total loop failure ?

OceanOpportunity · 30th July 2007, 00:52

Looking for some discussion on total loop failures:

Who has had one? Caused by what (human or equip error)? What exatly failed? How was the dive aborted? From a training perspective, did you feel well-prepared to deal with the issue?

Bahamacave · 30th July 2007, 03:30

Hey there Mike,
Hope all is well with you up north. Just signed up for this site. Seems cool. Anyway, I had a cave rebreather student diving a KISS when she had a caustic cocktail. We were at 1600' penetration at a depth of 145 feet.

She was going through a restriction in a head-down orientation which put water into the scrubbing medium. We did a bubble check before and after the dive and found nothing wrong with the unit. We can only assume that she was allowing water to seep by her mouthpiece...she has changed to a different mouthpiece now and has never repeated the problem.

When the loop flooded, she immediately switched to O/C (stage on her left side) while she was still in the restriction. She signaled me and her husband and we immediately called the dive and headed out. We swapped stages when she breathed down 1500 psi from her al. 80 bailout. We reached the entrance before she had to do another swap with her husband.

I feel she did a great job considering where we were and what happened. The only reminder I had to give her during the incident was to change over to O/C on her VR-3. Deco was uneventful though she did try to take another sip off the loop during deco just to see if it was still caustic...that bit of curiosity got her a blister on the inside of her lip from chemical burn.

Hope this is the type of stuff you were looking for. Take care Mike and safe diving,
Brian

***Decodiver*** · 30th July 2007, 10:17

I have had two.

One in 1989, was caused by equipment failure, the rig was damaged entering the water, I was about 30 cm underwater at the time and aborted relatively safely.

The second was last year, again equipment failure 130 minutes into a dive and I was at 18 metres. Over-pressure valve was the probable suspect.

I knew what it was on both occasions and yes my training kept me alive.

Cheers,

Dave Cooper.

Drmike · 30th July 2007, 12:37

Ive had a few.

User error/gear failure:- Leaking dsv made frequent hose clearing necessary, on one clearing forgot to close mouthpiece and flooded unit (cave, 50m+, 800m+ to exit)

User error:- switching between rbs forgot to close mouthpiece

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

User error:- forgot to close bailout Rebreather mouthpiece on descent

Gear failure:- O-ring failure BOV fully flooded scrubber

...There may have been others i forget

***caveseeker7*** · 30th July 2007, 12:57

You might wanna look for a 2nd hand Fieno DSV, Mike.

OceanOpportunity · 30th July 2007, 13:55

Quote: (Originally Posted by Drmike)

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

Gear failure:- OPV leaked fully flooded scrubber

jeepers....hope that OPV has been replaced!

all of this is helpful. I'm trying to assemble information on two fronts, one: identify areas for potential mechanical improvement to avoid this worst case scenario, and two: identify areas that can be more strongly emphasized pre-dive to avoid a TLF, be it identify a potential mechanical problem, or user oversight..

keeep them coming!

mathias · 30th July 2007, 15:12

ive had one, on my first Rebreather dive !
Gear failure:- OPV leaked, fully flooded scrubber (Dräger Dolphin)

DZLHED · 2nd August 2007, 06:08

Me too.

While assembling the counter lung (Mk15) I clamped it too tight and bunched it up. Passed the neg pressure test and I didn't block the opv to do a pos test. Slow leak over the course of the dive. Nursed it along as the dive was 80ft for 3hrs. Finally lost the loop near the end of the dive and switched to open for the swim in. Fussed with and attempted to maintain the loop as long as possible. Interesting experience. Nice aftertaste.

silent running · 2nd August 2007, 07:53

Quote: (Originally Posted by OceanOpportunity)

Looking for some discussion on total loop failures:

Who has had one? Caused by what (human or equip error)? What exatly failed? How was the dive aborted? From a training perspective, did you feel well-prepared to deal with the issue?

I guess it all depends on how "total" is total. Is a total flood one which happens suddenly and totally? Or one which will become total if not noticed?

