TDI Semi-Closed Circuit Rebreather Diver

This is the entry-level certification course for recreational divers wishing to utilize a TDI approved semi-closed circuit rebreather (SCR). The objective of this course is to train sport divers in the benefits, hazards and proper procedures for using a SCR.

Who this course is for:

  • Nitrox divers who are interested in using semi-closed circuit rebreathers to extend their bottom time

Course prerequisites:

  • Minimum age 18, 15 with parental consent
  • Minimum certification of TDI Nitrox Diver or equivalent, may be combined in program at the discretion of the instructor

What you can expect to learn:
The TDI Diving Rebreathers Student Manual and the manufacturer’s manual are mandatory for use during this course but instructors may use any additional text or materials that they feel help present these topics. The following topics must be covered during this course:

  • History and evolution of rebreathers
  • Comparison of open circuit, closed circuit, and semi-closed circuit rebreathers
  • Practical mechanics of the system
    • Assembly and disassembly of the rebreather
    • Layout and design
    • Scrubber recharge
    • System maintenance
    • Breathing loop decontamination procedures
  • Review of nitrox
    • Dalton’s law (triangle)
    • Optimum nitrox mix
    • Oxygen tracking
    • Gas preparation
    • Dive planning examples
  • Gas physiology
    • Oxygen (O2) toxicity
    • Hyperoxia
    • Hypoxia
    • Asphyxia
    • Hypercapnia
    • Nitrogen absorption
    • Carbon monoxide (CO2) toxicity
    • Gas consumption
  • Formula work and metabolic consumption
    • Oxygen (O2) metabolizing calculations
    • Inspired oxygen (O2) calculations (rebreather equation)
    • Equivalent air depth (EAD)
  • Dive tables
    • Inspired oxygen (O2) table
    • Equivalent air depth
  • Dive computers
    • Mix adjustable
    • Oxygen (O2) integrated
    • PO2 monitoring devices
  • Problem solving
    • Canister flooding
    • Mouthpiece loss
    • Scrubber exhaustion
    • Battery or sensor loss
    • Breathing bag rupture
    • Open circuit bailout system
    • Hyperoxia scenario
    • Hypoxia scenario
    • Hypercapnia scenario
    • Post problem maintenance of equipment
  • Dive and operational planning

Required skill performance and graduation requirements
The dive depth shall not exceed 1.6 ATM PO2. The following skills must be completed by the student during open water dives:

  • Properly analyze gas mixture
  • Perform all pre dive checks, positive, negative, flow rate, by-pass regulator operation, relief valve pressure, a minimum of 6 times
  • Demonstrate a leak check and repair scenario
  • Demonstration of integrity of exhale counter-lung
  • Properly packing a scrubber canister a minimum of 2 times; if using the ExtendAir cartridge one packing must be with granular material
  • Properly execute set-up and breakdown; a minimum of 6 times for Azimuth or 4 times for Draeger and Submatix ST100 rebreathers
  • Demonstrate adequate pre-dive planning
  • Properly execute the planned dives within all pre-determined limits
  • Properly execute a recovery from a system failure and switch to bail-out stationary a minimum of 2 times
  • Properly execute a recovery from a system failure and switch to bail-out hovering a minimum of 2 times, one of the bail-out scenarios the diver must switch to open circuit and complete dive and safety stop on open circuit; direct ascent must begin when diver switches to open circuit, this scenario should be conducted no deeper than 20 metres/60 feet
  • Properly demonstrate hose clearing technique after each bail-out scenario
  • Perform block switch a minimum of 2 times, Azimuth only
  • Proper PO2 monitoring on all dives, if unit is equipped with PO2 monitoring device
  • Properly execute a mask clearing exercise with emphasis on minimal gas loss
  • Safely and properly execute a buddy out of air scenario, it is preferable the buddy is on a SCR unit also
  • Diver will demonstrate actual safety stops at pre-determined depths
  • Properly execute cleaning and maintenance of the rebreather, including breathing loop decontamination

What’s in it for you?

  • Upon successful completion of this course, graduates may engage in no decompression diving activities utilizing a TDI approved semi-closed circuit rebreather to a maximum depth of 40 metres/130 feet, without decompression; utilizing nitrox mixes not exceeding their level of certification

TDI Semi-Closed Circuit Rebreather Diver minimum requirements:

  • Satisfactorily complete the TDI Diving Rebreathers Course written examination with a passing score of 80% followed by 100% remediation by the instructor
  • Complete all open water requirements safely and efficiently
  • Demonstrate mature, sound judgment concerning dive planning and execution

How to take this course!

pdf Course Standards & Procedures
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