Section: 3. Procedures

3.1 Dive plan
3.1.1 Planner settings
3.1.2 Planning

3.2 Dive preparation

3.2.1 Replacement of CO₂ sorbent
3.2.2 Assembling the rebreather body
3.2.3 Mounting the rebreather body
3.2.4 Attaching the counterlungs and hoses
3.2.5 Cylinder filling
3.2.6 Battery charging
3.2.7 Helium sensor calibration
3.2.8 Calibration of the oxygen sensors
3.2.9 Preparing the bailout cylinder
3.2.10 Setting parameters
3.2.11 Directional valve check
3.2.12 Physical inspection

3.3 Pre-dive inspection

3.3.1 Internal testing of the control units
3.3.2 Pressure sensor test
3.3.3 Comparison of oxygen sensors and their calibration
3.3.4 Helium-sensor test
3.3.5 Battery testing
3.3.6 Solenoid testing
3.3.7 HUD inspection
3.3.8 BD inspection
3.3.9 Negative pressure test
3.3.10 Positive pressure test
3.3.11 IP Pressure
3.3.12 Predive checklist
3.3.13 Prebreathe

3.4 Diving

3.4.1 Breathing high oxygen content gases
3.4.2 Putting on the apparatus
3.4.3 Using the DSV
3.4.4 Monitoring of devices
3.4.5 Switching to CCR mode
3.4.6 Water entry
3.4.7 Submersion
3.4.8 In-water check
3.4.9 Descent
3.4.10 Controlling buoyancy and trim
3.4.11 Mask clearing
3.4.12 Increased physical exertion
3.4.13 Ascent

3.5 Post-dive procedures

3.5.1 Immediately after surfacing
3.5.2 CO₂ scrubber maintenance
3.5.3 Cleaning and disinfection
3.5.4 Battery care
3.5.5 Dive log download
3.5.6 Long-term storage

3.6 Emergency procedures

3.6.1 Emergency ascent (bailout)
3.6.2 Oxygen-source malfunction
3.6.3 Diluent-source malfunction
3.6.4 Scrubber malfunction
3.6.5 Inadvertent release of the mouthpiece
3.6.6 Flooding
3.6.7 Loss of buoyancy
3.6.8 Rescue on the surface
3.6.9 Malfunction of oxygen-concentration measuring

3.7 Maintenance

3.7.1 Tools and replacement parts
3.7.2 Detection of leaks
3.7.3 Regular service inspection
3.7.4 Long-term maintenance
3.7.5 Firmware update

3.8 Transport

3.8.1 By car
3.8.2 By boat
3.8.3 By plane

3. Procedures

3.1 Dive plan

For planning a dive in the strict sense (gas management and decompression) the internal functions of the CCR Liberty can be used. The planner calculates a dive plan in CCR mode or with an emergency bailout on open circuit. To compute the decompression, the Bühlmann ZHL-16B algorithm (with adjustable gradient factors) as well as, an on-line decompression calculation is used.

3.1.1 Planner settings

Particularly in the case of breathing mixtures for bailout, it is necessary to check only those mixtures which are actually available during the dive and to make sure their composition, pressure, and cylinder parameters are set correctly. If any other mixtures are checked or mixtures have a larger gas reserve set, they will be included in the planning and will cause serious distortion to the dive plan, which may have tragic consequences.

A detailed guide for setting these parameters can be found in the following sections:

• 2.4.2 Setpoints
• 2.4.3 Mixtures
• 2.4.4 Decompression

Ascent gas

Determine whether you want to plan the bailout ascent using all of the set gases, the Optimal option, or only one current gas. The most widely used gas in the planner is the Current option. This setting also influences the TTS calculation during the bailout of the output. It is either planned with all available mixes (optimal) or just current (current).

Ascent SP" [High] / [Current]

Setpoint with which the scheduler counts the output (from the end of bottom time). Current is a low setpoint setting. Use this option if you want to dive with a low SP for the entire dive, or simply want to see a TTS with a current setpoint instead of a high SP.

Gas switch

Select this option to set the minimum switching stop length for open circuit bailout ascent. In this stop the diver tries to use the high ppO₂ and the oxygen window effect when changing the mixture. The stop depth is set automatically according to the ppO₂ mixture. The ascent ppO₂ 1.6 is used. If the stop is deeper than the first decompression stop, a separate stop is created and is included in the ascent and gas consumption plan. If the depth is in the step decompression zone, the setting determines the minimum stop length. The numeric value represents the length in minutes. If a zero value is selected, the stop is not counted.

Deep stops

Here you can include extra deep stops to reduce silent bubbles. Richard Pyle’s calculation procedure is used to halve the pressure between the start of the ascent and the depth of the first decompression stop. In this option, it is necessary to consider setting the gradient factors so that the medium and slow tissues are not saturated.

3.1.2 Planning

In the scheduler, choose a planning mode (CCR / Bailout).

• No deco – Time with no decompression at the bottom with the current mixture
• TTS – “Time to surface” total ascent time
• Total – total dive time
• CNS – accumulated exposure of CNS for planned dive
• NoFly: – Expected time limit of flying after surfacing

In addition, when planning a bailout mode, an “Insufficient gas” warning may appear if the specified amount of gas is not sufficient to complete the open circuit ascent.

Press the bottom button to go to the next page. Use the top button to return to the previous page.

Helium blends are labeled brown, nitrox mixtures are green (various tints by amount of oxygen), air or diluent is white, oxygen is blue.

If the plan is longer than 8 steps, the plan is continued on the next page. The summary is expressed in pink. The first number represents the total time of the ascent, and the second number represents the total time of the entire dive.

3.2 Dive preparation

3.2.1 Replacement of CO₂ sorbent

Sorbent service life

Continually keep records of the extent of scrubber consumption. Set a stack time warning, and don’t forget to reset the stack timer after replacing the sorbent. If ever in doubt, replace the sorbent.

The recommended scrubber filling material is Sofnolime 797 sorbent (producer: Molecular Products). The cartridge holds approximately 2.5 kg of sorbent.

The maximum safe operating period of the sorbent is 168 min, determined by a test in accordance to EN 14143:2013 (Article 6.6.2). During the test, 1.6 l/min of CO₂ were added to the breathing loop with a ventilation rate of 40 l/min and an exhalation temperature of 32±4 °C; the unit was submerged in 4 °C water to a depth of 40 m with a ppCO₂ of 5mBar (test provided by Life Support Test Facility – LSTF 0916). This is the worst case scenario, and it considers a very high level of body exertion, with oxygen consumption of 1.78 l/min.

The physiological limit is not ppCO₂ 5 mBar, but ten times higher (Knafelc, 2000). A respiratory quotient 0.9 is too high; a more realistic estimate is 0.8-0.85. Sorbent service life is longer (or safety margin is bigger) than previously stated.

In the course of the sorbent’s service life, it is allowed to remove the scrubber cartridge a maximum of two times (see section 3.5.2 CO₂ scrubber maintenance).

Sorbent replacement procedure

Handle the sorbent in accordance with the manufacturer’s instructions. Comply with all safety instructions and use protective gear. Take environmental protection into account when disposing of used sorbent.

Remove all of the old sorbent content from the cartridge.

If you disinfect the rebreather, proceed according to section 3.5.3 Cleaning and disinfection. It is preferable to disinfect after a dive rather than waiting for a longer period.

If you cannot ensure the cleanliness of a surface, place the cartridge on a clean towel.

Follow these hygienic principles when filling and handling the scrubber in any way.

If you are working outside (recommended) and there is, at the least, moderate wind, stand sideways to the wind and pour the sorbent slowly into the cartridge from a height of approximately 20-30 cm (1 ft). Allow the wind to remove the finest dust particles.

If you are working indoors, pour the sorbent into the cartridge from a minimal height. Sorbent dust is aggressive and can cause corrosion. Therefore, we do not recommend working with the scrubber inside of an automobile, for example.

