O2 slug

silent running · 17th April 2008, 23:25

Hi JK, not to imply that I'm quoting you directly but...

Quote: (Originally Posted by jkaterenchuk)

Direct from the source....

Hi John,

This is a fairly common question, at first glance injecting oxygen on the inhale side would seem counter intuitive. However, CNS is not a condition that "strikes" with a breath of pure O2, it is a combination of time and level of PO2. If your operating envelope is anywhere near normal PO2 range a CNS hit is not an issue from a an occasional injection of O2.

What about running the unit manually at say, 70 meters? Even 1 breath of pure O2 at a PO2 of nearly 8.0 can't be good for you, and this is what would happen each time you injected at depth. I'm no doctor, but I'd guess that 1 breath at some very high PPO2, an O2 tox would be near to instant.

Quote: (Originally Posted by jkaterenchuk)

On the other side of the envelope if your PO2 had dropped to dangerously low levels and you were on the edge of Hypoxia you may not have the 3 or 4 breaths left to pull O2 from the exhale side, through the loop to your lips before you pass out.

The only time I can see this scenario playing out is with a very hypoxic single digit O2 % dil, no O2 injects for a while and a rapid ascent from shallower than 20 meters, which seems an unlikely combination. The times I have run my ECCR manually during an ascent, I was very concious of my falling PO2 and injected frequently. On dives requiring hypoxic dil, I was doubly paranoid and extra vigilant of my PO2 during ascent. And when manually injecting O2, I have never needed more than 1 breath to see my sensors start to rise.

If I'm understanding the Meg loop properly, given that the O2 is in the inhale CL, does that mean that the dil addition is in the exhale CL? If that is true and given the more common problem of ADVs not working right and the possibility of CO2 retention during periods of high workload, I would much rather have my dil addition in the inhale lung and have fresh gas near to my inhale hose that is breathable for the majority, if not all of my dive. Maybe I'm missing something.

Quote: (Originally Posted by jkaterenchuk)

The overall design of the Meg is based on crictical controls being assessable to either hand and the ability of a diver on the edge of unconsciousness from whatever cause to have the best chance of self rescue.

Is there any OTS CL unit out there that doesn't allow access to the manual dil and O2 addition with both hands? Isn't that one of the benefits of OTS CLs, easy access to manual addition buttons?-Andy

**NEDIVER** · 24th April 2008, 01:06

Thank you for the replies so far.

All of the feed back has helped me start to form an opinion. Still undecided.

OceanOpportunity · 24th April 2008, 01:13

not to dis-sway you from buying any stock unit, Meg included, but have you considered converting an SCR? Converting my Dolphin was the best educational experience I could have gone through...learned a ton, learned to be very selective about specific features/benefits, and ended up with a small, light, compact, and very functional unit. Food for thought

**NEDIVER** · 24th April 2008, 01:19

Quote: (Originally Posted by OceanOpportunity)

not to dis-sway you from buying any stock unit, Meg included, but have you considered converting an SCR? Converting my Dolphin was the best educational experience I could have gone through...learned a ton, learned to be very selective about specific features/benefits, and ended up with a small, light, compact, and very functional unit. Food for thought

I am currently an owner and diving an Evolution

I was most interested for a second rig.

mountain diver · 24th April 2008, 03:06

Quote: (Originally Posted by NEDIVER)

Thank you for the replies so far.

All of the feed back has helped me start to form an opinion. Still undecided.

02 in the right lung simply for the purpose of an 02 flush, place the hose to
the left lung and you no longer have the ability to 02 flush.

all the best.

Nailer99 · 24th April 2008, 05:17

Jerry's response is correct- a brief exposure to high P02 is not a problem- a brief exposure to a LOW P02 can be a huge problem.....

snicks · 24th April 2008, 07:35

Quote: (Originally Posted by mountain diver)

02 in the right lung simply for the purpose of an 02 flush, place the hose to
the left lung and you no longer have the ability to 02 flush.

all the best.

??? I thought it was exactly the other way around. My concern when switching offboard dil injector to the inhale CL (4th cell) was that a dil flush from offboard gas has become difficult to impossible. Whatever you inject into exhale CL goes throught the scrubber, inhale CL and out of your mouthpiece (into your lungs or the water). Gas injected in inhale CL goes through your mouthiece and then OPV->exit... no flush functionality...

What am I missing?

greets
snicks

Guilhem · 24th April 2008, 09:34

FWIW, the submatix mCCR also inject O2 in the inhale lung. Their answer to the often-asked question is at the bottom of their FAQ page. It does lack hard numbers though.

