The G-Works Adapter – 100% Propane for Backpacking

Backpacking gas canisters are for backpacking and car camping canisters are for car camping, right?  Well, yes, generally that's true – but not if you have a G-Works adapter.

A G-Works propane adapter connects a backpacking stove to a car camping type 100% propane canister.

A G-Works adapter screws on to the top of an everyday ordinary Coleman type 100% propane canister, the kind that are used for car camping, picnics, BBQ's, etc.  The other side of the adapter is a 7/16" UNEF threaded connector – just like the one on the top of a backpacking type gas canister.  You screw in 100% propane on one side of the adapter and your backpacking stove on the other, and, voila! – you're cooking on 100% propane.

Now, the big 16.4 oz/465 g 100% propane canisters are pretty heavy and bulky.  Why use them?  Well, see my list of reasons, below.

However, note, that there are a lot of techniques and technologies that can help you use regular backpacking canisters in cold weather; see Gas Stoves in Cold Weather – Regulator Valves and Inverted Canisters.  You can also use a liquid fueled stove in cold weather.  This adapter is just another option.  Each person should evaluate his or her own circumstances and preferences and choose accordingly from among the options.

Regarding the weight of the 100% propane canisters:   I have a couple of Coleman brand 465 g canisters of 100% propane in front of me.  They weigh about 850 g each.  The weights vary, but the lowest I've seen for a full 100% propane canister is about 840 g.  By contrast, a 450 g Jetboil brand backpacking type canister weighs 660 g.  That's a minimum difference of about 80 g (roughly 3 oz) for comparably sized canisters.  Some Coleman 100% propane canisters weigh 870 g.  That's about about 110g (about 1/4 pound) more than a comparable backpacking canister.

Is the weight worth it?  Well, that's something you're going to have to decide for yourself.  Read the rest of the post and see if benefits are sufficient to justify the weight of the heavier canister.

A car camping type canister of 100% propane
16.4 oz/465 g net fuel weight

Cautions
High pressure!
Now, remember, the vapor pressure of propane is WAY HIGHER than a normal backpacking canister. Start on low, and open up gradually the valve on your stove.  This is a big boy/big girl, grown ups only, type adapter.  There's no built in safety.  YOU are the safety.  In order to operate this safely, you have to control the gas flow with the valve on your stove.  Turn it up too high, and you might blow out the flame.  If the flame goes out, you've now got a highly flammable, potentially explosive gas rushing toward the red hot metal of your stove. I'm thinking maybe that's not such a good idea – if you get my drift.  So, BE CAREFUL.

Do not tip over!
Also, DO NOT tip the canister over.  The canister needs to be upright.  If you lay the canister on it's side, you're going to be feeding liquid fuel into the burner instead of gaseous fuel.  Don't lay the canister on its side UNLESS you've a) got a remote canister type stove with a generator (pre heat device) of some type and b) your stove is good and hot.  If you don't know what a generator or pre heat device is, don't lay the stove on its side!  You could get a huge yellow fireball.  This is highly dangerous.  Don't do it.

Not recommended for regulator valved stoves above 40 Fahrenheit/5 Celsius.
If your stove is equipped with a regulator valve, I would not use this adapter in cool, warm, or hot weather.  Why?  Well the regulator in your valve is not built to handle the high pressure of propane.  Can your stove's regulator handle the high pressure of propane?  I have no way of knowing – so don't do it.  If you use 100% propane on a regulator valved stove, you could damage the regulator.  If the regulator fails, how are you going to control the flow of gas?  I'm not sure exactly what would happen if your regulator failed while your stove was lit, and I don't want to find out.

Of course, in colder temperatures, high canister pressure is hardly a problem.  At temperatures around 40 Fahrenheit/5 Celsius, 100% propane has roughly the same vapor pressure as an 80/20 isobutane/propane mix at 110 F/43 C.  Your stove should be able to handle such pressures. You should be pretty safe so long as you start with the stove on low and turn it up slowly.  Particularly below freezing, a regulator valve equipped backpacking stove should be fine.  However, note the effects of altitude.  The pressure inside the canister relative to the outside air will become greater at higher elevations.  For every 1000 feet in elevation gained, you should deduct 2 Fahrenheit degrees from my 40 Fahrenheit estimated safe temperature limit.  That would be about 1 Celsius degree for every 300 m.  For example, at 10,000, instead of a 40 Fahrenheit safe limit, you would want to not operate a regulator valve stove above 20 Fahrenheit.  

The vast majority of stoves do not have a regulator valve, but you should check with your manufacturer as to whether or not your particular stove has a regulator valve.

Here are some stoves with regulator valves.  Do not use this adapter with these stoves in cool (above 40 F/5 C), warm, or hot weather.  Use only in cold weather (below 40 F/5 C).

• Jetboil Joule
• Jetboil MightyMo
• Jetboil MicroMo
• Jetboil MiniMo
• Jetboil Sol
• MSR Reactor
• MSR Windburner
• Soto Micro Regulator
• Soto WindMaster

That's all the regulator valved backpacking type stoves I can think of off the top of my head.  Remember to check your stove to see if it has a regulator valve before using this adapter.  Usually it will say on the manufacturer's website if a particular stove has a regulator valve.

Reasons to use this Adapter
1.  Cold weather.
Why 100% propane?  Well, for starters, cold weather.  Butane, which is often the majority component in backpacking gas canisters, vaporizes at 31F/-0.5C.  That's really not all that cold.  Not only that, but you have to be about 20 Fahrenheit degrees (10 Celsius degrees) above the vaporization point before you have consistently good pressure.

