The Professional Scuba Association International’s (PSAI) Fundamentals Mixed Gas Closed Circuit Rebreather Diver course is designed for those divers who wish to use a Closed Circuit Rebreather with a trimix diluent during their diving activities. A diver able to dive with a rebreather and two or more off-board bailout cylinders in the company of at least one other certified diver without supervision in conditions similar to those experienced during this course to 60m
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The PSAI Fundamentals Mixed Gas Closed Circuit Rebreather Diver Course student will be able to demonstrate proper Rebreather care and maintenance, both pre and post dive. The student will also demonstrate proficiency in the skills outlined below Skill Requirements, of this outline.
A diver able to dive with a rebreather and two or more off-board bailout cylinders in the company of at least one other certified diver without supervision in conditions similar to those experienced during this course.
Prerequisites for Course Entry
Course Minimums and Standards
Approximately 8 to 12 hours for classroom and practical demonstration (oxygen analysis, helium analysis, equipment marking and equipment rigging) are required to complete the PSAI Fundamentals Mixed Gas CCR Diver course.
Confined Water Dives
All new skills shall be introduced in shallow water and all critical skills should be mastered by the student in that environment before attempting them in open water.
Open Water Dives
1. The complete PSAI Fundamentals Mixed Gas CCR Diver course consists of six (6) dives required of 60 minutes duration each.
2. To achieve certification all dives are using a trimix diluent and one dive in each phase must be within three (3) meters (10 feet) of the desired certification level.
3. Oxygen percentage is no lower than 16% (+/- 1%). The maximum depth is 60 meters or 200 feet.
4. Students shall have experience of at least 80% of the specified maximum working depth during this course.
5. Planned stage decompression dives will be included in the course.
6. For any training dives that do not include required decompression stops, safety stops are required.
1. Acceptable Gas Mixtures
Course participants must be trained in the use of heliox and normoxic trimix mixtures with a recommended END of 30 metres/100 feet or shallower and an absolute maximum END of 40 metres/130 feet. Air may be used as a diluent for shallower training dives.
2. Maximum Oxygen Partial Pressures
a. The maximum PO2 during the dive is 1.4 bar.
b. A maximum PO2 of 1.6 bar can be used during the decompression phase of the dive or for emergency open circuit bailout.
c. On-board diluent gases must have a maximum PO2 of 1.1 bar at the expected maximum operating depth.
Course Instructional Materials Requirements
Course Equipment Requirements
Standard Rebreather diving equipment appropriate for the environment of the CCR Mixed Gas dive. For all oxygen concentrations in excess of 40% by volume, or as specified by the individual equipment manufacturer or local regulation, all regulators and high-pressure equipment shall be appropriately oxygen cleaned.
Oxygen Analyzer equipped with an appropriate flow restrictor assembly/interface. An additional oxygen analyzer without an appropriate flow restrictor assembly/interface may also be shown, but only as an adjunct. The instructor should demonstrate how these secondary devices, if used, may result in inaccurate measurements.
Helium Analyzer with appropriate interface assemblies. An instructor may use a combination analyzer that has the provision to measure both oxygen and helium in the same unit.
Nitrox cylinder(s), appropriately cleaned, marked and maintained appropriately rigged as stage/decompression cylinders with an appropriately cleaned and serviced regulator and pressure gauge.
Two Delayed Surface Marker Buoys (DSMB) and appropriate main reel and backup reel or spool. One DSMB to be in fluorescent red and one in fluorescent yellow.
Redundant regulator/ADV, redundant time and depth monitors and redundant line cutting devices. Appropriate back-up tables and run-time schedules shall be used even in conjunction with dive computers.
The PSAI Fundamentals Mixed Gas CCR Diver course requires the use of a PSAI Mixed Gas CCR Diver manual. This manual will have all the necessary information to appropriately cover, in the detail necessary for this level of certification, the following areas of information:
History of Re-breather Diving.
Early techniques of Mixed Gas Diving.
Evolution of Mixed Gas Diving Courses.
PSAI’s involvement in Mixed Gas Diving Courses.
Mixed Gas diving and Rebreathers.
Review Physical Principles of Mixed Gas Diving.
Physiological Principles of Mixed Diving.
Hazards of Excess Oxygen.
Effective (Accelerated) Decompression.
Equipment for Extended Range Diving.
Gas Management Planning.
a. Bottom Gas Requirements.
b. Decompression Gas Requirements.
Descent and Ascent Techniques and Considerations.
a. Down Lines.
b. Navigation from Shore or Vessel.
c. Reference Magnetic Headings.
By the end of the course the candidate shall have an appropriate knowledge of the following concepts for rebreather diving (course content should include all the following concepts unless inapplicable for the rebreather model used):
A. All of the theory competencies outlined in the Technical Rebreather Diver Level 1 standard
B. Additional equipment required to be able to conduct decompression dives
C. Planning for redundancy of key life-support equipment
D. Techniques to be able to conduct decompression diving
E. Ensuring adequate bailout gas available for safe exit at any point during dive
F. Staying within maximum limits to avoid central nervous system (CNS) oxygen toxicity
G. Effect of gas density on breathing resistance
H. Planning and conducting decompression dives
I. Manual operation of a functioning rebreather
J. Manual control options to manage a malfunctioning rebreather
K. Techniques for:
1. Removing and replacing two bailout cylinders at the surface and underwater
2. Exchanging a bailout cylinder with another diver while stationary in mid-water and maintaining neutral buoyancy
3. Exchanging a bailout cylinder with another diver during a simulated open circuit bailout ascent
4. Diluent flush
5. Use of CCR in SCR mode
6. Manual oxygen control
7. Manual diluent control
8. Manual setpoint control during ascent
9. Off-board plug-in to a CCR of oxygen and diluent gas supplies
Land Based -
A PSAI Fundamentals Mixed Gas Closed Circuit Rebreather Diver student shall:
Confined Water -
All new skills shall be introduced in a confined water situation and all critical skills should be mastered by the student in that environment before attempting them in open water.
