CCR Skills MOD 1 basic

               

Hypoxia

  1. Upright Position

  2. Full Diluent Flush while gas free flows out of side of mouthpiece, breathe and vent out nose

  3. Shut DSV

  4. Purge 2nd stage as you put into your mouth

 

Hyperoxia

  1. Shut DSV

  2. Purge 2nd stage as youput into your mouth

  3. Switch Shearwater from CC to OC

  4. Ascend

  5. Shut Off Oxygen if it causes buoyancy problems on ascent

 

Hypercapnea

  1. Upright Position

  2. Full Diluent Flush while gas free flows out of side of mouthpiece

  3. Breathe Open Loop “into lungs and vent out nose” add dil as needed for 1 minute

  4. Shut DSV

  5. Purge 2nd stage as you put into your mouth

 

Ka Boom!

  1. Close both valves: Diluent (valve rolls backwards) & Oxygen (valve rolls forward) < 3 seconds

  2. Check Po2, or status of leak

  • If gas leak is Inside loop, feel inflating gas

    • Diluent will lower Po2

      • if diluent turn oxygen back on and abort ascend, feather valve if dil needed

    • Oxygen will spike Po2*option #1 on loop

      • if oxygen, turn diluent back on and immediately full flush, abort ascend, feather oxygen to maintain Po2 or bail-out if unmanageable

    • Oxygen will spike Po2*option #2

      • if oxygen , turn diluent back on and immediately full flush, abort ascend, feather oxygen to maintain Po2 or bail-out if unmanageable

  • If gas leak is exterior – gas or bubbles evident, check pressure gauge for rapid depleting gas

    • Diluent – consider minor nuisance, abort ascend

      • Normal ascent may occur as gas in loop expands, monitor Po2

      • Plug in bailout deep mix add if need

    • Oxygen – consider serious as Po2 drops on ascent – consider ascent options

      • Plug in off-board oxygen to MAV – manuallyadd, abort ascend to safety/deco stop

      • Ascend monitoring Po2 until it drops to where O.C is better Po2 then Bail Out

      • Shut DSV and Bail Out

      • If deeper than 60 fsw you may add diluent to Semi-Close (see exercise)

 

Stuck Open Solenoid 

                (gas may be felt expanding loop, or subtle un-detected and first sign may be spike in Po2)

  1. Shut off oxygen

  2. Full Diluent Flush until Po2 is breathable (watch Po2 as flush occurs)

  3. Feather oxygen valve on/off rapid to allow only 300-400 psi to bleed in

  4. Abort ascend monitoring Po2 closely feathering oxygen into loop with on/off valve

 

*OW Skills on solenoid CCR, the instructor signals handset KaBoom and changes set point controller to high 1.3.  Student feels solenoid firing and does steps 1-3, swim minimum :05 minutes feather oxygen valve to maintain 1.0 Po2

 

Stuck Diluent / Oxygen MAV (manual add valve)

                (starts out like KaBoom but gas is felt leaking into loop)

  1. Close both valves: Diluent (valve rolls backwards) & Oxygen (valve rolls forward) < 3 seconds

  2. Check Po2

  • Diluent will lower Po2 – consider minor nuisance, abort ascend

    • Turn oxygen valve back on, monitor Po2

    • Normal ascent may occur as gas in loop expands

    • Plug in bail out deep mix add if need

    • Abort Ascend

  • Oxygen will spike Po2

    • Turn diluent back on

    • Full Flush monitor Po2 until breathable

    • Feather Oxygen to maintain Po2

    • Abort Ascend and consider Bail Out if unmanageable

 

*OW Skills, the instructor signals pinch button on his MAV, then holds students button.  Dive 1 or 2 the instructor may signal which button to develop muscle memory of tank valve on/off.  Proceeding dives 3-6 they alternate dives to switch from Oxygen/Diluent and sees student react to raise or fall in Po2.  Student feels gas in loop, detects Po2 and shuts off correct gas. 