Propane on the other hand, vaporizes all the way down to -44 Fahrenheit/-42 Celsius.  That's cold!

Vaporization (Boiling) Point
 n-butane    -0.5°C    31°F
 isobutane    -12°C    11°F
 propane      -42°C   -44°F

And yes, I know they usually blend in some isobutane and propane into the typical backpacking gas canister, but still, nothing beats 100% propane for cold weather.

NOTE:  If you're going out in really cold weather, TEST YOUR SET UP FIRST.  Propane is typically not pure (well, maybe if you work in a laboratory or something).  The temperatures listed above are based on pure propane which you can't buy at least in the US, so you're not going to get quite the good cold weather performance that you might expect.  The propane typically sold in the US conforms to the HD5 standard which is as follows:

• Minimum 90% propane (no less than 90%)
• Maximum 5% propylene (no more than 5%)
• The remainder is comprised of "other" petroleum based gasses

The "other" might include methane, ethane, isobutane, butane, etc., some of which will give you less performance in cold weather, others of which will give you better performance.  So, the number -44F/-42C is something of an approximation, depending on exactly what you've got in the canister.  Still, 90% minimum propane is going to be significantly better than any backpacking canister's mixture which is typically no more than 30% propane.  And remember that you need to be about 20 Fahrenheit degrees (10 Celsius degrees) above the vaporization point before you have decent pressure.  Of course, one can always warm the canister by various means, and so long as isn't warmed to the point of being too hot to touch, it should be safe while giving one good pressure.

2.  Instantly "winterize" your existing stove. 
With this adapter, you don't have to shell out the cash for a dedicated winter stove.  Here's what I mean:  Say you're basically a summer camper.  Most people are.  But every couple of years you get a wild idea and go out when it's cold.  A stove is pretty close to a necessity on a winter trip.  But do you really want to spend the money on an expensive stove that you're only going to use every couple of years?  No, of course not.  No problem.  Just get this little adapter, and voila! you instantly have a winter capable stove.

3.  Outlying areas (no backpacking canisters available).
In a lot of outlying areas, specialty items like backpacking canisters may simply not be available.  I know guys who have hiked in rural New Mexico where they just couldn't find backpacking canisters, but, walk into a hardware store or gas station, and, there they are:  100% propane car camping type canisters.  Having this little adapter might mean the difference being able to do a given trip – and having to just go home.  This is particularly true if you have to fly in for a given trip and cannot take canisters from home.

4.  Natural Disasters.
You could look at this adapter as $20 worth of cheap insurance.  This adapter opens up a whole new fuel supply for your backpacking stove.  The ability to boil water for drinking can be critical in times of natural disaster.

5.  Cheap fuel.
Another reason for buying 100% propane is that it's typically cheaper.  I've seen propane for as cheap as $2.50 (USD) per canister.  About the cheapest you'll find for the equivalent amount of backpacking gas is $7 or $8.  That's a HUGE price difference.  Why?  Well, think about it.  For every backpacker, there are hundreds of car campers, hunters, picnickers, and back yard barbecuers.  The economies of scale just aren't there for backpacking canisters.

6.  Trailhead camping – or just using your backpacking stove for everything.
You might also want to bring 100% propane to cook your supper and/or breakfast if you spend the night before a backpacking trip at the trailhead.  That way, you start with a 100% full backpacking canister for your hike.  Or heck, maybe you just want to own one stove, and your backpacking stove is it.  You use backpacking canisters when backpacking, but when car camping, picnicking, etc. you just use cheap propane, and who cares about the weight when you're using your car, right?

Other Compatible Canisters
Of course there's no reason that you have to restrict yourself to the big, fat 16.4 oz/465 g propane canister.  The 14.1 oz/400 g canisters will work just as well and may be more packable.  For a remote canister stove that can handle liquid feed gas (inverted canister type operation), this might be a nice option.  Heat the stove up with the canister upright, then when the stove is hot, lay the canister on its side for liquid feed.

A 14.1 oz (400 g) propane canister

Really, any fuel canister with compatible threads could be used – but is it a good idea?  For example, the little 5.45 oz/155 g Bernzomatic QuickFire canisters appear to be compatible.  This has NOT been tested with this adapter or with a backpacking type stove is NOT recommended.  Note that the gas contained is NOT pure propane.  Bernzomatic QuickFire canisters contain MAPP gas which does have propane in it but also has a high percentage of propylene.  Propylene burns at a much hotter temperature than straight propane.  What will this high heat do to your stove?  I don't know, but I do know your stove is not built to handle that kind of heat.  I wouldn't do it, but it's up to you.  If you decide to go against my advice, exercise extreme caution with any non-propane canisters.

A Bernzomatic QuickFire 5.45 oz/155 g canister of MAPP (high propylene content) gas.
This has NOT been tested and is NOT recommended with this adapter.

Weight
Some of you may remember my post a few years ago on the Kovea propane adapter.  The Kovea propane adapter is a great little adapter, but it weighs 105g – that's nearly a quarter of a pound!  By contrast, the G-Works adapter weighs 33 g, about 1.2 oz – only about one-third the weight of the Kovea adapter.  In other words, the Kovea adapter weighs roughly triple what the G-Works adapter weighs.

