Disappearing gas mixture ratios

[Ent]

Hi All

Noticed that on more than a few brands of gas cylinders the ratios are disappearing and been replaced by marketing hype such as "Premium" or "Winter formula". etc, etc. A dig on the Internet reveals that is code for 75/25 or even as bad as 80/20. I hope that we are not seeing a precursor to the drop in the standard of gas with the screw type cylinders that happened with the tall canister type. Most of the tall cylinders are 100 percent butane which is pretty much useless of winter even at coastal temperatures.

Just out of interest what is the best winter mixture that is available commercially, especially in Tassie? I have some 70/30 ones and from memory have used 65/35.

At Lees Paddocks when the water froze a 6pm my Optimus Crux struggled with a less than quarter full cylinder of 75/25 yet belted along nicely with a near fresh cylinder of the same bred. The Primus ETA was unphased by a near empty cylinder at Pelion Hut but that plus 3 at the lowest temperature in the hut.

Cheers Brett

[kuriaken]

Hi Brett
Roger Caffin provides some very useful info via this link that may address your post.
Cheers
Phil.
http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm

[Franco]

A neat trick to warm up the canister is to put it in some water (IE standing inside another pot or a water container wide enough but not tall, like the S2S Kitchen sink)
Franco

[sthughes]

Yes it is annoying not having a clue on what the mix actually is. I avoid cans that don't say.

Remember it's not just the amount of propane but also if it's butane or iso-butane (that will be about as good as an extra 10% propane).

You could always try one of these stoves Brett: http://www.backpacker.com/editors-choice-2010-soto-od-1r-micro-regulator-stove/gear/14015

[Tony]

Yes it is annoying not having a clue on what the mix actually is. I avoid cans that don't say.

Remember it's not just the amount of propane but also if it's butane or iso-butane (that will be about as good as an extra 10% propane).

You could always try one of these stoves Brett: http://www.backpacker.com/editors-choice-2010-soto-od-1r-micro-regulator-stove/gear/14015

Nice stove but the usual marketing garbage. The laws of physics are still the same regulator or not. http://en.wikipedia.org/wiki/Boyle's_law

In the cold you are much better off with a stove with a remote canister that can be turned upside down, as kuriaken has pointed out, read Roger FAQ site.

Tony

[sthughes]

Nice stove but the usual marketing garbage. The laws of physics are still the same regulator or not. http://en.wikipedia.org/wiki/Boyle's_law
Tony

Lol I figured as much, hence why I haven't rushed out to get one. Would be nice for Brett to buy one and prove it though, just so we could all have a chuckle reading his LONG rant afterward

[WarrenH]

I just think;
50/50 I'm having breakfast down on the coast sitting in the sun, all is fine.
65/35 I'll be stopping for lunch shortly on my way home. I've just topped the escarpment at Clyde Mountain and now approaching Braidwood maybe check an art or craft gallery or two, it is time for a cuppa, all is fine.
70/30 it's cold here in the mountains now I'm at home, all is still fine. I'm pleased to now have 70/30.

If you don't have 70/30 on a frosty morning here in the mountains ... the term is, 'really sluggish'.

On my next trip in August, I can't take the fuel that I'll need with me, from home. I've had to ring ahead to the pick up point, specifying 70/30. I'll be at the top of the Divide for weeks making my way along it and it will be cold ... what is the bet that it wont be 70/30 waiting for me to collect. I specified 70/30, from delightfully warm Queensland.

This is Aus-trail-eee-yarr. That reminds me of an old song, it must be time for another cuppa ... 70/30.

Warren.

[corvus]

For what it is worth I have made a "cosy" for the 230g cans out of a give away wine carry bag (thin neoprene would post a pic if I knew how )and it improved the cold weather performance quit substantially.
I also use a Brunton remote stove stand which enables me invert the cannister if needs be.
Will find the link and post later.
corvus

[corvus]

Here tis,
http://www.brunton.com/product.php?id=596
corvus

[Tony]

Hi Corvus,

For what it is worth I have made a "cosy" for the 230g cans out of a give away wine carry bag (thin neoprene would post a pic if I knew how )and it improved the cold weather performance quit substantially.
I also use a Brunton remote stove stand which enables me invert the cannister if needs be.
Will find the link and post later.
corvus

Could you please expain to me how a canister cosy works.

Tony

[Lizzy]

Found this- gas canister cozy & these explanations....may be of interest...or not
http://www.suluk46.com/RandD%20-%20RD8% ... 0Cozy.html
http://www.backpackinglight.com/cgi-bin ... d_id=29306

Last edited by Lizzy on Wed 23 Jun, 2010 10:15 pm, edited 1 time in total.