In order to prevent the sorbent from falling into the central tube, place the canister’s metal disc lid over the opening, or plug it by other suitable means. Pour sorbent into the cartridge until it is approximately one-third full. Then gently lift the cartridge, and allow it to fall three times from a height of approximately 1 cm (1/2”). Repeat this process when the cartridge is two-thirds full and again when it is completely full. The cartridge is completely full when the sorbent reaches a level between the min and max lines marked on the central tube.

After filling, place the metal disc and spring-loaded pressure plate on top of the sorbent. Then remove the pressure plate and lid, and verify that the surface of the sorbent is levelled and that no channels have formed. Place the metal disc and spring-loaded pressure plate on top of the sorbent again; press down and secure the assembly with the retaining ring. The retaining ring must fit into the slot on the pressure plate.

If the cartridge is not filled sufficiently, a gap of less than 6 mm or less will remain between the edge of the lid and edge of the metal mesh. In such a case, add sorbent and then shake and close the cartridge according to the procedure described above.

If the cartridge is overfilled, there will be a gap greater than 17 mm between the edge of the lid and the edge of the metal mesh, and it will not be possible to insert the retaining ring without excessive force. In such a case, remove the excess sorbent with a clean teaspoon or any other suitable tool. Shake the cartridge, and close the lid again.

Before inserting the cartridge into the scrubber canister, check to ensure that the water trap is dry. If that is not the case, remove the water trap, and dry it with a towel.

After each scrubber change, the stack timer Menu / Predive / Stack time reset must be reset

The stack timer measures the use of the scrubber by simply counting the time spent in the dive mode. You can adjust whether stack time is calculated on the surface or not.

Sorbent dust damages textiles, especially polyamide and cotton fabrics. Therefore, after working with the scrubber, immediately wash the towel on which the cartridge was placed and all clothing that was exposed to sorbent dust.

Do not work with sorbent in the vicinity of load-bearing straps, ropes, or even metal mountain climbing or speleological equipment. In the event of possible exposure to sorbent, ropes and load-bearing straps should be discarded immediately, as their loading capacity can deteriorate significantly.

Condition of the scrubber before submersion

The scrubber must have sufficient absorption capacity for the planned dive.

The sorbent must contain some amount moisture so that the chemical reactions that enable the scrubber to remove CO₂ from the breathing mixture can take place. This means that the scrubber cannot be completely dry or frozen.

In freezing weather, stow the rebreather in a warm space prior to the dive. If you are outside with the apparatus and a delay happens, maintain the temperature of the sorbent by breathing from the apparatus.

3.2.2 Assembling the rebreather body

Mount the head on the CO₂ scrubber canister.

3.2.3 Mounting the rebreather body

Procedure:

1. Mount the body of the apparatus on the frame so that the recesses in the lower part fit into the protrusions on the base.
2. Lift the lever in the center of the backplate.
3. Press the rebreather body against the backplate so that the tongue in the upper part of the backplate fits into the recess in the head of the apparatus. If necessary, forcefully press the top of the head downward.
4. Press down on the lever in the middle of the apparatus and check whether the lock is closed.
5. Check whether the apparatus is firmly attached.
6. Secure the body with the securing strap.

3.2.4 Attaching the counterlungs and hoses

The position of the counterlungs in relation to the diver’s body determines the work of breathing. Adjust the position by shifting the upper strap on the back side of the counterlung.

Procedure:

1. Attach the counterlungs using the buckles so that the T-piece bulkheads are roughly at shoulder level and the flaps with Velcro are facing the center (toward each other).
2. Connect the manual diluent bypass valve to the lower bulkhead of the left breathing bag.
3. Connect the overpressure valve to the lower bulkhead of the right breathing bag.
4. Connect the manual oxygen bypass valve to the middle bulkhead of the right breathing bag.
5. Attach the inhalation T-piece (without the partition) to the upper bulkhead of the left breathing bag.
6. Attach the exhalation T-piece (with the partition) to the upper bulkhead of the right breathing bag.
7. Attach the terminal elbow of the inhalation (left) corrugated hose to the opening in the center of the head.
8. Attach the terminal elbow of the exhalation (right) corrugated hose to the opening on the edge of the head.
9. Screw the short oxygen hose to the 9/16” elbow on the side of the head. Tighten the union nut firmly by hand.
10. Route the LP hoses to the ADV and to the manual diluent bypass valve and the HP hose to the diluent pressure gauge so that they pass together over the shoulder strap from the outside to the inside of the strap.
11. Attach the ADV to the middle bulkhead of the left counterlung.
12. Attach the quick-release connector of the LP hose to the manual diluent bypass valve.
13. Straighten the hoses and secure them under the Velcro flap of the left breathing bag.
14. Route the LP hose to the manual oxygen bypass valve, and the HP hose to the oxygen pressure gauge so that they unit pass together over the shoulder strap from the outside to the inside of the strap.
15. Attach the quick-release connector of the LP hose to the manual oxygen bypass valve.
16. Straighten the hoses and secure them under the Velcro flap of the right breathing bag.
17. Route the LP hose of the buoyancy control device (BCD) under the first rubber band on the corrugated inflator hose of the BCD, then under the rubber band on the left shoulder strap above the D-ring, and finally under the second rubber band on the corrugated inflator hose.
18. Connect the quick-release connector to the inflator of the BCD.
19. Adjust the position of the BCD inflator hose so that it is easily accessible when diving.

For attaching devices to the connectors, see also

• section 1.3.1 Corrugated hoses
• section 1.3.3 Connection to the breathing bags
• section 1.4 Inhalation bag
• and section 1.5 Exhalation bag

3.2.5 Cylinder fillings

When filling the cylinders with the breathing mixture, follow the procedures and rules with which you were familiarized in a technical gas blending course (trimix blender, etc.). If you have not successfully completed such a course, leave mixture blending to a qualified person.

When handling oxygen, follow the procedures and rules with which you were familiarized in a trimix course and, subsequently, in a CCR Liberty course. If you have not successfully completed such a course, do not handle the CCR Liberty.

3.2.5.1 Diluent

Choose a diluent that is able to flush a high oxygen mix from the breathing loop. Prepare the diluent so the partial pressure of oxygen will be 0,2 bar lower than the planned setpoint at the greatest depth of your planned dive. Partial pressure of nitrogen should not exceed 4 bar (3.2 bar is recommended). In regards to oxygen compatibility and cleanliness for oxygen service of the parts working with diluent, do not exceed an oxygen concentration of 21% (± 1%) in the diluent. Minimum oxygen concentration is 5%.
Diluent contamination should not exceed the limits given by the standard EN12021:2014. Section 6.2 when using compressed air for the unit.

Make sure that the diluent was filled by a compressor with properly maintained filters.

The gas must meet the requirements of EN12021:2014 Alternatively, you can use an personal filter. When using a compressor with a combustion engine, ensure that the exhaust gases from the engine cannot get into the compressor intake.

Mixtures with higher helium present more advantages for a number of reasons. But a low O2 mix on the surface in shallow depths, with a lack of breathability, significantly increases risks.

After filling, write the mixture composition with a permanent marker on a label (piece of duct tape) and attach it to the cylinder.

The consumption of diluent depends on the dive profile, frequency, and extent of depth changes. Diluent capacity is not limited by time but by the dive profile. This should be taken into account especially when planning dives in caves. Diluent is consumed mainly during the descent. During the ascent there is a zero theoretical consumption, and any practical consumption is mainly due to mask clearing. Based on a practical experience, the typical diluent consumption during a simple dive to a depth of 40 m is approximately 50 to 70 bar. This usually does not increase by staying longer at the same depth.

Always keep a sufficient safety margin (at least 50 bar) to cover unplanned situations. If the pressure in the diluent cylinder is lower than 70 bar, not even a brief dive should not started.

According to the standards to which the CCR Liberty is CE certified and designated, do not dive to depths greater than 40 m. Therefore, the CCR Liberty is CE certified to 40 m.

