Hollis Prism II

The Prism 2 is a fully closed circuit Rebreather, ideal for exploring open ocean, cave, or wrecks. This unit can be electronically or manually controlled which means you choose how you want the loop PPo2 maintained.

Includes shoulder mounted counter lungs and rear mounted radial scrubber which provide easy breathing with low resistive effort and low hydrostatic loading. The Prism 2 has also been tested by ANSTI at 100M and has the lowest WOB of any mixed gas CCR on the market at 0.94 J/L.

The standard kit includes an electronic secondary control and primary LED displays with a backplate/wing assembly that provides a complete kit ready to dive out of the box. Unit can also be purchased with or without tanks/valves.

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Technically Focused

The PRISM 2 is an electronically or manually controlled, constant PO2, modular, closed circuit diving system.

As open circuit (SCUBA) divers we rely upon filling our lungs with air from a pressurized gas tank with every inhalation and then exhausting that volume of air into the surrounding water with every exhalation. As we descend deeper the water pressure around us increases and the volume required to fill our lungs increases; in other words, our air supply depletes more quickly the deeper we dive.

A rebreather recycles rather than vents the exhaled breath. The exhaled breath passes into a closed loop, where it is pushed through a chemical absorbent (scrubber) to remove the carbon dioxide, and returns through the other side of the loop for the diver to re-breathe, hence the name “closed circuit rebreather” or CCR.

Breathing Loop

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 at 0.94J/L.

Status check

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.

Scrubber design

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).

Electronics

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.

Counter lungs

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.

Secondary Display (COMPUTER)

The Shearwater Predator is the computer display on the Prism 2 and was chosen for this application as it is one of the most advanced mixed gas CCR computers available today. The Predator is designed to control the Prism 2 setpoint and uses a basic decompression algorithm known as Buhlmann ZHL-16C which has been modified by the use of Gradient Factors.

Primary Display (HUD)

The Primary Display (HUD) consists of 3 bicolor (red/green) LEDs
mounted on either the right or left side of the DSV/BOV mouthpiece just below eye level. Each LED provides a status indicator for its corresponding O2 sensor by using a “Smithers Code” flashing the status on a cycling 5-second loop during the dive.

Features:

  • Shoulder mounted counterlungs provide easy breathing with low hydrostatic loading
  • Lowest Work of Breathing in industry at 0.94 J/L – Tested at 100M by ANSTI
  • Unit weight when fully charged, in standard
    configuration – approx. 47lbs
  • 3.5 Liter split counterlungs allows inhale and exhale counterlungs for high work loads
  • Counterlung drains for easy to remove water during a dive
  • All gas lines external to the breathing loop prevents leaks from affecting the PPO2
  • Automatic diluent addition valve adds diluent during descent or when the loop volume is low
  • Manual diluent addition valve adds on board or off board diluent for loop flushing
  • Gases – Air, Trimix, and Heliox
  • Manual oxygen addition valve allows for manually controlling oxygen PPO2
  • High performance open circuit Bail Out Valve option
  • Integral harness and BC or
    Backplate standard makes the Prism 2 ready to dive out of the box
  • Full range of wings/harness gives the ultimate customization
  • Accepts 13, 19, or 30 cu.ft. cylinders for flexible gas management
  • Eye level LED Primary display provides easy to monitor system status
  • Displays PPO2 for each oxygen sensor is used to control PPO2 manually & assure electronics system is nominal
  • External power switch is easy to power on
  • Easy calibration with a push button O2 calibration
  • Large OLED Secondary Display is easy to read, even for your buddy
  • PPO2 Monitoring of Three Sensors Continuous display of each sensor’s PPO2, mv reading easy to access
  • Closed Circuit & Open Circuit, 5 gases    supports diluent switching & Multi-gas mix dive plans
  • 2 button push OC bailout – If you have to leave the loop, quickly switches to bailout support
  • CNS Tracking based on real time
    oxygen exposure
  • Software Update via web
  • Dive Log download and software updates via Bluetooth

Be trained with few kinds of rebreather units, you can learn more at our Closed Circuit Rebreather CCR Training page.

More SCUBA Courses and Services We Offer

Maori Warrior Charter
SDI Diver Courses
Emergency First Responder

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