Avalanche airbags work by the principle of Inverse Segregation. Or for those who are unfamiliar with that term, the "Brazil Nut Effect."
Let's say you have a can of mixed nuts and all the different sizes of nuts are dispersed equally throughout the can. If you shake that can of nuts back and forth, the Brazil nuts (or any of the relatively large nuts) will eventually end up on top. This is because the smaller nuts fit into the void spaces and sink to the bottom, thus making the bigger nuts "float" to the top.
In an avalanche, snow particles act in a similar way. The smaller pieces sink to the bottom and the bigger pieces tend to float to the top. This is why it's common to see large chunks of a cornice on top of an avalanche debris pile.
If an avalanche victim has an inflated airbag during the avalanche, not only is he much larger than the surrounding snow particles, but he is also much lighter and less dense, since about six cubic feet of air is contained inside the airbags.
Avalanche airbags have been around since the 1980s in Europe and SnowBigDeal has been selling them in North America since 2004. They have grown immensely in popularity over recent years, due to their very high success rate in keeping avalanche victims alive. Statistics show that since airbags have been on the market, around 98 percent of avalanche victims who deployed an airbag have survived.
However, the exact success rate for avalanche airbags in general is unknown, due to the fact that many avalanche survivors do not report their incident to the airbag manufacturer.
We at SnowBigDeal have worn each type of airbag and are thoroughly familiar with each one. Here's a very brief review of each brand currently in production, in the order they were introduced into the market.
ABS is headquartered in Germany and has been making avalanche airbags since the 1980s. The company started with a single airbag design, but now all ABS packs have dual airbags. The dual airbag system has two airbags attached to the sides and inflates to a total airbag volume of 170 liters.
The activation trigger contains an explosive charge that punctures a canister filled with compressed nitrogen that fills the bags. ABS uses nitrogen to fill their airbags because nitrogen prevents the system from freezing up at extremely low temperatures and it has a fast expansion rate. The new ABS packs have removable storage packs that can be purchased individually and docked to the base unit that contains the airbag system.
This will be the fourth season for SnowPulse airbags in North America. Headquartered in Switzerland, the company manufactures a 150-liter single airbag that is filled with compressed air. The SnowPulse airbag is attached to the shoulder straps and creates a U-shaped airbag around the head and upper body of the user. This design is intended to float an avalanche victim face-up and to provide more protection for the head, neck and upper spine.
A large number of avalanche victims die from trauma. Many even die before the avalanche stops moving, so Snow- Pulse has addressed this issue with the added trauma protection of its unique airbag design.
WARI LLC of Minnesota is the manufacturer of the AviVest. This will be the third year of the AviVest on the market and the company makes two types of avalanche vests: the original AviVest and the Impact Vest. Both are very comfortable since weight is evenly distributed due to the fact that they don't have narrow shoulder straps like the backpack models do.
The AviVest has storage for a shovel, probe and other gear in the back and also two pockets in the front for goggles, radio, GPS, etc.
The Impact Vest has storage in the back, but not in front. The Impact Vest has a protective plate over the sternum of the user to offer protection from tree branches, handlebars, etc. Both AviVest packs use a compressed air canister with a pressure gauge, so it's easy to see if the canister is full. One single airbag is attached to the back of the vest, filling with 150 liters of air.
In 2010, Backcountry Access, located in Boulder, CO, became the first company to release a $500 airbag pack to the market. Since then, the pack has increased in price, but so has the performance. The BCA airbags use compressed air to fill a 150-liter single airbag that is attached to the top of the pack.
The BCA "Float" airbags are deployed by pulling a cable on your right shoulder strap, so snowmobilers can pull with their left hand while keeping their right hand on the throttle to outrun an avalanche. BCA packs come with several O-rings so you can refill the canister and additional refill kits are cheap.
Editor's Note: Beck is sales director at SnowBigDeal.com.