Gas Inwards Mutual Coldness Weather: The Myth Of Fractioning
I'd similar to dispel a myth that's out there: the myth of "fractioning."
Supposedly, if you've got a typical canister of gas (i.e. containing propane together with roughly shape of butane), inwards mutual frigidity weather condition (temps below the vaporization hollo for of all but the propane), solely that fraction of the fuel that is propane volition burn. Supposedly.
Here's an illustration of the myth: You guide keep a canister that is 70/30 butane/propane. Propane vaporizes at -44F/-42C; butane at +31F/-0.5C. Now, enjoin it's 20F/-7C out. According to the myth, solely 30% (that fraction of the mix that is propane) volition dismiss off.
That's the myth. What actually happens? Well, guide keep a 70/30 canister out inwards 20F/-7C weather and dismiss it until it's empty. Now weight it. You'll honor the weight is lower than if solely 30% of the fuel had burned off.
Why? Well, when you lot mix liquid hydrocarbons, they combine to shape a blend. The blend has properties that prevarication "between" the properties of the cistron fuels. For example, the boiling hollo for of a 70/30 blend of propane together with butane volition guide keep a boiling hollo for betwixt -44F/-42C together with +31F/-0.5C. The math is non-trivial, but if you lot know the formulae, you lot tin calculate the resultant boiling point. In this case, a 70/30 blend has a boiling hollo for of well-nigh 0F at criterion pressure level (1 atmosphere/1013mBar).
Now at that topographic point is a piddling flake of a choose guide keep of to all this. This "blend" of liquid hydrocarbons inwards a canister of gas (recall that there's thus much pressure level within a cansiter that our gasses liquefy) yet has 2 distinct molecules inwards it: Propane molecules (C3H8) together with butane molecules (C4H10). The propane molecules guide keep a higher vapor pressure level than the butane molecules. In other words, the propane molecules tend to vaporize to a greater extent than than the butane molecules inwards the blend. How does a canister typically work? Well, you lot depict vapor off the top, together with and then to a greater extent than of the liquid component subdivision of the fuel vaporizes to supersede the drawn off vapor. If the propane is what most readily vaporizes, together with then the propane volition live on removed from the blend to a greater extent than speedily than the butane. This is called "preferential" vaporization. Because the propane is vaporizing faster than the butane, your blend volition modify over fourth dimension every bit the canister empties. As the blend changes, thus volition the vaporization point. Toward the destination of the life of the cansiter, all the propane volition live on gone together with solely your secondary fuel volition remain.
Uh, isn't this "preferential" vaporization the same every bit "fractioning?"
No, non at all. Remember that the myth of fractioning calls for only the propane to dismiss leaving behind all of the butane. What happens inwards reality is that the blend vaporizes roughly butane together with roughly propane throughout the life of the canister until the propane is gone. Yes, you lot volition achieve a hollo for where all of the propane is gone together with solely butane remains, but the fact of the affair is that you lot volition live on burning off far to a greater extent than fuel than if solely propane solitary were burning.
With fractioning (if it were true), you lot could solely dismiss of 30% of the fuel inwards a 70/30 canister. With preferential burning, you lot dismiss to a greater extent than similar 75% of your fuel earlier you lot current of air upward alongside nada but butane left (the actual amount burned varies alongside height together with temperature of course).
This brings upward 2 of import points:
1. Don't role canisters alongside regular butane inwards mutual frigidity weather. Eventually all your propane will dismiss off, leaving behind whatsoever else is inwards your canister. If you've got isobutane (vaporizes at +11F/-12C) every bit your secondary fuel you've got a 20F (10C) aeroplane advantage over a canister that has regular butane (vaporizes at +31F/-0.5C) every bit its secondary fuel.
2. Stoves that tin handgrip running alongside the canister upside downwards (inverted canister stoves) depict fuel off the bottom of the canister. If you're drawing fuel off the bottom, you're solely drawing liquid. If you're non drawing vapor, together with then it doesn't affair which fuel vaporizes at what rate. Inverted canister stoves kickoff together with destination alongside the same fuel blend. If you lot kickoff alongside 70/30, you lot destination alongside 70/30, together with your vaporization hollo for stays low, allowing you lot to run your stove inwards much colder weather condition than a conventional upright (screws onto the meridian of the canister) gas stove. With an inverted canister stove, you lot tin dismiss all of your fuel inwards mutual frigidity weather condition (assuming that your blend's vaporization hollo for is sufficiently high for the weather).
So, at that topographic point you lot guide keep it: What's actually going on inwards that canister of yours inwards mutual frigidity weather. I promise this puts the myth of "fractioning" to bed.
I give thank you lot you all for joining me on roughly other Adventure inwards Stoving,
HJ
Supposedly, if you've got a typical canister of gas (i.e. containing propane together with roughly shape of butane), inwards mutual frigidity weather condition (temps below the vaporization hollo for of all but the propane), solely that fraction of the fuel that is propane volition burn. Supposedly.
