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Main CCR Body

consist of the robust Scrubber Canister and CCR Head, Upper Canister and Top Head, all 
made of Black Delrin.

The Scrubber Canister is made of durable Delrin tube and has 
a  mounted bottom with a small water trap.

The bottom has a lower protective ring made of stainless steels, 
which can be replaced if damaged.

The Scrubber Canister can be 
equipped with one or  two Quick 
Release Fasteners for easy 
attaching and replacing on-board 
cylinders, if used. 

Quick Release Fasteners provide very 
easy and secure attaching of the cylinders 
to the canister.

Radial Scrubber

FLEX2 CCR unit is standardly equipped with the radial scrubber 
placed in the Scrubber Canister.

The Radial Scrubber (H=212mm) 
has capacity of 2,5 kg / 5,5 lb of soda lime with minimal 
operating time of up to 6 hours even in extreme conditions 
such as cold water (4°C) and depths over 100m.

The Scrubber consist of the finely perforated concentrical tubes 

made of stainless steel with the 
robust bottom and top lid made of 
Delrin. The white top ring reinforces 
and protects the outer perforated tube. 

The Top lid is equipped with an 
easy to use bayonet lock and has a 
self-packing feature – the spring 
loaded plate ensuring sustained 
compression of the soda lime to 

protect against gas channeling (bypassing the soda lime).

The top lid has integrated radial handle for easy and safe removal 
of the scrubber from the Canister.

CCR Head & electronics

The CCR head is the heart of the FLEX2, 
which contains the control electronics, the 
solenoid valve for controlled dosing of 
oxygen, the removable Cartridge carrying 
three oxygen sensors, two replaceable Li- 
Ion batteries 18500, watertight connectors 
for connection of external computers as 
well as connectors with unique Click-Lock 
bayonets for easy and fast connecting of 
the Counterlungs.

The Control electronics 
(Shearwater SOLO board) is built in the 
hermetic compartment inside the head. 

The SOLO board uses ppO2 readings from 
three O2 sensors to autonomously 
maintain the ppO2 in the breathing loop in 
accordance with the current chosen 
setpoint.

Modular design compartmentalizes critical functions for redundancy. The Solenoid and Oxygen 
electronics (on the SOLO board) can measure and inject oxygen independently of the Primary 
Controller handset even in case that the handset or its cable is unplugged or damaged, while the 
SOLO board continues to control loop PPO2 until the diver is surfacing.

The control electronics uses the DiveCAN®, a digital communication standard developed by 
Shearwater Research Inc. specifically for rebreathers  for robust error-checked communications, 
when a message is either received correctly or it isn’t received at all.  The DiveCAN® is easily 
upgradable and expandable.

PPO2 reading output from all three oxygen sensors are electronically separated one from another 
as well as the PPO2 reading outputs to the Primary Controller Bus and the Secondary Monitoring 
Bus are electronically separated one from another. 
The Secondary Monitoring Bus is independent on the Primary Controller Bus and provides backup 
PPO2 monitoring in the event of a failure on the Primary Controller.

A fault or short circuit on any sensor or one connected device, it does not affect the remaining 
ppO2 readings on the working device.

The Primary Controller handset, the Head-Up Display or NERD2 are connected via the watertight 
connectors rated up to 300m depth. The connectors allow flexible connection of the controller 
and monitoring devices as well as easy disconnection of the devices for travel, upgrades and repair.

The watertight connectors are color coded this way: 
GREEN DiveCAN Controller Bus.
BLUE / RED DiveCAN and Analog Monitoring Bus.

Three Oxygen sensors are placed in the 
easily removable sensor cartridge making it 
easy to dry, check or replace the sensors. The 
sensor  cartridge is connected to the head 
electronics via the robust 6-pin connector 
with gold plated banana pins.

The cartridge is equipped with the wire 
handle to easily pull the cartridge out.

The covering lid is closed and secured by a 
bayonet locking ring.

The Solenoid valve has a Stainless steel AISI 316 
body and operates up to 17 bar (above the ambient 
pressure), therefore no low-pressure adjustment on 
the 1st stage regulator is needed.