Oxygen

Use oxygen intended for breathing. Oxygen contamination shall not exceed the limits given by the standard EN 12021 Section 6.2 vhen using compressed air for the unit.

We recommend using oxygen with a purity of at least 99.5%.

Oxygen consumption for gas duration calculations is 1.78 l/min according to the EN 14143:2014. When considering the initial cylinder pressure of 200 bar and a final pressure of 50 bar in the cylinder, the oxygen supply suffices for 253 minutes. In this calculation, oxygen contained in the diluent is not considered.

These conditions correspond to high levels of physical effort during a dive. If a diver is calm during a dive, consumption significantly decreases, and the quantity of oxygen and the sorbent service life is extended. A dive plan that relies on an entire dive being a low-effort dive is inaccurate.

In any case, an oxygen cylinder filled to 200 bar is sufficient for a dive, which greatly exceeds the duration of the CO₂ scrubber.

If the pressure in the oxygen cylinder is lower than 70 bar, not even a brief dive should be started.

According to the valid technical standards, filling oxygen to an operating pressure greater than 200 bars is prohibited.

3.2.6 Battery charging

Before charging the batteries, remove the jumpers from the sockets.

For charging the batteries, use the enclosed charger or any USB charger dimensioned to 2 A (most chargers used with vehicle power outlets are not sufficiently dimensioned). Fully discharged batteries require approximately eight hours of charging.

Charging from a computer’s USB port is possible, though charging is done with a significantly lower current. The time required for charging fully discharged batteries in this manner is approximately 15 hours. Charging from a computer’s USB port can be done via an adapter connected to the external connector of the handset.

In you prepare the CCR Liberty for diving no more than one week after charging, insert the jumpers so that their pins are inserted into the connector. The rebreather will thus be switched to standby mode, and it will be possible to switch on the control unit using the handset. If the jumpers are inserted in reverse position with the pins outside; in this position, the power supply is completely disconnected, and the control unit cannot be switched on. The Liberty 2021 edition can be stored for up to half a year with the jumpers connected. During this time the batteries will discharge to about 50%.

A 30 sec switch-off timeout is active during charging. The timeout is prolonged by pressing a button in editor, but not by tilting. Do not alter the settings while charging, because the unit may switch-off suddenly.

3.2.7 Helium sensor calibration

For proper helium measurement in the loop and indirect oxygen measurement, it is necessary to calibrate the helium sensors before their first use or if the measurement values are inaccurate.

Before calibration, make sure only air and no other gas is present in the inlet chamber of the helium sensor (inside the head) and that the helium sensors are not contaminated with moisture.

Select Menu / Setup / Calibration / Calibrate He – Air

The measured speed of sound should approximately be around 0.5500 ms. Start the calibration by pressing the start button. After the sensors stabilize, press the upper “Accept” button again.

3.2.8 Calibration of the oxygen sensors

Insert the measuring probe into the inhalation opening (in the center of the head). The head can be mounted on the scrubber canister, but is not required. Connect the flow limiter to the oxygen hose quick-release.

The hissing sound that accompanies the flow of oxygen can barely be heard in a quiet environment. The flow becomes more apparent if one uses a moistened finger to cover the discharge aperture. Connect the sampling tube between the flow limiter and measuring probe.

Procedure:

1. Start O₂ sensor calibration on HS in Predive → Calibration O₂
2. Wait for mV stabilization (this could take a while)
3. Start calibration
4. Save

During calibration, the status of a sensor’s service life is also determined.

At higher altitudes above sea level, the partial pressure of oxygen in the calibration mixture decreases in proportion to lower atmospheric pressure. The CCR Liberty measures atmospheric pressure and takes it into account during calibration. Therefore, do not perform any corrections at higher altitudes above sea level.

3.2.9 Preparing the bailout cylinder

The bailout apparatus must ensure a reliable return to the surface at any time during a dive.

The standard solution is to use a corresponding number of stage and decompression cylinders with mixtures according to depth, distances, and the bailout plan. For a deep diving backup, it is recommended to use a mixture rich in He, regardless of the financial costs. The mixture will probably not be used for many dives. A higher content of He results in less negative buoyancy, which makes transporting the cylinder under water more convenient.

Preparation of the bailout stage cylinders is similar to that of open-circuit diving with trimix. When planning and preparing, proceed according to the rules with which you were familiarized in a trimix course.

The gas must meet the requirements of EN12021:2014

3.2.10 Setting parameters

Set or check the settings of all dive parameters.

For a detailed description, see section 2.4 Setup.

3.2.11 Directional valve check

The purpose of this test is to detect possible leaks in the directional valves of the dive/surface valve (DSV). This type of leakage could seriously endanger the diver. It is not possible to assemble the complete breathing loop in the wrong direction, but the diver has to be sure that this part is not missing or leaking.

Procedure:

1. Put the bayonet socket cover on both T-pieces.
2. Cover the left (inhale) elbow.
3. Place the mouthpiece in your mouth, open the DSV and try to inhale. Inhaling should not be possible. The left corrugated hose collapses. Exhaling should be possible.
4. Close the DSV, and check for leakage (the corrugated hose should stay collapsed).
5. Open the DSV, unplug the inhale elbow, and cover the right (exhale) elbow with bayonet socket cover.
6. Inhale from the mouthpiece, and try to exhale. Inhaling should be possible.
7. Pull the exhalation elbow to extend the corrugated hose on the right side. Check for leakage (the corrugated hose stay extended).

If some leakage occurs, change the directional valves or do not dive.

3.2.12 Physical inspection

Check to ensure that the CCR Liberty is complete, correctly assembled, and mechanically undamaged.

If the CCR Liberty is operated within an organization where someone other than the diver is responsible for the physical preparation of the apparatus, we recommend providing them a list of detailed organizational rules. An assembly checklist in editable form is prepared for download on the divesoft.com website.

3.3 Pre-dive inspection

The user confirms the results of the individual inspection steps:

OK — test result is positive top button; press the top button to continue.

FAIL — partial test failure, but the other steps of the PDI will be performed normally. To continue with the PDI, press the bottom button.

ABORT — press both buttons to terminate the PDI. It is also necessary to use the ABORT command when a reparable defect is detected and the full PDI must be carried out again. The ABORT command is carried out automatically if the user does not respond to the prompt within two minutes.

The results of testing are recorded in the log.

During the test, no oxygen is added. The user is warned before the test begins. This must be confirmed for the test to take place.

The test result notifies the user if the unit is divable, but does not influence the subsequent behavior of the apparatus; in particular, it does not block the functions necessary for undertaking a dive (in accordance with the Responsibility of the CCR Liberty User set forth in the introduction). Ignoring the conclusions of the pre-dive inspection is the diver’s choice, for which he/she bears responsibility.

3.3.1 Internal testing of the control units

If the individual elements of the system are connected correctly, a green line appears between them. If the connection has failed for some reason, or if part of the system is missing (for example, a disconnected handset), the line appears red.

3.3.2 Pressure sensor test

The purpose of the pressure sensor test is to determine whether the pressure sensor values correspond to the actual pressure (altitude) and do not show any significant deviations from the expected pressure or from each other.

3.3.3 Comparison of oxygen sensors and their calibration

During testing, keep in mind that sensors measure the actual value of ppO₂ in the loop. If testing is preceded by oxygen manipulation, this will be reflected in the sensor voltage.

Sensor check

• – A sensor is Offline or reports Error.
• – Online sensors are checked for minimum voltage; at least 5mV must be measured on air at sea level.
• – The permitted tolerance between the largest and the smallest voltage is 5%.
• – The calibration age must be less than the set value in the configuration.

Setup / Calibration / Recomm. Days

3.3.4 Helium-sensor test

A functionality test of the He-concentration sensors is performed. The user is informed of the ongoing test on the HS display.

3.3.5 Battery testing

The user then decides whether he/she considers the batteries’ estimated duration to be sufficient for the planned dive.

3.3.6 Solenoid testing

3.3.7 HUD inspection

3.3.8 BD inspection

The buddy display successively lights up green at low, medium, and high intensities, then in red at low, medium and high intensities.

