister top) for under $60. For a shellite stove (MSR Whisperlite from the US) I am going to pay about $100 more. Assuming a 230g gas cartridge costs $10 (I can usually buy them a bit cheaper) and it lasts 7 days (over time I use 30g/day for 2 people) then I can buy 10 weeks worth of gas with the $100 I saved buying the gas stove. A shellite stove uses about 50g per day and a litre of Shellite costs about $8 (I think my figures here a adequately conservative). Thus the cost of Shellite per week is around $3. So the fuel price differential is about $1 per day - not even the cost of a muesli bar - and this needs to be split between 2 people. So I can actually walk for 100 days before the Shellite stove becomes cheaper than the gas stove. For most, this is 3 to 4 years of activity. What I haven't considered is the increased cost of maintenance of a Shellite stove compared to a gas stove and while the accountant in me wants to discuss the time value of money I will resist!

+1 corvus

[Onestepmore]

We have an impressively clever bunch of people here

[Strider]

We have an impressively clever bunch of people here

Are you including Corvus' post with this comment?

[Mark F]

A have a feeling Corvus likes to crow a bit - he is always raven on.

[corvus]

A have a feeling Corvus likes to crow a bit - he is always raven on.

Mark F ,
G'day ,
What is your claim to fame eh!! how many stoves do you own /have tested and yes thank you I am a Raven not a Crow
corvus

[hikin_jim]

On a theoretical point only - if you plan to refill a canister with a butane/propane blend from a pure butane source and a pure propane source then you need to partly fill the canister with butane before topping it up with propane otherwise the vapour pressure difference between butane and propane is likely to cause problems with the refilling. With an inverted canister stove there only needs to be a small amount of propane in the canister to provide the pressure at low temperatures to force the butane into the heated vaporisation section of the stove so you can most probably get by with only 5 or 10% propane in the canister as long as you switch to inverted mode asap each time you run the stove.

"as long as you switch to inverted mode asap each time you run the stove"
Aye, and there's the rub. That propane is going to burn off at a faster rate than the butane whenever the canister is upright (as in starting). With only 5 to 10% propane, I'd be worried about running out by the end of canister.

So, again this is theoretical, one might do well to put a bit more propane in, maybe 20%. Canisters in the US come with up to 30% propane, so filling to 20% in a canister that came with 30% should be relatively safe.

HJ

[Orion]

On a theoretical point only - if you plan to refill a canister with a butane/propane blend from a pure butane source and a pure propane source then you need to partly fill the canister with butane before topping it up with propane otherwise the vapour pressure difference between butane and propane is likely to cause problems with the refilling. With an inverted canister stove there only needs to be a small amount of propane in the canister to provide the pressure at low temperatures to force the butane into the heated vaporisation section of the stove so you can most probably get by with only 5 or 10% propane in the canister as long as you switch to inverted mode asap each time you run the stove.

Theoretically, couldn't you warm the source canister and chill the receiving one?

Without looking up the numbers I suspect that the difference between 5% propane/butane and 20% propane/butane is significant in terms of the minimum temperature where you can still get positive gauge pressure.

If I were bothering to refill I'd go big with the propane and take care not to leave the canisters anywhere too warm. I know hikin_jim won't do this though. He's kind of a chicken.

[wander]

Mark F, do you apply the same absolute $ analysis to all your equipment? If so may we see a gear list?

[Mark F]

Wanderer - I don't do this thing for my gear list because the cost is not the most important factor - function and weight are far more important to me. I did it because I consider the Solohike74's statement "shellite/white gas stoves are far more economical to operate" is not backed by the facts and there are several urban myths of this sort that get trotted out without analysis. I am more than ready to admit that a homemade metho setup is more economical and from a functional viewpoint there are many factors that go into determining the choice of stove.

[hikin_jim]

Theoretically, couldn't you warm the source canister and chill the receiving one?

Propane is going to have significant vapor pressure down to at least -35C. Well, if you're chilling things to below -40C, then fill in any order you like, but above that I think you'd still want to put the propane in last.

Without looking up the numbers I suspect that the difference between 5% propane/butane and 20% propane/butane is significant in terms of the minimum temperature where you can still get positive gauge pressure.

Quite significant. It's not that the propane drives out the butane and so all you need is a little propane and you can operate down to, say, -15C. Not quite. The propane and butane blend together in effect creating a single fuel with a vaporization point between the boiling points of the two constituents. Any propane will help, but if you want to get down to -15C and below, you'll need about 30% propane. For those temps, I probably would buy a canister of 80/20 isobutane/propane or possibly 70/30 butane/propane, but I'd rather have the isobutane.

If I were bothering to refill I'd go big with the propane and take care not to leave the canisters anywhere too warm. I know hikin_jim won't do this though. He's kind of a chicken.

What and take the honor of being the first from you? I shall do no such thing. After you; I insist.

HJ

[wander]

I don't do this thing for my gear list because the cost is not the most important factor - function and weight are far more important to me. I did it because I consider the Solohike74's statement "shellite/white gas stoves are far more economical to operate

Fair call, but as you say cost is not the only factor to consider with gear selection and use and I share this view. To some extent with gear you get what you pay for up to a point.

I must admit I had never noticed claims that gas was cheaper to operate that shellite. Your figures actually say the difference is not a lot (in my view) and I could add the costs get closer when you consider the wastage factor. Consider our last 11 night trip, we took 1 litre of shellite with us and had less than 50ml to throw away prior to getting on the flight home. The group next to us at the trail head gave away 6 full and 3 1/2 full canisters of gas at the end of their trip. I'm thinking that we were starting get ahead financially at that rate of fuel purchasing. And what is the issue if the payback on the stove is 5 plus years? I have had 3 shellite stoves over 20 years and onsold the 2 previous anyhow. I'm not trying to have a go at you Mark F, just pondering alternative calculations or viewpoints on the cost question.

As a separate note we started to boil up a cuppa at the trail head after the adjacent group got their stoves out but we were drinking our tea before they'd got theirs to boil. Not point having a stove that will boil a litre 2 minute faster than your mate (in lab tests or whatever) if you are disorganised. All modern gas and liquid stoves boil water in a near enough to similar time in the field to not be a real difference when making a stove choice.