Using the Adapter
OK, so how well does the darned thing work?  Pretty darned well, actually.  Here's a video demonstrating its use:

  
Compatible Stoves
There is a rim around the threads where your backpacking canister attaches.  I used a Kovea Spider stove with my G-Works adapter, and it worked great, but some stoves with a really wide base might not work.  The rim around the threads is about 25 mm outside diameter and about 21 mm inside diameter.  Again, however, I would not recommend that this adapter be used with any regulator valved stove.

The G-Works adapter is made in Korea.  Generally stoves made in Korea work well with the adapter if they fit within the rim.  I've had reports of some stoves from China where the pin on the stove was too short to open the valve on the adapter.  A lot of stoves are made in Korea including some MSR, Snow Peak, and of course Kovea stoves.

Price and Availability
They're available on e-Bay for about $20 although there may be better deals out there.  Amazon is a lot more expensive.

OK, that's it.  That's my presentation on the G-Works adapter, a very nice piece of gear.  Thanks for joining me,

HJ

The MSR Pocket Rocket 2 vs. the Soto Amicus

Recently, I've reviewed two small upright canister stoves, the MSR Pocket Rocket 2 and the Soto Amicus.  Which is the better stove?

The Soto Amicus, left.  The MSR Pocket Rocket 2, right.

Well, it depends.

I try to be pretty even handed with the brands. If a given brand puts out a solid stove that is reasonably well executed, I'm generally going to give them a good review, but this doesn't mean that they're necessarily my top pick for that class of stove.

With respect to the MSR Pocket Rocket 2 ("PR2") and the Soto Amicus, they're pretty much in the same class:

• About the same price – $40 (without ignition) or $45 (with ignition) for the Amicus* – vs $45 for the PR2.
• Roughly the same weight, 73 g/2.6 oz for the PR2 vs 78 g/2.8 oz for the Amicus.
• About the same level of compactness and packability.
• Both have needle valves – as opposed to a regulator valve which can handle cold weather better (see:  Canister Stoves in Cold Weather – Regulator Valves and Inverted Canisters).

So, which is better? Well, I guess that depends on what one values. The Soto is clearly the more sophisticated, and for the same price*, you get a piezo ignition, better wind resistance, and better pot stability.

But the PR2 is dead simple. It's really beefy, and there's little to go wrong with it. It's most vulnerable point is its aluminum threads which can wear out with heavy use. The Amicus has a brass insert which will wear better – but which can still wear out.  Note however that there are many people who have done multiple long distance through hikes with stoves that have aluminum threads and have reported no problems.

With all canister stoves, always:

• Keep the stove's threads clean.  Do NOT set a stove base down in the dirt!
• Keep the canister's threads clean.  You might actually want to keep that little cap.
• Thread the stove on carefully
• Gently tighten; never over tighten

Dimensions

Soto Amicus, folded:  1 9/16" x 1 9/16" x 2 7/8" (40 mm x 40 mm x 73 mm)

Soto Amicus, unfolded: 4 1/8" x 4 1/8" x 3 5/16" (105 mm x 105 mm x 84 mm)

MSR Pocket Rocket 2, folded:  1 11/16" x 1 11/16" x 3" (43 mm x 43 mm x 76 mm)

MSR Pocket Rocket 2, unfolded:  4 3/4" x 4 3/4" x 3 9/16" (121 mm x 121 mm x 90 mm) 

The Amicus is slightly more compact in terms of width and a bit shorter when packed.  

The Pocket Rocket 2 has a wider span to its pot supports when unfolded, but as I say in my write ups, the Amicus actually has better pot stability with it's four pot supports compared to three for the Pocket Rocket 2.  

When unfolded, the Pocket Rocket 2 is slightly taller than the Amicus.

The MSR Pocket Rocket 2, left.  The Soto Amicus, Right.
Note spark point on the Amicus' ignition.

Conclusion
So, sophisticated with lots of features for the same price – or dead simple? Both are pretty good stoves. One has to decide what is most important to them. For me... probably the Amicus. I really like the improved pot stability and the wind resistance. The piezo is nice too.

But I know a lot of people – particularly through hikers who typically want simple, strong, and reliable – are going to go with the PR2.  The PR2 has everything you need but nothing you don't.

Advantages of the Amicus vs. the PR2:

• With no ignition, lower price – $40 for the Amicus* vs. $45 for the PR2.
• With an ignition, the same price but a more sophisticated stove.
• Better pot stability
• Better wind resistance overall, quite a bit better
• Better simmering, particularly in wind (although the PR2 generally simmers very well)
• Threaded brass insert (vs. aluminum for the PR2)
• Simpler, quicker set up than the "rotate out and around" pot supports of the PR2

Advantages of the PR2 vs. the Amicus

• Simple
• Strong
• Reliable (not that the Amicus is unreliable but there's little to go wrong on the PR2)

If you would like to read my detailed reviews on each stove, here are the links:

• The MSR Pocket Rocket 2  
• The Soto Amicus. 

I thank you for joining me,

HJ

*There are some screamin' deals on the Amicus right now:

• Backcountry Gear is selling the Amicus with ignition for $45 – but they're including a free cookset in the deal.  I've never used the cookset, but for free, hey, why not?
• Campsaver has the Amicus without ignition for $32 and with ignition for $36.  Tough to beat that.  Supposedly, if you sign up for their email list, you can get an additional discount.

Unfortunately, the PR2 is a new stove just coming out, so it may be a while before you can find discounts on it.

The Soto Amicus, left.  The MSR Pocket Rocket 2, right.

