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**PhilSiswick** · 31st March 2008, 07:48

Quote: (Originally Posted by mattmexico)

yo

Particular to mCCR I had an incident a couple of month ago that had a ccr cave diver student in a high stress and work load situation on a mCCR doing a zero viz exit out of a cave ... and it could have been out of a wreck too .... and had me on my toes.

While doing a high stress, high work load, high breathing zero viz exit out of a cave a mCCR diver exeeded his active O2 injection rate of his mCCR. While I was told by the diver upon inquiry how he is going to deal with the situation ahead of time and prior to the dive I was told he is gonna count to 120 and then inject some O2.

In the heat of battle so to speak I had to abort the drill as I realized the diver was at at a normoxic Po2 level and was about to exit the cave in the final stage, means coming up shallow and going back to the entrance - surface.

I amin my opinion confident that the diver would have suffered a hypoxic event even when only coming from about 40 feet - 12 meters ... but again he was at .21 when at depth.

My point here is not so much to point fingers or make a big fuzz, it just got me thinking about mCCR in zero viz situations, especially when under high stress and work load.

Just wanted to let the forum know about this potential issue that was prevented and how to overcome it in future procedure.

greetings
Matt

I'm not a cave diver, so don't know exactly what zero vis means (I know, I know). Would a HUD have helped in this circumstance, or is this the point where only an audible or vibrating warning would have helped?

I know that mCCR is statistically safer than eCCR - not a debate I want to start again

, but this risk and that of the surface hypoxia that has been reported here a few times is one of the factors that led me to eCCR (i.e I'm monitoring the active management of the system, rather than both managing it and monitoring myself managing it). I'm wondering whether a Diva or Inspo like buzzer would contribute to maintaining the mCCR safety record?

Thanks for posting.

Cheers,

31st March 2008, 07:48	#3 (permalink)
PhilSiswick WSKD 0001 Current Rebreather/s: Evolution Other Rebreather/s: Inspiration Vision Join Date: Apr 2006 Location: Oxford, UK Posts: 902	Re: mCCR and zero viz exit Quote: (Originally Posted by mattmexico) yo Particular to mCCR I had an incident a couple of month ago that had a ccr cave diver student in a high stress and work load situation on a mCCR doing a zero viz exit out of a cave ... and it could have been out of a wreck too .... and had me on my toes. While doing a high stress, high work load, high breathing zero viz exit out of a cave a mCCR diver exeeded his active O2 injection rate of his mCCR. While I was told by the diver upon inquiry how he is going to deal with the situation ahead of time and prior to the dive I was told he is gonna count to 120 and then inject some O2. In the heat of battle so to speak I had to abort the drill as I realized the diver was at at a normoxic Po2 level and was about to exit the cave in the final stage, means coming up shallow and going back to the entrance - surface. I amin my opinion confident that the diver would have suffered a hypoxic event even when only coming from about 40 feet - 12 meters ... but again he was at .21 when at depth. My point here is not so much to point fingers or make a big fuzz, it just got me thinking about mCCR in zero viz situations, especially when under high stress and work load. Just wanted to let the forum know about this potential issue that was prevented and how to overcome it in future procedure. greetings Matt I'm not a cave diver, so don't know exactly what zero vis means (I know, I know). Would a HUD have helped in this circumstance, or is this the point where only an audible or vibrating warning would have helped? I know that mCCR is statistically safer than eCCR - not a debate I want to start again , but this risk and that of the surface hypoxia that has been reported here a few times is one of the factors that led me to eCCR (i.e I'm monitoring the active management of the system, rather than both managing it and monitoring myself managing it). I'm wondering whether a Diva or Inspo like buzzer would contribute to maintaining the mCCR safety record? Thanks for posting. Cheers, __________________ Phil No comment on open circuit... it's an evolutionary dead end not really worth discussing here. Dave Sutton, 2007 I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007 www.hugsac.org.uk
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