O2 Injection Point

**Steve** · 8th April 2006, 12:05

Quote: (Originally Posted by hirudin)

-Quote from Steve-

"...I have been running my Meg with the manual O2 addition on the exhalation lung for some time now ..."

Steve,

Do you simply route the manual O2 addition into the mixed gas bypass, or do you actually switch the inhale/exhale CL's?

-Jesse-

I have simply moved the O2 addition to the standard mixed gas bypass port.

Yann A. · 8th April 2006, 14:00

Hi Yann, first of all you will not press the manual addition for X number of seconds, then you should try to synchronize it with an exhale, this way you will push the new O2 added around the whole loop, so you will get it mixed for a longer period of time.

/Jonny[/quote]

Hi Jonny,
This is indeed what I do but I'm trying to get someone come up with some form of numbers as the distance between the O2 manual injection point and the diver's mouth O2 has some time to mix with the gas in the exhale lung. It is not like if one puts his O2 reg in the mouth and take a breath...
Reading some posts it's like having the O2 injection on the inhale side is such a negative / potential life threatening feature, I would just like to see numbers as to me numbers are the best to back up any theory. By “x” number of seconds I meant “we know the manual injector has a flow of that many liters per minute, if the diver press it for x amount of time he’ll get that much O2 in his inhale CL” according to O2 and gas mixing characteristics what is the diver going to get in his lungs given worst case scenario of inhaling at the same time? How long does it take for O2 to mix in air? In Tx?

Yann.

jknights · 8th April 2006, 16:54

Cant see any good ones for injection into inhale lung unless you are into pO2 hotspots.

Injection into the exhale lung or better yet into the exhale port point so that the O2 gets to mix in the scrubber would seem to be a simple and desirable solution.

Gadget · 8th April 2006, 18:43

I know it is not being manually injected. but do inspo divers have to time their breaths so they are not breathing in when the solinoid fires?????

My understanding of the way they work is the gas is fired into the top of the head by the cells on the inhalation side of the breathing loop.

no difference that i can see to manually injecting into the lung simalar distances and gas mixing opertunities in the lung before you breath it.

only thing i can see is you cannt hold the button down for minuets at a time.

bubnotbub · 8th April 2006, 20:13

Quote: (Originally Posted by Gadget)

I know it is not being manually injected. but do inspo divers have to time their breaths so they are not breathing in when the solinoid fires?????

My understanding of the way they work is the gas is fired into the top of the head by the cells on the inhalation side of the breathing loop.

no difference that i can see to manually injecting into the lung simalar distances and gas mixing opertunities in the lung before you breath it.

only thing i can see is you cannt hold the button down for minuets at a time.

I agree.

Regards

Aldo

Yann A. · 9th April 2006, 04:04

Quote: (Originally Posted by jknights)

Cant see any good ones for injection into inhale lung unless you are into pO2 hotspots.

Why? Can you come up with numbers? How long does the O2 requires to mix and blend into an acceptable gas mixture?

Injection into the exhale lung or better yet into the exhale port point so that the O2 gets to mix in the scrubber would seem to be a simple and desirable solution.

This is your preference. I respect that. I personaly like the idea "Right" "Rich".

What is the difference in time / distance when injecting O2 on the exhale side of the loop? I'd like to ask again: How long does O2 needs to mix in Air / Tx so that an acceptable homogenous mix is obtained?

I believe the MK series inject O2 in the lung / inhale side of the loop no (same as the inspiration)? Does anyone have any datas on issues with this particular location of O2 injection?

Yann.

Drmike · 9th April 2006, 05:09

I suspect if you add the gas volumes in the CL, hoses and the divers lungs together then look at the spike seen at the divers lung when a small amount of O2 is injected into the CL, combined with the likely long time between injections, it wouldnt be a significant tox risk given the bodys ability to tolerate very high ppo2s for very short (seconds) periods of time.

divetheworld · 9th April 2006, 10:01

Quote: (Originally Posted by Yann A.)

Thanks Brent for your explanation,

Quote: (Originally Posted by Yann A.)

