When in a dive do equipment failures seem to happen

Tom Rose · 8th November 2007, 11:54

This is split off the thread on the new Cis Lunar.

The discussion got around to the size of the bailout/dil bottle on the new rebreather and for dives in shallow water 120 or so feet that still end up as decompression dives due to time at depth. It occurred to me that except for one time I made a stupid design error and fell into my own trap *, my systems have always failed early in the dive, due to leaks or failure of O2 sensing. Since I am using a MCCR, I have no ECCR failure problems and I got out of cave diving many years ago.

This thread is to discuss this issue and will help provide some good information on failure times and that impacts how much gas you really need to take for bailout.

Thanks in advance for the lively discussion.

Tom

*Ok here is what happened....I had put hoses that were too short on an RGU when I changed to a longer counterlung. Coming out from under a wreck at 60 or so feet, I looked up and the mouthpiece came out of my mouth with a flood of bubbles. After I stopped laughing at myself, I switched to OC and swam up and in. I did not even try try the unit again in the water. At the beach, I opened it up and my crystal water trap had prevented any problems and the unit was usable. The only casualty was the dive and the disposition of my dive buddy of 16 years who saw all those bubbles and my mouth open as I was laughing out more bubbles.....until he saw me go to OC and give him a thumbs up.

dave t · 8th November 2007, 13:16

I think not doing proper predive checks and missing badly connected hoses or whatever will show up in the first few moments of the dive, the possibility of sensors going bad is more likely the longer you are in the water due to condensation , heat/cold and pressure, electronics can freak when the hell they like but sods law says its just when its the most difficult time for the diver.
Most rebreathers these days are well built and mechanically they are pretty robust. If you carry bailout gas it should be sufficient to get you out from the worst case point of the dive and I guess that is at or near the end of the bottom time

Dave

***Decodiver*** · 8th November 2007, 19:15

Hi Tom,

I always believed floods would happen early on then I had one, with a full caustic cocktail, 130 minutes into a dive.

Now I believe it can happen whenever, there is no hard and fast rule.

I still love my rebreathers, but I'm sure they talk at night how they want to off me from this mortal coil!!

As Dave says though, bailout is the key to survival. Without it I would have died at least 3 times.

That does not bear thinking about.

Cheers,

Dave Cooper.

Mark Chase · 8th November 2007, 19:38

I have only ever witnessed one totally flooded unit and it happened on the planned ascent following about 40mins at 65m.

Prior to that i had always thought floods would happen early but i guess i was wrong.

ATB

Mark

8th November 2007, 11:54	#1 (permalink)
Tom Rose Still Learning Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Prism Topaz Other CCR Home Build Join Date: Oct 2005 Location: USA,North Carolina Posts: 330	When in a dive do equipment failures seem to happen This is split off the thread on the new Cis Lunar. The discussion got around to the size of the bailout/dil bottle on the new rebreather and for dives in shallow water 120 or so feet that still end up as decompression dives due to time at depth. It occurred to me that except for one time I made a stupid design error and fell into my own trap , my systems have always failed early in the dive, due to leaks or failure of O2 sensing. Since I am using a MCCR, I have no ECCR failure problems and I got out of cave diving many years ago. This thread is to discuss this issue and will help provide some good information on failure times and that impacts how much gas you really need to take for bailout. Thanks in advance for the lively discussion. Tom Ok here is what happened....I had put hoses that were too short on an RGU when I changed to a longer counterlung. Coming out from under a wreck at 60 or so feet, I looked up and the mouthpiece came out of my mouth with a flood of bubbles. After I stopped laughing at myself, I switched to OC and swam up and in. I did not even try try the unit again in the water. At the beach, I opened it up and my crystal water trap had prevented any problems and the unit was usable. The only casualty was the dive and the disposition of my dive buddy of 16 years who saw all those bubbles and my mouth open as I was laughing out more bubbles.....until he saw me go to OC and give him a thumbs up. __________________ The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time. www.atlimp.com
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8th November 2007, 13:16	#2 (permalink)
dave t Custom Title Allowed! Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss Dolphin Ray Azimuth Home Build Other Rebreather/s: Dolphin Ray Azimuth Home Build Join Date: May 2005 Location: UK Posts: 654	Re: When in a dive do equipment failures seem to happen I think not doing proper predive checks and missing badly connected hoses or whatever will show up in the first few moments of the dive, the possibility of sensors going bad is more likely the longer you are in the water due to condensation , heat/cold and pressure, electronics can freak when the hell they like but sods law says its just when its the most difficult time for the diver. Most rebreathers these days are well built and mechanically they are pretty robust. If you carry bailout gas it should be sufficient to get you out from the worst case point of the dive and I guess that is at or near the end of the bottom time Dave
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8th November 2007, 19:15	#3 (permalink)
*Decodiver* Administrator Current Rebreather/s: Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Sport Kiss Classic Kiss rEvo Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,179	Re: When in a dive do equipment failures seem to happen Hi Tom, I always believed floods would happen early on then I had one, with a full caustic cocktail, 130 minutes into a dive. Now I believe it can happen whenever, there is no hard and fast rule. I still love my rebreathers, but I'm sure they talk at night how they want to off me from this mortal coil!! As Dave says though, bailout is the key to survival. Without it I would have died at least 3 times. That does not bear thinking about. 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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8th November 2007, 19:38	#4 (permalink)
Mark Chase I go down for ages Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,561	Re: When in a dive do equipment failures seem to happen I have only ever witnessed one totally flooded unit and it happened on the planned ascent following about 40mins at 65m. Prior to that i had always thought floods would happen early but i guess i was wrong. ATB Mark __________________ Is it supposed to make that noise ? I took my unit to the dive shop and demanded they bolt on every thing that would fit. Join my elite diving teem and get a Tshirt "Doing It Chasey"Hammerhead Eccr Advanced Diving System
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