+ Reply to Thread
Page 1 of 5 1 2 3 4 5 LastLast
Results 1 to 10 of 43

Thread: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

  1. #1
    Jakob Selbing jaksel will become famous soon enough jaksel will become famous soon enough jaksel will become famous soon enough jaksel's Avatar
    Join Date
    Oct 2008
    Location
    Stockholm
    Posts
    178
    AP Evolution+

    Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Earlier this year a serious CCR-related incident occured to a diver I know (he wishes to remain anonymous). On a dive to 52 meters, using an APD Inspiration, two out of 3 cells failed simulatenously and with closely matching cell voltages, while the third cell continued to operate properly. This caused the setpoint controller to reject the single functioning cell and instead derive its measured ppO2 from two current-limited cells.

    I think many CCR divers can learn something from this story, and this prompted me to ask the diver if I could post his story here, which he agreed to. Attached you will find a screen shot of the graph showing depth and ppO2 (a bit hard to read due to the resolution limitations when uploading images).

    I have also attached APD's reply to the incident.

    The diver's description

    This is the new story about my experiences of oxygen cells.

    After the dives below, the cell voltages (in air) were measured to:
    135072 to 12,3 mv (Cell no 1)
    135071 to 10,0 mv (Cell 2 or 3)
    135073 to 9,9 mv (Cell 2 or 3)

    Those values sounds fair, don’t they?

    Let’s now see what happened during the dives just before I measured them.

    Dive No. 1 (day 1), depth 32 meter, vis 1 meter.
    Everything worked fine. As usual I got a cell warning when I went to high setpoint. At the end of the dive I flushed O2 and all cells could show above 1,53 at 5,4 metre.

    Dive No. 2 (day 14), depth 52 metre, vis 1-2 metre.
    This is the messdive where two cells freaked out.

    When I turn to high setpoint the beep started and I got the usual cell Warning. Since this happened regularly when I turn on high setpoint, I just check the display and noticed that two cells where in proper values and I kept on to the bottom. Cell 1 was rising, but the others were still fair to me. Here I made my great misjudgment and thought that no 1 was the wrong cell and the other worked fine. There was not in my mind that two, recently checked, cells suddenly should fail. Since the beeper kept making noise I couldn’t hear the solenoid operating. So I just checked that I felt OK and continued the dive. After 10 min I started to feel some discomfort, and when I checked the PPO2 at that time it was 2,16 - 1,18 - 1,34. I was still thinking that no 1 was was the wrong one, but started to flush diluent without noticing any change. I then thought the discomfort was because of the stress from all noise, the trawl and the bad vis, but I called the dive and we started to go back to the line again. No 1 had now reached 2,55 and my discomfort was escalating so I kept on flushing diluent. At first we couldn’t find the line so we had to search for some minutes since I felt that I was no longer in the shape to make a long silty ascent without the line. When I found the line I felt a great discomfort, could hardly breathe and my lips had started to flap like the wings of a hummingbird. I immediately went over to OC, but now I was so dizzy that I couldn’t change the computer to OC and had great problems staying on the OC-regulator, keep telling myself that that was an OK gas to breathe. Anyway, I started the ascent and somewhere here I got a feeling that the solenoid where filling up the loop so I closed the O2 valve and reached 21 m where I changed to my decogas. Now things started to feel better and I changed the computer to OC although I didn’t set on the exact gasmix since I was rather exhausted and I was ascending on my manual decoplan. The rest of the ascent went on smoothly.

    After the dive I could see one warning for high O2 at 20:14-20:18 but only there. Seams peculiar to me since I thought a high O2 warning always are displayed even if only one sensor is above 1,6 and I’m pretty sure I was on high oxygen on this dive.

    Dive No. 3 (day 14), depth 18 metre, vis 6-8 metre.
    After changing cell no 2 and 3 to new ones I flushed O2 at different depths. I did get some cell warnings but for most of them I couldn’t see any strange figures on the display. I even got at cell warning at surface all cells where showing 0,70-0,71. Strange, but I decide that everything worked good enough for further diving.

    Dive No. 4 (day 15), depth 52 metre, vis 1-2 metre.

