The Avi Vest is constructed from 4 components: Vest, Activation System, Inflation System, and Gas Cylinder. The Vest holds all the Avi Vest components while providing pockets for the user to carry items such as probes, radios and extra clothing. It is also a structural component, keeping the inflated airbag attached to the user during an avalanche.

The Activation System takes input from the user and initiates the inflation process of the Avi Vest airbag. Pulling the activation handle releases a spring loaded bayonet inside the Firing Head. The spring forces the bayonet through a disk in the head of an attached gas cylinder, releasing the gas.

The Avi Vest uses a DOT/TC approved Gas Cylinder to inflate the avalanche airbag. A lightweight cylinder head allows each cylinder to contain approx. 78 grams of compressed air (at a pressure of 3000 psi). Each cylinder can be reused, but must be recharged after each use. For the 2009/2010 season Avi Vest cylinders will be available for sale and replacement directly from WARI.

After the contained gas in the cylinder is released, the Inflation System routes it through a high pressure hose to a Venturi mounted on the airbag. Consisting of a jet and body, the Venturi uses the high pressure gas from the cylinder to create a low pressure in the ambient air surrounding it. As the high pressure gas continues down the body of the Venturi it literally 'pulls' in ambient air, filling the airbag. By using the Venturi we are able to fill a 150 Liter airbag with approximately 50 Liters of compressed air.

The Avi Vest utilizes the principal of inverse segregation to keep the avalanche victim on the surface of the avalanche. In the simplest terms, inverse segregation is the likelihood that the largest objects by volume will stay on the top of a turbulent medium. The smaller objects can more easily fill in the small spaces as the materials in a turbulent flow mix and interact.

An avalanche is made up of billions and billions of grains of snow. The size of the particles is determined by many factors: slab hardness, size and class of avalanche, etc. Typically the grains of snow are broken into very fine particles. As these particles fall and tumble down the mountain they are constantly mixing and churning. During the turbulent slide gravity exerts an equal force on all of the particles in the avalanche. The smallest of the particles have less resistance to falling into the spaces that constantly open due to the chaotic motion. This action causes the smallest of the particles to inversely or reverse segregate.

So now you might ask yourself, "What can inverse segregation do for me"? A tenet of inverse segregation is that the largest objects will be separated to the top of the turbulent medium. So for snow riders caught in an avalanche this principal can be very useful.

The next question is then, "How can we use inverse segregation to stay on the surface of an avalanche"? An airbag is the best way to implement this principal. The best chance for staying on the surface is if the airbag inflates instantly. When you pull the activator handle on the Avi Vest, steel spring drives a pin through a burst disk releasing air that is pressurized to 3000 psi. The air travels through a steel hose and is routed through a venturi mounted on the airbag.

The venturi is a device that uses the venturi principal to inhale ambient air. As the air rushes through this valve the high velocity causes a low pressure area or vacuum. The outside air is pulled into the airbag along with the air from the gas cylinder. By using the venturi we are able to fill a 150 Liter airbag with approximately 50 Liters of compressed air.

When wearing an Avi Vest it is very important not to be concerned with activating the airbag. It can not harm you and will not interfere with your ability to ride out of the avalanche. The airbag is located behind your head and can easily be deflated after you are safely out of harms way. We do recommend leaving the airbag inflated until you are sure you are out of any other avalanche paths. Remember that if there has been one avalanche, a second or third could happen also.