All avalanche airbags regardless of brand work on the principle of Inverse Segregation or Inverse Grading. It states that if you shake a selection of shapes, the larger ones will rise to the top, even though they may be heavier. The principle is well proven and also known as the 'Brazil Nut Effect'. In a bag of mixed nuts, the Brazil nuts will always be on top. In an avalanche, it's best to make yourself like a Brazil nut.
The airbag itself is either packed into the top or shoulder straps (or both) of a pack and connected to a cylinder of compressed gas (air or nitrogen) or, in the case of the Black Diamond Jetforce packs, a high powered fan. The airbag is triggered by the wearer pulling a handle connected to one of the shoulder straps. All designs incorporate a stowable trigger handle which releases the gas inside the cylinder to fill the airbag. The airbag has a greater volume than the cylinder, with the extra air volume supplied by air drawn into the system using the 'Venturi Effect'.
Here is a video of a Mammut and BCA airbag being inflated
The airbags stocked by Facewest come in 2 basic shapes. The Mammut Protection (also original Snowpulse Lifebag) shape which provides side protection to the head and to the front of the chest whilst still leaving the user completely free to carry on skiing or boarding to try and get out of trouble. The other shape is generally known as the 'Wings' shape, these airbags just extend behind the user and is there to provide the volume for inverse segregation rather than also providing extra protection. Whilst the Mammut Protection shape does provide the best protection, the fact that the arm straps contain the airbag means they are thicker, heavier and less flexible than a standard pack. The Wings shape means the shoulder straps of the pack are more like a general pack, and offer a less complicated construction, but do not protect the users head as much. As the primary function of the airbag is to offer extra volume all systems work well.
|Mammut 'Protection' airbag||Ortovox Avabag airbag|
|Mammut 'Removable' airbag||Jetforce airbag|
A short video showing the 'Protection' and 'Wings' shapes side by side.
Airbags system cylinders can be filled with either Nitrogen or compressed air. To the user there isn't any noticeable difference. Once discharged Non Refillable cylinders used by Mammut need to be exchanged with a suitable dealer. You pay a small charge, currently £30, and exchange your empty cylinder for a full one. This is best done in person in the local resort or town if possible or can be done by post once you are back in the UK. Mammut and Ortovox now only offer a carbon non refillable cylinder rather than an option of a carbon or steel one. Carbon is much lighter than steel and the price is now the same as the steel ones once were.
You cannot fly with a full compressed gas cylinder in North America, so people arrive at destination needing to easily and cheaply fill their cylinder before skiing. This means you'll need a refillable cylinder if you're flying in North America with your airbag. For refillable cylinder then once the canister is discharged you need a small spares kit to replace a consumable part and then you take the cylinder to any place that will fill paint ball cylinders as the fitting is the same. Using the same attachment as an already popular sport means there is an established network of places that can do this for you. The Mammut refillable cylinder can be used with any of their packs. Refillable cylinders can normally be recognised because they have a pressure gauge whereas non refillable cylinders do not.
|Non refillable Cylinder||User Refillable Cylinder|
After use on the hill, you will probably deflate your airbag and move to safer ground, check you know how to do this before you take your airbag out. The instruction manual that comes with your airbag or the manufacturers website are the best places to find out how to do this correctly.