Disclosures:  

• I don't think I've ever purchased anything from either of these two sites.  They look reputable, but these links do not constitute an endorsement.  Friends have bought stuff at Campsaver and had a good experience.  I can't say either way.
• I receive no remuneration posting these links or writing this blog post.
• I receive no benefit if you purchase something at either of those two sites
• I have no financial relationship with either site.  I'm not even a customer as of this writing.

Considering the above disclosures, you probably have realized that I know a lot about stoves, but I don't know much about making money on the internet, lol.  Have a nice day, and get out there.  

Gas Stoves in Cold Weather – Regulator Valves and Inverted Canisters

There has been a lot of talk about canister gas and cold weather.  Let's see if we can separate some fact from fiction and make sense of things.

In this article, I'd like to discuss what regulator valves and inverted canisters can do for the cold weather backcountry traveller.  But first some background.

If one goes high enough, it can be cold any time of the year.

Who cares about Cold Weather?
You do.  Well, if you intend to cook with canister gas, you do.  Why?  Well, the colder your canister gets, the less pressure it has.  On a hot day, the gas will come blowing out of your canister with great force.  On a cold day, you'll barely hear a hiss of escaping gas.  Without a decent flow of gas, you can't get a proper flame, and, on a really cold day, you simply can't cook.

Particularly for mountaineers, the only way to get water is to melt snow.  With no canister pressure, if you need to melt snow, you can't.  No melting snow = no water = dehydration, and that's bad because dehydration can hasten hypothermia.  Hypothermia is extremely serious and can be fatal.

But even if you're not a high elevation mountaineer, having to eat an uncooked backpacking dinner is pretty unpleasant and forgoing a hot beverage on a cold morning nearly equally so.

Coping with Cold Weather
When using canister gas as a fuel, there are two strategies for dealing with cold weather:

1. Warming the canister
2. Technology

With respect to warming the canister, really, it doesn't matter what the air temperature is provided that you can keep the canister warm.  But can you realistically keep that canister warm when it's really cold out?  

Notice the frost on the lower part of the canister.
The temperature was above freezing at the time this photo was taken.
Canisters cool from within as you use them.

There are two issues here:

1. Canisters cool from within as you use them.  (This is why canister cozies are of limited value.)
2. On a seriously cold day, that little metal canister can get very cold very quickly just from being out in the environment.  

Here now is where technology comes in.  Technology can give us an edge.  Technology can make it so we are a bit less dependent on temperature.

While technology can help us, there's no substitute for the basics.  What are the basics?  

• Choose good gas.  
• Start warm
• Stay warm

We then use technology in conjunction with (NOT in lieu of) the basics.  

With respect to the basics of cold weather gas stove use, I here refer you the article I re-wrote in 2014:  Gas Stoves:  How Cold Can I Go?

Wouldn't a nice, hot beverage be just the thing on a morning like this?
Uh, you did choose the right stove technology before your trip, didn't you?

Technology, Canister Gas, and Cold Weather

What kinds of stove technology can help us use our gas stove in cold weather?  There are two approaches:

1. Regulator valves (as opposed to the more typical needle valves)
2. Inverted canister operation

Approach 1.  Regulator Valves
What is a regulator valve, and how can it help?  There are several layers here, so bear with me.  It should make sense in the end.

First, a regulator valve has a pressure regulator built into it.  This pressure regulator can insure that no more than a certain flow of gas is fed to the burner at a time.

Uh, Jim, that's great, but I thought you said the problem was not enough gas.  Now, you're talking about a device that prevents too much gas.

Well, yes, and here's the issue:  A stove has to be able to operate safely in hot weather as well as cold.  If the stove designer "opens up" a stove too much in terms of gas flow, then there could be a disaster in the offing.

Here's what I mean:  It's a hot day.  Your canister pressure is at an all time high.  You open up your valve all the way without really thinking about it.  The gas rushes through with such force that the flame lifts off the burner and is pushed out and away from where the gas is coming from.  If pushed far enough, the flame will go out even though there was no interruption to the flow of gas.

Now, let's think about this.  We've got a red hot stove, and the flame is out.  We've got volumes of highly flammable petroleum gas rushing out of the tank.  Say, do you think that having a highly flammable, potentially explosive gas rushing toward red hot metal could be a problem?  This could go bad very quickly.  I think you get my drift here.

If a stove designer opens up a stove too much, he or she risks putting someone into the burn ward of the hospital unless... unless there's a pressure regulator present of course.  Now, with a pressure regulator, the stove designer can "open up" the flow all he or she likes without worrying about exceeding a maximum safe amount.  If the canister pressure gets too high, the regulator steps in and inhibits the pressure.  In cold weather, our "opened up" stove lets plenty of gas through, and we can cook even when the canister pressure is fairly low.

Take a look at the photo below.  On the left is the jet of a regulator valved stove, a Soto WindMaster
(perhaps the highest quality upright canister stove on the market today).  On the right is the jet of a non-regulator valved stove from Primus.  You can see even with the naked eye that the aperture of the jet on the left is quite a bit larger.  Measurements reveal that the regulator valved stove has a jet size of 0.4 mm.  The non-regulator valved stove has a jet size of 0.23 mm.  (It's a bit confusing because the jet on the right is stamped "32" which may be a part number, but the size is 0.23 mm.)

If we calculate the cross sectional area of each jet, we find that the regulated jet's area is more than triple that of the non-regulated jet.  You can get a lot more gas through that larger opening.