By the later definition, I had 3, number 1 was on a Drager Dolphin. P-port felt engaged but wasn't. Passed neg and pos and came loose about 5 minutes into the dive. Luckily, it was a shallow dive and I was able to get to the surface on the loop easily with most of the scrubber filled. Noticed that the unit got heavy, started to breathe very poorly, gurgled loudly and I knew imediately what it was. I could've bailed OC to the onboard gas, but I wanted to see if it was still possible to get to the surface with the scrubber flooded from 60ft. It was, no big deal, stayed vertical the whole time, so no cocktail. I wasn't trained for it, but I had enough hrs on the thing to stay calm and think it through. I should have tugged hard on all the P-ports, and did from then on.

It seems to me, that short of fully flooding a BO rebreather, most people would notice any leak big enough to flood more than say 1/3 of the scrubber material as the WOB does start increase noticeably. If you can stay more vertical than not and have some way of trapping the fluid somewhere in the loop with either a hydrophobic membrane or in the bottom of your over the shoulder lungs, it would be manageable for quite a while.

The flood number 2 was from a rip btw the hose fitting in the top of my exhale lung on my Prism. The rip had happened during transit, was very small, and got worse as the trip progressed. I thought my loose OPV was the cause of the bad neg tests, as it often was. I had about 3 cups of water in there and didn't even know it until I finshed the dive, which was slightly over 3 hrs. Very little of the water made it into the scrubber due to the fact that the lungs held so much volume and that the hose fittings are located high enough up to keep the water mostly at the bottom in all but an inverted position. I fixed it with some aquaseal and dove the following day and for the rest of the trip without a problem.

Flood number 3 may not even qualify, it was from pinched scrubber o-rings and the tell tale bubbles were noticed by my dive buddy during descent. I aborted the dive, stayed on the loop and surfaced. Very little water made it in and stayed on the bottom of the scrubber in the trap, didn't even get the scrubber material wet. I fixed the o-ring and was back in the water in 15 minutes. The Prism has a transparent scrubber bucket and the seals are visable for about 85% of the circumference. I hadn't looked at the seal close enough and didn't due a pressure test that morning as I had had no trouble with the unit during the trip. I also forgot how old the o-rings were-2 yrs and compressed and floppy-and should have changed them before the trip, one of ther hazards of infrequent diving. My new back plate allows for inspection of the entire circumference of the bucket sealing O-rings, shouldn't happen again.

All mine were operator error and could have been easily avoided with more diligence. But all these experiences do make we wonder if an OPV really is that crucial. Mine was a continual source of bad neg tests and became the scape goat for other problems-who would not vent out of their nose/mouth in the event of an over expansion? Sure I was not as patient and diligent with the pressure tests, but because I don't disassemble my unit everyday and could see the scrubber o-rings almost all the way around, I became a bit complacent-bad. I also now make sure to do dip tests as often as I can, which has also helped me spot a few bad LP hose crimps, something that would not be found during pressure tests...

Mdemon · 2nd August 2007, 10:19

Not total loop failure, but loop failure nonetheless: On my MOD1 I got a noisy, gurgly breathe. I bailed after a few minutes because I wasn't sure - my instructor pointed out that I had managed to unscrew the dil inflator at some stage and there was now a counterlung with some water in it.

Same happened to someone else, only it was the O2 inflator.

Quite reassuring really, that on my unit (Classic) I can have a big hole and the thing still works OK.

30th July 2007, 00:52	#1 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 595	total loop failure ? Looking for some discussion on total loop failures: Who has had one? Caused by what (human or equip error)? What exatly failed? How was the dive aborted? From a training perspective, did you feel well-prepared to deal with the issue? __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
(Online)

