Clean Deco

***jradomski*** · 27th April 2005, 03:06

Quote: (Originally Posted by ROB DAVIE)

Joe,

Just a couple of thoughts, if I may. While divers do tend to build up some tolerance, research has shown that our tolerance varies between individuals, and varies within individuals from day to day.

Also, research tends to show that CO2 can potentiate O2 toxicity, but its presence is not necessary for it to occur.

Just my PPO2's worth.

Cheers!

Rob

1) I agree.. Tolerence SEEMS to increase on consecitive days... 1.6 really is that extreme I remember the days I used to use that as a bottom po2 and deco on a 1.8 like many militaries do..
I have a firend thas a comex/hse diver saturation diver and he is required to take oxygen tolerance tests every several months(to stay current),, he has to survive an exposure of ~3.0 for 30 minutes (If I remember they peak the test at a 3.5) while on a stationary bike..

2) CO2is amajor factor.. for Oxygen toworkon its own the exposure really has to be extreme..

AM · 27th April 2005, 09:25

From my research, the presence of CO2 dramatically increases the physiological effects of O2 - and vice versa.

Tolerance to oxygen is completely variable.

CO2 permanently damages O2 sensors.

Regards

AnneMarie

***EBT*** · 27th April 2005, 11:12

Thread split and CO2/Cells debate moved to; http://www.rebreatherworld.com/t722-.html

AM · 28th April 2005, 23:14

Can I make a suggestion? It's "sort" of related to using oxygen efficiently...

If using an Inspiration, when you ascend, if you dump gas overboard using your nose and mouth, you actually are dumping FRESH O2 overboard, this in turn triggers the solenoid to fire again, it renders decompression quite inefficient and also uses a lot more oxygen. New divers seem to be getting taught to dump gas this way a lot.

If you use the pull cord on the Inspiration do dump gas on ascent, you're actually then venting old gas out of the loop, you won't hear the solenoid fire as much.

Regards

AnneMarie

***jradomski*** · 28th April 2005, 23:54

Quote: (Originally Posted by jptaylor9)

Tried this in the pool tonight with "fag end" of my scrubber/O2... pool's about 3m & was able to hit ~1.3bar. Useful technique, thanks. Must try on a sea dive

Glad I can help..

buggeriamold · 29th April 2005, 10:19

Quote: (Originally Posted by AnneMarie)

Can I make a suggestion? It's "sort" of related to using oxygen efficiently...

If using an Inspiration, when you ascend, if you dump gas overboard using your nose and mouth, you actually are dumping FRESH O2 overboard, this in turn triggers the solenoid to fire again, it renders decompression quite inefficient and also uses a lot more oxygen. New divers seem to be getting taught to dump gas this way a lot.

If you use the pull cord on the Inspiration do dump gas on ascent, you're actually then venting old gas out of the loop, you won't hear the solenoid fire as much.

Regards

AnneMarie

I must be missing somthing here, but the way i see it if you are dumping gas out your nose then it must be used?

Mark

***Beanie*** · 29th April 2005, 10:28

Quote: (Originally Posted by buggeriamold)

I must be missing somthing here, but the way i see it if you are dumping gas out your nose then it must be used?

Mark

thats what I though out of nose used but out of mouth dumps fresh gas

please feel free to correct if I'm talking BS

dteubner · 29th April 2005, 10:32

Quote: (Originally Posted by Beanie)

thats what I though out of nose used but out of mouth dumps fresh gas

please feel free to correct if I'm talking BS

I guess it depends on which side of the loop O2 is added. If on the inhale side then what you dump might be the high O2 "fresh" gas. If the O2 is added on the exhale side then it should be nice and mixed before you dump it out your nose.

Dave T

***Decodiver*** · 29th April 2005, 10:37

Quote: (Originally Posted by Beanie)

thats what I though out of nose used but out of mouth dumps fresh gas

please feel free to correct if I'm talking BS

If the gas was injected by Solenoid, on Kato you will be dumping O2 rich gas if you dump from the mouth.

If the gas was injected manually then you will be dumping O2 rich gas if you then dump from the counterlung dump.

All above is correct assuming you are dumping within a breath of injection.

Bear in mind that the solenoid opens for long periods on ascent, so on the Inspiration the c/l dump is more effective.

I generally use a combination of both methods of dumping, I never dive with less than 200 bar O2 so am not too worried, however I do manually control my setpoint so it is rare for my solenoid to fire.

Also on the Meg the manual O2 injector is on the inhale side and the dump is on the exhale side, so I'm damned either way.

Cheers,

Dave

dteubner · 3rd May 2005, 02:12

Quote: (Originally Posted by jradomski)

Your spreadsheet is a nice idea, the problem is the HT doesn't give an accurate display of whats going on.. for example a ccr dive to 100m for 20min using 50%he, 13% oxygen, the controlling compartment is compartment 8 (yours is close to 7 which does still have significant loading) compartments 8 + 9 have significant gas loading and are much slower to release so it will have an effect for a longer period of time.. the fast compartments do have a gas load, but they will be taken care of pretty quickly,, even compartment 5 is still less than 30m HT..

The way you see the offgassing into the loop makes sense, early on the fast compartents are causing the po2 drop, once these drop they have less of an effect and the slow compartments take over, since they take longer to ogffgas they have less an effect on the loop.

Different tissues has different capacities to hold various gases...