A regulator valved stove, left (a Soto WindMaster).  A non-regulator valved stove on the right.
The regulator valved stove has a jet size of 0.4 mm.  The non-regulator valved stove has a jet size of 0.23 mm

A non regulator valved stove can't be opened up like this; it just isn't safe.  The designer has to build a non regulated stove such that it is safe at maximum canister pressure; there is no inhibiting regulator.  He or she has to "choke" the stove, and cannot allow it to be opened up.  When cold weather comes, a non-regulator valved stove doesn't have the capability to let enough gas through, and performance falls off quickly.

A regulator valved stove can be built such that the stove can operate at near 100% flame when there is, say, only 15% of maximum pressure available.  On the other hand, a non-regulator valved stove operated at 15% of maximum pressure will have a flame that is about 15% of maximum.  Being able to have a 100% flame at, say, 15% pressure is the true advantage of a regulator valved stove in cold weather.  Note that I'm using "15%" here.  This number is meant to be illustrative more than it is meant to be exact.  Each stove's design will be different.

Ah, but what happens when pressure falls below that 15% mark? In that case, a regulator valved stove quickly loses performance.  At truly low canister pressures, there is no real advantage to a regulator valved stove, and, no, I don't care what any stove company may tell you to the contrary.  Technology only goes so far, and at a certain point, it can do no more.  This is why I say one should use technology in conjunction with – not in lieu of – the basics of good cold weather gas stove operation.  See links below for more information on the basics of good cold weather gas stove operation.

Don't believe me?  Well, how about a demonstration?  Below is a video of not one but two regulator valved stoves.  Here are the test conditions and relevant background information:

• The canisters contain 100% "plain" butane (not isobutane) with no propane.
• The canister temperature is near freezing, i.e. 32 Fahrenheit (0 Celsius).  
• Butane vaporizes at 31 Fahrenheit (-0.5 Celsius).  
• The canisters will cool from within as they are used.
• A canister needs to be about 20 Fahrenheit degrees (10 Celsius degrees) above the vaporization point of the fuel it contains in order to have good pressure. 

In other words, I'm setting up conditions where the canisters will have very low pressure in them.  I think you'll see that neither stove does very well in the video.  One stove does marginally better than the other, but neither stove operates at anything like a normal flame.  Please watch:

I think you can see that a regulator valved stove can only take one so far.  Technology must be used in conjunction with good cold weather gas stove practices.

Hopefully you now understand that a regulator valved stove, if is designed properly, can offer a distinct performance advantage in cold weather because it can be "opened up" whereas a non-regulator valved stove must be restricted in order to operate safely in all temperatures.

Approach 2.  Inverted Canisters
I have been studiously avoiding going into much of the science behind all this.  I don't want to lose people.  Here, though, I have to talk just a little bit about the science or this will make no sense at all.

But fear not.  I am (I hope) a reasonably good communicator of things technical.  If you can't follow me, then post questions in the comments, and let's work together on this.

Why do canisters cool from within?
Recall that I said that canisters cool from within.  I even posted above a photo of a canister with frost on it – frost despite the fact that the ambient temperature was above freezing.

Why do canisters cool from within?  Well, this due to the contents changing state from a liquid to a vapor.  Shake a half full canister some time.  That sloshing sound you hear?  That's liquid in there.  Yes, I know that they're called "gas" canisters, but that gas in there is under so much pressure that it turns into a liquid.

When you open the valve on your stove, that pressure is released, and the liquid inside your canister starts turning back into a vapor.  There's just one thing.  A certain amount of heat is required, the heat of vaporization ("HVap" for those of you who like such things).  For example, let's say you want to vaporize water.  Typically, one would put a pot on the stove and apply heat.  The water heats up, begins to boil, and turns into steam.  Steam is a vapor.  Just as the water you boil in your kitchen requires heat in order for it to turn into a vapor, so also the liquid in your canister requires heat in order to vaporize.  Where does this heat come from?  The surroundings.  In the case of your stove, that heat is taken from the canister and fuel.  As one part of the fuel vaporizes, the remainder of the fuel (and the canister itself) gets cold.

This is the same principle by which an air conditioner, refrigerator, or freezer works.  In a refrigerator, freon (typically) is compressed into a liquid and then allowed to expand back into a vapor.  The heat required to turn the freon into a vapor comes from the surroundings, and the air in a refrigerator is thus chilled.  Think of your canister as its own mini refrigerator/freezer. The principle is the same.

OK, so why this science background?  Well the point is this:  In order for a gas stove to operate, there has to be enough heat to vaporize the fuel.  Gas stoves run on, you guessed it, gas (i.e. a vapor).  You've got to have gas, not a liquid, to run a gas stove.  In order to have gas, you have to transform the liquid fuel in the canister into a vapor, and for that, you have to have a certain amount of heat.  Where that heat comes from matters.

In normal operation, with the canister right side up, gas is drawn off the top.  The heat required to turn the liquid into gas comes from the surrounding canister and fuel.  If however you turn the canister upside down, then you are drawing liquid off the bottom.  In drawing liquid, nothing is vaporizing in the canister.  The liquid can then be fed to the burner.  The burner.  Get it?  A burner is what?  A burner is hot.  Really freaking hot.  In fact, there's all the heat we'll ever need at the burner to convert that liquid we've drawn off the bottom of the canister into a vapor so we can burn it.  There's just one catch.  Your stove MUST be designed to be able to handle this.  The fuel has to significantly heated before  it hits the actual flame in order for things to work properly.  Typically this is done by means of a generator (a.k.a a "pre heat loop") such as the one in the photo below.