With stuck diluent divers signal thumbs up to signify abort ascend.  Cut skill resume dive

With Stuck Oxygen the diver holds button in as they swim for minimum of:05 minutes feathering oxygen to maintain 1.0 Po2 horizontally.  Cut skill resume dive

 

Semi – Closed Circuit

(Simulation of loss of Po2 display, all sensors gone, sensors out of parameter.  Extreme emergency use only when bailout gas is not sufficient to ascend safely.  Maximum breaths in Mod 1 is 5 breaths with the last 2-3 breaths out nose to vent loop before re-fill.  Diver would only ascend to no shallower than 30 feet before switching to open circuit or open loop on remaining ascent)

  1. Upright Position

  2. Full Diluent Flush while gas free flows out of side of mouthpiece

  3. Breathe In and back into Loop 3 breaths (count 1,2,3 - loop)

  4. Breathe In and Out Nose 2 breaths (count 4,5 - out nose)

  5. Add Diluent MAV to re-fill lung volume

  6. Continue 3 in loop, 2 out nose

  7. Plug in Off-Board Bailout to extend breathing and save on-board gas for BCD

 

*OW Skill – done between 30’ – 60’ , horizontal swim only, with care to monitor Po2.  The display is imagined to be gone, but is visible for safety.  The diver will porpoise or lose buoyancy as they nose vent, re-fill and swim normal, to again porpoise.  Swim minimum of :05 minutes starting with back gas, then plug in off board bailout mix.  For eCCR diver set point low.

 

Loss of Diluent

  • Ascend normally

  • Plug in Bail Out to MAV

  • Plug in Bail Out to BCD inflator

  • Bail Out to OC

 

Loss of Oxygen

  • Plug in off board 50% - 100% deco mix, add via MAV to maintain Po2

  • Plug in Bail Out 21% to MAV – monitor Po2 on ascent closely, breathe semi closed on ascent as Po2 falls, then bail out before you reach 30 fsw

  • Bail Out to OC

 

*OW skill –  be sure to have diver tap the “off board” dil button to be sure the BCD nipple couples to the MAV, few cases a BCD hose and nipple do not couple?  Be sure diver replaces BCD whip so it does not dangle during rest of dive.

 

Water in exhaust hose

(Typical when training since students frequently remove and replace DSV, and timing of blow before open or forgetting is common hence wet loop)

  • Roll left shoulder down and complete barrel roll Counter Clockwise – water drains to exhale counterlung

  • Shut DSV, remove from mouth and lift overhead stretching or shaking left hose into exhale counterlung

 

*OW Skill watch direction to be sure rotation lowers left to allow water to drain to the exhale lung.  If DSV remove shake, on any return to loop, watch for blow before open and then look at Po2 display. 

 

 

Flood

(Rare and totally preventable by doing proper build check list, typically occurs getting in or on descent.  Heavy gurgling sound combined with loss of loop volume. Caustic Cocktail is possible and very dangerous)

  • Shut DSV -

  • Purge Bail Out regulator when inserting

  • Switch Shearwater to OC

  • Oxygen On may be irrelevant as a flooded loop is significantly negative, oxygen may be shut off if it poses an ascent issue.

 

*OW Skill – Signal Slash Throat to signify Bail Out!  Make sure student is pushing purge button as 2nd stage goes into mouth.  Look for student to switch Shearwater from CC to OC.  After Bail Out is safely conducted, be sure to check DSV closed.  

 

Oxygen Flush

  • 6 – 3 Meter Flush “Blast”

    • After completing 6-3 meter safety stop/ deco stop at 1.3

      • Upright flush – Tap-Tap on O2 MAV, with nose vents

      • Flush oxygen at surface

  • Surface Flush “Short Blast or Taps” (more of constant adding, venting not required)

    • At surface the diver can hit the oxygen at ANY time, frequently

      • Jumping in, swimming to shot line

        • Tapping Oxygen MAV

      • Diver arrives surface from last stop, diver swims boat, diver climbs ladder

        • Tapping Oxygen MAV

        • On Boat, on shore diver has loop in breathing rich oxygen

  • 6Meter Flush “Strategic” efficient to test sensor current limiting

    • After completing 6 meter safety stop/ deco stop at 1.3

      • Vent nose -hit O2, vent nose- hit O2, vent nose – hit O2,Continue until Po2 reaches 1.6