**NEDIVER** · 24th April 2008, 12:23

Quote: (Originally Posted by Guilhem)

FWIW, the submatix mCCR also inject O2 in the inhale lung. Their answer to the often-asked question is at the bottom of their FAQ page. It does lack hard numbers though.

Why the oxygen flow is feeded at the ADV?

An often asked question is why the oxygen is feeded at the ADV and not in the scrubber tank at our CCR rebreather.

An explanation of the most important reasons you will find in the following:

As argument for a feeding of the oxygen in the scrubber tank a better mixture of the oxygen with diluent is named. In principle the thought that the oxygen has to be mixted up with diluent is right. When oxygen is feeded to the ADV, oxygen is mixed up immediately with diluent through the gas flow. This will happen while every breathing.

Explanation:

In the breathing circulation about 10 litres of breathing gas are existing. Through breathing this gas moves permanently (at a calmly breathing about 10 breathes per minute). In this permanent moving about 1 litre oxygen per minute is feeded to the system through the constant flow. Through the moving of the breathting gas the oxygen is mixed up constantly with the gas of the breathing loop. The result will be a constant mixing of the oxygen with the diluent. This is confirmed through large-scale measurings.

At a feeding of oxygen in the scrubber tank the oxygen is also mixed up with diluent. But the problem will be the danger of hypoxia in the case of a streamed scrubber tank.

Example:

For any reasons the scrubber tank is streamed. The diver will recognize the symptoms and end its dive. When he/she changes now to the bailout system, no problem will arise. But when he/she further breath from the rebreather, the following problems will arise: Through water in the scrubber tank, the gas flow is interrupted and the bypass will response at every breath. When the diver starts the dive to the water surface now, the gas expands in the system and the bypass do not deliver any fresh gas. This means that he/she breathes only diluent. If the used diluent is compressed air or in the worst case trimix, a black out will arise through hypoxia. The result will be an accident in flat water.

While the feeding of oxygen in the ADV this possible problem is ruled out.

1. This discussion was towards me considering a MEG as a second unit. Submatrix is not an option I want to entertain.

2. You can not compare one manufacturers explanation to another.

3. It even states that the fact that the O2 needs to be mixed and dispersed as "correct thinking" then goes on to justify the fact that it is okay because it is mixing with 1 liter of air rather than 10 liters. With simple math, anyone can see that a shot of 100% O2 is far more concentrated in 1 liter than the same shot dispersed in 10 liters.

4. It seems to me that by saying that you "need the high O2 the most when you low" seems a little far fetched. If you have enough cognitive function to have the mental aptitude to switch off the loop, or add O2, you have plenty of time to live and breath as little as .21 or anything that is not hypoxic. If that theory was correct; (this is a stretch, I know

) then, why would you want just breathable gas on your bail out and not pure O2 or 80% O2, after all, thats when you need it the most and that is what you get with an O2 slug?!

5. Lastly, this is a question from other previous initial posts. If I understood this right, you can switch the O2 to the exhale CL? is this correct? If so, that seems like a viable option for someone.

i am just trying to figure this out, so when I retire the Evolution to the wife when she is ready to switch to CCR I will know what I want for a second rig.

regards,

**wedivebc** · 24th April 2008, 12:47

Quote: (Originally Posted by mountain diver)

02 in the right lung simply for the purpose of an 02 flush, place the hose to
the left lung and you no longer have the ability to 02 flush.

all the best.

It is actually easier to O2 flush from the exhale side. Your lungs push the gas through instead of having to crimp off the inhale hose and let the pressure circulate it.