3.3.9 Negative pressure test

Procedure:

1. Close the diluent and oxygen cylinder valves.
2. Open the DSV, and create sufficient negative pressure with your mouth according to the indication on the HS display. The negative pressure is indicated by a white bar graph. For sufficient leakage testing, it is advisable to develop such a negative pressure where the white bar graph will cross over the green field.
3. Close the DSV and cease all movement of the rebreather; in particular, do not move the bags and breathing hoses. After closing the mouthpiece, place the breathing hose loosely on the device. Movement of the breathing hoses and counterlungs causes pressure changes in the loop and distorts measurement results.
4. Wait 60 seconds; the countdown runs automatically on the display.
5. The test can be considered successful if the pressure loss after 60 seconds is less than 10 mbar (do not count the initial pressure change, as it is caused by the change of hose length).

Final evaluation of the test and confirmation of the result are left at the user’s discretion.

See also section 3.7.2 Detection of leaks.

Note: In spite of a positive result of a negative pressure test, leaks may occur during the dive. This is most often caused by a loose or punctured rubber mouthpiece.

Procedure:

1. Close the oxygen cylinder valve and open the diluent cylinder valve.
2. Close the DSV, and close the overpressure valve.
3. With the manual diluent valve, create sufficient overpressure according to the indication on the HS display. It is also possible to do this using your mouth if you want to conserve gas in the diluent cylinder. If you want to set the device straight to the higher setpoint, pressurize the loop with oxygen.
4. Cease all movement of the rebreather; in particular, do not move the bags and breathing hoses.
5. Wait 60 seconds; the countdown runs automatically on the display.
6. The result is influenced by the opening of the over-pressure valve, which is set to a maximum of 35 mbar. If you notice a pressure leakage above this value, verify that it is only the over-pressure valve and that the leakage has no other source. The pressure should no longer fall below the set limit of the ovre-pressure valve.

Final evaluation of the test and confirmation of the result are left at the user’s discretion.

3.3.11 IP Pressure

The last item of the pre-dive check is the intermediate pressure gas leak check. (It works only if pressure transmitters are connected).

1. The screen will display the initial pressure.
2. Open the oxygen and diluent cylinders to pressurize the intermediate and high pressure compartments.
3. Close the cylinder valves and observe any pressure drop as the display counts down. Any pressure drop indicates a leak in the intermediate or high pressure compartment. If this occurs, detect and correct the fault before diving.
4. Open the valves fully again.

3.3.12 Predive checklist

Upon entering Dive Mode, the unit automatically checks the oxygen sensors and their calibration. In the case of an old calibration or a sensor deviates of more than 10%, a warning will be issued along with recommendations for re-calibration. Follow the checklist. The diver is required to personally verify all the items listed.

3.3.13 Prebreathe

3. Put the mask on your face and keep it on throughout the entire test period to prevent the intake of ambient air through the nose, thereby compromising the accuracy of the test
4. Start breathing from the device, and start the countdown on the handset.
5. Monitor the partial pressure on the second handset and the behavior of all oxygen sensors.
6. Make sure you breathe comfortably, that your breathing does not stop, and that there are no feelings of breathlessness, nausea, headache, or other unusual conditions.
7. After finishing the test with a positive result, you can start the dive.

Warning: If you are pre-breathing in temperatures below freezing, under no circumstances should you stop breathing from the unit up until full submersion. When you are not breathing from the unit, you are running the risk of letting your scrubber’s interstitial space freeze, hindering its functionality

3.4 Diving

3.4.1 Breathing high oxygen content gases

The mixture in the CCR Liberty circuit usually contains oxygen at a much higher partial pressure compare to the air we breathe on the surface.

Acute (CNS) oxygen poisoning

Exposure to high oxygen partial pressure may, under certain circumstances, cause acute (CNS) oxygen poisoning. This can potentionally cause the affected person to drown.

The so called “oxygen clock” is a percentage of consumption of CNS toxicity limit. Limit the maximum partial pressure and total exposure so that acute oxygen toxicity cannot occur, according to the following NOAA table.

Whole body oxygen toxicity

Long term exposure to oxygen partial pressure higher than 0.5 bar, common when using the CCR Liberty, leads to whole body (or pulmonary) oxygen poisoning. At exposures common to amateur technical diving, whole body toxicity symptoms are not significant. During rebreather diving, however, the diver is exposed to a relatively high partial pressure of oxygen throughout the dive, unlike with open circuit. Exceeding the whole body toxicity threshold is extremely dangerous.

For very long dives or a series of rebreather dives it is necessary to calculate with long-term exposure limits and to limit the overall exposure.

The main symptom of chronic toxicity is a temporary reduction in vital lung capacity. Another symptom may be nearsightedness (hyperoxic myopia). Symptoms may persist for several months.

When ppO₂ ≥ 1.4 bar then the CNS toxicity limit is always shorter than the pulmonary toxicity limit.

For calculations related to chronic toxicity, use the REPEX method that you learned from your nitrox diving course. The CCR Liberty does not perform calculations associated with chronic oxygen toxicity.

3.4.2 Putting on the apparatus

After the pre-dive inspection, set the CCR Liberty on its stand on a hard surface – on the ground, a bench or table, or in a vehicle’s cargo space. Properly secure the rebreather so that it cannot fall, for example, by having a partner hold it.

Procedure:

1. Flip the breathing bags and corrugated hoses with the DSV to the opposite side of the rebreather’s body.
2. Position yourself under the shoulder straps. 101
3. Put on the shoulder straps, ideally with both arms at the same time.
4. Stand up on both feet. Due to the weight of the CCR Liberty, avoid rotating your spine, which could lead to injury. Before you stand up, carefully assume a kneeling position, and then stand up.
5. Take the crotch strap up between your legs and pass the belt buckle through the eye of the crotch strap.
6. Gently tighten the belt and fasten the belt buckle.
7. Flip the breathing bags and corrugated hoses with the DSV to the front.
8. Attach the breathing bags to the crotch strap V-straps with the buckles.
9. Make sure that all of the straps are adequately tightened and are not twisted.
10. Secure the handsets to your wrists. Ensure that the HS cables are wrapped around your arms.
11. Ensure that the HUD is attached to the DSV and its cable is wrapped around the corrugated hose.
12. Check the accessibility of the BCD inflator.

3.4.3 Using the DSV

The DSV must be closed at all times when it is not in your mouth. Close it before taking it out of your mouth; open it after putting it in your mouth, and clear the DSV before inhaling.

Opening the DSV when it is not in your mouth will cause an immediate loss of buoyancy and could possibly flood the breathing loop.

Do not rely solely on the alarm indicating reduced partial pressure of oxygen.

Reduced partial pressure of oxygen is also signaled on the buddy display. Familiarize your diving partners with the BD signals so that they will be able to recognize in time that you need help.

For monitoring ppO₂, it is not enough to monitor the average value of all sensors, which is highlighted by a larger font. All sensors must be monitored, either on the main display of the handset or on the screen containing all the sensors. In case one doubt’s the displayed measurement of one or more sensors, compare the indirect oxygen measurement values with helium sensors (only if the helium fraction in the diluent is greater than 20% and helium measuring is enabled in the settings). These values can be found on the sensor voltage screen.

Another option is a diluent flush (correctly taught in the CCR Liberty Diver course) after which you compare the result with the value in the lower left corner on the sensor voltage screen. This gives the ppO₂ diluent at the current depth. The sensor, which after a diluent flush corresponds to the displayed value, can be considered valid. Pay attention if you are using a hypoxic diluent at a low depth.

The system can automatically disable one or two sensors. Always use your common sense, and make sure the discarded sensors are really the faulty ones and not the other way around.

Oxygen and diluent pressure

We recommend checking the pressure of oxygen and diluent approximately once every five minutes.

Compared to an open-circuit apparatus, the oxygen and diluent cylinders have a small volume. Even a minor leak can cause rapid loss of pressure. Therefore, it is necessary to check the oxygen and diluent pressure gauges (SPGs) more frequently than when diving with an open circuit.