[corvus]

Hi Corvus,

For what it is worth I have made a "cosy" for the 230g cans out of a give away wine carry bag (thin neoprene would post a pic if I knew how )and it improved the cold weather performance quit substantially.
I also use a Brunton remote stove stand which enables me invert the cannister if needs be.
Will find the link and post later.
corvus

Could you please expain to me how a canister cosy works.

Tony

G'day Tony,
I will try
You fully enclose the remote cannister in the cosy with a opening for the connector and that is it ,perhaps a wool sock would do the same thing without needing to sew,can inversion will cause some flare up but with the cosy did not really need to do it last trip however I intend to rig a heavy copper wire "heat exchanger" with the stove stand to see if I can prevent possible flare up.
If I knew how I would post a photo

corvus

[Tony]

Hi Corvus,

Hi Corvus,

For what it is worth I have made a "cosy" for the 230g cans out of a give away wine carry bag (thin neoprene would post a pic if I knew how )and it improved the cold weather performance quit substantially.
I also use a Brunton remote stove stand which enables me invert the cannister if needs be.
Will find the link and post later.
corvus

Could you please expain to me how a canister cosy works.

Tony

G'day Tony,
I will try
You fully enclose the remote cannister in the cosy with a opening for the connector and that is it ,perhaps a wool sock would do the same thing without needing to sew,can inversion will cause some flare up but with the cosy did not really need to do it last trip however I intend to rig a heavy copper wire "heat exchanger" with the stove stand to see if I can prevent possible flare up.
If I knew how I would post a photo

corvus

Thank you for your try at an explanation, I will have to do some thinking about it. Below is an very good explanation from Stuart Robb on BPL, basically canister cosies are a waste of weight especially in the mild climate of Tasmania.

A gas canister (any type) will benefit from a cosy only _whilst_ its contents are warmer than the ambient temp.

So, a pre-warmed inverted canister will benefit: there is no evaporative cooling and the cozy will keep the contents warm(er).

However, an upright canister is cooled from within by evaporative cooling. If it has a cosy you will not know when it has cooled below ambient so any benefit of the cozy will be short lived and then becomes a disadvantage.

For both types, there is no benefit at all if the canister has not been warmed above ambient to start with.

[corvus]

Cosy worked for me in our mild ? temperature 3% perhaps because I dont run my stove for long ,as for excess weight it is 19g.
corvus

[Macca81]

my views are the same as tony's quote. a cosy will only help if the canister is already warm. otherwise its just insulating something that is X temp from the surrounding air which is also X temp... i may as well try and warm my sleeping bag of an evening by putting a big stick in it before i go to bed... it will have much the same result... none

[corvus]

Been using gas cannisters for years and I know all about warming them up especially in our very cold winter conditions so perhaps that is why it worked for me
However no skin off my back if folks dont agree and I will just keep reminding myself that a Dumbledore does not look like it should be able to fly but does
corvus

[durks]

... however I intend to rig a heavy copper wire "heat exchanger" with the stove stand to see if I can prevent possible flare up.
corvus

I have seen various home-made heat exchangers used on gas stoves in the Alps, and there was an article about how to build a home-brew one published in the (long gone) magazine Mountain Review. It used something like 1/2 inch copper pipe, hammered flat and then drilled through to lessen the weight, as the exchange mechanism. As with anything like this, you have to very careful the cylinder doesn't get *too* hot.

Myself, I have always managed by, first, keeping the cylinders warm enough in my sleeping bag, and then subsequently letting them get enough direct heat from the stove flame when in use. How easy that is depends on the design of the stove, of course.

[corvus]

Thanks for that durks,
I use a Brunton stove stand so my cannister is remote ,I will be using copper wire as it is easy to work with and a bit lighter than flat hammered or even strip and can be wound /unwound down the feed pipe a bit longer .
All supposition of course as I have not done it as yet ,got a nice cold Winter walk in early July coming up so I better set to soon and post my result (if it works).
corvus

[Ent]

Nice stove but the usual marketing garbage. The laws of physics are still the same regulator or not. http://en.wikipedia.org/wiki/Boyle's_law
Tony

Lol I figured as much, hence why I haven't rushed out to get one. Would be nice for Brett to buy one and prove it though, just so we could all have a chuckle reading his LONG rant afterward

Sorry Simon I would make this rant shorter but the right icon is missing from this forum Maybe I should have warmed my cylinder in the coals of the fire rather than on the edge

Hi Tony, I agree fully re your comments on the stove. I must admit I am well and truly feed-up with marketing hype and well done on debunking this little piece of marketing prose as I looked at the stove and struggled to see what was so special. The cold does not appear to worry the Primus Eta as it has a remote cylinder and pre-heating tube. The Optimus Crux struggles in comparison. Trouble is the Optimus ETA is a very heavy solution, especially for a single person. Curious the stove unit itself is quite light so if they wanted that could get something with the features for under 100 grams.