      • Flush oxygen at surface

*OW Skill – There are two types of flushes with the typical flush being an emergency “Blast” of diluent.  Oxygen is not considered an emergency flush as underwater a rich oxygen flush could by hyperoxic.  An oxygen flush is reserved for at or near surface.  The first Oxygen Flush is a quick blast to enrich loop prior to final ascent.  The second flush is short burst constantly till on shore or boat.  The thirds is efficient enrichment like the surface oxygen calibration.  The loop volume is inhaled and exhaled with oxygen added until the Po2 reaches 1.6. Note only one breath out with each tap-tap of oxygen in as you do not want to lower loop volume to point the ADV would “water down” the Po2.

 

 Oxygen Sensor Check (Current Limiting) Ascent 20fsw/6 meters

( AP Diving and history showed us current limiting was best done at end of dives.  See more theory on 5 steps to sensor integrity as one check alone is not sufficient.  This exercise is done regularly at end of dive with other steps proceeding.  If any question on sensor age and surface Mv, linearity then see “OSC on descent”)

  • 6Meter Flush “Strategic” efficient to test sensor current limiting

    • After completing 6 meter safety stop/ deco stop at 1.3

      • Vent nose -hit O2, vent nose- hit O2, vent nose – hit O2,Continue until Po2 reaches 1.6

      • Flush oxygen at surface

 

*OW Skill –The loop volume is inhaled and exhaled with oxygen added until the Po2 reaches 1.6. Note only one breath out nose with each tap-tap of oxygen in as you do not want to lower loop volume to point the ADV would “water down” the Po2.

 

Oxygen Sensor Check (Current Limiting) Descent 20fsw/6 meters

( See rEvo’s testing of old sensors and spike at beginning of dive.  This exercise is done at beginning of dive if there is a gap or time delay since diver conducted an end of dive current limiting, i.e. at beginning of dive outing.  Note the first dive on un-tested sensors is a limited test dive for value of doing current limit at end of dive where sensors are temperature and stress limited.  Any question the sensors should be replaced with new prior to big dive outing)

  • On descent diver stops at 6 Meters for Po2 spike, unit check, bubble check

    • After completing 6 meter Buddy, Bubble, Unit Check Flush Oxygen

      • Vent nose -hit O2, vent nose- hit O2, vent nose – hit O2,Continue until Po2 reaches 1.6

      • Add Diluent with Open Loop Nose Vents to lower Po2before continue descent

 

 

*OW Skill –The loop volume is inhaled and exhaled via Open Loop Nose Vents, with oxygen added until the Po2 reaches 1.6. Note only one breath out nose with each tap-tap of oxygen in as you do not want to lower loop volume to point the ADV would “water down” the Po2.  Lower Po2 to continue descent and avoid unnecessary oxygen spike at depth.

 

Oxygen Sensor Check Mv during dive

  1. Measure the sensor mV output in ambient air at sea level, using the CCR electronics.

  2. Divide the sensor output (mV) by the ambient air (20.9). (First convertrelevant numbers to decimal).

  3. Multiply the calculated output by 100 (100% oxygen) The expected answer willbe the mV output for 100% oxygen

Example 1: Calculate the expected mV output when calibrating with 100% Oxygen.

  1. Sensor 1 measures 9.0mV in ambient air.

  2. 9.0⁄.209=43.06mV Calculated at 100% Oxygen

 

The next calculation is calculating PO2 at depth using the sensor mV.

  1. Sensor 1 measures 9.0mV.

  2. 9.0⁄.209=43.06mV

  3. 43.06mV×1.3 PO2 (Set point)=55.978mV calculated mV output.

  4. 55.97mV expected output of oxygen sensor at 1.3 set point at any depth below10fsw/3msw.