17th April 2008, 23:25	#11 (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: 1,677	Re: O2 slug Hi JK, not to imply that I'm quoting you directly but... Quote: (Originally Posted by jkaterenchuk) Direct from the source.... Hi John, This is a fairly common question, at first glance injecting oxygen on the inhale side would seem counter intuitive. However, CNS is not a condition that "strikes" with a breath of pure O2, it is a combination of time and level of PO2. If your operating envelope is anywhere near normal PO2 range a CNS hit is not an issue from a an occasional injection of O2. What about running the unit manually at say, 70 meters? Even 1 breath of pure O2 at a PO2 of nearly 8.0 can't be good for you, and this is what would happen each time you injected at depth. I'm no doctor, but I'd guess that 1 breath at some very high PPO2, an O2 tox would be near to instant. Quote: (Originally Posted by jkaterenchuk) On the other side of the envelope if your PO2 had dropped to dangerously low levels and you were on the edge of Hypoxia you may not have the 3 or 4 breaths left to pull O2 from the exhale side, through the loop to your lips before you pass out. The only time I can see this scenario playing out is with a very hypoxic single digit O2 % dil, no O2 injects for a while and a rapid ascent from shallower than 20 meters, which seems an unlikely combination. The times I have run my ECCR manually during an ascent, I was very concious of my falling PO2 and injected frequently. On dives requiring hypoxic dil, I was doubly paranoid and extra vigilant of my PO2 during ascent. And when manually injecting O2, I have never needed more than 1 breath to see my sensors start to rise. If I'm understanding the Meg loop properly, given that the O2 is in the inhale CL, does that mean that the dil addition is in the exhale CL? If that is true and given the more common problem of ADVs not working right and the possibility of CO2 retention during periods of high workload, I would much rather have my dil addition in the inhale lung and have fresh gas near to my inhale hose that is breathable for the majority, if not all of my dive. Maybe I'm missing something. Quote: (Originally Posted by jkaterenchuk) The overall design of the Meg is based on crictical controls being assessable to either hand and the ability of a diver on the edge of unconsciousness from whatever cause to have the best chance of self rescue. Is there any OTS CL unit out there that doesn't allow access to the manual dil and O2 addition with both hands? Isn't that one of the benefits of OTS CLs, easy access to manual addition buttons?-Andy
(Offline)

24th April 2008, 01:06	#12 (permalink)
NEDIVER Sic Semper Tyrannis Current Rebreather/s: Evolution Other Rebreather/s: Join Date: Jan 2008 Location: Nashua, NH Posts: 112	Re: O2 slug Thank you for the replies so far. All of the feed back has helped me start to form an opinion. Still undecided. __________________ -Tom- "slow is smooth, and smooth is fast" TM "Insanity is repeating the same thing over and over again, expecting different results" Albert Einstein
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24th April 2008, 01:13	#13 (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: 447	Re: O2 slug not to dis-sway you from buying any stock unit, Meg included, but have you considered converting an SCR? Converting my Dolphin was the best educational experience I could have gone through...learned a ton, learned to be very selective about specific features/benefits, and ended up with a small, light, compact, and very functional unit. Food for thought __________________ Michael Lombardi Oceans of Opportunity www.oceanopportunity.com Gear Reviewer, The Summit Journal exploration & scientific diving resources www.explorationtechnologiesgroup.com
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24th April 2008, 01:19	#14 (permalink)
NEDIVER Sic Semper Tyrannis Current Rebreather/s: Evolution Other Rebreather/s: Join Date: Jan 2008 Location: Nashua, NH Posts: 112	Re: O2 slug Quote: (Originally Posted by OceanOpportunity) not to dis-sway you from buying any stock unit, Meg included, but have you considered converting an SCR? Converting my Dolphin was the best educational experience I could have gone through...learned a ton, learned to be very selective about specific features/benefits, and ended up with a small, light, compact, and very functional unit. Food for thought I am currently an owner and diving an Evolution I was most interested for a second rig. __________________ -Tom- "slow is smooth, and smooth is fast" TM "Insanity is repeating the same thing over and over again, expecting different results" Albert Einstein
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24th April 2008, 03:06	#15 (permalink)
mountain diver Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Mar 2006 Location: edmonton, ab. Posts: 149	Re: O2 slug Quote: (Originally Posted by NEDIVER) Thank you for the replies so far. All of the feed back has helped me start to form an opinion. Still undecided. 02 in the right lung simply for the purpose of an 02 flush, place the hose to the left lung and you no longer have the ability to 02 flush. all the best.
(Offline)

24th April 2008, 05:17	#16 (permalink)
Nailer99 Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jan 2007 Location: Seattle, WA, USA Posts: 131	Re: O2 slug Jerry's response is correct- a brief exposure to high P02 is not a problem- a brief exposure to a LOW P02 can be a huge problem.....
(Offline)

24th April 2008, 07:35	#17 (permalink)
snicks New Member Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Join Date: Jul 2006 Location: Germany Posts: 17	Re: O2 slug Quote: (Originally Posted by mountain diver) 02 in the right lung simply for the purpose of an 02 flush, place the hose to the left lung and you no longer have the ability to 02 flush. all the best. ??? I thought it was exactly the other way around. My concern when switching offboard dil injector to the inhale CL (4th cell) was that a dil flush from offboard gas has become difficult to impossible. Whatever you inject into exhale CL goes throught the scrubber, inhale CL and out of your mouthpiece (into your lungs or the water). Gas injected in inhale CL goes through your mouthiece and then OPV->exit... no flush functionality... What am I missing? greets snicks __________________ Weltmacht mit drei Buchstaben? ICH!
(Offline)