3.4.5 Switching to CCR mode

In surface mode, pull up the menu and switch to CCR mode.

Perform an inspection according to the displayed checklist.

3.4.6 Water entry

Do not enter the water without having performed a pre-dive inspection according to chapter 3.3 Pre-dive inspection!

We recommend breathing from the rebreather for at least three minutes right before entering the water in order to make certain that the scrubber and the rest of the apparatus are working properly.

In freezing weather, do not allow the scrubber to cool down after transferring the rebreather from a warm environment. Limit the rebreather’s exposure to freezing air. If necessary, keep the sorbent warm by breathing from the rebreather.

We recommend gradually entering the water and submerge the rebreather slowly.

If it is necessary to jump into the water, use the “giant stride” method, whereby your legs and buttocks impact the water first, thus protecting the breathing bags and corrugated hoses from direct impact. When entering the water in this manner, have the DSV in your mouth; have it closed at the moment of entry. Sudden entry into the water must be supervised by a person qualified to provide assistance in the event that problems arise.

Perform a bubble check after entering the water. Due to the small volume of the oxygen and diluent cylinders, minor leaks in the high-pressure and low-pressure parts, can lead to a rapid decline of pressure in the cylinders.

3.4.7 Submersion

During submersion, use the compensator (BCD) to control buoyancy.

Choose an appropriate amount of ballast with respect to any possible change in weight during a dive. Do not overload yourself to facilitate submersion. Unlike in open-circuit diving, weight reduction due to consumption of gases is minimal. The possible use of the open-circuit bailout apparatus has a more significant impact on weight reduction. Determining of the correct amount of ballast is one of the skills that you will learn in the CCR Liberty course.

3.4.8 In-water check

Verify the ppO₂ control system and adjust buoyancy.

Perform a bubble check with your diving partner. Scan all parts of the breathing loop in the direction of the gas flow. Rotate horizontally using the “helicopter turn”.

Check your bailout source. Take a few breaths from the bailout bottle to see if the regulator is easily and quickly available and functional. Check the pressure in the bailout cylinder.

3.4.9 Descent

During the descent, the ADV adds diluent to the breathing loop; you can also add diluent manually. Diluent is added to the inhalation bag. During a rapid descent, the mixture delivered to the DSV is practically identical to the diluent.

If you use diluent with a low oxygen content (e.g. when starting a descent to a great depth), it is necessary to significantly limit the descent rate. Continue this until you reach a depth where the ppO₂ in the diluent exceeds 0.2 bar. It is also possible to isolate the ADV and administer the diluent manually for maximum control over the injected hypoxic diluent.

Do not descend rapidly in order to reach the depth at which the mixture is breathable. Low partial pressure of oxygen in the loop leads to a significantly faster loss of consciousness than if you descend while holding your breath. Do not take this risk.

Upon completion of the descent, it is possible to isolate the ADV to accurately maintain the optimum loop volume.

3.4.10 Controlling buoyancy and trim

When diving with a rebreather, buoyancy cannot be controlled by breathing as in open-circuit diving. Since you are breathing within a closed loop, there is no effect on the overall buoyancy.

Buoyancy corrections, however minor, is controlled with the compensator.

For a very small, increase of buoyancy temporarily (e.g. when swimming over an obstacle), you can add a small amount of diluent into the breathing loop instead of using the compensator. Though this method is convenient, it also leads to a greater consumption of oxygen and diluent. Remember: swimming around an obstacle is better than swimming over it.

Keep balance corrections to a minimum by using other sources of buoyancy, such as a dry suit. The increased difficulty of controlling several points of buoyancy can overload the diver with tasks.

The optimum trim of the diver is horizontal, even when descending and ascending. During the course on diving with the CCR Liberty, you will find the optimum ballast position. Do not use a weight belt.

When training to achieve the correct balance and trim, try to remain motionless and not change depth or body position for several tens of seconds.

A buouancy backup system is always needed when diving. For example, this can be a dry suit, disposable ballast, a lift bag.

3.4.11 Mask clearing

When diving with a rebreather, a significant portion of the mixture consumed during a dive can be lost when clearing the mask. Therefore, keep mask clearing to a minimum.

3.4.12 Increased physical exertion

The CCR Liberty adds oxygen to the breathing loop as needed. Unlike with some mechanical rebreathers, increased physical exertion does not lead to a reduction of the partial pressure of oxygen.

In the case of longer physical exertion, check the pressure in the oxygen cylinder frequently.

Take increased physical exertion into account for your decompression planning.

Increased effort also causes greater CO₂ production. In addition to shortening the life of the scrubber, increased CO₂ production (along with reduced ventilation due to gas density) has a significant effect on the increase in arterial CO₂. This phenomenon causes a greater susceptibility to oxygen toxicity and nitrogen narcosis. There is also the risk of acute hypercapnia. Avoid increased strain at depth.

3.4.13 Ascent

Under normal conditions (i.e. when ascending at a rate less than 15 m/min., with a minimum setpoint 0.8 bar) and a normal functioning apparatus, a decline in oxygen partial pressure (ppO₂) below the limit of 0.16 bar does not occur.

If an inadvertent rapid ascent occurs in shallow depths, pay great attention to the ppO₂. It is possible that a short-term decline will happen, but this will be automatically corrected with two to three inhalations.

Before starting an ascent, check to ensure that the oxygen cylinder valve is fully open.

During the ascent, expansion of the breathing mixture in the circuit occurs due to the reduction of ambient pressure. It is necessary to expel the excess breathing mixture. The overpressure valve on the exhalation (right) counterlung is used for this purpose. Open the overpressure valve completely. Some divers consider it more convenient to expel excess breathing mixture via the nose through the mask. Do not expel excess gas via the mouth as doing so increases the risk of water leaking into the breathing circuit via the mouthpiece.

3.5 Post-dive procedures

3.5.1 Immediately after surfacing

Close the DSV, put the rebreather in a suitable place, close the cylinder valves and switch off the control units.

If a stable, firm, and level surface is available, set the rebreather up on its stand and take measures to prevent it from falling.

If you are in the field where it is not possible to place the rebreather on its stand, lay it down.

When handling the rebreather, focus particular attention on protecting the corrugated hoses against damage.

As a general rule, it is necessary to dry out the water trap after every dive or at least at the end of the diving day. Detach the head, remove the scrubber cartridge, remove the water trap, and dry it with a paper towel. Use another paper towel, to dry the exterior surface of the cartridge.

The head should be left to dry to ensure proper functionality of the oxygen and helium sensors. Helium sensors are sensitive to moisture and condensation. Since moisture can condense directly inside the sensor, it is vital to dry out your head properly after diving.

This is important to ensure a long lifetime and functionality of your sensors.

In areas or periods with increased humidity, we strongly recommend using the DIVESOFT Head drying fan.

3.5.2 CO₂ scrubber maintenance

If the sorbent capacity is sufficient (with reserve for the next planned dive and not disinfecting the rebreather until the next dive), it is possible to reinsert the scrubber cartridge into the canister and leave it in the rebreather. You can leave the scrubber canister opened for a maximum of 24 hours if stored in a dry place. Mount the dry head and close the breathing loop openings for longer storage. We recommend using the “DIVESOFT scrubber cover with stickers”. It is advisable to write the date of the first filling and the times of the individual dives on which the scrubber was used. Change the label after replacing the sorbent. Do not store used and sealed scrubber for more than 30 days after its first use.

3.5.3 Cleaning and disinfection

When in use, the rebreather’s breathing loop is colonized by microorganisms from the diver’s respiratory tract and from the external environment. The purpose of regular cleaning and disinfection is to prevent the multiplication of these microbes to an extent that would pose a hazard to the user and to prevent the transmission of infection between various users.

No more than a week may pass from the first dive after disinfection until the next disinfection if the CCR Liberty is stored in a cool place. When storing the rebreather at a temperature higher than 25 °C, this interval decreases to four days; the weekly interval can be maintained only for the scrubber cartridge. It does not matter how many dives you undertake during the stated period.