A Kovea Hydra stove.  Note the fuel line passing through the flame.
As liquid fuel flows through the fuel line, it is heated greatly and expands into a vapor.

By using the heat of the flame itself to vaporize the fuel, we don't have to worry so much about the temperature of our surroundings, and our canister doesn't turn into a mini freezer.

Preferential vaporization/preferential burning
Not only is there the issue of canister chilling with upright canister use, but there is the issue of preferential burning.  Let me explain:  Backpacking canister fuels are typically a blend.  There's some percentage each of propane, isobutane, and n-butane.  Take a look at the below table:

 Vaporization (Boiling) Point
n-butane    -0.5°C    31°F
isobutane    -12°C    11°F
propane      -42°C   -44°F

Each type of fuel has a temperature at which it will vaporize.  The lower the fuel's vaporization point, the easier it is to maintain good gas pressure in your canister in cold weather.  The various fuels are blended together with the intention of providing a mix that will a) not have such high pressure that it will burst the canister in hot weather while b) still providing decent canister pressure in cold weather.

Propane is going to vaporize all the way down to -42 C (-44 F).  Propane is your best cold weather fuel.  However, in normal right side up canister use, the propane vaporizes more readily and is drawn out of the blend at a faster rate.  This is referred to as "preferential vaporization" or "preferential separation."  Since you're pulling the propane out at a faster rate, you're burning it at a faster rate.  This is referred to as "preferential burning."  They're two sides of the same coin, and both are to be avoided.

For example, if one starts out with a good cold weather mix, say 20% propane and 80% isobutane, by the end of the life of the canister, the propane will be all but gone.  Your blend instead 20/80 will be more something like 1/99.  Whereas your blend started with a nice percentage of propane (which will vaporize all the way down to -42 C / -44 F), you will finish with almost all isobutane (which only vaporizes down to -12 C / +11 F).   You'll have lost that part of your fuel which was serving, in effect, as a propellent.  Recall also that the fuel has to be about 10 Celsius degrees (about 20 Fahrenheit degrees) above its vaporization point in order for there to be decent canister pressure with most stoves.  You cannot use a fuel just barely above its vaporization point and expect decent pressure.

In our example, above, at the start of the life of your canister, you might have had a blend giving you good canister pressure down to maybe -15 Celsius / 5 F or even -20 / -4 F, but by the end of the canister, the blend you have left is maybe only good down to 0 Celsius / 32 F.

Avoiding Preferential Burning
In order to retain an effective cold weather gas blend, we have to avoid the loss of our best cold weather fuel components.  If we pull vaporized fuel off the top of the canister, as in upright use, the propane is just naturally going to come out of the blend faster.

On the other hand, if we pull fuel off the bottom, as in inverted canister operation, it doesn't matter what vaporizes at what temperature.  You're not vaporizing it!  You're drawing off liquid.  The liquid drawn off will be the same blend as the blend in the canister as a whole.  Thus, when running with the canister upside down, your fuel blend does not change significantly.  You start and end with roughly the same percentage of propane, your best winter fuel.

No chill and No Change
So, when you turn your canister upside down, you're essentially eliminating the two big enemies of cold weather performance:

• Internal canister chilling
• Changing (for the worse) fuel blend.  

Practical Application
OK, so I've talked about the two technologically based approaches to mitigating the effects of cold weather:

• A stove built around a regulator valve and 
• A stove designed to handle inverted canister operation.  

Which is best for what?

Well, truth be told, either approach will work, so long as you can keep the canister "warm."  By warm here, I mean warm relative to the surroundings, not balmy tropical weather.  When it's -15 C (5 F) out, then 0 C (32 F) is "warm."  It's just that when it gets really cold, it's hard to keep the canister warm. When it gets really cold, you want to use the technological approach that gives you the biggest boost so that you don't have to struggle so much with keeping the canister warm.

Which approach is the more effective?  Inverted canister operation.  Why?  As I said above,
"no chill and no change."  No matter how well designed around a regulator valve a given upright canister stove is, there will still be internal canister chilling, and there will still be a change (for the worse) in fuel composition.  Inverted canister use eliminates these two killers of cold weather performance.

In practical terms, maybe an upright canister stove is best used in temperatures above something on the order of -15 C (5F)  –  and I'm assuming here that you're already using good gas and keeping the canister warm.  Could you go colder?  Sure, so long as you can keep the canister sufficiently "warm."  I just think it's going to get increasingly difficult to keep the canister warm as the temperature falls.  I've seen a pot of boiling water thrown into the air where all the water freezes before it hits the ground.  That's cold.  If you can keep your canister warm under those conditions, you're a better man or woman than I.

So for really cold conditions, a stove that can handle inverted canister operation is the better choice.  All you need is enough pressure in the canister to get the fuel to flow to and through the burner assembly.  The heat of the flame will take care of the vaporization.  You don't have to worry about the canister chilling from within, and you don't have have to worry about your propane preferentially burning off.  Again, though, your stove must be designed for this.  You can't just take any canister gas stove and run liquified petroleum gas to the burner.

A Jetboil Joule

And, there's no law against combining the two approaches.  In fact, there is a stove that does just that, the Jetboil Joule.  The Jetboil Joule is a snow melting monster.  It has a regulated valve and it is designed to run with the canister upside down.  Not only that, it has a heat exchanger pot.  The heat exchanger causes more of the heat of the burner to get transferred to the contents of the pot.

Why not just use White Gas or Kerosene?
Oh, for crying out loud.  I mean really, Jim.  Why all this messing around?  Why not just use white gasoline or kerosene?