At the PSAI instructor’s discretion, confined water exercises may be conducted to familiarize the student with equipment rigging and placement, etc
Open Water - A PSAI Fundamentals Mixed Gas Closed Circuit Rebreather Diver student shall, in addition to confirming abilities required of previous courses:
Conduct the dive according to their plan, as approved by the PSAI instructor.
Monitor gas pressures and surface with an acceptable safe margin.
Not to exceed any Maximum Operating Depth or Oxygen exposure limitations.
Correct setpoint choice.
Not to exceed any absorbent limitations.
Perform buoyancy control drills both at depth greater than 30 meters (100feet) and in shallow water 6-10 meters (20-33 feet).
Properly execute a recovery from a system failure to bailout whilst stationary on two (2) separate dives.
Properly execute a recovery from a system failure to bailout whilst hovering on two (2) separate dives.
Perform gas switch skills where required by equipment on two (2) separate dives.
Manually maintain an elevated setpoint (maximum 1.4 bar) during the bottom and ascent phase of a mixed gas dive.
Simulate a recovery from a flooded Rebreather simulating the last 2 minutes of a 60-meter dive with 15-minute bottom time elapsed including all ascent and safety stops to the surface.
Record and compare gas usage upon completion.
Deploy a reel and surface marker buoy from a stationary position on the bottom phase of a dive at least twice (2 times).
Use the reel for all ascent practice.
Deploy a reel and surface marker buoy from a hover position on the bottom phase of a dive once.
Use the reel for all ascent practice.
At 18 meters deploy as second fluorescent yellow SMB to simulate a loss of gas scenario.
Conduct accurate safety stops.
Practical Skill Requirements
The student shall have experience of at least 6 dives/water sessions and at least 360 minutes total open water time during the course.
By the end of the course the candidate shall be able to perform the following skills (course content should include all the following items unless inapplicable for the rebreather model used):
A. All of the practical competencies outlined in the PSAI Advanced Rebreather Diver standard
B. Remove and replace two bailout cylinders at the surface and underwater
C. Exchange a bailout cylinder with another diver while stationary in mid-water and maintaining neutral buoyancy
D. Exchange a bailout cylinder with another diver during a simulated open circuit bailout ascent
E. Manual operation of the functioning rebreather
F. Use an off-board plug-in diluent gas supply to diver's CCR
G. Use an off-board plug-in oxygen gas supply to diver's CCR
H. Manual setpoint control during ascent
I. Manual response(s) to the following rebreather malfunctions (if applicable to the specific rebreather):
4. Cell problems
5. Loss of diluent
6. Loss of oxygen
7. Other rebreather warnings/alarms as appropriate
J. Use of CCR in SCR mode
K. Rescue of a rebreather diver
L. Conduct of decompression or safety stops
M. Switching to off board bail out and conducting an ascent
N. Correctly respond to simulated emergencies
Course Completion Performance Requirements
To be awarded the Professional Scuba Association International’s Fundamentals Mixed Gas Closed Circuit Rebreather Diver certification, the student must:
A. Attend all academic sessions.
B. Successfully master all academic and in-water skills.
C. Correctly set-up all electronic monitoring parameters fitted to Rebreather.
D. Correctly perform all dry land-based checks and maintenance.
E. Complete the PSAI Fundamentals Mixed Gas Closed Circuit Rebreather Diver written examination with a score of at least 80%. All questions shall be correctly answered or remediated and explained. Each level will have a separately reviewed exam.
F. Conduct the open water dives with appropriate skill and attention to all dive parameters and requirements, including maximum operating depths and adherence to decompression stop depths.
G. Perform a minimum of two (2) DSMB deployments for the purpose of decompression depth reference. The student will demonstrate the skill necessary to deploy the DSMB in an expeditious manner, completing the deployment in less than one (1) minute. Other dives may be performed utilizing anchor line reference or other natural references as long as the instructor has verified the competence of DSMB deployment.
H. Demonstrate the procedure to identify and isolate a malfunctioning bottom mix diluent and oxygen regulator. This skill shall not be conducted deeper than 40 meters (132 feet).
I. Demonstrate navigational techniques appropriate for the CCR Mixed Gas dives performed.
J. Tow a simulated un-conscious diver for a minimum of 10 meters (33 feet) while at a depth in excess of 40 meters (132 feet) and then simulate an emergency rescue ascent on one of the training dives to 12 meters.
K. Conduct correct post-dive cleaning and maintenance procedures.
L. Correctly plan, execute, and log the required dives.
The PSAI Instructor is responsible for ensuring that the Fundamentals CCR Mixed Gas Diver student has demonstrated the appropriate respect and understanding for diving with helium-based diving gases as well as the various decompression gases. If the student fails to maintain proper depth control, gas management awareness, etc., the instructor must require additional training until the appropriate standards are achieved prior to certification.
A diver that successfully completes the first level of Mixed Gas CCR diving will be awarded certification credentials that verify their achievement of dives within 3 meters (10 feet) of 60 meters (200 feet).
After successful completion of a further 15 logged mixed gas CCR dives to 60 meters (200 feet) following a Fundamentals CCR Mixed Gas course the student may apply to undertake the next phase of the qualification PSAI Advanced Mixed Gas CCR Diver to 100 meters (300 feet).
All levels of PSAI Rebreather certification cards are Brand & Model specific. The Brand and Model the student was trained on will be listed on the certification card. No “generic” rebreather certification cards will be issued by PSAI at any level.
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