I had asked the question on another forum some months back but without any reply. Now I get the begining of one. How fast is O2 going to mix in the inhale lung? As from what I remember from my chemistry classes it should be quasi instant... Now at depth it could be different due to different gas density, maybe.
I dive a Meg and would be interested to see some numbers. English isn’t my mother tongue so something like: I press my manual O2 injector for “x” seconds, I get that much O2 in my CL if I inhale at the same time I breathe “y%” of O2.
I’m just thinking out loud here but to me numbers talk more than words sometimes.
It used to be a time where people used to tumble their nitrox tanks after blending….

Yann.

Quote: (Originally Posted by silent running)

Hello Brent, thanks for the sceince explanation. I had heard this He not mixing with O2 thing in regaurd to how these gasses mix in the loop from 2 different people, maybe I misunderstood the idea. I can see that the differing gas densities would allow for a faster diffusion rate. But how fast is fast? Would it be near to instantaneous? There is not much time in btw the respritory cycle that pushes the gas around the loop, so this is why I ask. Thanks, -Andy

I do all my best rocket scientist stuff on a double Illy expresso.

It all depends on the volume of gas that is introduced into the first gas. If the amount is small in relation to the volume available then you can assume it is too quick to be of any concern. If the gas is at saturation or close to, then the proportion of gas which is of different mass is not significantly different for the propogation to occur with typical efficiency.

If you inject o2 into the loop to maintain po2, even when inhaling, there will be little chance of a spike in o2 to be of significance if the volume of the loop is adequate.
I hope you all see that it is a directly proportional relationship between the amount of differing gases and the volume that gives us our propogation.

Practical examples include the Dolphin (inhale bag) and the AP I(Inhale before bag) which maintains a Po2 within 0,10 bar during constant depth phases. This at a ventilation of 40 l min-1 and associated oxygen consumption of 1,78 l min-1 Standard Temperature and Pressure, Dry. When gas is injected into the breathing circuit the volume of oxygen added in 1 min shall be at least 6 l. You see the handsets change, but real time monitoring at the mouthpiece demonstrates the diffusion process.

Its not a big deal. The further away from the mouth that you inject, the more the gas will diffuse based upon volumes of gas. It makes little difference whether it is inhale or exhale side, it is about the minimum gas ratio between loop and oxygen between the injection point and the mouth.
Big lumps of o2, when inhaling, in a low volume loop = bad.
Tumbling tanks/room temperature = wank.

Piece of piss.

Brent.

(all assuming constant temperature and a rocket scientist at hand)

Mark Chase · 9th April 2006, 10:45

Quote: (Originally Posted by divetheworld)

[

Tumbling tanks/room temperature = wank.

Right Ill stop doing that then

ATB

Mark Chase

Yann A. · 9th April 2006, 16:18

Big lumps of o2, when inhaling, in a low volume loop = bad.
Tumbling tanks/room temperature = wank.

Piece of piss.

Brent.
[/quote]

Thanks Brent,

Maybe people arguing that O2 injection on the inhale side of the loop are the same who are / were tumbling their nitrox tanks after blending.
Although I can't come up with any numbers myself, I'm a bit tired to read some scientific wannabe comments on "how bad is to have the O2 inject on the inhale side"...
Before condemning a system, let's try to explain why. I'm open to suggestions but so far nobody managed to really give any datas against O2 inject on the inhale side.

Yann.

