SF2 Advanced Mixed Gas
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![](https://advanceddiving.eu/media/wysiwyg/SAV_8540_2_-topaz-enhance-2.jpg)
The highest level of Closed Circuit Rebreather (CCR) training that TDI offers, the Advanced Mixed Gas Course will teach you how to use the full capabilities of a CCR. With a maximum depth of 100 metres/330 feet, this course opens up a whole new realm of diving including new wrecks, caves and walls to explore in depths you previously could not reach on a rebreather. This intensive course conducted over seven dives will focus on all the elements needed to plan and execute dives to these depths.
Interested?
Who this course is for:
The certified TDI Mixed Gas CCR Diver (or equivalent) looking to extend their depth limitations.
Course prerequisites:
- Minimum age 18
- Certified TDI CCR Mixed Gas Diluent diver, or equivalent from agencies recognized by TDI
- Have verified logs of a minimum of 100 hours as a certified CCR diver over a minimum of 100 dives; a minimum of 50 hours and 50 dives must be on the unit specific CCR. Fifty percent of these dives must be deeper than 30 metres/100 feet. All dives to be deeper than 9 metres/20 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
Skills you will have to demonstrate:
The following open water skills must be completed by the student during open-water dives with the following course limits:
- No dives deeper than 100 metres/330 feet
- No dives shallower than 40 metres/130 feet other than the 1 air diluent configuration dive
- 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 TDI 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 a 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, disaster scenarios
- Flooded absorbent canister
- Cell errors
- SCR drill (minimum of 10 minutes)
- Oxygen rebreather mode in depths less than 6 metres/20 feet
- Manually control CCR Unit for one full dive including all decompression stops
- Demonstrate competence managing 3 bailout cylinders, including drop and recovery while maintaining position in the water column
- Demonstrate proper understanding and implementation of team bailout procedures and conduct a team bailout from a depth greater than 40 metres/130ft
- Demonstrate ability as a team to plug in and share off-board gas, including team sharing/swapping of off-board bailouts
- On 2 of the dives, demonstrate an ascent with ascent reel and lift bag and perform staged decompression
- Proper execution of the dive within all pre-determined dive limits
- Ability to manage multiple failures in adverse conditions
- Demonstrate of surface support/support divers in dealing with bailout scenarios
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 depth of 100 metres/330 feet utilizing any mixed gas diluent appropriate to the dive plan provided:
- The diving activities approximate those of training
- The areas of activities approximate those of training
- Environmental conditions approximate those of training
Minimum requirements:
- Complete to the instructors satisfaction all confined and open water skill development sessions
- Demonstrate mature, sound judgment concerning dive planning and execution
- Course must be completed within 6 weeks from the starting date
- Complete a refresher course following a period of inactivity greater than 6 months following the course