Is a BOW fast enough to save a life?

**Dave Sutton** · 6th June 2007, 13:07

Quote: (Originally Posted by Drmike)

Personally my first reaction/habit to any feeling of weirdness or inappropriate increased breathing rate is to exhale through my nose a few times and fire the adv.

DrMike hits the nail on the head yet again:

Nose-vent as exhaust and ADV as the demand valve *is* open circuit. It's a "hands free" BOV.

Assuming that the loop hoses are intact, it's can really stand as the definitive "fix", as long as the ADV has reasonable mechanical characteristics.

Venting and ADV replacement of the loop gas ought to be second nature. This opens up (yet again) the "keep your diluent sensible" argument, otherwise you have lost this extremely useful mode.

Dave

depth · 6th June 2007, 13:32

Quote:

Personally my first reaction/habit to any feeling of weirdness or inappropriate increased breathing rate is to exhale through my nose a few times and fire the adv. Aware now and sensitive of a possible issue I am ready to turn the bov (if im using one) or go to OC if the fresh gas doesnt show signs of illeviating the problem to a manageable level

In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv.

Drmike · 6th June 2007, 13:41

Quote: (Originally Posted by depth)

In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv.

its not as fast as going OC but its likely faster than fumbling for OC regs

The point is to get into the habit of using this method to halt the CO2 runaway train before it builds up enough momentum (Thinking more CO2 hit rather than O2 hit)

But in the case of a suspected O2 hit - I wouldnt hang around

I had a tingling lip once with 4hrs deco above me and I can tell you I hit that OC gas prity damn fast

as I clipped myself to the line

**nigelh** · 6th June 2007, 13:52

Quote: (Originally Posted by depth)

Ok, I see the points above. But I have never heard of a Rebreather diver actully identifying O2 or CO2 problems and succesfully switching to OC on a normal 2. stage or a BOW and recover!

I think you should find lots of these.
People who have seen high or low ppO2 and bailed in time.
People who have had scrubber problems and bailed.
That's why you are taught to always know your ppO2 and to come off the loop fast if you suspect a problem so you make your decisions breathing a known gas.

I messed up packing a scrubber and had to get of the loop by the Dr. Mike trick, scaring myself to death in the process. I then went out and bought a BOV so next time it would be a quick turn on the valve not a desperate mask flooding struggle.

You do get warning. Not much but even Cousteau describes diving an Oxygen rebreather to 45 feet (2.4bar), dumping his weight belt when he felt himself going twitchy and being hauled out by his surface team. After that happened twice he "lost interest in rebreathers".

Twice !$%&*!!

rdmmdr · 6th June 2007, 19:07

a good bov it the best thousand dollars ever spent. no worry about a loop flood durring a panic switch to oc. i have used mine many times while doing controller testing, and find it to be second nature now.

if in doubt, bail out.

rick

MHD · 6th June 2007, 20:39

Quote: (Originally Posted by depth)

Ok, I see the points above. But I have never heard of a Rebreather diver actully identifying O2 or CO2 problems and succesfully switching to OC on a normal 2. stage or a BOW and recover! (but maybe i'm just not searching hard enough ;-) I found articles that describes how the RB diver senses that something is wrong, and the next thing he/she wakes up in a hospital thanks to the buddy.

But maybe switching to OC when you feel something is not like it is supposed to be, it is allready to late, and breathing from OC will not suppress the reaction of the buddy (convulsion)?

You are hearing the worst of the worst so to speak, those that really end up scary. I have bailed out twice due to CO2 problems to OC. Both times I had huge amounts of anxiety as my predominant symptom and bailed out no problems to OC reg.

So now you have heard of 2 events

Matt

**Dave Sutton** · 6th June 2007, 23:22

Quote: (Originally Posted by depth)

In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv.

You can fully dump the loop in just a few seconds around the mouth or thru the nose, so this is not a practical issue to worry about. Maintaining reasonable loop volumes helps lots. If you have more than about 1.5 lung volumes in the CL, you are probably running excess loop volume.

Dave

jaap · 6th June 2007, 23:23

Quote: (Originally Posted by MHD)

You are hearing the worst of the worst so to speak, those that really end up scary. I have bailed out twice due to CO2 problems to OC. Both times I had huge amounts of anxiety as my predominant symptom and bailed out no problems to OC reg.

