Fragile Oasis

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Propane

Classic wisdom says that propane stoves do not work well in cold climes. The propane bottle will get so cold that the liquefied gas would rather stay in the tank than come out to play. Snow-bound expeditions use the old classic white gas stove. Like a medieval dragon, these white gas stoves belch black smoke and frequently squirt billows of yellow flames nearly to the tent roof. Singed eyebrows are a norm. Ironically, tent fires are probably a greater risk than frost bite. And the white gas stove always seems to run out just when you need it the most, requiring a trip out in -40 blowing snow with numb bare fingers fumbling with cold metal gas cans that greet damp flesh the same as sticking your tongue on a frozen playground jungle gym.

We decided to avoid all this fun and use propane stoves. We chose a two burner model with PZT igniter, a small bit of modern technology that allows one to live in the wilderness without the need for any matches. We ran these stoves directly from a standard 20 pound propane tank which is the key to its success. At -20°C, the vaporization rate for propane is rather small, and in the process of doing this, the tank becomes even colder. A small propane bottle, such as what a backpacker might use, has such a small liquid surface area that it can not keep up with the gaseous propane demands of a stove when at freezing temperatures. Our large tanks have significant liquid propane surface area from which vaporization can take place and had no trouble keeping up with our stoves. We kept the propane tank near the door between our Scott tent walls, which added some degree of warmth from outside conditions. And best of all, we had easy, push button start, clean flames that did not belch smoke and blacken the bottoms of our greasy pans. A propane tank would last about six days, thus freeing us from the middle of the night refueling ritual. For an expedition with 8000 kilograms of supplies pulled by eight snow mobiles on Nansen sledges, the mass and volume of these propane tanks were not an issue.

Propane stoves do come with their own set of nuances. Every so often, the jets that meter the propane into the stove plug up. Sacrificing a few milliliters of single malt scotch from a team member’s stash will provide the necessary solvent to soak out any residue.

Another discovery we made is the consequences of leaving the tank valve open when the stove is off. Normally, this is not an issue;
simply turn the stove off with the burner’s individual control valves. There is no need to shut off the propane at the tank. Or so we thought. Our tents get cold, especially when the stove is not lit. If this condition lasts for hours, like overnight or between breakfast and dinner, the liquid propane in the tank, like the proverbial camel sticking its nose in the tent, will vaporize and re-condense as a liquid wherever it happens to be coldest, which in this case, is in the stove’s pressure regulator. The pressure regulator reduces the pressure of gaseous tank propane to a much lower value for use in the burners. The regulator is not meant to be filled with liquid propane and as such, will fail when you light the stove. Returning back from a full day's gathering of meteorites, we naively lit the stove with the now liquid filled propane regulator. We scrambled to keep our socks and other clothes hanging in the chimney from catching fire. One look at the regulator showed it caked in ice. Obviously, liquid propane was evaporating in the regulator, extracting the latent heat of vaporization from the surroundings. We now recommend closing the tank valve if there is to be a long period of inactivity. It seems wherever there is fire, there are lurking dragons anxious to spray flames.

Even the convenience of a self-lighting propane stove that runs a week between fueling does not compensate for the painful ritual of making water from snow. With no source of liquid water, we have to make all our needs by melting snow. Snow has a miserably low density, somewhere around 10 to 20 percent that of water. To make a pot full of water takes five pots of snow. And like any pot, it needs to be watched. The slowest step in melting snow is the heat transfer from the pan bottom into this low density mass. It takes a painfully long period of time. Glacier ice is different. With densities about 80 percent of water (due to it being loaded with millimeter sized bubbles) it takes a shorter time to convert these cold shards into a pot full of liquid. If given the choice, we prefer to make our water from glacier ice. In either case, making water takes a big chunk of your off duty time.

It is humbling to think that this blue glacier ice we are camped on is tens of thousands of years old. The ice shards in your pot have been around longer than human civilization. You see little gas bubbles being liberated from the ice, floating to the surface and popping. Perhaps they contain the last breath from a mastodon. We are melting this using petroleum-derived propane, in part formed during the age of the dinosaurs, and all this simply to make macaroni and cheese for dinner.