For the first time in a rebreather, the electronics system has been developed by a leading dive computer company. Control, setup, decompression and alarm systems evolved from the VR3 dive computer and includes proven features and design based on a considerable knowledgeable base, research, development and design for underwater computer systems.
The Sentinel has the most richly featured, integrated software for a rebreather on the market, with electronics designed for intelligent monitoring. No single electronics failure will cause failure of the complete system. Any problems are clearly described on the main and summary screens.
Calibration in ambient air ensures calibration in a known gas, that no over pressurization has occurred, and reduces the risk from improper flushing of the loop. An on-screen checklist guides the user through the pre-dive sequence. The auto set point selects the appropriate setting for current depth and dive duration.
Options allow the user to set preferences for: last stop depth, HUD brightness, deco set point, safety factors, CNS alarm level, auto set point max, auto or manual mode, HP alarms on/off, cell configuration (on/off), gas configuration options for Dil and bailout. Main screen dive data includes: PO2, depth and max depth, dive time, decompression obligation, temperature, CNS, and battery level.
The electronics head holds the 3 oxygen sensors and the battery compartment. The ADV and oxygen solenoid housings are mounted on either side of the head. The Sentinel uses 3 rechargeable lithium polymer batteries, which can be recharged at any time without a significant memory effect. Two of the batteries act as main batteries, and when they become low the third will activate as will the battery reserve alarm.
The battery pack lasts for approximately 60 hours in light on mode and has a backup display independent from the main electronics and with an independent power source that allows the user to stay on the loop in the event of a main electronics failure. The backup is not software driven and consists of 3 separate digital voltmeter LCD displays with the ability for calibration. The backup display's independent battery is recharged as the main battery charges. Highlights of other Sentinel electronics features include:
Auto turn-on with the detection of a PO2 drop (detection of breathing) or at greater than 1.6 atm absolute pressure (detection of depth). Diver and back mounted Heads Up Displays (HUDs) configured for color blind and highly stressed divers by positioning and flashing or solid state. Vibrating alarm on diver HUD.
Digital pressure sensors for monitoring of HP Dil and O2 cylinders for low levels and high rate of use; will alarm when Dil reaches the amount needed for exit.
Maintains 0.4 set point in OC mode to keep loop breathable.
- Pre-breathe screen in the Pre-dive checklist sequence includes a bar graph showing the temperature difference across the filter.
- Auto calibration immediately triggered when sensor is replaced, ensuring calibration is in ambient air.
- Scrubber duration analysis from an oxygen injection meter and a temperature profile monitor.
- Valve over inject and no inject sensors to help detect sensor failure or leak.
- Sensor percentage remaining analysis and a dynamic algorithm for automatically removing a sensor from the PO2 averaging.
- PC Link option allows reprogramming and upgrades via downloads through the Internet as well as downloading of dive profile data with ProLink software.
Full decompression dive computer incorporating a derivative of the Bühlmann ZH-L16 algorithm with modifications to support deep stops, adjustable shallow stop depth, and dynamic decompression ceilings. An optional upgrade allows switching between the Bühlmann ZH-L16 and Varying Permeability Model (VPM)B/E algorithm.