The solenoid is connected to the UNF 9/16” fitting 
with built-in O2-filter.

Two independent, easily replaceable, rechargable Li-Ion 18500 batteries 
provide power supply of the control electronics board. 
They are located in two separate compartments on the 
sides of the head and are completely separated from 
the breathing loop.

Battery #1 supplies the 
Solenoid,

Battery #2 supplies the 
Head-Up Display and 
ppO2 reading output for 
NERD2, if used.

The batteries are easy accessible via the battery caps on the CCR head. 
The CCR head is attached to the Upper Canister and is mounted and locked to the Scrubber 
Canister by 4 safety stainless steel latches. 
To remove the head from the canister, just unlock the latches and pull the CCR head up.

Primary Controller Handset

is the Shearwater DiveCAN Petrel 3 Controller, specifically designed for the XCCR and FLEX2.

The Primary Controller Handset is connected to the control electronics in the CCR head via a robust, 
durable and very flexible cable with the X-connector, made of AISI 316L rated up to 300m depth 
and marked with a GREEN ring.

Primary Controller Feature List

– Two PPO2 set-points, which can be set between 0.5 and 1.5
– Automatic PPO2 set-point switching (configurable)
– Depth, time, 3x ppO2 and deco data display
– Strong Vibration alert system
– Up to 4 pressure transmitters for gas pressure monitoring
– Bühlmann decompression model with gradient factors
conservatism – Optional VPM-B decompression model
– 5 CC and 5 OC gases
– Gases can be changed and added during a dive
– CNS tracking
– Any combination of oxygen, nitrogen, and helium (Air, Nitrox,
Trimix) – Open and closed circuit, switchable during a dive
– No lockout from violating deco stops
– Metric and Imperial units
– Automatic turn off on the surface (after 15 minutes)
– Tilt compensated digital compass
– Dive Planner
– 1000 hour dive log memory
– Log downloads and firmware upgrades using Bluetooth
– Flexible user replaceable “AA” battery of almost types

Head-Up Display

The Head-Up Display (HUD) is compact Shearwater DiveCAN HUD with PPO2 monitoring on three
O2 sensors.

The main feature of the Head-Up Display (the HUD) is to show the current status of ppO2 in the 
breathing loop as well as ppO2 alarms to the diver.

The HUD has wet contacts for automatic turning on when entering water. 
The HUD is power supplied by the battery #2 in the CCR head.

The HUD is connected to the control electronics in the 
CCR head via a robust, durable and very flexible cable 
with the X-connector, made of AISI 316L rated up to 
300m depth and marked with a BLUE ring.

The HUD is placed in a two way adjustable holder 
located on the SM BOV Neo or SM DSV.

NERD 2

The FLEX2 CCR can optionally be fitted with a NERD 2 – the compact near to eye Shearwater 
DiveCAN Computer in place of the HUD. NERD 2 acts as a secondary computer with PPO2 
monitoring on three O2 sensors and Trimix decompression. 
The NERD 2 has wet contacts for automatic turning on when entering water. 
The NERD 2 is power supplied by its own Integrated rechargeable battery for up to 15 h operation 
time.
The NERD 2 is placed in a three way adjustable holder located at the SM BOV Neo or SM DSV. 
The NERD is connected to the CCR head control electronics via a robust, durable and very flexible 
cable with the X-connector, made of AISI 316L rated up to 300m depth and marked with a BLUE 
ring.

NERD 2 Feature List

– Depth, time, 3x ppO2 and deco data display
– Bühlmann decompression model with gradient 
factors conservatism – Optional VPM-B 
decompression model
– 5 CC and 5 OC gases
– Gases can be changed and added during a dive
– CNS tracking
– No lockout from violating deco stops

– Any combination of oxygen, nitrogen, and 
helium (Air, Nitrox, Trimix) – 
Open and closed circuit, 
switchable during a dive

– Automatic turn off on the surface (after 15 minutes)

– Tilt compensated digital compass
– Dive Planner
– 1000 hour dive log memory
– Log downloads and firmware upgrades using 
Bluetooth.