Frost in Arctic Sleeping Bags

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Authors
  1. Osczevski, R.J.
Corporate Authors
Defence R&D Canada - Toronto, Toronto ONT (CAN)
Abstract
After many nights in extreme cold weather, ice builds up in the insulation of sleeping bags making them much heavier and colder to sleep in. The history of sleeping bag use in extreme cold is reviewed and the possible sources of this water are described. Quantitative investigations reveal that the weight gain during field use is highest during the first couple of nights and then reduces to a constant value. Laboratory experiments with a device simulating a warm occupant show that at –30 ºC, only 30% of the water that evaporates manages to diffuse through the bag. Internal vapour barriers and external waterproof but water vapour permeable coverings may be useful in some conditions, but the polymer coatings of outer coverings are not as permeable in the cold as they are at room temperature, while the coatings of some vapour barriers become more permeable when subjected to the warmth and high humidity in a well insulated sleeping bag. Much of the problem probably stems from warming the tent and melting the frost in the sleeping bag, then letting it refreeze in a compressed condition when not in use. One strategy that has proven successful is to never let the sleeping bag get warm enough to melt the frost that has formed in its outer layers, however this might be impractical in a military setting. It might be possible to construct the bag and/or the insulating layer so that frost can be physically removed, or so that it causes no problems if it melts.

Il y a un résumé en français ici.

Keywords
Cold weather clothing;Vapour barrier;Extended use
Report Number
DRDC-TORONTO-TR-2003-070 — Technical Report
Date of publication
01 May 2003
Number of Pages
24
DSTKIM No
CA023171
CANDIS No
520372
Format(s):
Electronic Document(PDF);CD ROM

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