So now you have heard of 2 events

Matt

Yes something similar for me. I have had to abort still on the Rebreather or bailing out to OC a few times.Never had any high/low O2 issues that could not be handled on the loop. But I have had a one caustic cocktail and three CO2-hits. Did not have a BOV then (have them on two of my units now). At least one hit was really stupid, bad and fast eventually giving a feeling of imminent death. I did feel the thing coming but endured (very stupid). But since it was only on an o2-Rebreather, when the "death is coming"-feeling finally fell upon me I just went to the surface fast adding extra O2 on the way and was fine. Same with the cocktail. On one of the CO2 issues I was at ~ 42m and felt a creeping feeling of anixiety and unmotivated need to breath faster. Did a dil flush and felt OK. After a few minutes the same feeling came back so I did another dil flush as we turned back for the line up. After a while the interval of anxiety attacks got shorter so I did go semi closed for a while then over to OC without problems. Arriving at the 6m stop I went back to the loop to give it a try and stayed on it running on O2 only dumping the loop every few minutes just to stay safer.The last issue where a BOV could have been nice I was again foolishly pushing a failing loop. I started feeling my breathing go up and figured CO2 but stayed on the loop dumping it now and then. After a while the need to breath started going out of control so I bailed to OC. I really felt that had I not gotten off the loop in time my rate of breathing could have accelerated to a point where I could not have made the switch to OC. So from my own very limited experience from not so great depths I would say that if you know the drill and act as soon as you notice it you have time to go for your OC.

Explorer · 7th June 2007, 03:55

Quote: (Originally Posted by Drmike)

its not as fast as going OC but its likely faster than fumbling for OC regs

With my Golem BOV, it's a quick switch, then off to my OC regs. Just one step. It gets you off the loop in a blink of an eye.

Thanks again Jakub.

Drmike · 7th June 2007, 04:23

Quote: (Originally Posted by Explorer)

With my Golem BOV, it's a quick switch, then off to my OC regs. Just one step. It gets you off the loop in a blink of an eye.

Thanks again Jakub.

your point is?

1) I was comparing time to get fresh gas in your lungs via firing the adv/flushing the loop to fumbling for OC regs - read my post - it quite clear. I wasnt talking about BOVs

2) I think everyman and his dog knows how a bov works and how fast the switch is - its not a hard concept to grasp and hardly needs reiterating