    When I turned on to high setpoint, cell no 1 couldn’t show above 1,1.
    Though the others two now worked fine I changed back to low setpoint and manually flushed O2 to get the PPO2 as close to 1.0 I could. At this time I was so tired and frustrated both at the annoying beeper, but also to all sensors. The dive went on smoothly, but I did get a long deco.

    Dive No 5 (day 15), depth 26 metre, vis 1-2 metre.
    I again flushed O2 at different depth and noticed that cell no 1 could reach above 1,3 at lower depth but not below 10 m!

    Ergo:
    - 3 cells show a proper value at lower depth even after all 3 have stopped working at depth within 24 hours.
    - One can’t thrust what you measure the cell at surface.
    It might not work at depth even if the value was OK at surface.
    - One can’t thrust a cell even though it can reach 1,6 at 6 meters.
    You never know what will happened until you reach your final depth.
    - There can be something strange about high oxygen warnings.

    Hints from the manufacturer (APD)

    Once you get that kind of swing on the O2 cells, it is essential to completely change the gas in the loop for diluent. You may have added diluent but the dil flush was not anywhere near long enough or done properly. In this situation you would probably be fighting the solenoid so you’d have to do something drastic like shut the O2 cylinder valve just temporarily until after you had completed your check but such wide disparity calls for prompt and effective action. Thankfully you had the gumption to go open circuit once the physical symptoms started to manifest themselves.
    An alternative test, which you have been doing later, is to check for current limited cells by adding some O2 to makes sure the PO2 rises, in this case, 2 and 3 wouldn’t have risen and you’d have then known early on what the problem is and perhaps bailed out earlier.
    When you get your new cells: do a calibration and note what values they get to during “flushing” just before “calibrating” is displayed on the screen. Then, as you calibrate in future, keep an eye on those values and be wary of downward or upward trends.
    Attachments Pending Approval

  2. #2

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    It's not in the story so I was curious how the predive cell calibration went with O2?

    Also not in the story, did your friend do a 6m O2 flush at the start of the dive to check for limited cells?

  3. #3
    aka Scotty com1 will become famous soon enough com1 will become famous soon enough com1 will become famous soon enough com1's Avatar
    Join Date
    May 2007
    Location
    Frankfurt & Budapest
    Posts
    362
    inspiration vision

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Had something similar a few weeks ago.
    During the dive 2 cells became current limited. at 1.29 and the other at 1.35 . I spotted it a 70m, the values did not change between 2 checks (I check my handsets regularly). I decided to add a bit O2 but still no change, only Cell 3 was going towards 2.00.

    Called the dive, switched to SP 0.7 and stayed on the loop constantly verifying the function of the 3rd cell.

    The 3rd died on the way to the pressure pot and showed an unexpected behavior, 10mV in Air, 81mV at PO2 of 2, 80mV at PO2 of 1! Than going back to ambient conditions in air the sensor was showing around 40mV going slowly towards 10mV (took around 30 minutes).

    Cheers Scotty

  4. #4
    The raffle shiest-er Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth is just really nice Garth's Avatar
    Join Date
    Jan 2011
    Location
    Mooresville, North Carolina
    Posts
    638
    Hammerhead Extreme eCCR

    Interesting. Cell warnings and you kept diving?

    I've not been trained yet but that struck me as odd. Glad you are okay.


    Sent from my She-er-water Per-redator!

  5. #5
    RBW Member osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris is a splendid one to behold osiris's Avatar
    Join Date
    Feb 2006
    Location
    Auckland
    Posts
    1,382
    HH INSPO HYBRIB BASTARDISED MK

    KISS/IDA64/72/60/Mk15/Cobra

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Lessons learned there I should think. Thank goodness he got out of it Ok.

    Drills, Drills, Drills - if the world has gone bonkers and one is in a situation, it's the drills that will get you out of it.

    I'm hoisting aboard your mate's experience myself and I'll be in the pool practicing my dill flush and b/out drills.

    Thanks for posting this and all the best to your mate.

  6. #6
    RBW Member PatB is an unknown quantity at this point PatB's Avatar
    Join Date
    Nov 2007
    Location
    MA
    Posts
    66
    Inspiration Vision

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    How old and what brand cells?

