ProTec Sardinia ASD
Via Collodi 9
08020 Cala Gonone (NU) Sardegna, Italy

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SF2 Air Diluent

This is the first level certification course for divers wishing to utilize the 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:
Engage in diving activities using a SF2 ECCR  to a maximum of  30 m  / 100 ft. using air as a diluent

Instructor Qualifications

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

Student – Instructor Ratio

Unlimited, as long as adequate facility, supplies and time are provided to insure comprehensive and complete training.

Confined Water: (Swimming pool-like conditions):
4 students per active SF2 Instructor

Open Water: (Ocean, lake, quarry, spring, river or estuary)
2 students per active SF2 Instructor
Number of students can be increased to 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:

18 Years old
25 logged open water dives.
Nitrox Diver (Nitrox Diver may be combined with this course) or equivalent from agencies recognized by SF2 Manufacturers

Course Layout and Duration:

Confined Water:
60 Minutes confined water training to 10 m / 33 ft.

Open Water execution:
420 Minutes open water training over 7 dives with a gradual increase in depth to a 30 m / 100 ft.

Course Layout:
SF2 Manufacturers allow instructors to structure courses according to the number of students participating and their skill level.
The exam may be given orally if not available in a language the student understands.

6 Hours academic development
2 Hours equipment maintenance workshop.
5 Days

If a student is 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:
60 Minutes confined water training to 10 m / 33 ft.
240 Minutes open water training over 3 days
4 Dives to 30 m / 100 ft.

Required Materials:

Rebreather Manual (where available).
Rebreather PowerPoint® (where available).
Manufactures’ Manual & Updates.

Equipment for the Course:

A complete SF2 electronic closed circuit Rebreather.
1  CCR dive computer and / or bottom timer and depth gauge.
Mask, fins and a suitable line-cutting device.
Slate & pencil.
Reel with a minimum of forty 40 m / 130 ft. of line
Lift Bag / Delayed Surface Marker Buoy (DSMB) with a minimum of 25 lb / 12 kg lift
Exposure suit appropriate for the environment
Access to an oxygen analyzer.
Appropriate weight.
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:

History and evolution of Rebreather

Comparison of Open Circuit, Closed Circuit and Semi Closed Circuit Rebreather systems and the benefits/problems with each

Practical Mechanics of the System:
Assembly and disassembly of the ECCR
Layout and design of the unit
Absorbent canister design and maintenance
Breathing loop cleaning procedures
Manufacturer supported additional items (Automatic Diluent Valve, etc.)

Gas Physiology:
Oxygen toxicity
Nitrogen absorption
CO2 toxicity

Proper scrubber packing (in accordance with manufactures recommendation):
Gas consumption

Electronic or manual systems design and maintenance:
O2 metabolizing calculations
Fuel Cells
System electronics functionality and calibration procedures

Dive Tables:
Constant PPO2 theory
CNS and awareness of OTU tracking

Dive Computers

Mix adjustable:
Constant PO2
O2 integrated

Dive Planning:
Operational Planning
Gas requirements including bailout scenarios
Oxygen limitations
Nitrogen limitations

Emergency Procedures:
Bailout onboard or off board
Three H’s problems
Flooded Loop
Cell Warnings
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:
All open water dives must be between 10 m / 33 ft to 30 m / 100 ft.
Two dives must be deeper than 20 m / 66 ft.
One dive must be deeper than 25) m / 90 ft.
PO2 not to exceed manufacturer recommendation or a working limit of 1.3 bar
All dives to be completed within PO2CNS% limits with a recommended maximum of 80% of the total PO2 CNS limit
Safety stops to be conducted with a minimum 3 minutes at 6 m / 20 ft.
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:

Pre dive checks:
Unit buildup
Scrubber canister check
Breathing loop check
Positive & negative check

Verify diluent and O2 cylinder contents using O2 analyzer

Demonstrate correct pre dive planning procedures including:
Limits based on system performance.
Limits based on oxygen exposures at chosen PPO2 levels.
Limits based on nitrogen absorption at planned depth and PO2 setpoint.
Thermal Constraints

Emergency procedures:
Mouthpiece familiarity drills.
Gas shutdowns and loss of gas.
Broken hoses.
Flooded absorbent canister.
CO2 breakthrough.
Low oxygen drills.
High oxygen drills.
Flooding Loop.
Electronics and Battery Failure.
Properly execute the ascent procedures for an incapacitated CCR diver

Use of wing/suit and effective management of loop breathing volume for buoyancy control

Stop at three to six (3-6) m / ten to twenty (10 – 20) ft on descent for leak bubble check

Electronics systems monitoring for PO2 levels (SETPOINT) and switching setpoints

Manual control of setpoint

Use of Lift Bag / Delayed Surface Marker Buoy and Reel. (where relevant and applicable)

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

Demonstration of safety stops at pre-determined depths

Constant Loop Volume Management

Post dive clean of unit:
Mouth piece and hoses
Clean and disinfect unit
Inspect components of unit

Diver maintenance of unit:
Cell remove and replace
Mouthpiece strip and rebuild
Replacing batteries


Satisfactorily complete the written examination with a pass mark of greater than eighty (80) %.
Complete to the Instructors satisfaction all confined and open water skill development sessions.
Demonstrate mature, sound judgment concerning use of Rebreather, 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

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.