CCR Mixed Gas Diver/Trimix - HOLLIS PRISM II or Liberty

  • Brand: TDI
  • Product Code: Trimix CCR
  • Availability: In Stock

CCR Mixed Gas Diver/Trimix - HOLLIS PRISM II or Liberty

As a  CCR Air Diluent Decompression or Helitrox Diluent Decompression Diver, the  Mixed Gas CCR Diver course is your next step into closed circuit rebreather diving, it is your opportunity to explore a little deeper. Using the latest in technology CCR’s maximize your gas supply and provide the optimum breathing gas for any depth by maintaining a constant partial pressure of oxygen (PPO2). During the dives your  Instructor will teach you all the necessary skills to conduct CCR dives utilizing helium as a diluent gas and oxygen levels as low as 16 percent to a maximum depth of 60 metres/200 feet.

Who this course is for:

The certified  Air Diluent Decompression or Helitrox Diluent Decompression Diver (or equivalent) looking to extend their depth limitations.

Course prerequisites:

Minimum age 18 

Provide a verified log of a minimum of 50 rebreather hours distributed over a minimum of 50 dives on the specific rebreather. If the diver has 50 hours on another CCR unit recognized by , only 25 hours are required to be on the specific unit 

Have completed and qualified the  Air Diluent Decompression Procedures Rebreather/ CCR Helitrox Diluent Decompression Procedures Diver course or equivalent from agencies recognized by 

What you can expect to learn:

The  Diving Rebreathers Student Manual is required for use as a review/recap document. The instructor may use any additional text or materials they feel will represent the topic in an educational manner. The following topics must be covered during the course:

Gas physiology 

Oxygen (O2) toxicity 


Nitrogen absorption 

Helium absorption 


Carbon dioxide (CO2) toxicity 

Gas consumption 

Gas mixing

Formula Work 

Oxygen (O2) metabolizing calculations 

Manually controlled closed circuit rebreathers 

Equivalent narcosis depth theory 

Central nervous system (CNS) tracking 

Oxygen tracking units (OTU) 

Gas management

Dive tables 

Creation of custom dive tables appropriate to dive depths 

Creation of lower percentage of oxygen (PO2) diluent to support loop flushing and bailout at depth

Dive computers 

Mix adjustable 

Constant partial pressure of oxygen (PPO2) 

Oxygen (O2) integrated

Dive planning 

Operational planning

Equipment maintenance 

Fuel cell management 

Loop configurations 

Additional fitted equipment and modifications

Required Skill Performance and Graduation Requirements

The following open water skills must be completed by the student during open water dives with the following course limits

No dives deeper than 60 metres/200 feet 

No dives shallower than 40 meters/130 feet, other than the 1 air diluent configuration dive are credited toward the dive requirements. Subsequent training dives in shallow water are permitted if necessary during the course 

Equivalent narcosis depth not to exceed 30 metres/100 feet 

Calculate all off-board gas at 45.30 litres/1.06 cubic feet per minute usage to cover stress situations 

PO2 not to exceed manufacturer recommendation or a working limit of 1.3 bar during the bottom phase of the dive and 1.4 bar during the decompression phase of the dive 

Diluent PO2 should not exceed 1.2 at maximum depth 

All dives to be completed within appropriate fixed PO2 decompression tables or decompression planning software 

All dives to be completed within CNS percentage limits with a recommend maximum of 80 percent of the total PO2 CNS limit 

The student is only certified for CCR mixed gas diving on the rebreather being used

Land Drills

Build unit based on manufacturer’s specifications using manufacturer’s manual/build checklist 

Demonstrate familiarity with basic and intermediate hand signals 

Select and prepare equipment suitable for soft overhead environment with long decompression obligations 

Conduct team oriented drills for lift bag deployment and bailout procedures 

Drills for buddy rescue 

Properly analyze all gas mixtures to be used 

Demonstrate adequate pre-dive planning 

Limits based on system performance 

Limits based on bailout gas requirements 

Limits based on oxygen exposures at chosen PPO2 levels 

Limits based on manually controlled closed circuit rebreathers 

Limits based on nitrogen absorption at planned depth and PPO2 (set-point) level 

Limits based on helium absorption 

Correct narcotic depth planning and diluent selection to allow cell flushing at target depth (diluent should not exceed a PO2 of 1.2 at maximum planned depth)

Pre-dive Drills

Conduct pre-dive checks using  Pre-flight checklist 

Use START* before every dive 

Stress analysis and mitigation

Open Water Skills

Show good awareness of buddy and other team members through communications, proximity and team oriented dive practices 

Demonstrate buoyancy control; ability to hover at fixed position in water column without moving hands or feet 

Properly execute a recovery from a system failure and conclude the dive and decompression on open circuit gases carried 

Properly execute a recovery from system failure and conclude the dive and decompression with the unit in manual mode 

Gas shutdowns and loss of gas, correct choice and switching to off board gases 

Broken hoses, catastrophic failure scenarios 

Flooded absorbent canister 

Cell errors 

SCR drill (minimum of 10 minutes) 

Oxygen rebreather mode in depths less than 6 metres/20 feet 

Stop at 3 to 6 metres/10 to 20 feet on descent for leak bubble check 

Demonstrate competence managing 2 bailout cylinders, including drop and recovery while maintaining position in the water column 

Deployment of a lift bag/delayed surface marker buoy (DSMB) at depth and mid water 

Simulate failed lift bag/DSMB deployment 

On 2 of the dives, demonstrate an ascent with ascent reel and lift bag and perform staged decompression 

Electronics systems monitoring for PPO2 levels 

Proper execution of the dive within all pre-determined dive limits 

Demonstration of decompression stops at pre-determined depths 

Demonstrate controlled ascent with toxed diver including surface tow at least 30 metres/100 feet with equipment removal on surface, in water too deep to stand in

What’s in it for you?

Upon successful completion of this course, graduates may engage in technical diving activities utilizing the unit specific CCR to a maximum of 60 metres / 200 feet, utilizing a mixed gas diluent containing 16 percent or greater oxygen provided:

The diving activities approximate those of training 

The areas of activities approximate those of training 

Environmental conditions approximate those of training 

Ability to enroll in  Advanced Mixed Gas CCR Diver course


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