  7. #7
    RBW Member jukkao is on a distinguished road jukkao is on a distinguished road jukkao's Avatar
    Join Date
    Apr 2005
    Location
    Finland
    Posts
    113

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Thanks for sharing.

    I consider driving manually as these problems continues. I have been lucky so far and succeeded to make the right guessing. I do not like aborting dives. I flush to the right lung when I like to change the mix. It is more effective if you like to change the whole mix in the loop or just to check the cells. Just be carefull not to flush with O2.

    Jukka

  8. #8
    Supporting Member Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36 has a reputation beyond repute Dsix36's Avatar
    Join Date
    Aug 2007
    Location
    Deerfield_Beach, Florida
    Posts
    4,023
    rEvo

    Defender Optima Dolphin

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Thanks to both you and your friend for posting this dive report. I am glad that everything worked out and did not end in a fatality. It is a good reminder for us that cells can and will try to kill us if we do not keep our wits and follow our training
    .
    I guarantee that if you CLICK HERE you will not have your view blocked by clothing





    Quote Originally Posted by kwinter  View Original Post
    I could just be blowing smoke out my butt.
    Quote Originally Posted by kwinter  View Original Post
    And note the wisdom from DSix36
    MY ADVICE AND POSTS ARE WORTH EXACTLY WHAT YOU PAID FOR THEM!!!!!!
    POLITICAL CORRECTNESS IS SO YESTERDAY AND I AM DONE WITH IT!!!!!

  9. #9
    RBW Member paca_mike is an unknown quantity at this point paca_mike's Avatar
    Join Date
    Nov 2011
    Posts
    47
    Meg

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Hello,

    First thanks to share the incident and glad to see your friend is still with us

    Do you think , it's possible to know the diluant gas and bail out gas during the dives

    Thanks

  10. #10
    RBW Member Paul S is on a distinguished road Paul S is on a distinguished road Paul S's Avatar
    Join Date
    Sep 2008
    Location
    UK, Twickenham
    Posts
    147
    rEvo III Mini hCCR

    Re: Serious incident (hyperoxia) when 2 cells fail simulatenously and identically

    Firstly, glad they made it out OK. I hope that goes without saying, but it's nice to say anyway.

    Second in the interest of learning from this, and not criticising anyone, a couple of things I noticed.

    Quote Originally Posted by jaksel  View Original Post
    After the dives below, the cell voltages (in air) were measured to:
    135072 to 12,3 mv (Cell no 1)
    135071 to 10,0 mv (Cell 2 or 3)
    135073 to 9,9 mv (Cell 2 or 3)
    Are those serial numbers? If so that suggests that all three cell have exactly the same manufacture dates and history.

    After 10 min I started to feel some discomfort, and when I checked the PPO2 at that time it was 2,16 - 1,18 - 1,34
    We're in one of two situations here:
    1. We're breathing ~1.2, and cell 1 is rocketing high
    2. We're breathing ~2.2, and cells 2 & 3 are current limited.
    I'm under the impression that cells going high is fairly rare, and given cells of the same age and history, what are the chances of two going together. I'd think situation 2 is probably the more likely one, especially as we're not feeling good. Of course, when we're not feeling good we're not likely to think it through like this.

    Dive No. 2 (day 14), depth 52 metre, vis 1-2 metre.
    This is the messdive where two cells freaked out.
    [....]
    Dive No. 3 (day 14), depth 18 metre, vis 6-8 metre.
    He got back in! Take the day off. Give your body a chance to recover. (Ok, maybe that one is a little critical )

    I basically agree with APDs notes, a Dil-flush would have been the right reaction, but it's difficult to do when you're fighting a solenoid you're not aware is firing because the alarm is masking the sound (diver's observation). Then there's the fact it may not show that the cells are limited. Depends on the diluent and depth.

    Also, through it all I wonder why controllers (All controllers, not just APD) don't notice they're injecting O2, and we're descending, but the readings aren't rising. Surely that's a detectable cause for concern.

    Thanks for the report. It's an interesting / educational chain of events to think about.

+ Reply to Thread
Page 1 of 5 1 2 3 4 5 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts