It’s breathing loop which is a keyed one way assembly consists of a closable mouthpiece assembly with mushroom/check valves either side, which ensure uni-directional flow.
Independent 3rd party testing has also rated the Prism 2 the lowest work of breathing of any mixed gas rebreather available today.
With the electronics switched on, the secondary also provides a status check for the battery and displays the set point selected for the dive along with other critical information. The electronics vote between the three proprietary galvanic sensors and control the operation of a low wattage solenoid valve on the oxygen supply.
A radial flow scrubber canister is mounted vertically on a backplate attached to the integrated BC, between twin supply cylinders (one each, oxygen and diluent).
The electronics, sensors and batteries are mounted in the electronics head assembly at the top of the scrubber, with supply hoses feeding over the diver’s shoulders into the top of the counterlungs. An analog LED primary display offers a quick reference of unit performance with status and alarm indicators while an independent digital OLED secondary display verifies the unit’s performance.
Dual, front mounted counterlungs provide the diver with a flexible reservoir equivalent to the maximum displacement of the diver’s own lung volume and ensures the lowest possible hydrostatic loading.
These counterlungs are fitted with both automatic and manual gas addition systems and a variable volume control valve (used upon ascent to vent excess expanding gas volume or to purge the loop). Diluent addition is automatically achieved as hydrostatic pressure increases and the counter lung collapses against the valve actuator.