8th April 2006, 12:05	#21 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,117	Re: O2 Injection Point Quote: (Originally Posted by hirudin) -Quote from Steve- "...I have been running my Meg with the manual O2 addition on the exhalation lung for some time now ..." Steve, Do you simply route the manual O2 addition into the mixed gas bypass, or do you actually switch the inhale/exhale CL's? -Jesse- I have simply moved the O2 addition to the standard mixed gas bypass port. __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
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8th April 2006, 14:00	#22 (permalink)
Yann A. New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Location: Indonesia Posts: 49	Re: O2 Injection Point Hi Yann, first of all you will not press the manual addition for X number of seconds, then you should try to synchronize it with an exhale, this way you will push the new O2 added around the whole loop, so you will get it mixed for a longer period of time. /Jonny[/quote] Hi Jonny, This is indeed what I do but I'm trying to get someone come up with some form of numbers as the distance between the O2 manual injection point and the diver's mouth O2 has some time to mix with the gas in the exhale lung. It is not like if one puts his O2 reg in the mouth and take a breath... Reading some posts it's like having the O2 injection on the inhale side is such a negative / potential life threatening feature, I would just like to see numbers as to me numbers are the best to back up any theory. By “x” number of seconds I meant “we know the manual injector has a flow of that many liters per minute, if the diver press it for x amount of time he’ll get that much O2 in his inhale CL” according to O2 and gas mixing characteristics what is the diver going to get in his lungs given worst case scenario of inhaling at the same time? How long does it take for O2 to mix in air? In Tx? Yann.
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8th April 2006, 16:54	#23 (permalink)
jknights New Member Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Other CCR Join Date: May 2005 Location: Oliva, Valencia, Spain. Posts: 121	Re: O2 Injection Point Cant see any good ones for injection into inhale lung unless you are into pO2 hotspots. Injection into the exhale lung or better yet into the exhale port point so that the O2 gets to mix in the scrubber would seem to be a simple and desirable solution.
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8th April 2006, 18:43	#24 (permalink)
Gadget Custom Title Allowed! Current Rebreather/s: Megalodon rEvo Dolphin Home Build Other Rebreather/s: rEvo Dolphin Home Build Join Date: May 2005 Location: Hoddesdon, Herts. Posts: 164	Re: O2 Injection Point I know it is not being manually injected. but do inspo divers have to time their breaths so they are not breathing in when the solinoid fires????? My understanding of the way they work is the gas is fired into the top of the head by the cells on the inhalation side of the breathing loop. no difference that i can see to manually injecting into the lung simalar distances and gas mixing opertunities in the lung before you breath it. only thing i can see is you cannt hold the button down for minuets at a time. __________________ Si Lawrence www.divehdi.com
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8th April 2006, 20:13	#25 (permalink)
bubnotbub Silent diver Current Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Ouroboros rEvo Other CCR Other Rebreather/s: Inspiration Classic Sport Kiss rEvo Other CCR Join Date: Sep 2005 Location: France Italy Posts: 393	Re: O2 Injection Point Quote: (Originally Posted by Gadget) I know it is not being manually injected. but do inspo divers have to time their breaths so they are not breathing in when the solinoid fires????? My understanding of the way they work is the gas is fired into the top of the head by the cells on the inhalation side of the breathing loop. no difference that i can see to manually injecting into the lung simalar distances and gas mixing opertunities in the lung before you breath it. only thing i can see is you cannt hold the button down for minuets at a time. I agree. Regards Aldo __________________ Aldo Ferrucci *Trimix and Rebreather IT* *Expedition Leader* *www.bubnotbub.com* I like bubbles only in my glass of Champagne
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9th April 2006, 04:04	#26 (permalink)
Yann A. New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Location: Indonesia Posts: 49	Re: O2 Injection Point Quote: (Originally Posted by jknights) Cant see any good ones for injection into inhale lung unless you are into pO2 hotspots. Why? Can you come up with numbers? How long does the O2 requires to mix and blend into an acceptable gas mixture? Injection into the exhale lung or better yet into the exhale port point so that the O2 gets to mix in the scrubber would seem to be a simple and desirable solution. This is your preference. I respect that. I personaly like the idea "Right" "Rich". What is the difference in time / distance when injecting O2 on the exhale side of the loop? I'd like to ask again: How long does O2 needs to mix in Air / Tx so that an acceptable homogenous mix is obtained? I believe the MK series inject O2 in the lung / inhale side of the loop no (same as the inspiration)? Does anyone have any datas on issues with this particular location of O2 injection? Yann.
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9th April 2006, 05:09	#27 (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: 3,301	Re: O2 Injection Point I suspect if you add the gas volumes in the CL, hoses and the divers lungs together then look at the spike seen at the divers lung when a small amount of O2 is injected into the CL, combined with the likely long time between injections, it wouldnt be a significant tox risk given the bodys ability to tolerate very high ppo2s for very short (seconds) periods of time. __________________ 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 : 9th April 2006 at 05:12.
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9th April 2006, 10:01	#28 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,585	Re: O2 Injection Point Quote: (Originally Posted by Yann A.) Thanks Brent for your explanation, Quote: (Originally Posted by Yann A.) I had asked the question on another forum some months back but without any reply. Now I get the begining of one. How fast is O2 going to mix in the inhale lung? As from what I remember from my chemistry classes it should be quasi instant... Now at depth it could be different due to different gas density, maybe. I dive a Meg and would be interested to see some numbers. English isn’t my mother tongue so something like: I press my manual O2 injector for “x” seconds, I get that much O2 in my CL if I inhale at the same time I breathe “y%” of O2. I’m just thinking out loud here but to me numbers talk more than words sometimes. It used to be a time where people used to tumble their nitrox tanks after blending…. Yann. Quote: (Originally Posted by silent running) Hello Brent, thanks for the sceince explanation. I had heard this He not mixing with O2 thing in regaurd to how these gasses mix in the loop from 2 different people, maybe I misunderstood the idea. I can see that the differing gas densities would allow for a faster diffusion rate. But how fast is fast? Would it be near to instantaneous? There is not much time in btw the respritory cycle that pushes the gas around the loop, so this is why I ask. Thanks, -Andy I do all my best rocket scientist stuff on a double Illy expresso. It all depends on the volume of gas that is introduced into the first gas. If the amount is small in relation to the volume available then you can assume it is too quick to be of any concern. If the gas is at saturation or close to, then the proportion of gas which is of different mass is not significantly different for the propogation to occur with typical efficiency. If you inject o2 into the loop to maintain po2, even when inhaling, there will be little chance of a spike in o2 to be of significance if the volume of the loop is adequate. I hope you all see that it is a directly proportional relationship between the amount of differing gases and the volume that gives us our propogation. Practical examples include the Dolphin (inhale bag) and the AP I(Inhale before bag) which maintains a Po2 within 0,10 bar during constant depth phases. This at a ventilation of 40 l min-1 and associated oxygen consumption of 1,78 l min-1 Standard Temperature and Pressure, Dry. When gas is injected into the breathing circuit the volume of oxygen added in 1 min shall be at least 6 l. You see the handsets change, but real time monitoring at the mouthpiece demonstrates the diffusion process. Its not a big deal. The further away from the mouth that you inject, the more the gas will diffuse based upon volumes of gas. It makes little difference whether it is inhale or exhale side, it is about the minimum gas ratio between loop and oxygen between the injection point and the mouth. Big lumps of o2, when inhaling, in a low volume loop = bad. Tumbling tanks/room temperature = wank. Piece of piss. Brent. (all assuming constant temperature and a rocket scientist at hand) __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe Last edited by divetheworld : 9th April 2006 at 10:30.
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9th April 2006, 10:45	#29 (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: 2,694	Re: O2 Injection Point Quote: (Originally Posted by divetheworld) [ Tumbling tanks/room temperature = wank. Right Ill stop doing that then ATB Mark Chase __________________ 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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9th April 2006, 16:18	#30 (permalink)
Yann A. New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Feb 2005 Location: Indonesia Posts: 49	Re: O2 Injection Point Big lumps of o2, when inhaling, in a low volume loop = bad. Tumbling tanks/room temperature = wank. Piece of piss. Brent. [/quote] Thanks Brent, Maybe people arguing that O2 injection on the inhale side of the loop are the same who are / were tumbling their nitrox tanks after blending. Although I can't come up with any numbers myself, I'm a bit tired to read some scientific wannabe comments on "how bad is to have the O2 inject on the inhale side"... Before condemning a system, let's try to explain why. I'm open to suggestions but so far nobody managed to really give any datas against O2 inject on the inhale side. Yann.
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