Well, yes, and many people will do just that.  With a white gasoline or kerosene type stove, you don't have to worry much about the temperature of the fuel.  Pressure is not provided by the fuel itself but rather by an external pump.

However:

• Priming a liquid fueled stove (gasoline or kerosene) takes skill, dexterity (it's cold, remember), extra fuel, and extra time.
• In truly cold weather, one is often forced to cook in one's shelter.  Do you really want to prime a stove inside a tent or other shelter? 
• Pumps often fail in cold weather.
• Gas stoves are generally lighter and are more mechanically reliable than liquid fueled stoves.

In truly cold weather, my recommendation is that teams coordinate carrying both liquid fueled and canister gas stoves such that there are back ups in case one or the other proves unworkable.  Ideally, a backup pump (as well as a maintenance kit and spare parts) should be taken for each white gasoline/kerosene stove.

By the way, MSR has just come out with a new pump, specifically designed for cold weather, the MSR Arctic Pump.  It is not supposed to be used above 32 F / 0 C.  It's seals and pump cup are designed to remain flexible in extreme cold.

The new MSR Arctic Pump – designed for extreme cold weather use

Summary

• Canister pressure drops in cold weather.
• Canisters chill not only due to cold outside temperature but also chill from within during use.
• In order to maintain sufficient canister pressure, one must learn the basics of cold weather gas stove operation.  See list of links, below.
• Technology can help augment the basics of cold weather canister stove operation.
• There are two technological approaches to augmenting the basics:   
• Using a stove designed around a regulator valve or 
• Using a stove designed for inverted canister operation. 
• Regulator valve technology can be very helpful in cold weather, but regulator valves can only take one so far (and must always be used in conjunction with the basics of cold weather gas stove operation).
• Perhaps a practical cut off point for upright canister stoves is something on the order of -15 C (5F) – if you're using the basics of cold weather gas stove operation augmented by technology.
• A stove designed for inverted canister operation may be best for temperatures below those where an upright canister stove is typically practical.
• The two technological approaches can be combined and used simultaneously as in the Jetboil Joule.
• In extreme cold weather, teams should coordinate carrying a combination of canister gas and liquid fueled (white gasoline/kerosene) type stoves. 

Closing
This has been a long and complex post, a fact for which I apologize.  I hope that you have found this useful.  If not, then comment below and let's get it properly revised.

HJ

Related articles and posts:

• Cold Weather Tips for Gas Stoves
• What's the Best Gas for Cold Weather?
• Gas Stoves: How Cold Can I Go?   
• Canisters, Cold, and Altitude:  Gas in a Nutshell
• Canister Stoves 101:  Thread Care
• Gas Blends and Cold Weather Performance.  (Why not just use propane?)
• The "Super Gnat"  (Camping Gaz or threaded canisters with one lightweight stove)
• Backpacking Gas Canisters 101
• Gas in Extreme Cold:  Yes or No?
• Gas in Cold Weather:  The Myth of "Fractioning"
• Stoves For Cold Weather I (Upright canister stoves) – Seattle Backpacker's Magazine
• Stoves for Cold Weather II (Inverted remote canister stoves) – Seattle Backpacker's Magazine

Warming a canister, demonstration:
If a picture is worth a thousand words, what's a video worth?  Dunno, but here's a video showing an integrated upright canister stove in cold weather.  You will notice that it is struggling as the canister cools from within.  Part way through the video, I will place the canister in some lukewarm water, and... well, watch what happens.

MSR Pocket Rocket 2 – Review Supplement #1

A few questions have come up since I posted my Review of the new MSR Pocket Rocket 2.  I therefore have put together this, which acts as a supplement to my original review.

UPDATE 25 January 2017:  See also  MSR PocketRocket Review Supplement #2
See also: The MSR Pocket Rocket 2 vs. the Soto Amicus

The generations of the Pocket Rocket Line.
Left: The original Pocket Rocket.  Center:  The Micro Rocket.  Right:  The new Pocket Rocket 2

Availability
When I first inquired, I was told that the new Pocket Rocket 2 would be available in "January."  However, I see that two sites already have the stove listed.  I shall list links below as a service to you my readers.  I receive no benefit from placing these links here, and I receive no benefit if you purchase.  The below links in no way constitute an endorsement.  These links are herein listed simply for your convenience.  In no particular order:

• LL Bean
• Backcountry Gear

Disclosures:  

• I have purchased things in the past from LL Bean. I have no financial relationship with LL Bean other than that of an ordinary customer.
• I don't think, going on my memory which is far less than fully reliable, that I've ever purchased anything from Backcountry Gear.  I certainly nave no financial relationship with Backcountry gear.

Simmering
The stove simmers well.  I was trying to illustrate just how good the flame control is in Appendix II (which is well worth referring to).  Let me here show a photo of the food as opposed to the flame.  Look at the photo below.  If you look a bit to the left of center.  You can just barely see a few bubbles.  Now that's a true simmer (a simmer being the ability to hold contents of a pot at or just below a low boil).  And look at the food debris left on the sides of the pot.  Only moments before, I practically had a boil over, things were boiling so furiously.  That's some nice flame control.

Note:  The majority of the flame control occurs in the range of approximately 1/6th to 1/2th of a turn of the valve adjuster.  You have to have a fairly deft touch, but with just a minimum bit of skill, you can have just about any flame setting you so desire.