 

​​

  • Write Sensor Mv on side of Shearwater Display for desired operating Po2

 

*Classroom Skill – after CCR building checklist is complete, review the math for oxygen Mv to Po2

*OW Skill –have diver compare the Mv on sensors according to the desired Po2 or set point

 

Po2 Control

Instructor gives students set point to maintain with both manual on full manual CCR, and manual on HeCCR (Hybrid electronic CCR). Divers are to be responsible for maintaining low SP until switch depth, and to maintain high set point thru safety stop/deco.  For divers on HeCCR, the last two dives the diver may utilize eCCR to maintain set point.   Set points are low .50 - .70 and high 1.0 – 1.3, with max 1.6 for “current limiting only”

  • Manual Po2

    • Shallow set point switch depth 30 fsw / 10 meters

      • MAV add surface to 30 fsw .50 - .70

      • MAV add below 30 fsw to max depth and all ascent to safety stop 20 fsw/6 meters 1.0 – 1.3

  • eCCR set point controller

    • Shallow set point switch depth 30 fsw / 10 meters

      • Diver switches from .19 “surface build” to low .50 – 70 during Pre Breath

      • Diver switches from low .50-.70 below 30 fsw/10 meters to high 1.0 – 1.3

        • Tapping Oxygen MAVis encouraged to maintain “muscle memory” adding O2

      • Diver maintains high 1.0-1.3 on all ascent, throughout safety/deco stop.

        • Tapping Oxygen MAV is encouraged to maintain “muscle memory” adding O2

      • Diver switches high 1.0-1.3 to low .50 - .70 at discretion either end of last stop or at any time if manual addition is easier to maintain buoyancy.

        • Oxygen blast/flush is completed before leaving stop and at surface

 

*OW Skill – Instructor views student’s primary display to ensure on surface Pre Breath they are moved from .19 to .50-.70 and when crossing 30 fsw depth they can manually maintain Po2 throughout the dive.  Different descents from slopes to walls can be used to get divers used to oxygen spikes on fast descents.   On eCCR the student needs to switch from high set point to low set point when they leave the 20 fsw or the solenoid will “pop” them to the surface.  

 

Swim 15 meters without breathing – Bail Out

(Simulates a divers who’s bail out failed and needs to swim distance to buddy for Bail Out)

  1. Inhale normal breath

  2. Shut DSV

  3. Swim horizontal for 15 meters holding 2nd stage in hand in front

  4. Purge 2nd stage when inserting into mouth

Cut Skill return to CCR

  1. Insert DSV Mouthpiece, Blow, Open

  2. Hold 2nd stage in hand while inserting DSV, do NOT drop/release until confirmed

  3. Check Po2 as orifice has been flowing during swim, dil flush/add if need lower Po2

  4. Stow 2nd stage

 

*OW Skill – instructor swims side by side with 2nd stage in hand, ensuring diver stays at steady depth and does not ascend without venting to prevent lung injury.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  After cut signal to end skill diver returns to CCR.  Be sure that diver does NOT drop 2nd stage as they insert DSV.  Never release/drop a breathing source until the new one has been confirmed.   Watch Po2 upon return to CCR as orifice has been flowing while diver is off loop.

 

Switching from CCR to Bailout and Back

(There are two important considerations for switching from CCR to Bail Out and Back to CCR.  First is the Muscle Memory of mechanics of shutting DSV, purging 2nd stage to get first breath, recover loop, blow before open DSV, and immediately look at Po2.  The second value is for specific skill of “Sanity Breaths” when a diver may go back on a failed CCR to make corrections.  See next skill “Sanity Breath”)

  • Inhale normal breath

  • Shut DSV

  • Deploy 2nd stage and purge regulator while inserting into mouth (not purging after)

  • Switch Shearwater from CC to OC

  • Loop DSV may be below the divers mouth/2nd stage or floating above

  • * Shut off Oxygen is option on actual ascent to prevent excess loop buoyancy, where venting would be required

Cut Skill return to CCR

  1. Recover Loop

  2. Insert DSV Mouthpiece, Blow, Open

  3. Hold 2nd stage in hand while inserting DSV, do NOT drop/release until confirmed

  4. Check Po2 as our mantra is “Always Know Po2”

  5. Switch Shearwater from OC back to CCR

  6. Stow 2nd stage, hose

 

*OW Skill – instructor has their 2nd stage in hand during BO to CCR and back.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  After cut signal to end skill diver returns to CCR.  Be sure that diver does NOT drop 2nd stage as they insert DSV.  Never release/drop a breathing source until the new one has been confirmed.   Watch diver to see bubbles blow out of DSV water channel before they open loop.  Watch Po2 upon return to CCR as Always Know Your Po2 must be engrained early and often.

 

Sanity Breaths or  CCR to Bailout and Back

There is honest debate amongst industry Pros on virtue of Bail Out Sanity Breaths before returning to failed CCR to attempt fix, or two additional opinions of: Full Diluent Flush staying on loop with nose vents to get on-board Sanity Breaths, then fix problem.  And the opinion that if the CCR “bucks you off” meaning overwhelming failure that you bail out to OC, that you do NOT return to a broken CCR.  Typical for spike in oxygen due to rapid descent, stuck oxygen inflator, stuck oxygen solenoid.  Less consideration but may be overexertion “over breathing” loop to build up momentary C02.  Note on Co2 scrubber failure there is NO going back on crashed loop as Co2 is too hard to rid from system and disastrous if you stay on loop.  Momentary over breathing of loop causes anxiety of breathing that is due to over exertion and sanity breath, loop flush is beneficial both psychological as well as physical.  *Note if breathing anxiety returns when you have sanity breath, flush and stopped exertion, then it is real Co2 crash and you must bail out)

  • Bail Out Sanity Breath – Back to CCR

    1. Inhale normal breath

    2. Shut DSV

    3. Deploy 2nd stage and purge regulator while inserting into mouth (not purging after)

    4. Breath one minute of OC fresh gas for Sanity

    5. During Off Loop Period fix problem: shut off stuck oxygen, or fresh breath to rid breathing anxiety.

    6. Replace DSV, Blow Open

    7. Full Loop Flush with Open Loop Nose Vents

    8. Check Po2, check condition – any question to safety of loop – Bail Out!

  • If In Doubt Flush It Out

  • If In Doubt Bail Out

 

*OW Skill – instructor has their 2nd stage in hand during BO to CCR and back.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  Be sure that diver does NOT drop 2nd stage as they insert DSV.  Never release/drop a breathing source until the new one has been confirmed.   Watch diver to see bubbles blow out of DSV water channel before they open loop.  Watch for Full Diluent Flush with Open Loop Nose Vents, at same time diver is monitoring the Po2 upon return to CCR as Always Know Your Po2 must be engrained early and often.

 

 

 RMV Swim

(must know constant depth, time :05 or :10 minutes, Start and End psi for psi total used, cylinder size used

  1. Write down depth, psi start pressure, note time start

  2. Shut DSV

  3. Deploy 2nd stage and purge regulator while inserting into mouth (not purging after)

  4. Switch Shearwater from CC to OC

  5. Swim constant depth for minimum :05 or :10 slow steady swimming

  6. At time end, record end PSI

 

Cut Skill return to CCR

  1. Recover Loop

  2. Insert DSV Mouthpiece, Blow, Open

  3. Hold 2nd stage in hand while inserting DSV, do NOT drop/release until confirmed

  4. Check Po2 as our mantra is “Always Know Po2”

  5. Switch Shearwater from OC back to CCR

  6. Stow 2nd stage, hose

 

*OW Skill – instructor has their 2nd stage in hand during BO to CCR and back.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  After RMV swim time ends, diver returns to CCR.  Be sure that diver does NOT drop 2nd stage as they insert DSV.  Never release/drop a breathing source until the new one has been confirmed.   Watch diver to see bubbles blow out of DSV water channel before they open loop.  Watch Po2 upon return to CCR as Always Know Your Po2 must be engrained early and often.

*Classroom Skill – Post dive the student and instructor will go through a RMV calculation.  Encourage diver to repeat if they have not done RMV calculations to get a quality number through comparison.  The RMV is key to knowing how much bailout is needed.

