The Prism 2 gains gas efficiency by circulating breathing gas in a breathing loop, unlike an open circuit SCUBA system that dumps the exhaled gas with each breath. The Prism 2 maintains safe oxygen levels, removes CO2 from the breathing loop, and delivers warm breathing gas to the diver.
The Prism 2 accomplishes this through the following breathing loop cycle:
1. The Oxygen and Diluent (air, trimix or heliox) tanks provide the source gas.
2. Exhaled gas enters the breathing loop, and a one-way valve inside the Dive Shutoff Valve (DSV) directs the breath to the righ side counterlung.
3. The right side counterlung is the location of the manual oxygen addition valve and system over pressure relief valve.
4. The exhales gas then enters the scrubber cannister where the carbon dioxide is removed.
5. Gas leaving the scrubber passes the three (3) O2 sensors which analyze the breathing mix, and the Prism 2 electronics add oxygen as required.
6. The breathing gas passes through the left side counterlung where the manual diluent addition valve is located, and maintained gas volume is available for breathing.
7. Gas leaving the left counterlung travels again through a one-way valve in the Dive Shutoff Valve (DSV).
8. The gas is inhaled by the diver, and the next exhalation begins the cycle again.