Here's an illustration of the myth: You guide keep a canister that is 70/30 butane/propane. Propane vaporizes at -44F/-42C; butane at +31F/-0.5C. Now, enjoin it's 20F/-7C out. According to the myth, solely 30% (that fraction of the mix that is propane) volition dismiss off.
That's the myth. What actually happens? Well, guide keep a 70/30 canister out inwards 20F/-7C weather and dismiss it until it's empty. Now weight it. You'll honor the weight is lower than if solely 30% of the fuel had burned off.
Why? Well, when you lot mix liquid hydrocarbons, they combine to shape a blend. The blend has properties that prevarication "between" the properties of the cistron fuels. For example, the boiling hollo for of a 70/30 blend of propane together with butane volition guide keep a boiling hollo for betwixt -44F/-42C together with +31F/-0.5C. The math is non-trivial, but if you lot know the formulae, you lot tin calculate the resultant boiling point. In this case, a 70/30 blend has a boiling hollo for of well-nigh 0F at criterion pressure level (1 atmosphere/1013mBar).
Now at that topographic point is a piddling flake of a choose guide keep of to all this. This "blend" of liquid hydrocarbons inwards a canister of gas (recall that there's thus much pressure level within a cansiter that our gasses liquefy) yet has 2 distinct molecules inwards it: Propane molecules (C3H8) together with butane molecules (C4H10). The propane molecules guide keep a higher vapor pressure level than the butane molecules. In other words, the propane molecules tend to vaporize to a greater extent than than the butane molecules inwards the blend. How does a canister typically work? Well, you lot depict vapor off the top, together with and then to a greater extent than of the liquid component subdivision of the fuel vaporizes to supersede the drawn off vapor. If the propane is what most readily vaporizes, together with then the propane volition live on removed from the blend to a greater extent than speedily than the butane. This is called "preferential" vaporization. Because the propane is vaporizing faster than the butane, your blend volition modify over fourth dimension every bit the canister empties. As the blend changes, thus volition the vaporization point. Toward the destination of the life of the cansiter, all the propane volition live on gone together with solely your secondary fuel volition remain.
Uh, isn't this "preferential" vaporization the same every bit "fractioning?"
No, non at all. Remember that the myth of fractioning calls for only the propane to dismiss leaving behind all of the butane. What happens inwards reality is that the blend vaporizes roughly butane together with roughly propane throughout the life of the canister until the propane is gone. Yes, you lot volition achieve a hollo for where all of the propane is gone together with solely butane remains, but the fact of the affair is that you lot volition live on burning off far to a greater extent than fuel than if solely propane solitary were burning.
With fractioning (if it were true), you lot could solely dismiss of 30% of the fuel inwards a 70/30 canister. With preferential burning, you lot dismiss to a greater extent than similar 75% of your fuel earlier you lot current of air upward alongside nada but butane left (the actual amount burned varies alongside height together with temperature of course).
This brings upward 2 of import points:
1. Don't role canisters alongside regular butane inwards mutual frigidity weather. Eventually all your propane will dismiss off, leaving behind whatsoever else is inwards your canister. If you've got isobutane (vaporizes at +11F/-12C) every bit your secondary fuel you've got a 20F (10C) aeroplane advantage over a canister that has regular butane (vaporizes at +31F/-0.5C) every bit its secondary fuel.
2. Stoves that tin handgrip running alongside the canister upside downwards (inverted canister stoves) depict fuel off the bottom of the canister. If you're drawing fuel off the bottom, you're solely drawing liquid. If you're non drawing vapor, together with then it doesn't affair which fuel vaporizes at what rate. Inverted canister stoves kickoff together with destination alongside the same fuel blend. If you lot kickoff alongside 70/30, you lot destination alongside 70/30, together with your vaporization hollo for stays low, allowing you lot to run your stove inwards much colder weather condition than a conventional upright (screws onto the meridian of the canister) gas stove. With an inverted canister stove, you lot tin dismiss all of your fuel inwards mutual frigidity weather condition (assuming that your blend's vaporization hollo for is sufficiently high for the weather).
So, at that topographic point you lot guide keep it: What's actually going on inwards that canister of yours inwards mutual frigidity weather. I promise this puts the myth of "fractioning" to bed.
I give thank you lot you all for joining me on roughly other Adventure inwards Stoving,
HJ
Related articles together with posts:
- Cold Weather Tips for Gas Stoves
- What's the Best Gas for Cold Weather?
- Gas Stoves: How Cold Can I Go? <==Most comprehensive article on canister gas together with cold
- Canisters, Cold, together with Altitude: Gas inwards a Nutshell
- Canister Stoves 101: Thread Care
- Gas Blends together with Cold Weather Performance. (Why non simply role propane?)
- The "Super Gnat" (Camping Gaz or threaded canisters alongside 1 lightweight stove)
- Backpacking Gas Canisters 101
- Gas inwards Extreme Cold: Yes or No?
- Gas inwards 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
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