Disinfection is always necessary before changing users of the CCR Liberty. Never lend or borrow a rebreather that has not been disinfected! Transmission of infection can happen with a single inhalation. An infected user will not necessarily have any symptoms of infection.

Begin cleaning by rinsing the assembled rebreather with clean fresh water. Disassemble the rebreather into its individual parts.

Procedure:

1. remove the ballast.
2. unscrew and detach the oxygen and diluent cylinders, insert watertight stoppers in the regulator inlets.
3. remove the HUD from the DSV.
4. remove the breathing bags with corrugated hoses from the head.
5. remove the ADV, manual valves, and overpressure valve from the breathing bags.
6. detach the breathing bags from the harness.
7. remove the head with the attached handsets and HUD.
8. remove the CO₂ scrubber from the cartridge and dispose of it safely.
9. remove the scrubber canister from the backplate, and remove the water trap.

Put the head with the control units in a clean, cool, and dry place.

Prepare the antiseptic solution in a suitable container, free of mechanical and chemical impurities. For example, a bathtub, mortar tub, or large Tupperware container is suitable for disinfection.

For ordinary disinfection, use a 0.5% concentrated Divesoft antiseptic. Follow the instructions when working with the antiseptic agent.

Rinse with clean fresh water and place the tube, water trap, corrugated hose assembly with an open DSV, breathing bags, and CO₂ filter in the tub. Manipulate the corrugated hose assembly and the DSV to expel air so that the antiseptic solution fills the entire space (this necessary skill is taught in the CCR Liberty training course). Completely fill the breathing bags with the antiseptic solution.

If you notice mold growth, it is necessary to perform a thorough disinfection and surface cleaning. Most surfaces can be wiped with an antiseptic soaked rag. Use a bottle or tube brush to clean the inner surfaces of the corrugated hoses.

Leave the parts in the antiseptic solution for one hour. Remove the parts when complete and rinse with clean fresh water, allowing them to dry afterwards. Do not dry the parts in direct sunlight.

When more intensive disinfection is required, use a more concentrated solution (maximum 2%) or leave the parts in the antiseptic solution for a longer time (maximum four hours).

Instead of Divesoft disinfection, one can use a different antiseptic agent based with quaternary ammonium salts that is compatible with the materials from which the CCR Liberty is made. The CCR Liberty’s manufacturer does not guarantee the compatibility of antiseptic agents other than Divesoft disinfectant. In any case do not use chlorine-based agents.

In normal circumstances, the head, ADV, manual bypass valves, and overpressure valve do not need to be disinfected.

If a more thorough disinfection is required, the oxygen sensors can be removed from the head, and the remaining parts can be washed with antiseptic solution. The ADV, manual bypass valves, and overpressure valve can be disinfected by submerging them in the antiseptic solution.

The antiseptic solution is highly toxic to aquatic organisms. Dispose of it in an environmentally friendly manner.

3.5.4 Battery care

Prevent complete discharging of the batteries. If possible, charge the batteries after each day of diving.

3.5.5 Dive log download

The control unit (CU) offers a micro DC card insert. Such a card is installed by the manufacturer, and a separate dive log (which is not dependent on the CU’s memory), is stored on it. The card’s capacity is sufficient for storing detailed logs throughout the apparatus’s service life, though the diver can delete logs from the card whenever they want. The card is generally accessed in the same manner as accessing a mass storage device via a USB cable, though in the case of damage to the CU, the micro SD card can be removed from the connector on the control-unit board and the dive log can be read using an ordinary reader.

Diver may upload the Liberty dive logs into the cloud at wetnotes.com.

Wireless Dive Log Download (Bluetooth)

The 2021 Edition has Bluetooth connectivity, making it possible to download logs wirelessly. To connect to your personal computer or mobile phone, you need to download the Divesoft.App for mobile phones or Divesoft.Center for Windows and Mac.

Pairing

Launch the app on your mobile phone or personal computer. On Liberty, enter Menu\Applications\Bluetooth. This activates the Bluetooth signal and the device should appear in the app. Add the device and follow the app's instructions.

3.5.6 Long-term storage

Before storing the rebreather for a period longer than one week, proceed according to section 3.5.3 Cleaning and disinfection.

If the CCR Liberty is stored in a dry and clean environment, do not connect the corrugated- hose assembly with the DSV to the head or to the breathing bags, and store the rebreather open. Dust occurs almost everywhere and is inevitable. Limit the accumulation of dust by, for example, covering the unit with a washed bed sheet. Store the detached corrugated hose assembly in a suitable container that will allow complete drying.

If you store the CCR Liberty in an environment with a lower degree of cleanliness, such as a home with pets, store it assembled and closed (without sorbent).

Before putting the closed rebreather in storage, all parts must be thoroughly dried, including all creases in the corrugated hoses and the interior surface of the bags.

Charge the batteries at least once every six months.

If, after storing the unit for more than a month, you find that moisture persists inside the apparatus, or you can smell mustiness or mold from the corrugated hoses, it is necessary to disinfect the apparatus again.

When storing the rebreather, make sure that no rubber parts (hoses, cables) are pinched or compressed.

Ensure that the rebreather is securely fastened, and no other objects are leaning against it.

3.6 Emergency procedures

Prevent the occurrence of emergency situations through high-quality training. Do not exceed the limits of your diving qualifications. Carefully adhere to the prescribed procedures before, during, and after every dive. In the event that prior to a dive you discover a problem associated with the rebreather, and you are not able to resolve it, do not dive with the rebreather, regardless of the severity of the problem.

3.6.1 Emergency ascent (bailout)

For safety purposes, it is necessary to carry a bailout aparatus whenever diving on a rebreather. A common type of backup device is a standard stage bottle.

If, during a dive, a malfunction occurs in the CCR Liberty that you are not able to resolve or precisely identify, or if you have a suspicion that something is wrong with the rebreather, switch to the bailout apparatus:

1. place the bailout breathing apparatus in the standby position,
2. exhale into the circuit and close the DSV, but hold a sufficient amount of gas in your lungs for removing water from the mouthpiece of the bailout apparatus,
3. Perform the standard procedure associated with beginning to breath of the bailout apparatus, e.g. for stage cylinders, check to be sure that you are breathing from the correct stage cylinder.

If you subsequently resolve the rebreather malfunction or if you determine that the cause of the problem is outside the rebreather, you can resume breathing off the rebreather.

After switching to bailout OC mode, the safety level is automatically set using the bailout gradient factors (BoGF). It is possible to switch between the standard and bailout GF sets in the menu without affecting the mode in which the CCR Liberty is operating.

Knowledge and skills related to stage bottle use is a necessary requirement for anyone interested in diving on the CCR Liberty. In a CCR Liberty diving course accredited by the manufacturer, the use of stage bottles for backup purposes is thoroughly practiced.

3.6.2 Oxygen-source malfunction

Low pressure in the oxygen cylinder

In this case, it is necessary to terminate the dive.

It is necessary to switch to the bailout breathing apparatus no later than when the partial pressure of oxygen in the circuit falls below 0.3 bar.

If this situation arises due to a lack of thoroughness when preparing for the dive or due to failing to regularly check the pressure during the dive, please consider whether diving with a rebreather represents too great of a risk for you.

Solenoids have stopped delivering oxygen

If the partial pressure falls significantly below the setpoint, but there is still sufficient pressure in the oxygen cylinder, use the manual bypass valve to add oxygen.

Add oxygen gradually by performing short presses. Breathe regularly. Oxygen will be delivered to the exhalation bag. It takes several inhalations before the oxygen in the scrubber blends with the breathing mixture and reaches the sensors on the inhalation side.

If the situation persists, control the delivery of oxygen manually. In a stabilized state (a low level of exertion at a fixed depth), it is necessary to add oxygen approximately once or twice per minute.

