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  1. #41
    PCT, Sheltowee, Pinhoti, LT , BMT, AT, SHT, CDT 560 miles 10-K's Avatar
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    Erwin, TN


    Quote Originally Posted by Mags View Post
    To sum it up: Propane is better than mixed isobutane..but is required to be in too heavy of a canister for backpacking.
    So, are you saying that isobutane is not as good as propane because isobutane canisters aren't heavy enough for propane?

    (nobody likes a smarta$$.... but you know...sometimes you just can't resist)

  2. #42
    Getting out as much as I can..which is never enough. :) Mags's Avatar
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    Front Range Zoo, Colorado


    Quote Originally Posted by 10-K View Post

    (nobody likes a smarta$$.... but you know...sometimes you just can't resist)
    I'm from the Northeast...why resist?
    Paul "Mags" Magnanti
    Twitter: @pmagsco
    Facebook: pmagsblog

    The true harvest of my life is intangible...a little stardust caught,a portion of the rainbow I have clutched -Thoreau

  3. #43



    Cold Weather Operation

    One of the biggest limitation of canister stoves is their decreased performance or complete failure at low temperatures. This is due to the lack of effective gas pressure once the temperature of the canister drops below the boiling point of the fuel. When fuel fails to build up enough pressure to effectively feed your stove, your stove slows and eventually stops. To compound matters, running a stove releases gases from a canister, which cause more of the liquid fuel to vaporize, which requires energy that in turn drops the temperature of the canister even more. The longer you run your stove the colder the canister becomes and you may need intermittent rewarming or continuous heating to keep your canister going. See The Nature and Behaviour of Mixtures of Fuels by Roger Caffin for more information on gas dynamics.

    Propane boils at -43° F (-40° C)

    Butane boiling at 31° F (0.5° C)

    Isobutane boils at 11° F (-12° C)

    One way to improve performance is to use fuels that have lower boiling points. Pure propane is the best commonly used liquefied gas for cold weather but requires a heavy duty steel canister which isn't suitable for most backpacking needs. Butane can be stored in much thinner walled cans, making it more suited for backpacking but butane doesn't work in subfreezing temperatures. Often isobutane and/or propane are added to butane cans to allow the stove to get started in subfreezing temperatures. Unfortunately, in very low temperatures, the propane and/or isobutane will boil off and leave the majority of the butane fuel unusable at those temperatures.

    You may want to set your fuel on an insulating platform to protect it from snow or ice.

    Another way to improve fuel performance in the cold is to get the fuel temperature up. There are several ways to to this and some are quite dangerous if done inappropriately.

    Safe methods of warming fuel canisters

    keep it in your jacket to warm it up

    sleep with it in your bag

    place or dip it in warm water

    pour a bit of hot water on it

    urinate on your stove

    chemical hand-warmers may help a little

    Risky methods of warming fuel canisters - using heat from a stove - overzealousness and carelessness can lead to an explosion - do so at your own risk

    use a carefully ventilated windscreen (if you do too good of a job insulating the canister, it may explode)

    use a heat exchanger (flattened copper wire with one end wrapped around the canister once and with the other end protruding up into or near the flame)

    warm a canister by placing it near the stove (too close for too long and you might end up dead or without one of your hands)

    Note - most canisters are designed with concave bottom that will pop outwards before complete canister rupture if over pressurized. The valves themselves may also bleed off overly pressurized gasses unless a stove or lantern is securely attached to it.

    Another method to maximize fuel pressures is to feed your stove with liquid instead of gas fuel. This will allow the vapor pressure of the more volatile fuels to force mixed liquid fuel into your stove instead of just burning up first and leaving unusable butane. There will also be less phase change from liquid to gas in the canister resulting in less canister cooling. This concept is used with the Coleman PowerMax fuel canisters, which have a weighted diptube to pick up the liquid at the bottom of the can and not the gas at the top.

    Coleman® Exponent® Powermax® Fuel Adapter

    With some setups, canisters may be used upside down. This would force out liquid instead of gas into your fuel line, similar to running PowerMax canisters. Coleman in fact makes an adapter to run screw on canisters upside down.

    Use with Coleman Exponent X-series stoves that are fueled by Powermax Fuel to adapt to threaded butane/propane canisters.

    Fits the 9770 series Coleman® Exponent® Fyrestorm™ series stoves

    * Legs swing-out from adapter to form stable platform for inverted canister.

    * Unique liquid-withdrawal method for threaded canister fuels produces high-performance in cold weather or high-altitudes.

    The Primus Himalaya manual states that one safe cold environment trick is to:

    "Turn down the control valve as low as possible. Now hold the gas cartridge and turn it upside down slowly and very carefully. While doing so, you must never lift the cartridge higher than the stove itself to avoid a sudden burst of flames."

    When asked via email if the MSR Windpro could operate with the canister upside down, a tech at MSR replied:

    "Yes, you can turn the canister upside down when using the WindPro but you would want to use the same precautions stated in the Primus manual."

    Since the Primus Himalaya EasyFuel, MSR WindPro, MSR Rapidfire, and Snowpeak GigaPower BF Stove [GS-300A] have similar designs with a hose connection and heated vaporizer tube, they should be able to run PowerMax canisters (you may need an adapter) or regular fuel canisters upside down - do so at your own risk.

    There are several remote fueled canister stoves, such as the Markill Spider, that don't have vaporizer tubes (generators). This feature is desirable to vaporize the fuel prior to it exiting the jet. Running a canister upside down without a vaporizer tube isn't recommended and can be dangerous.

    Gauging the Contents of a Gas Cartridge

    You can float both an empty canister and a full canister in water and mark the water lines. Transfer the full and empty lines to the canister you take to the field. As the canister empties you can measure the remaining fuel level by floating it in water and noting where the water line is relative to the full line and empty lines.
    Last edited by veteran; 12-20-2010 at 09:04.
    “Only two things are infinite; The universe and human stupidity,
    And I’m starting to wonder about the universe.”
    Albert Einstein

  4. #44

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