30th July 2007, 03:30	#2 (permalink)
Bahamacave New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Dec 2006 Location: Abaco Island, Bahamas Posts: 6	Re: total loop failure ? Hey there Mike, Hope all is well with you up north. Just signed up for this site. Seems cool. Anyway, I had a cave rebreather student diving a KISS when she had a caustic cocktail. We were at 1600' penetration at a depth of 145 feet. She was going through a restriction in a head-down orientation which put water into the scrubbing medium. We did a bubble check before and after the dive and found nothing wrong with the unit. We can only assume that she was allowing water to seep by her mouthpiece...she has changed to a different mouthpiece now and has never repeated the problem. When the loop flooded, she immediately switched to O/C (stage on her left side) while she was still in the restriction. She signaled me and her husband and we immediately called the dive and headed out. We swapped stages when she breathed down 1500 psi from her al. 80 bailout. We reached the entrance before she had to do another swap with her husband. I feel she did a great job considering where we were and what happened. The only reminder I had to give her during the incident was to change over to O/C on her VR-3. Deco was uneventful though she did try to take another sip off the loop during deco just to see if it was still caustic...that bit of curiosity got her a blister on the inside of her lip from chemical burn. Hope this is the type of stuff you were looking for. Take care Mike and safe diving, Brian __________________ It's Better in the Bahamas.
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30th July 2007, 10:17	#3 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,194	Re: total loop failure ? I have had two. One in 1989, was caused by equipment failure, the rig was damaged entering the water, I was about 30 cm underwater at the time and aborted relatively safely. The second was last year, again equipment failure 130 minutes into a dive and I was at 18 metres. Over-pressure valve was the probable suspect. I knew what it was on both occasions and yes my training kept me alive. Cheers, Dave Cooper. __________________ CCR/OC Trimix Instructor Trainer CCR Training to Mixed Gas in Switzerland, France, UK & Germany on Megalodon/COPIS-Megalodon/KISS/Sport KISS/Ouroboros/rEvo/Inspiration/Evolution/Sentinel www.zerogravitydiving.com Rebreather World Terms & Conditions
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30th July 2007, 12:37	#4 (permalink)
Drmike RBW Member Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,378	Re: total loop failure ? Ive had a few. User error/gear failure:- Leaking dsv made frequent hose clearing necessary, on one clearing forgot to close mouthpiece and flooded unit (cave, 50m+, 800m+ to exit) User error:- switching between rbs forgot to close mouthpiece Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber User error:- forgot to close bailout Rebreather mouthpiece on descent Gear failure:- O-ring failure BOV fully flooded scrubber ...There may have been others i forget __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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30th July 2007, 12:57	#5 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,555	Re: total loop failure ? You might wanna look for a 2nd hand Fieno DSV, Mike. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
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30th July 2007, 13:55	#6 (permalink)
OceanOpportunity for a world of water Current Rebreather/s: Other CCR Dolphin Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Other CCR Dolphin Home Build Join Date: Nov 2006 Location: Providence, RI USA Posts: 595	Re: total loop failure ? Quote: (Originally Posted by Drmike) Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber Gear failure:- OPV leaked fully flooded scrubber jeepers....hope that OPV has been replaced! all of this is helpful. I'm trying to assemble information on two fronts, one: identify areas for potential mechanical improvement to avoid this worst case scenario, and two: identify areas that can be more strongly emphasized pre-dive to avoid a TLF, be it identify a potential mechanical problem, or user oversight.. keeep them coming! __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Elected Director, Society for Human Performance in Extreme Environments MN'07, The Explorers Club Project Manager, Diving a Dream
(Online)