An **extremely** low simmer can be achieved on the new MSR Pocket Rocket 2

And now, a flame shot.  I mean who doesn't love flame shots?  But, seriously, look closely.  That's a nice, low flame (and you can get it even lower) – with absolutely no spillage up the sides of the pot.  This is just the flame control you want to have on a stove.  

The Pocket Rocket 2 – really good flame control

Pot Supports
I covered the subject in the general case in my Review of the new MSR Pocket Rocket 2, however, let me respond to one specific question and then give one more general example.

First, the specific question:  "How do the supports on the new Pocket Rocket 2 fit on an MSR Titan Kettle?"  Presumably they were referring to the standard sized (850 ml capacity) kettle.

Well, inasmuch as a picture is worth a thousand words, I give you:

An MSR Titan Kettle (850 ml) atop the new Pocket Rocket 2

Now, notice in the photo above that the inner circle of the bottom of the kettle match nearly exactly the inner diameter of the pot supports.  With respect to the outer diameter, the pot supports extend a mm or two beyond the outer periphery of the kettle.  I'd say that the Titan Kettle is a really strong candidate for use with this stove, particularly for a soloist.  I think it a tad small for two.

Incidentally, MSR has announced that they are coming out in 2017 with the "Big Titan Kettle," a two liter version of the current Titan Kettle.  Why they went all the way from 850 ml to 2000 ml (two liters), I'm not sure, but that's my understanding.  I typically recommend something on the order of 750 ml per person in terms of pot capacity, so a 2 L kettle would be a pretty good match for a group of two or three people.  I haven't seen one.  I'll keep you apprised if I get any further information.

Now, for a more generic example:  Here is a photo of the Pocket Rocket 2 with standard 355 ml (12 fl oz) beverage can.  This particular beverage can has been made into a Trail Designs 12-10 alcohol stove, but the outside diameter of course has not changed.   Now, the point here is not that you should use a Coke can to cook in, really it's not practical, but rather that this stove will support really small pot diameters.  Note however that all you Heineken and Fosters "pot" lovers had best turn down the stove lest you ruin your pot.

The MSR Pocket Rocket 2 with a standard 355 ml beverage can

Valve block
The valve block of the Pocket Rocket 2, to include the threads, is made from anodized aluminum.  Note that this is not "hard" anodization (the type of anodization that makes aluminum pots tougher) but is merely the means by which the valve block has been colored that nice MSR red.  The valve spindle, at least what I can see of it, is brass.  I have not disassembled the unit (nor do I intend to), but presumably it is all made of brass.  The valve adjuster handle is stainless steel.

The valve block of the MSR Pocket Rocket 2 is made out of aluminum.

Some stoves* will have a brass insert in the valve block for the portion that threads on to a canister.  Brass generally wears a bit better than aluminum, but aluminum has not been shown to to be a poor choice of materials.  Many a through hiker has done a long trail  (for example the Pacific Crest Trail) without a problem.  The threads on all canister gas stoves, whether brass or aluminium, will wear with time.  Do not over tighten.

I hope this review supplement will be of assistance,

HJ

*I just went into the gear room (the very room my wife detests but is of course entirely necessary) and pulled out a couple of canister stoves that my memory suggested had a threaded brass insert, specifically the Soto Amicus and the Snow Peak GigaPower.  Both of those stoves do in fact have a threaded brass insert.

Deal Alert! (Stove on Sale)

I'm going to depart from the normal here and put a commercial link in a blog post.  May my readers forgive me.

Please understand that I derive NO BENEFIT from this post nor if you make a purchase*. This is just a good deal I noticed.

UPDATE 30 December 2016:  I just noticed today that Campsaver has also placed the smaller but similar Amicus on sale as follows:

• Version without ignition:  $32.
• Version with ignition:  $36

Cold weather testing the WindMaster.

It's no secret that I consider the Soto WindMaster to be the best quality upright canister stove on the market today.  I believe I said as much in my review of the WindMaster.  It's wind resistant in a way other stoves of this class just aren't (well, except for its budget minded cousin, the Amicus), and it's a good balance of versatility, efficiency, and weight.  Not only that, it's just quality in every respect.

The Soto WindMaster

That said, Campsaver.com has the Soto WindMaster on sale for about $20 less than MSRP.  For your convenience here is a link:  Soto WindMaster on sale at Campsaver.

As far as I know, Campsaver is a reputable establishment.  Friends of mine have had good experiences.  However, note that I have never done business with them.  Caveat emptor.  This is information only; do with it what you will.

Simul-testing the WindMaster against a "control" stove.
The WindMaster is at left.
No matter the conditions, the WindMaster always came out ahead – while using less fuel.

I hope this is helpful to someone, and I do hope you will forgive the commercial intrusion on this, a site focused on what we do in our lives outside of work (well, unless you're a guide or something).

HJ

*Note to Campsaver if you happen to read this:  I can't be bought, but it wouldn't hurt you to try, now would it?  I like dark chocolate.  :)    Seriously though, Campsaver, I've been Jonesing like mad to have a look at one of those Optimus Polaris Optifuel multi-fuel burners.  Send me one, and I guarantee all other stoves will go on hold.  I will straight away review the Polaris.  I'm completely serious about this.  You can leave a comment below and I'll get an email and physical address to you forthwith.

Performance testing the Soto WindMaster against a "control" stove.
Note:  The individual in the photo is a highly trained stove professional.
Don't try this at home (seriously, go for a hike; you have a much better stove already in your kitchen at home).
Apologies for the waste generating food.  We got a free case because they were due to expire.