Tag Archives: cold

Mini Trangia and winterizer at -32.6 C

About a year ago, I tested my home made winterizer for the Mini Trangia alcohol stove at –25 C (-13 F). To my great surprise, my “not good at really cold weather” Trangia managed to boil 500 ml of +4 C (+39 F) water in about 7 minutes, mainly due to the help provided by my DIY winterizer.

Since then, it has been ridiculously warm, and now was my first opportunity to try to find the limits for an alcohol fueled stove.

So, this is how it went. First, I left the stove and the fuel outdoors at -32.6 C (-26.7 F), and 500 ml of water into the fridge for overnight.

In the following morning, I loaded sthe stove and soaked the wick of the winterizer with -32 C alcohol (Note to self: Do not spill it on to your fingers. It is damn cold!). Despite the syrup like behaviour of the cold alcohol, lighting up the alcohol soaked wick was very, very easy. However, due to the 5 m/s wind, it took albout 13 minutes to bring the water to boiling. Therefore, I repeated the experiment using a simple windscreen made out of fire retardant fabric.

With the windscreen, the boiling time was reduced to 9 minutes and 40 seconds.

As conclusion, with a proper protection from the wind, an alcohol burning stove (with DIY winterizer) still works beautifully at -32 C !

As soon as the good old -40 to -50 winter days (hopefully) return, I’ll test and report whether there really are any limits for my little Trangia stove.

Using a once frozen water filter may kill you

Modern hollow fiber water filters are true technical wonders with their ability to get rid of bacteria, protozoa, and even viruses from unbelievably large amount of contaminated water. After reading the descriptions of some of the best filtering devices in the market, one easily gets impression that problems with dirty water are ancient history, at least for the wealthy westerners. However, somewhere from the manufacturer’s website you may find a following kind of warning: “After iniatial wetting, do not expose your water filter to temperatures below freezing. There is no definitive way to tell if a filter has been damaged due to freezing.”

I have heard of several occasions where a hiker has ran into trouble with a clogged water filter due to cold weather, “but after I kept the filter inside my jacket for awhile, everything was OK, and the filter worked again.”

No, everything was not OK! After the thawing, the water filter did let the water flow again OK, but most probably, it did not any more do its job as it should have, as the freezing process itself had destroyed the filtering structures.

And here is what happened. (Warning: light science content!)

As you may remember from high school science class, water has some interesting properties.

Water has the highest density, pretty close to 1g per cubic cm (0,999973 g/cm3, to be exact), i.e. it is heaviest, at +4 C temperature. When water freezes, its density decrease to about 0.917 g/cm3, i.e. it becomes lighter than liquid water. One can easily test that by dropping an ice cube into a glass of water, and see whether the cube floats. The reason why the ice cube floats is in the formation of ice chrystals, which need more space than free water molecules, and therefore when a gram of liquid water happily fits into a single cubic centimeter of space, a gram of ice needs about 1.09 cubic centimeters. And the ice truly takes its space. There are some variables in the behavior of the ice, but it can be pretty safely said that in standard natural situation, freezing water applies some 100 Mpa pressure against anyone or anything trying to resist it (that is about 1000 kg/cm2, and about 14500 psi). So, no wonder that boulders crack and water pipes burst during cold spells, and it is not difficult to imagine what happens to the tiny filtering pores and the tubes in a water filter filled, or even partially filled with freezing water. Yes, they crack, and even if the water flows beautifully through the filter after thawing, the filter is no longer filter, but a sieve, no longer capable of filtering harmful bugs.

The internet is full of “expert” advices of how to test whether your water filter is OK after freezing, and each advice is, if possible, even more stupid than the previous one. For example, one rather common “expert” way to test the filter is to try to blow air through the filter against the direction of the water flow, and according to this wonderful advice, if you cannot blow the air through the filter, your filter is in perfect working condition. OMG! The only thing the blow test is good for, is to check whether the filter is still capable of filtering bugs such as ants or cockroaches. Size of bacteria is typically about 0.5-5 micrometers, and there is no way that someone could detect some 10-100 micrometer cracks by blowing air to the filter, where as our friend, the bacteria, which used to stay behind the filter’s 0.1 micrometer pores, now happily swims through the giant cracks.

So, please, if you even suspect that your wet water filter could have been exposed to freezing temperature, get rid of it, buy a new one and be 100% sure that you know where your water filter has been at all times!

In my honest opinion, a warning about the dangers of freezing the water filter should not be hidden somewhere in back pages of companies web sites, but written with flaming letters (with proper explanation of hows and whys) at the home/front pages of all of the water filter manufacturers!


FYI, here is a screenshot from Sawyer.com FAQ:

Screenshot from 2015-03-04 22:21:15

Mini Trangia DIY Winterizer test at -25 C


A little while ago I made a pre-heater for my Mini Trangia stove. Initially, I was able to test it at -12.5 C temperature, and was pretty happy with the results (500 ml of water from +4 C to boiling in 7 minutes and 39 seconds).

Now, the winter finally seems to kick in, and it is time to test what the winterizer is good for.

To begin the test, I left the Trangia stove and a bottle of fuel outdoors for overnight, and some water into the fridge. In the morning, the temperature was -25 C. Not as cold as I was hoping for, but so far the coldest weather during this winter anyway. So, I filled up the stove, and soaked the glass wool wick of the winterizer with -25 C alcohol, and stroke a match. The ignition was kind of lame, but easy and instantaneous anyway. Next I poured 500 ml of +4 C water into the Trangia pot, placed it (with the lid on) on to the stove, and prepared myself for a long wait.

To my pleasant surprise, after mere seven minutes and six seconds the water was boiling merrily. That was over 20 seconds faster than in my first test run at -12.5 C! How could that be? When comparing the conditions of the two tests, in addition to the difference in the temperature, the only remaining variable of any significance was the wind, which, during the first test wasn’t particularly strong, but strong enough to slightly disturb the flame and to cool down the pot a little bit, whereas during the second test the wind was hardly noticeable.

The test results confirmed the general belief that a good wind protection is essential for successful cooking with camping stoves, but more importantly, the results proved that my DIY winterizer works beautifully even at -25 C temperature. I can’t wait for the arrival of really cold weather to test the winterizers limits (if there are any).