Mixed Gas CCR

As a TDI CCR Air Diluent Decompression or Helitrox Diluent Decompression Diver, the TDI 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 TDI 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% to a maximum depth of 60 metres/200 feet.

What you can expect to learn

The TDI 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
    • Hypoxia
    • Nitrogen absorption
    • Helium absorption
    • HPNS
    • 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

Course Equipment Requirements

The following equipment is required for each student:

  • A complete closed circuit rebreather configured within the manufacturers’ recommendations; this should be the student’s personal unit
  • One (1) CCR mixed gas computer and 1 backup OC/CCR computer for bailout in the event of a system failure
  • Bailout gas cylinders (minimum 2) with the appropriate capacity for the planned dive, each equipped with a first and second stage and SPG
  • Mask, backup mask, fins and a suitable line-cutting device
  • Slate and pencil
  • Reel with a minimum of 60 metres / 200 feet of line
  • Reel with a minimum of 30 metres / 100 feet of line
  • Two lift bags / delayed surface marker buoys (DSMB’s) with adequate lift and size for the dive environment. Required for open water environments only
  • Exposure suit adequate for the open water environment where training will be conducted
  • Access to an oxygen analyzer
  • Access to a helium analyzer
  • Adequate weight

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 TDI, only 25 hours are required to be on the specific unit
  • Have completed and qualified the TDI Air Diluent Decompression Procedures Rebreather/TDI CCR Helitrox Diluent Decompression Procedures Diver course or equivalent from agencies recognized by TDI

Want to know more?

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