Cheers Brett

[Tony]

Hi Brett,

I will have to clarify one thing, the few LW stoves with pressure regulators have some advantages when the ambient temperature is warm as they do not allow the flame to be set too high or fast, this does make the stove more efficient as a fast boil is not an efficient boil and this brings me to another bit of marketing garbage that nearly all stove manufacturers market “that boiling fast is efficient”, this is complete rubbish and the manufactures know it is but obviously there are enough gullible people out there that they continue to market garbage.

When it comes to stoves for very cold conditions, there is not too much that is very light, my winter stove setup of a Coleman Extreme plus a JetBoil GCS pot is not the lightest by a long way but when cooking and melting snow for two at around -20C, speed to get warm fluids into me to me is more important than LW or super efficiency, but I am not sure if my winter stove setup would work in extreme cold and the thick scrub of Tasmania.

On the disappearing gas mixtures from the sides of canisters, I am very annoyed with Kovea dropping the mix data from their canisters, the 230g size used to have a mix of 30%/70% propane/butane printed on the side but I am not sure what mix it is at the moment, I have been refilling my canisters from a larger 450g Kovea canister which still has the mix of 25%/75% propane/butane on the sides. The Coleman max canisters have a mix of 35%/75% propane/butane. A source of 35%/75% propane/butane canisters was from Bernzomatic but they seem to have dropped this mix.

The well over priced MSR which has a 20%/80% propane/iso-butane (caution see warning http://www.bushwalking.org.au/FAQ/FAQ_S ... #Isobutane ) this mix does work at a bit lower temperatures for upright stoves but for a upside down remote canister stoves it has no advantages at all, the 30%/70% propane/butane mix would be better.

For more information on gas mixtures, Roger Caffins FAQ site http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm has the best information available.

Tony

[Ent]

Hi Tony

I think your stove setup would be ok in Tassie Not so sure about some the rain jackets though Kovea appear to be playing the same game as the tall cylinders by first removing the mixture ratios and then down grading the ratios. I had cylinders I seam to recall that were 65/35 and then 70/30 and now 75/25. Found another brand that uses 70/30 (Coleman I think) that is made in France so hopefully this will be the goods. At Lees paddock when the temperature dived below freezing before 6.00pm was the first time I experienced dramatic heat drop off with the Optimus Crux. A near full cylinder fixed the problem but I assume once the low temperature gas burns off I would be back to the same issue.

It is disappointing to downright wrong that in Tassie in winter time shops are starting to only have 80/20 mixtures. Ok for summer but most walks this time of the year mean minus temperatures are to be expected at 1000 metres where most of the walking takes place. When heading in a group the Primus ETA is the way to go but at 1.5 kilograms for the setup light it is not, though fast and efficient it is. Might have to drag the fuel stoves out of retirement as they work as well (or badly) regardless of the temperature and height in Tassie.

Cheers Brett

[Orion]

Remember it's not just the amount of propane but also if it's butane or iso-butane (that will be about as good as an extra 10% propane).

It's far more important that it be based on isobutane versus n-butane. The loss in pressure as you use a canister is roughly linear with a lower limit being the pressure of the base fuel.

Nice stove but the usual marketing garbage. The laws of physics are still the same regulator or not. http://en.wikipedia.org/wiki/Boyle's_law

Not Boyle's as it's not a gaseous fuel. It's a liquid. The relevant physics are Raoult's Law and the Clausius–Clapeyron relation. But you're right that a regulator cannot be expected to increase the pressure in the cold.

In the cold you are much better off with a stove with a remote canister that can be turned upside down

Quite right. But upright systems tend to be lighter and with a little care can be made to work in a variety of conditions.

[Tony]

Hi Brett,

Hi Tony

I think your stove setup would be ok in Tassie Not so sure about some the rain jackets though Kovea appear to be playing the same game as the tall cylinders by first removing the mixture ratios and then down grading the ratios. I had cylinders I seam to recall that were 65/35 and then 70/30 and now 75/25. Found another brand that uses 70/30 (Coleman I think) that is made in France so hopefully this will be the goods. At Lees paddock when the temperature dived below freezing before 6.00pm was the first time I experienced dramatic heat drop off with the Optimus Crux. A near full cylinder fixed the problem but I assume once the low temperature gas burns off I would be back to the same issue.

