SF2 Air Diluent

This is the first level certification course for divers wishing to utilize a SF2 Electronic Closed Circuit Rebreather (ECCR) for air diving. The objective of the course is to train divers in the benefits, hazards and proper procedures for diving a ECCR and to develop basic ECCR diving skills to a maximum of thirty (30) m / one hundred (100) ft / air as a diluent. This is a non decompression course

Student Qualifications:
Upon successful completion of this course, students may:
1. Engage in diving activities using a SF2 ECCR  to a maximum of  thirty (30) m  /one hundred  (100) ft, using air as a diluent

Instructor Qualifications
1. An active SF2 Instructor with a SF2 Air Diluent ECCR Instructor Manufacturers  rating on the SF2 being used.

Student – Instructor Ratio
1. Unlimited, as long as adequate facility, supplies and time are provided to insure comprehensive and complete training.
Confined Water (Swimming pool-like conditions):
2. A maximum of four (4) students per active SF2 Instructor (Open Water (Ocean, lake, quarry, spring, river or estuary)
3. A maximum of two (2) students per active SF2 Instructor
4. Number of students can be increased to four (4) with the use of certified assistants
Special note; A “certified assistant” is a  Divemaster or equivalent from agencies recognized by SF2 Manufacturers, with an Air  Diluent SF2  ECCR user qualification and a minimum of 30 hours logged diving on the SF2 ECCR being taught.

Student Pre-Requisites:
1. Be a minimum age of eighteen (18).
2. Show proof of twenty (25) logged open water dives.
3. Minimum certification level of  Nitrox Diver (Nitrox Diver may be combined with this course) or equivalent from agencies recognized by SF2 Manufacturers

Course Layout and Duration:
Confined Water
1. Minimum of sixty (60) minutes confined water training to a maximum  of Ten (10) m / thirty three (33) ft.
Open Water execution:
1. Minimum of four hundred twenty (420) minutes open water training to be completed over a minimum of seven (7) dives with a gradual increase in depth each day to a maximum of thirty (30) m / hundred (100) ft.
Course Layout
1. SF2 Manufacturers allow instructors to structure courses according to the number of students participating and their skill level.
2. The exam may be given orally if not available in a language the student understands.
1. Minimum of six (6) hours academic development and two (2) hours equipment maintenance workshop.
2. The duration of the entire course must be spread over a minimum of five (5) days.
1. If a student already qualified as  Air Diluent CCR Diver or equivalent from agencies recognized by SF2 Manufacturers, wishes to qualify on SF2  the student must follow all unit specific course standards with the exception of:
2. Minimum of sixty (60) minutes confined water training to a maximum of Ten (10) m / thirty three (33) ft.
3. Minimum of two hundred forty (240) minutes open water training to be completed over a minimum of  three days
4. Four (4) dives to a maximum of thirty (30) m / one Hundred (100) ft.

Required Materials:
1. Rebreather Manual (where available).
2. Rebreather PowerPoint® (where available).
3. Manufactures’ Manual & Updates.

Equipment for the Course:
1. A complete SF2 electronic closed circuit Rebreather.
2. Minimum of one (1)  CCR dive computer and / or bottom timer and depth gauge.
3. Mask, fins and a suitable line-cutting device.
4. Slate & pencil.
5. Reel with a minimum of forty (40) m / one hundred thirty (130) ft of line.
6. Lift Bag / Delayed Surface Marker Buoy (DSMB) with a minimum of twenty five (25) lb / twelve (12) kg lift.
7. Exposure suit appropriate for the open water environment where training will be conducted.
8. Access to an oxygen analyzer.
9. Appropriate weight.
10. Bailout gas supply. In addition the Instructor and any certified “assistant” will also carry a bailout gas supply for the student/s during all open water sessions. This redundant gas source must be greater than the Instructor and any certified “assistants” rebreather requirement.