 

Diluent Flush

(This skill is used throughout many emergency procedures on all CCR’s)

  • Full Flush “Blast”

    • Upright diver prepares to have positive buoyance change “lift”

    • Hold Dil MAV button down 5-6 seconds

    • Diver inhales fresh diluent, venting out nose

    • Watch Po2 drop

  • Short Flush “Blast”

    • Upright diver prepares to have positive buoyance change “lift”

    • Hold Dil MAV button down 3-4 seconds

    • Diver inhales fresh diluent, venting out nose

    • Repeat if necessary

  • Sensor Validation

    • Lower eCCR Set Point to Low (below dil Po2 at current depth)

    • Attach BCD whip from air bailout

    • Switch Shearwater to OC and confirm bailout mix

    • Upright diver prepares to have positive buoyance change “lift”

    • Hold Dil MAV button down 8-10 seconds

    • Diver inhales fresh diluent, venting out nose

    • Watch Po2 to

    • Click Shearwater “Right” button to compare Po2 shown to Po2 of gas at current depth.Note slight variation in increase Po2 is result of oxygen flowing orifice during flush.

 

*OW Skill – There are two types of flushes with the typical flush being an emergency “Blast” of diluent.  The instructor is looking for an immediate reaction, flush, nose venting, and Po2 monitoring.  The first “Blast” is an emergency to refresh to atmosphere with breathable gas, or to lower Po2 spikes.  The second type of flush is long drawn out and requires steps to validate a sensors reading as accurate

 

Open Loop Breathing

(Option for breathing the small amount of back gas, or breathing off board bailout gas through the loop of CCR, diver is not rebreathing/recycling any breaths, this is one in – one out)

  • Full Flush “Blast” then Open Loop Breath

    • Upright diver prepares to have positive buoyance change “lift”

    • Hold Dil MAV button down 5-6 seconds

    • Diver inhales fresh diluent, every exhalation out nose

    • As loop shrinks, diver adds gas via MAV from back gas or off board

    • For longer OL on CCR, plug in Bail Out to MAV

    • Switch Shearwater to O.C.

 

*OW Skill – Diver starts with Full Flush to ensure loop is fresh known gas.   Diver inhales and exhales out nose on every breath.  Breathing on a dry rebreather has very little value over open circuit, however if OC 2nd stage has leak or failure, the diver can breathe all OC gas through the CCR loop. 

 

 

Open Circuit Bailout Ascent

 

(This skill is likely the most valuable of all exercises as it is realistic to experience what would happen in event of a bailout that requires you to make ascent on O.C.  Theoretical knowledge is good, but reality is the real teacher.  “If In Doubt Bail Out”)

  • Bail Out Ascent

    • Shut DSV

    • Diver purges 2nd stage as they put into mouth to guarantee first dry breath, second breaths cautious based on first breaths.Stay calm and keep RMV as low as possible.

    • Begin ascent at no greater than 30 fpm

    • Switch Shearwater controller to Low set point on eCCR

    • Switch Shearwater computer from CC to OC and confirm correct bail out gas.

    • If unit is not flooded, shut off oxygen to prevent excessive internal loop buoyancy

    • Vent loop if buoyancy is excessive by placing DSV at or above eye level, and flick the lever open to “burp”, close DSV

    • Deploy SMB if appropriate

    • Stop at required deco or 20 fsw for safety stop for as much time as you can

 

*OW Skill – instructor has their 2nd stage in hand during BO ascent.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  Confirm diver switches computer to OC, and if necessary shuts off oxygen (note if student returns to CC you must verify oxygen is turned back on) .  Burp loop as needed.  During SMB deployment be aware that the diver is faced with consideration of purging 2nd stage into bottom of SMB, if they use tilt head to vent exhaust into SMB make sure they are not hung up on straps or line.  Diver may also use bcd nipple inflator on SMB.

 

 

 

Oxygen CCR at 20 fsw / 6 meters

(Origins are from the military style fully closed circuit rebreather, and apply only to very limited application such as a rebreather where all electronics fail and no display is available.   The unit has to be dry (not flooded) and Co2 absorbent working.  In event of extreme exposure where divers safety would be compromised if they did not complete a deco stop at 20 fsw on oxygen.  Like military O2CCR, the diver must completely flush, suck dry, flush the loop with only oxygen and occasionally vent loop as they off gas nitrogen into the loop.  Failure to completely flush out any inert gas can result in the loop oxygen being consumed and as loop shrinks the partial pressure increases where inert gas become greater constituent and the diver could become hypoxic.   See the skill Manual Po2 at Constant Depth ) 

  • 20 fsw/6Meter Flush “Oxygen CCR”No Po2 display available

    • Diver arrives at 20 fsw and is stable on SMB line or mooring to prevent dropping as depth must remain stable.