It is disappointing to downright wrong that in Tassie in winter time shops are starting to only have 80/20 mixtures. Ok for summer but most walks this time of the year mean minus temperatures are to be expected at 1000 metres where most of the walking takes place. When heading in a group the Primus ETA is the way to go but at 1.5 kilograms for the setup light it is not, though fast and efficient it is. Might have to drag the fuel stoves out of retirement as they work as well (or badly) regardless of the temperature and height in Tassie.

Cheers Brett

Kovea make the canisters for MSR and as I understand they also make canisters for a lot of the other suppliers too.

Tony

[Tony]

Hi Orion,

Nice stove but the usual marketing garbage. The laws of physics are still the same regulator or not. http://en.wikipedia.org/wiki/Boyle's_law

Not Boyle's as it's not a gaseous fuel. It's a liquid. The relevant physics are Raoult's Law and the Clausius–Clapeyron relation. But you're right that a regulator cannot be expected to increase the pressure in the cold.

You are right, because of the liquid fuel, it is much more complicated than Boyles law, but Boyles law keeps the relationship between Pressure Volume and Tempertature simple.

Tony

Boyles law

For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one increases, the other decreases).[

Last edited by Tony on Tue 29 Jun, 2010 11:31 am, edited 1 time in total.

[Orion]

For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one increases, the other decreases).[

That does not describe what happens inside a canister. The pressure is a function of temperature and fuel composition, not volume. Hold the temperature constant and change the volume -- the pressure will remain the same.

If it were like an ideal gas it would not matter if it were propane or butane or isobutane.

[Tony]

For a fixed amount of an ideal gas kept at a fixed temperature, P [pressure] and V [volume] are inversely proportional (while one increases, the other decreases).[

That does not describe what happens inside a canister. The pressure is a function of temperature and fuel composition, not volume. Hold the temperature constant and change the volume -- the pressure will remain the same.

If it were like an ideal gas it would not matter if it were propane or butane or isobutane.

Hi Orion,

Appologies, I did my previous post in a hurry and did not not put much thought into it, have edited my previous post, you are right what goes on inside the canister is a lot more complicated than Boyles law.

Tony

Edit: I was just reading Roger Caffins FAQ on fuels mixtures http://www.bushwalking.org.au/FAQ/FAQ_Mixtures.htm and apparently Waals force is important too http://en.wikipedia.org/wiki/Van_der_Waals_force

Here is an excellent Phase-diagram of The Clausius–Clapeyron relation From Wikipedia http://en.wikipedia.org/wiki/Clausius%E ... n_relation

530px-Phase-diag2_svg.png (25.61 KiB) Viewed 14977 times

[Tony]

This link turned up on BPL and I thought that some bushwalk.com members might find the information it contains interesting.

http://www.scunnered.pwp.blueyonder.co. ... _Stove.htm

Tony

[Ent]

Hi Tony

Pretty well sums up in graph form what I experienced at Lees Paddocks when I took about a half full large gas cylinder that was used before on another cold trip. The small MSR cylinder combined with the Primus Eta worked a treat at Pellion but then the hut temperature was 5 to 6 so not nearly the test the -1 or lower experienced at Lees Paddocks. Looks like my collection of half empty cylinders will grow Also means the 80/20 mixture ones are bad news for Tassie, at least in winter.

Cheers Brett

[Orion]

Interesting graphs, Tony, thanks for that link.

It's worth noting that in calculating these graphs he assumed that butane and propane form ideal gases, which is not true. Taking into account their true nature would bias the loss of propane somewhat, in favor of keeping the propane percentage somewhat higher. But the overall picture is the same: You lose the more volatile fuel(s), and at about the same rate regardless of operating temperature.

Also worth mentioning is that actual canisters are not the exact mixtures that their labels suggest. They contain other components, in particular higher volatile fuels in small amounts. This results in an initial canister pressure that is much higher than one would expect from the calculations.

Here is a graph produced from actual canister pressure data (please excuse the non-metric units). As with that guy's calculated graphs, you can see quite clearly that choosing a canister with isobutane as the base fuel is more important than the amount of propane in the mix.

[rcaffin]

I don't think I can add much on top of what has already been said.
Yes, the FAQ has a fair bit of info on gas mixtures and stoves.
Also, http://www.backpackinglight.com has a lot of articles on the use of canister stoves in winter (many by me). There will be another one soon explicitly on the behaviour of the gas canisters in the cold, against temperature and against time (as the canister empties). Lots of graphs ...
Putting the canister in a bowl of cool water DOES help.

But switching to a remote canister stove is really the more reliable solution. Yes, they are heavier - but so is a lot of winter gear. Sigh.

Cheers
Roger