This malfunction does not pose an immediate threat to the diver. However, do not continue in your descent or penetration. Start your ascent or return.

Manual O₂ bypass valve free-flow

Disconnect the quick-release. Disengaging the quick-release connector causes a disruption of the oxygen delivery via the manual bypass valve.

This malfunction does not pose an immediate threat to the diver. However, do not continue in your descent or penetration. Start your ascent or return.

Manual bypass valve does not function, oxygen is not added after pressing

This malfunction does not pose an immediate threat to the diver. However, do not continue in your descent or penetration. Start your ascent or return.

Oxygen delivery does not function by means of either the solenoids or manual bypass valve

In this case, it is necessary to terminate the dive.

It is necessary to switch to the bailout breathing apparatus no later than when the partial pressure of oxygen in the circuit falls below 0.3 bar.

3.6.3 Diluent-source malfunction

Low pressure in the diluent cylinder

In this case, it is necessary to terminate the dive. During the ascent, the diluent in the circuit expands and thus replenishes its volume in the circuit. If possible, do not increase depth during your return.

As long as the volume of diluent in the circuit is sufficient, it is possible to breathe from the rebreather. If it is not sufficient, it is necessary to switch to the bailout breathing apparatus.

Bear in mind that in this case it is not possible to perform the standard procedure for high ppO₂ (flushing out the loop, adding diluent) and that such a situation can be resolved only by immediately switching to the bailout breathing apparatus, which you should have in standby position.

ADV free-flow

Close the ADV by sliding the collar. This causes a disruption of the diluent delivery via the ADV.

This malfunction does not pose an immediate threat to the user. The dive can continue with manual addition of diluent to the circuit.

Manual bypass valve free-flow

Disconnect the quick-release. Disengaging the quick-release connector causes a disruption of the diluent delivery via the MBV.

This malfunction does not pose an immediate threat to the user. The dive can continue with automatic delivery of diluent into the circuit using the ADV. Manual delivery of diluent can be accomplished by pressing the ADV.

Manual bypass valve does not function, diluent is not added after pressing

This malfunction does not pose an immediate threat to the user. The dive can continue with automatic delivery of diluent into the circuit using the ADV. Manual delivery of diluent can be accomplished by pressing the ADV.

Neither the ADV nor the manual bypass valve functions

If the diluent pressure gauge indicates sufficient pressure, a malfunction in the first stage of the diluent regulator has likely occurred, and it is no longer possible to add diluent to the circuit.

In this case, it is necessary to terminate the dive. During the ascent, the diluent in the circuit expands and thus replenishes its volume in the circuit. If possible, do not increase depth during your return.

If the volume of diluent in the circuit is sufficient, it is possible to breathe from the rebreather. If it is not sufficient, it is necessary to switch to the bailout breathing apparatus.

Bear in mind that in this case it is not possible to perform the standard procedure for high ppO₂ (flushing out the loop, adding diluent) and that such a situation can be resolved only by immediately switching to the bailout breathing apparatus, which you should have in standby position.

3.6.4 Scrubber malfunction

If you feel the need to breathe more rapidly (ruling out your exertion level), it is possible that a higher carbon dioxide contration is present in the circuit due to a scrubber malfunction. Other symptoms of a CO₂ hit incluce nausea, headache, confusion.

On the contrary, another possible cause of similar symptoms is psychosomatic hyperventilation and reduced content of carbon dioxide in the blood and other bodily tissues. This usually occurs due to increased mental stress, such as when the diver is confronted with task overloading.

If the symptoms are severe, immediately switch to the bailout breathing apparatus, as there is a risk of a loss of consciousness. As soon as possible, take several slow, deep breaths from the backup apparatus. Of course, you should never allow such a situation to progress to the stage of severe symptoms.

If you experience discomfort when breathing but the symptoms are not severe enough to pose a risk of unconsciousness, test the concentration of carbon dioxide in your blood. Stay where you are without moving; do not in any case change depth significantly. Try to hold your breath for ten seconds.

If you are unable to hold your breath or it is extremly difficult to do so, it is apparent that the scrubber is not functioning properly (premature depletion of the sorbent, occurrence of channels in the sorbent by which air circumvents the scrubber) or there is a mechanical malfunction that has caused air to not pass through or to only partially pass through the scrubber (malfunction of the directional valve on the mouthpiece, joining of the inhalation and exhalation sides outside the scrubber). Switch to bailout and terminate the dive.

If holding your breath does not cause problems, the scrubber is working properly. Over the next several minutes, limit all other activity and concentrate on slow, steady breathing.

3.6.5 Inadvertent release of the mouthpiece

When the mouthpiece falls out of the diver’s mouth, the DSV has a tendency to float. However, its connection to the breathing bag prevents the mouthpiece from floating beyond the diver’s reach.

If the mouthpiece falls out, immediately place it back in your mouth. If the mouthpiece is returned quick enough, no significant amount of water will have entered the breathing loop.

If this problem is not solved quickly, then the loop would flood. In this case, proceed according to the following section 3.6.6 Flooding.

There may be a strap (bungee cord) holding the DSV, which prevents the mouthpiece from accidentally falling out. Adjust the length of the bungee by shifting the knots.

3.6.6 Flooding

The probability of significantly flooding the breathing circuit is very low. After carefully assembling the apparatus and performing the prescribed pre-dive procedures, flooding can be ruled out unless there is a major disruption of the breathing loop’s integrity due to mechanical damage. In the event of significant flooding, it is necessary to immediately switch to the bailout breathing apparatus and to use the compensator (BCD) to prevent loss of buoyancy.

Do not inhale if the mixture from the rebreather’s DSV contains fluid. In extreme cases, this could contain a so-called caustic cocktail (i.e. a caustic mixture with dissolved lye from the sorbent).

A smaller amount of water can enter the circuit through the opened DSV when the mouthpiece falls out of the diver’s mouth. In such a case, water gets into the exhalation bag. Though this does not present an immediate danger, it is advisable to expel the water from the exhalation bag with the overpressure valve as soon as possible. Open the overpressure valve completely and deflate the buoyancy compensator. In order to avoid a significant change in buoyancy. Add diluent to the circuit with the manual bypass valve. Assume a position that brings the overpressure valve to the lowest point of the exhalation bag. Expel the water from the bag by pressing on the bag with your hand.

3.6.7 Loss of buoyancy

The compensator (i.e. buoyancy control device or BCD) is the basic tool for controlling buoyancy. If the compensator is not functional, use other means of attaining buoyancy.

If the compensator’s lift capacity does not suffice or if it fails to fill (whether that be with the power inflator or orally), use your dry suit to attain buoyancy. The CCR Liberty user must have sufficient knowledge and skill to safely use a dry suit as a backup source of buoyancy.

If it is not possible to attain sufficient buoyancy by using the compensator and dry suit and if, there is no other appropriate option, jettison the ballast. If it is not necessary to completely jettison the ballast, try to attain buoyancy by first removing the ballast on the left side and then, if necessary, on the right side. Jettisoning the ballast on the left side helps to bring the dry-suit release valve and the compensator’s inflator in a better position for deflation.

Jettisoning ballast is a skill that, in addition to agility and mobility, requires training under the supervision of an instructor in a CCR Liberty diving course.

3.6.8 Rescue on the surface

When assisting an injured CCR Liberty user on the surface, it is possible to increase buoyancy by jettisoning the ballast.

Even if the diver’s life is in serious danger, and it would be necessary to remove all equipment during the rescue, buoyancy should be ensured by closing the DSV, inflating the compensator wings, and jettisoning the ballast. Complete removal of the CCR Liberty and any other equipment attached to the harness can be time consuming. Sufficient buoyancy provided by the CCR Liberty can aid in the rescue process.

3.6.9 Malfunction of oxygen-concentration measuring

If the chemical oxygen sensors are not functional (excluded, disabled, error or offline state, see section 2.4.8 Faulty sensors) and a trimix is used as the diluent and the helium sensors are functional, then the CCR Liberty can be switched to indirectly determine the ppO₂ by measuring the helium content. See section 1.9.3 Measurement of He content.