3) Jakub is a jolly nice bloke indeed - but he didnt invent the BOV concept

you can stop hugging that meg now

6th June 2007, 13:07	#11 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,672	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by Drmike) Personally my first reaction/habit to any feeling of weirdness or inappropriate increased breathing rate is to exhale through my nose a few times and fire the adv. DrMike hits the nail on the head yet again: Nose-vent as exhaust and ADV as the demand valve is open circuit. It's a "hands free" BOV. Assuming that the loop hoses are intact, it's can really stand as the definitive "fix", as long as the ADV has reasonable mechanical characteristics. Venting and ADV replacement of the loop gas ought to be second nature. This opens up (yet again) the "keep your diluent sensible" argument, otherwise you have lost this extremely useful mode. Dave __________________ "Changes in Lattitudes, Changes in Attitudes, Nothing remains quite the same".... www.nobubblediving.com
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6th June 2007, 13:32	#12 (permalink)
depth Christian Rasmussen Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Denmark Posts: 191	Re: Is a BOW fast enough to save a life? Quote: Personally my first reaction/habit to any feeling of weirdness or inappropriate increased breathing rate is to exhale through my nose a few times and fire the adv. Aware now and sensitive of a possible issue I am ready to turn the bov (if im using one) or go to OC if the fresh gas doesnt show signs of illeviating the problem to a manageable level In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv. __________________ I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not qualified to make my own meg batteries!!! I am not.............
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6th June 2007, 13:41	#13 (permalink)
Drmike Custom Title Allowed! 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: 3,323	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by depth) In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv. its not as fast as going OC but its likely faster than fumbling for OC regs The point is to get into the habit of using this method to halt the CO2 runaway train before it builds up enough momentum (Thinking more CO2 hit rather than O2 hit) But in the case of a suspected O2 hit - I wouldnt hang around I had a tingling lip once with 4hrs deco above me and I can tell you I hit that OC gas prity damn fast as I clipped myself to the line __________________ 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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6th June 2007, 13:52	#14 (permalink)
nigelh New Member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 837	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by depth) Ok, I see the points above. But I have never heard of a Rebreather diver actully identifying O2 or CO2 problems and succesfully switching to OC on a normal 2. stage or a BOW and recover! I think you should find lots of these. People who have seen high or low ppO2 and bailed in time. People who have had scrubber problems and bailed. That's why you are taught to always know your ppO2 and to come off the loop fast if you suspect a problem so you make your decisions breathing a known gas. I messed up packing a scrubber and had to get of the loop by the Dr. Mike trick, scaring myself to death in the process. I then went out and bought a BOV so next time it would be a quick turn on the valve not a desperate mask flooding struggle. You do get warning. Not much but even Cousteau describes diving an Oxygen rebreather to 45 feet (2.4bar), dumping his weight belt when he felt himself going twitchy and being hauled out by his surface team. After that happened twice he "lost interest in rebreathers". Twice !$%&*!! __________________ nigelh
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6th June 2007, 19:07	#15 (permalink)
rdmmdr designer of death Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2006 Location: kerman,california Posts: 372	Re: Is a BOW fast enough to save a life? a good bov it the best thousand dollars ever spent. no worry about a loop flood durring a panic switch to oc. i have used mine many times while doing controller testing, and find it to be second nature now. if in doubt, bail out. rick
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6th June 2007, 20:39	#16 (permalink)
MHD Custom Title Allowed! Current Rebreather/s: Home Build Other Rebreather/s: Sport Kiss Home Build Join Date: Feb 2005 Location: Brisbane, QLD, Australia Posts: 239	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by depth) Ok, I see the points above. But I have never heard of a Rebreather diver actully identifying O2 or CO2 problems and succesfully switching to OC on a normal 2. stage or a BOW and recover! (but maybe i'm just not searching hard enough ;-) I found articles that describes how the RB diver senses that something is wrong, and the next thing he/she wakes up in a hospital thanks to the buddy. But maybe switching to OC when you feel something is not like it is supposed to be, it is allready to late, and breathing from OC will not suppress the reaction of the buddy (convulsion)? You are hearing the worst of the worst so to speak, those that really end up scary. I have bailed out twice due to CO2 problems to OC. Both times I had huge amounts of anxiety as my predominant symptom and bailed out no problems to OC reg. So now you have heard of 2 events Matt
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6th June 2007, 23:22	#17 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Classic Kiss rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,672	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by depth) In case of a O2 hit, would this not worsen the problem, by breathing the O2 rich gas allready present in the loop? I would guess that i need atleast one full breath before fresh gas from the ADV has found it's way to the dsv. You can fully dump the loop in just a few seconds around the mouth or thru the nose, so this is not a practical issue to worry about. Maintaining reasonable loop volumes helps lots. If you have more than about 1.5 lung volumes in the CL, you are probably running excess loop volume. Dave __________________ "Changes in Lattitudes, Changes in Attitudes, Nothing remains quite the same".... www.nobubblediving.com Last edited by Dave Sutton : 6th June 2007 at 23:34.
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6th June 2007, 23:23	#18 (permalink)
jaap Normal people worry me Current Rebreather/s: Classic Kiss Other CCR RB80 / Clone Ray Other SCR Home Build Other Rebreather/s: Other CCR RB80 / Clone Ray Other SCR Home Build Join Date: Jun 2005 Location: Stockholm Sweden Posts: 451	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by MHD) You are hearing the worst of the worst so to speak, those that really end up scary. I have bailed out twice due to CO2 problems to OC. Both times I had huge amounts of anxiety as my predominant symptom and bailed out no problems to OC reg. So now you have heard of 2 events Matt Yes something similar for me. I have had to abort still on the Rebreather or bailing out to OC a few times.Never had any high/low O2 issues that could not be handled on the loop. But I have had a one caustic cocktail and three CO2-hits. Did not have a BOV then (have them on two of my units now). At least one hit was really stupid, bad and fast eventually giving a feeling of imminent death. I did feel the thing coming but endured (very stupid). But since it was only on an o2-Rebreather, when the "death is coming"-feeling finally fell upon me I just went to the surface fast adding extra O2 on the way and was fine. Same with the cocktail. On one of the CO2 issues I was at ~ 42m and felt a creeping feeling of anixiety and unmotivated need to breath faster. Did a dil flush and felt OK. After a few minutes the same feeling came back so I did another dil flush as we turned back for the line up. After a while the interval of anxiety attacks got shorter so I did go semi closed for a while then over to OC without problems. Arriving at the 6m stop I went back to the loop to give it a try and stayed on it running on O2 only dumping the loop every few minutes just to stay safer.The last issue where a BOV could have been nice I was again foolishly pushing a failing loop. I started feeling my breathing go up and figured CO2 but stayed on the loop dumping it now and then. After a while the need to breath started going out of control so I bailed to OC. I really felt that had I not gotten off the loop in time my rate of breathing could have accelerated to a point where I could not have made the switch to OC. So from my own very limited experience from not so great depths I would say that if you know the drill and act as soon as you notice it you have time to go for your OC. __________________ My initials: JAAP
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7th June 2007, 03:55	#19 (permalink)
Explorer I will teach you a..... Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Alberta, Canada Posts: 773	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by Drmike) its not as fast as going OC but its likely faster than fumbling for OC regs With my Golem BOV, it's a quick switch, then off to my OC regs. Just one step. It gets you off the loop in a blink of an eye. Thanks again Jakub. __________________ 20 dwarves, 20 dwarves, 20 dwarves took turns doing handstands on the carpet
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7th June 2007, 04:23	#20 (permalink)
Drmike Custom Title Allowed! 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: 3,323	Re: Is a BOW fast enough to save a life? Quote: (Originally Posted by Explorer) With my Golem BOV, it's a quick switch, then off to my OC regs. Just one step. It gets you off the loop in a blink of an eye. Thanks again Jakub. your point is? 1) I was comparing time to get fresh gas in your lungs via firing the adv/flushing the loop to fumbling for OC regs - read my post - it quite clear. I wasnt talking about BOVs 2) I think everyman and his dog knows how a bov works and how fast the switch is - its not a hard concept to grasp and hardly needs reiterating 3) Jakub is a jolly nice bloke indeed - but he didnt invent the BOV concept you can stop hugging that meg now __________________ 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 Last edited by Drmike : 7th June 2007 at 04:25.
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