Subject Areas to be covered:
The manufacturer’s manual is 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 the course.
1. History and evolution of Rebreather.
2. Comparison of Open Circuit, Closed Circuit and Semi Closed Circuit Rebreather systems and the benefits/problems with each.
3. Practical Mechanics of the System.
A. Assembly and disassembly of the ECCR.
B. Layout and design of the unit.
C. Absorbent canister design and maintenance.
D. Breathing loop cleaning procedures.
E. Manufacturer supported additional items (Automatic Diluent Valve, etc.)
4. Gas Physiology.
A. Oxygen toxicity.
B. Nitrogen absorption.
C. CO2 toxicity.
5. Proper scrubber packing (in accordance with manufactures recommendation)
A. Gas consumption.
6. Electronic or manual systems design and maintenance.
A. O2 metabolizing calculations.
B. Fuel Cells.
C. System electronics functionality and calibration procedures.
7. Dive Tables.
A. Constant PPO2 theory.
B. CNS and awareness of OTU tracking.
8. Dive Computers.
Mix adjustable.
A. Constant PO2
B. O2 integrated.
9. Dive Planning.
A. Operational Planning.
B. Gas requirements including bailout scenarios.
C. Oxygen limitations.
D. Nitrogen limitations.
10. Emergency Procedures.
A. Bailout onboard or off board
B. Three H’s problems.
C. Flooded Loop.
D. Cell Warnings
E. Battery Warnings

Skill Performance Requirements
The following open water skills must be completed by the student during open-water dives with the following course limits:
1. All open water dives must be between Ten (10) m / thirty three (33) ft to thirty (30) m / one hundred (100) ft.
2. Two dives must be deeper than twenty (20) m / sixty (66) ft and one dive must be deeper than twenty five (25) m / ninety (90) ft.
3. PO2 not to exceed manufacturer recommendation or a working limit of 1.3 bar.
4. All dives to be completed within PO2CNS% limits with a recommended maximum of 80% of the total PO2 CNS limit.
5. Safety stops to be conducted with a minimum three (3) minutes at six (6) m / twenty (20) ft.
6. Automatic Diluent Valve (ADV) fitted by the manufacturer, additional skills such as regular diluent gauge monitoring and addition control must be emphasized.
Open Water Skills:
1. Pre dive checks.
A. Unit buildup
B. Scrubber canister check
C. Breathing loop check
D. Positive & negative check
2. Verify diluent and O2 cylinder contents using O2 analyzer.
3. Demonstrate correct pre dive planning procedures including
A. Limits based on system performance.
B. Limits based on oxygen exposures at chosen PPO2 levels.
C. Limits based on nitrogen absorption at planned depth and PO2 setpoint.
D. Thermal Constraints
4. Emergency procedures.
A. Mouthpiece familiarity drills.
B. Gas shutdowns and loss of gas.
C. Broken hoses.
D. Flooded absorbent canister.
E. CO2 breakthrough.
F. Low oxygen drills.
G. High oxygen drills.
H. Flooding Loop.
I. Electronics and Battery Failure.
J. Properly execute the ascent procedures for an incapacitated CCR diver
5. Use of wing/suit and effective management of loop breathing volume for buoyancy control.
6. Stop at three to six (3-6) m / ten to twenty (10 – 20) ft on descent for leak bubble check.
7. Electronics systems monitoring for PO2 levels (SETPOINT) and switching setpoints.
8. Manual control of setpoint
9. Use of Lift Bag / Delayed Surface Marker Buoy and Reel. (where relevant and applicable)
10. Proper execution of the dive within all pre-determined dive limits.
11. Demonstration of safety stops at pre-determined depths.
12. Constant Loop Volume Management.
13. Post dive clean of unit.
A. Mouth piece and hoses
B. Clean and disinfect unit
C. Inspect components of unit
14. Diver maintenance of unit
A. Cell remove and replace
B. Mouthpiece strip and rebuild
C. Replacing batteries

1. Satisfactorily complete the written examination with a pass mark of greater than eighty (80) %.
2. Complete to the Instructors satisfaction all confined and open water skill development sessions.
3. Demonstrate mature, sound judgment concerning use of Rebreather, dive planning and execution.
4. Course must be completed within six (6) weeks from the starting date.
5. Complete a refresher course following a period of inactivity greater than six (6) months following

Additional Reading and Support Material
Richard Pyle - A Learners Guide to Closed Circuit Rebreather Operations.
Kenneth Donald - Oxygen & The Diver.
John Lamb - Oxygen Measurement for Divers.
Barsky, Thurlow & Ward - The Simple Guide to Rebreather Diving.
Bob Cole - Rebreather Diving.
Jeffrey Bozanic - Mastering Rebreathers.
Horst Dederichs - Rebreather Theory and Equipment Handling.

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