30th July 2007, 15:12	#7 (permalink)
mathias Ouroboros #31 Current Rebreather/s: Ouroboros Other Rebreather/s: Not Bought Yet Inspiration Classic MK 15.X Join Date: Sep 2006 Location: Switzerland - Murten Posts: 189	Re: total loop failure ? ive had one, on my first Rebreather dive ! Gear failure:- OPV leaked, fully flooded scrubber (Dräger Dolphin) __________________ Our dreams are other people's nightmares ;-) Plus près du fond, plus loin des cons !
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2nd August 2007, 06:08	#8 (permalink)
DZLHED Todd Winn VP NSE Current Rebreather/s: Inspiration Vision MK 15.X Other CCR Other Rebreather/s: Inspiration Classic Sport Kiss Classic Kiss Other CCR Join Date: Jun 2005 Location: Maui County, Hawaii Posts: 103	Re: total loop failure ? Me too. While assembling the counter lung (Mk15) I clamped it too tight and bunched it up. Passed the neg pressure test and I didn't block the opv to do a pos test. Slow leak over the course of the dive. Nursed it along as the dive was 80ft for 3hrs. Finally lost the loop near the end of the dive and switched to open for the swim in. Fussed with and attempted to maintain the loop as long as possible. Interesting experience. Nice aftertaste. __________________ Aloha, Dieselhead To err is Human... to ccr, Divine. www.NorthShoreExplorers.com
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2nd August 2007, 07:53	#9 (permalink)
silent running Mature mouth breather Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Jun 2005 Location: U.S.A. Brooklyn, New York Posts: 1,873	Re: total loop failure ? Quote: (Originally Posted by OceanOpportunity) Looking for some discussion on total loop failures: Who has had one? Caused by what (human or equip error)? What exatly failed? How was the dive aborted? From a training perspective, did you feel well-prepared to deal with the issue? I guess it all depends on how "total" is total. Is a total flood one which happens suddenly and totally? Or one which will become total if not noticed? By the later definition, I had 3, number 1 was on a Drager Dolphin. P-port felt engaged but wasn't. Passed neg and pos and came loose about 5 minutes into the dive. Luckily, it was a shallow dive and I was able to get to the surface on the loop easily with most of the scrubber filled. Noticed that the unit got heavy, started to breathe very poorly, gurgled loudly and I knew imediately what it was. I could've bailed OC to the onboard gas, but I wanted to see if it was still possible to get to the surface with the scrubber flooded from 60ft. It was, no big deal, stayed vertical the whole time, so no cocktail. I wasn't trained for it, but I had enough hrs on the thing to stay calm and think it through. I should have tugged hard on all the P-ports, and did from then on. It seems to me, that short of fully flooding a BO rebreather, most people would notice any leak big enough to flood more than say 1/3 of the scrubber material as the WOB does start increase noticeably. If you can stay more vertical than not and have some way of trapping the fluid somewhere in the loop with either a hydrophobic membrane or in the bottom of your over the shoulder lungs, it would be manageable for quite a while. The flood number 2 was from a rip btw the hose fitting in the top of my exhale lung on my Prism. The rip had happened during transit, was very small, and got worse as the trip progressed. I thought my loose OPV was the cause of the bad neg tests, as it often was. I had about 3 cups of water in there and didn't even know it until I finshed the dive, which was slightly over 3 hrs. Very little of the water made it into the scrubber due to the fact that the lungs held so much volume and that the hose fittings are located high enough up to keep the water mostly at the bottom in all but an inverted position. I fixed it with some aquaseal and dove the following day and for the rest of the trip without a problem. Flood number 3 may not even qualify, it was from pinched scrubber o-rings and the tell tale bubbles were noticed by my dive buddy during descent. I aborted the dive, stayed on the loop and surfaced. Very little water made it in and stayed on the bottom of the scrubber in the trap, didn't even get the scrubber material wet. I fixed the o-ring and was back in the water in 15 minutes. The Prism has a transparent scrubber bucket and the seals are visable for about 85% of the circumference. I hadn't looked at the seal close enough and didn't due a pressure test that morning as I had had no trouble with the unit during the trip. I also forgot how old the o-rings were-2 yrs and compressed and floppy-and should have changed them before the trip, one of ther hazards of infrequent diving. My new back plate allows for inspection of the entire circumference of the bucket sealing O-rings, shouldn't happen again. All mine were operator error and could have been easily avoided with more diligence. But all these experiences do make we wonder if an OPV really is that crucial. Mine was a continual source of bad neg tests and became the scape goat for other problems-who would not vent out of their nose/mouth in the event of an over expansion? Sure I was not as patient and diligent with the pressure tests, but because I don't disassemble my unit everyday and could see the scrubber o-rings almost all the way around, I became a bit complacent-bad. I also now make sure to do dip tests as often as I can, which has also helped me spot a few bad LP hose crimps, something that would not be found during pressure tests...
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2nd August 2007, 10:19	#10 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,946	Re: total loop failure ? Not total loop failure, but loop failure nonetheless: On my MOD1 I got a noisy, gurgly breathe. I bailed after a few minutes because I wasn't sure - my instructor pointed out that I had managed to unscrew the dil inflator at some stage and there was now a counterlung with some water in it. Same happened to someone else, only it was the O2 inflator. Quite reassuring really, that on my unit (Classic) I can have a big hole and the thing still works OK. __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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