    • Shut OFF Diluent and vent into BCD if necessary or out

    • Blow to purge, open DSV

    • MAV O2 button, initiate immediate Full Forceful Oxygen Flush with Open Loop Vents out nose

    • Switch to “Strategic Oxygen Flush”

      • Open Loop Vent nose to empty Loop volume

      • MAV O2 inflate Loop

      • Repeat Open Loop Vent – re-inflate Oxygen MAV 6 times

    • Every :05 minutes vent loop and re-inflate oxygen to purge any nitrogen that you off gas into loop

    • Flush loop Oxygen MAV before final ascent

    • Flush loop Oxygen MAV at surface

 

*OW Skill –  max depth 20 fsw/6 meters.  Diver starts with Full Flush to ensure loop is fresh known gas.   Diver strategically or efficiently purges and flushes loop 6 times to ensure that only pure oxygen is in loop.  As loop volume shrinks, the diver feels lack of loop volume or oxygen being metabolized and Tap-Tap on O2 MAV to replenish volume.  Make sure diver is stable on SMB line or mooring line.  The divers Po2 display is on and available and is used for safety to monitor.  You can slide it around divers wrist to simulate No Display, but instructor can see to monitor. 

 

Manual Po2 at Constant Depth

(This skill has little to NO value at depth, except from a conceptual form of experience for theory of how a loop volume depreciates as diver metabolizes oxygen.  At best it is used to validate the skill of Oxygen CCR at 20 fsw/6 meters.   As a result I will write the “Theoretical Concept” and minimize on the OW skill as bunk. 

First the value of skill is to say that a diver is in such jeopardy of NOT carrying enough OC bail out gas that they are forced to remain on a failed CCR, until they arrive at a depth/location where the OC gas would allow a safe ascent.  This is un-forgivable, yet at same time entirely possible due to human nature of pushing limits.  Second premises is that the divers Po2 display/electronics/sensors have all failed and the diver has no way of monitoring gas in loop.  Not knowing Po2 has proven to have killed several divers in past.  Third premises is that the diver is somehow able to stay at exact same depth for a period of time, such as a cave or shipwreck where the plain is perfectly level and depth does not change.  It is possible that a diver was sooooo far away from mooring ascent line, shore or in a dangerous shipping lane that they needed to swim horizontally to a safer location, but yet we are grasping at straws.   No river bed, lake, ocean, cave passage, or even artificial shipwreck is completely level to allow “constant depth”.  The fourth premises is that under a stressful situation of CCR failure, that a diver has composure to remain totally calm so they are able to sense a loop volume that shrinks as the oxygen is metabolized, and they are able to inflate only enough to maintain the same used oxygen and same Po2.  If the loop were to shrink enough where the divers ADV fires to inject diluent, then the game is totally off.  

The skill should be reserved for Oxygen CCR at 20fsw / 6 meters where it has some practical value, and not theory but real value of how oxygen is metabolized and causes loop volume to shrink.  )

 

  • Manual Po2 at Constant Depth example 60 fsw/18 meters

    • Diver arrives at 60 fsw with set point maintained manually at 1.3

    • Swim horizontally maintain perfect depth

    • As loop volume shrinks, and before ADV fires, sense volume loss and replace with Tap-Tap of Oxygen MAV to replenish loop volume lost due to metabolism of Oxygen

    • Check Po2 remains stable at 1.3 by manual control via sensing loop volume

 

*OW Skills – training agencies and CCR manufactures that focus on purely theoretical skills that are virtually impossible to complete, are wasting valuable time and clogging valuable “muscle memory” in brain with overload of bunk skills.  This should be reserved for a poos skill demo only, or used for Oxygen CCR at 20fsw/6 meters at the advanced mod of ccr training that require decompression.