24th April 2008, 09:34	#18 (permalink)
Guilhem New Member Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Oct 2005 Location: South-East France Posts: 42	Re: O2 slug FWIW, the submatix mCCR also inject O2 in the inhale lung. Their answer to the often-asked question is at the bottom of their FAQ page. It does lack hard numbers though.
(Offline)

24th April 2008, 12:23	#19 (permalink)
NEDIVER Sic Semper Tyrannis Current Rebreather/s: Evolution Other Rebreather/s: Join Date: Jan 2008 Location: Nashua, NH Posts: 112	Re: O2 slug Quote: (Originally Posted by Guilhem) FWIW, the submatix mCCR also inject O2 in the inhale lung. Their answer to the often-asked question is at the bottom of their FAQ page. It does lack hard numbers though. Why the oxygen flow is feeded at the ADV? An often asked question is why the oxygen is feeded at the ADV and not in the scrubber tank at our CCR rebreather. An explanation of the most important reasons you will find in the following: As argument for a feeding of the oxygen in the scrubber tank a better mixture of the oxygen with diluent is named. In principle the thought that the oxygen has to be mixted up with diluent is right. When oxygen is feeded to the ADV, oxygen is mixed up immediately with diluent through the gas flow. This will happen while every breathing. Explanation: In the breathing circulation about 10 litres of breathing gas are existing. Through breathing this gas moves permanently (at a calmly breathing about 10 breathes per minute). In this permanent moving about 1 litre oxygen per minute is feeded to the system through the constant flow. Through the moving of the breathting gas the oxygen is mixed up constantly with the gas of the breathing loop. The result will be a constant mixing of the oxygen with the diluent. This is confirmed through large-scale measurings. At a feeding of oxygen in the scrubber tank the oxygen is also mixed up with diluent. But the problem will be the danger of hypoxia in the case of a streamed scrubber tank. Example: For any reasons the scrubber tank is streamed. The diver will recognize the symptoms and end its dive. When he/she changes now to the bailout system, no problem will arise. But when he/she further breath from the rebreather, the following problems will arise: Through water in the scrubber tank, the gas flow is interrupted and the bypass will response at every breath. When the diver starts the dive to the water surface now, the gas expands in the system and the bypass do not deliver any fresh gas. This means that he/she breathes only diluent. If the used diluent is compressed air or in the worst case trimix, a black out will arise through hypoxia. The result will be an accident in flat water. While the feeding of oxygen in the ADV this possible problem is ruled out. 1. This discussion was towards me considering a MEG as a second unit. Submatrix is not an option I want to entertain. 2. You can not compare one manufacturers explanation to another. 3. It even states that the fact that the O2 needs to be mixed and dispersed as "correct thinking" then goes on to justify the fact that it is okay because it is mixing with 1 liter of air rather than 10 liters. With simple math, anyone can see that a shot of 100% O2 is far more concentrated in 1 liter than the same shot dispersed in 10 liters. 4. It seems to me that by saying that you "need the high O2 the most when you low" seems a little far fetched. If you have enough cognitive function to have the mental aptitude to switch off the loop, or add O2, you have plenty of time to live and breath as little as .21 or anything that is not hypoxic. If that theory was correct; (this is a stretch, I know ) then, why would you want just breathable gas on your bail out and not pure O2 or 80% O2, after all, thats when you need it the most and that is what you get with an O2 slug?! 5. Lastly, this is a question from other previous initial posts. If I understood this right, you can switch the O2 to the exhale CL? is this correct? If so, that seems like a viable option for someone. i am just trying to figure this out, so when I retire the Evolution to the wife when she is ready to switch to CCR I will know what I want for a second rig. regards, __________________ -Tom- "slow is smooth, and smooth is fast" TM "Insanity is repeating the same thing over and over again, expecting different results" Albert Einstein
(Offline)

24th April 2008, 12:47	#20 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,273	Re: O2 slug Quote: (Originally Posted by mountain diver) 02 in the right lung simply for the purpose of an 02 flush, place the hose to the left lung and you no longer have the ability to 02 flush. all the best. It is actually easier to O2 flush from the exhale side. Your lungs push the gas through instead of having to crimp off the inhale hose and let the pressure circulate it. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
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