Consider this as an emergency procedure only when it is not possible to proceed according to section 3.6.1 Emergency ascent (bailout).

3.7 Maintenance

Maintenance operations, including necessary technical information, are described in the maintenance manual. In the user manual, only basic maintenance operations that every CCR Liberty user should master are described.

Use only oxygen-compatible lubricant for the maintenance of parts that come into contact with oxygen under pressure.

3.7.1 Tools and replacement parts

Your toolbox for resolving problems in the field should contain:

• – Surgical gloves
• – Roll of paper towels
• – PE bag for storing the scrubber cartridge
• – DSV mushroom valves (2 pcs)
• – Mouthpiece
• – Tightening straps
• – Oxygen-compatible lubricant
• – 2.5 mm and 3 mm hex keys
• – #1 Phillips screwdriver
• – Tool for removing O-rings (O-ring pick, plectrum, bamboo toothpick)
• – Adjustable wrench
• – Duct tape
• – Permanent waterproof marker for writing on duct tape
• – Set of O-rings

3.7.2 Detection of leaks

If the source of a leak is not apparent, we recommend pressuring the unit to the find the leak.

Leaks can generally be found by submerging a part or the entire rebreather in water while exerting pressure in the breathing loop. It is also possible to find leaks by applying a soapy solution on a certain area.

After eliminating the problem, negative and positive pressure tests must be repeated.

3.7.3 Regular service inspection

The CCR Liberty requires yearly service inspections (maximum 12 months) or after 150 hours of usage, whichever occurs first.

Service inspections must be performed by a service technician certified by Liberty Systems or performed by the manufacturer. The replacement of components and the inspection process are determined by the manufacturer’s guidelines at the time of inspection.

3.7.4 Long-term maintenance

Oxygen sensors

When the oxygen sensors are calibrated, their degree of wear is checked. Of course, sensors can suddenly reach the end of their service life even during a dive, especially in an environment with a high partial pressure of oxygen. Therefore, we recommend replacing the sensors no later than one year after putting them into operation or 18 months max after their date of manufacture.

However, despite good handling, the sensors may, exhibit deviations or limitations even during their recommended life. For this reason, we recommend using the DIVESOFT Oxygen sensor tester kit regularly to test the linearity of the sensors. It is the only accurate and safe way to detect a faulty or limited sensor.

It is not necessary to discard replaced sensors. Even though a sensor’s degree of wear prevents it from reliably measuring higher partial pressures of oxygen in the rebreather, it is often usefull for measuring lower partial pressures of oxygen when preparing mixtures.

Hoses

If any hose shows signs of excessive wear or if damage is detected during a bubble check (see chapter 3.4.8 In-water check), replace it. Hoses should be replaced during annual inspection from normal wear and tear.

The service life of the hoses is five years max from the time they were first used and seven years max from their production date.

Straps

The harness straps are highly durable. A strap that has been damaged on the edge should only be replaced if it was cut more than one-third of its width.

Straps are generally replaced for aesthetic reasons. You can order a replacement when ordering a regular service inspection.

3.7.5 Oxygen Sensor Block Maintenance Instructions

Proper maintenance of the oxygen sensor block is crucial for extending the lifespan of the sensor wiring and ensuring accurate oxygen readings. Follow these instructions to maintain your CCR Liberty's oxygen sensors: Regular Drying Procedure

After each dive or diving day, dry the oxygen sensors thoroughly.

In normal conditions:

1. Open the rebreather head.
2. Place the head upside down in a well-ventilated area.
3. Allow it to air dry completely.

High Humidity Environments

1. Use the specialized Divesoft ventilation fan.
2. Attach the fan directly to the inhalation tube of the sensor block (located on the bottom side of the head).
3. Operate the fan until the sensors are completely dry.

Extreme Conditions or Flooding

If the unit has been exposed to extreme humidity or flooding:

1. Remove the oxygen sensor block from the rebreather head.
2. Carefully open the sensor block.
3. Dry the components in an air-conditioned room.
4. Ensure all parts are thoroughly dried before reassembly.

Note: Proper drying of oxygen sensors after use is essential for maintaining sensor accuracy and preventing corrosion of the wiring.

Always refer to the full CCR Liberty user manual for comprehensive maintenance procedures and safety guidelines.

3.7.6 Firmware update

To upgrade your new firmware, use the DIVESOFT.CENTER At the following link you will find the software download, user manual and other important information https://www.divesoft.com/en/center.

Minimum operating system requirements for Bluetooth functionality

macOS macOS 11 (Big Sur) Earlier macOS versions USB functions only

Windows Windows 10 or higher Earlier Windows versions USB functions only

Linux Any 64-bit build

3.8 Transport

3.8.1 By car

Transport the CCR Liberty in the case in which it was delivered. Make sure the case is secure and will not move around in the vehicle’s cargo space.

The dustiness of the sorbent increases when transported in its loose state in the distribution canister. It is better to transport sorbent in the scrubber cartridge.

3.8.2 By boat

On a dive boat, it is usually possible to fasten the apparatus to a bench.

For securing the rebreather, use a line of approximately 1.5-2 m with secure knots. Tie the apparatus to a suitable structure.

Secure the ready-to-dive CCR Liberty by passing the line over the cylinders and backplate, with the scrubber canister pressed to the back of the bench.

If you need to prepare the CCR Liberty for diving while onboard a boat, secure it to a bench using the holes in the upper part of the backplate. This will give you full access to the cylinders for filling, and you can easily remove the head and scrubber canister.

3.8.3 By plane

Pressure cylinders

Airline regulations generally require that all transported pressure cylinders should be empty with the valves dismounted. Place the valves in clean PE bags (Ziploc) and place duct tape over the cylinder necks to prevent contamination. It is possible that security personnel will want to look inside the cylinders, do not use tight plugs that are difficult to remove.

When checking in your luggage at the airport, notify the airport personnel that you have empty pressure cylinders in your luggage. Depending on local regulations, it is possible that you will have to take the cylinders to a special check-in desk.

Consider whether it might be better to rent cylinders at your destination. Dive centers equipped for closed-circuit diving usually have available cylinders that can be used with the CCR Liberty. If you want to arrange a cylinder rental, which is highly recommended, refer to the size specifications available at divesoft.com.

When traveling by plane, it is advisable to separate the head of the device and transport it in the hand luggage. You will significantly reduce the weight of your checked luggage, and you will have the most expensive and sensitive part of your device under constant vigil. Be prepared to explain to airport staff that the head is a vital part of modern diving gear and you have this manual with you.

Sorbent

The sorbent canister should be empty. If you are also transporting a supply of sorbent, it must be in the original packaging or in an appropriately sturdy and airtight container. Familiarize yourself with the regulations concerning the air transport of sorbent. Consider the possibility of purchasing sorbent at your destination.

Head

For the purposes of air transport, the batteries must be disconnected by removing or turning the battery jumpers. Do not transport the CCR Liberty in standby mode.

3.9 Marking

3.10 NOTIFIED BODIES

PPE Regulation EU 2016/425 by
Notified Body No. 0598 SGS FIMKO P.O.Box 30 (Särkiniementie 3), 00211 Helsinki, Finland From 9th December 2020
UKCA marking
Approved body No. 0120, SGS United Kingdom Ltd. Unit 202b, Worle Parkway, Weston-super-Mare, BS22 6WA, UK.
Declaration of conformity available at: https://divesoft.com/en/products/ccr-liberty/documents

3.11 MANUFACTURER

Product manufactured by
Divesoft s.r.o.
Hálkova 2495
413 01 Roudnice nad Labem
Czech Republic

CCR Liberty User Manual

• Author
  Adam Procháska, Jakub Šimánek, Aleš Procháska.

• Publisher
  Divesoft s.r.o. divesoft.com

• Issue
  Revision 2.17.2/40 Revision date 22.04.2024

Use of this manual approved by
Lucie Šmejkalová, CEO