 

Out Of Air “Gas” Buddy Share

(The term OOA is commonly used in basic training, however we realize we are not breathing air, as we are breathing a mixed gas nitrox.  At some time OOG will be yet another acronym added to the industry of SCUBA and CCR that are based on acronyms.  Also common hand signals such as “slash throat” to signify OOA can be substituted to OOG, or CCR diver who switches to their OC and finds it is non-functional or runs out.   This skill has building blocks and only second in value to mastering a Bail Out, Bail Out Ascent as this skill can build on the buddy to supply reserve gas to OOG CCR diver)

 

  • CCR diver breaths from buddies stage while swimming

    • Distress diver signals “Slash Throat” or eye contact buddy points to mouth not on loop! Need Gas Now!!

      • Buddy deploys “long hose” from stage bottle and presents to distressed diver.Do not block purge as distressed diver should purge on placing 2nd stage into mouth.

      • Swim horizontal with OOG diver breathing from buddy stage – do not pull out of divers mouth.

 

  • CCR diver bails out to broken OC, or runs out of their bail outwith Stage Bottle Swap

    • Distress diver signals “Slash Throat” or eye contact buddy points to mouth not on loop! Need Gas Now!!

      • Buddy deploys “long hose” from stage bottle and presents to distressed diver.Do not block purge as distressed diver should purge on placing 2nd stage into mouth.

      • Swim horizontal with OOG diver breathing from buddy stage – do not pull out of divers mouth.

      • Diver in control should assist or manage the exchange of stage bottle as distressed diver is focused only on survival.

      • Diver in control could take defective full stage and attempt to fix regulator, re-seat DIN, or swap regulators if needed.If empty stage poses any threat or detriment, it should be discarded .

      • In best case scenario distressed diver who bails out of broken CCR would only breath down the bailout stage bottle 2/3’rds, so there is no stress during the hand off exchange of dive buddies full cylinder.

  • Diver Bailed Out of CCR to OC executes Stage Bottle Swap

    • Bail Out Diver signals they are at 2/3’rds tank pressure and ready to switch full cylinder for remainder of bail out ascent

      • Donor Buddy removes their full cylinder and hands to Bail Out diver, or more simply clips the bail out cylinder to diver open side and hand the diver the new 2nd stage.

      • Bail Out diver accepts new cylinder and switches 2nd stage.

        • Bail Out diver in practice should manage stage exchange

 

 

*OW Skill – instructor has their 2nd stage in hand during BO ascent.  Watch diver to ensure they purge 2nd stage as they put regulator in mouth as first breath must be dry or choking/coughing will drain bail out.  At this point the muscle memory of switching Shearwater from CCR to OC is important, however we are focusing on “stage bottle” hand off or exchange.  At this point watch for dropping stage, especially when OOG diver is breathing from OC stage that is easily dropped during hand off.  Emphasize how a distressed diver may require extra assistance from buddy, but require that each diver in training show proficiency. 

 

 

Constant Mass Flow CMF

(*Confined Water Skill – essential for all divers with Oxygen Orifice to understand the metabolic flow rate)

  • Diver in classroom set up has measured IP of oxygen first stage to get relative pressure to flow relationship, having read Paul’s article on orifice.

  • Diver in classroom may have access to Dwyer .5 to 1.5 LPM flow meter and has tested the orifice for flow rate.

  • In shallow water pool the diver will swim maintaining a .70 Po2 (for eCCR the e set point is modified to .50 )

    • At steady .70 manually operated set point, diver stops and lays on bottom of pool

    • For :05 minutes diver monitors Po2 display

    • If Po2 creeps up, then oxygen flow exceeds resting oxygen metabolic rate

    • If Po2 slowly decreases, then oxygen flow is less than resting metabolic rate

 

*Confined Water – Note

*OW – note if Hybrid eCCR diver has completed pool skill with desired results, AND has Po2 spiking issues on deeper dives then more attention needs to be paid to the flow rate.  Especially since diver only uses e Set Points during last two dives, the manual addition does not always flag a higher flow rate.  However an e Set Point may during a swim on gentle slopes (not walls) creep up and exceed Po2. 

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