I have re written the spread sheet so it now uses a nine compartment model and includes a graph. It still makes a lot of assumptions (for a start it doesn't include any stops - just rate of offgassing with a Haldanian model at 1ATA) but it does address Joe's points above.

http://www.davidteubner.com/images/G...calculator.xls

Dave T

27th April 2005, 03:06	#41 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Quote: (Originally Posted by ROB DAVIE) Joe, Just a couple of thoughts, if I may. While divers do tend to build up some tolerance, research has shown that our tolerance varies between individuals, and varies within individuals from day to day. Also, research tends to show that CO2 can potentiate O2 toxicity, but its presence is not necessary for it to occur. Just my PPO2's worth. Cheers! Rob 1) I agree.. Tolerence SEEMS to increase on consecitive days... 1.6 really is that extreme I remember the days I used to use that as a bottom po2 and deco on a 1.8 like many militaries do.. I have a firend thas a comex/hse diver saturation diver and he is required to take oxygen tolerance tests every several months(to stay current),, he has to survive an exposure of ~3.0 for 30 minutes (If I remember they peak the test at a 3.5) while on a stationary bike.. 2) CO2is amajor factor.. for Oxygen toworkon its own the exposure really has to be extreme.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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27th April 2005, 09:25	#42 (permalink)
AM In love with the big blue Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Earth. Posts: 611	From my research, the presence of CO2 dramatically increases the physiological effects of O2 - and vice versa. Tolerance to oxygen is completely variable. CO2 permanently damages O2 sensors. Regards AnneMarie __________________ Attitude keeps you alive
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27th April 2005, 11:12	#43 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,996	CO2/Cells Thread split and CO2/Cells debate moved to; http://www.rebreatherworld.com/t722-.html __________________ Eagles May Soar, but weasels don't get sucked into jet engines! Rebreather World Terms of service Real diving t-shirts for real divers
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28th April 2005, 23:14	#44 (permalink)
AM In love with the big blue Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Earth. Posts: 611	Can I make a suggestion? It's "sort" of related to using oxygen efficiently... If using an Inspiration, when you ascend, if you dump gas overboard using your nose and mouth, you actually are dumping FRESH O2 overboard, this in turn triggers the solenoid to fire again, it renders decompression quite inefficient and also uses a lot more oxygen. New divers seem to be getting taught to dump gas this way a lot. If you use the pull cord on the Inspiration do dump gas on ascent, you're actually then venting old gas out of the loop, you won't hear the solenoid fire as much. Regards AnneMarie __________________ Attitude keeps you alive
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28th April 2005, 23:54	#45 (permalink)
*jradomski* Moderator Current Rebreather/s: Inspiration Classic Sport Kiss Optima rEvo Other CCR Home Build Other Rebreather/s: Inspiration Vision Evolution Megalodon Classic Kiss rEvo Other CCR Home Build Join Date: Mar 2005 Location: "Da" Bronx Posts: 2,998	Quote: (Originally Posted by jptaylor9) Tried this in the pool tonight with "fag end" of my scrubber/O2... pool's about 3m & was able to hit ~1.3bar. Useful technique, thanks. Must try on a sea dive Glad I can help.. __________________ Joe Radomski CCR Trimix Instructor Trainer ANDI Instructor Trainer Director #10 All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.
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29th April 2005, 10:19	#46 (permalink)
buggeriamold Custom Title Allowed! Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Feb 2005 Location: australia Posts: 100	Quote: (Originally Posted by AnneMarie) Can I make a suggestion? It's "sort" of related to using oxygen efficiently... If using an Inspiration, when you ascend, if you dump gas overboard using your nose and mouth, you actually are dumping FRESH O2 overboard, this in turn triggers the solenoid to fire again, it renders decompression quite inefficient and also uses a lot more oxygen. New divers seem to be getting taught to dump gas this way a lot. If you use the pull cord on the Inspiration do dump gas on ascent, you're actually then venting old gas out of the loop, you won't hear the solenoid fire as much. Regards AnneMarie I must be missing somthing here, but the way i see it if you are dumping gas out your nose then it must be used? Mark
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29th April 2005, 10:28	#47 (permalink)
*Beanie* give a man an inch....... Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,248	Quote: (Originally Posted by buggeriamold) I must be missing somthing here, but the way i see it if you are dumping gas out your nose then it must be used? Mark thats what I though out of nose used but out of mouth dumps fresh gas please feel free to correct if I'm talking BS __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk 0871 242 7808
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29th April 2005, 10:32	#48 (permalink)
dteubner Pedant Current Rebreather/s: Sport Kiss Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Adelaide, Australia Posts: 217	Quote: (Originally Posted by Beanie) thats what I though out of nose used but out of mouth dumps fresh gas please feel free to correct if I'm talking BS I guess it depends on which side of the loop O2 is added. If on the inhale side then what you dump might be the high O2 "fresh" gas. If the O2 is added on the exhale side then it should be nice and mixed before you dump it out your nose. Dave T
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29th April 2005, 10:37	#49 (permalink)
*Decodiver* Administrator Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Jan 2005 Location: Geneva Posts: 2,197	Quote: (Originally Posted by Beanie) thats what I though out of nose used but out of mouth dumps fresh gas please feel free to correct if I'm talking BS If the gas was injected by Solenoid, on Kato you will be dumping O2 rich gas if you dump from the mouth. If the gas was injected manually then you will be dumping O2 rich gas if you then dump from the counterlung dump. All above is correct assuming you are dumping within a breath of injection. Bear in mind that the solenoid opens for long periods on ascent, so on the Inspiration the c/l dump is more effective. I generally use a combination of both methods of dumping, I never dive with less than 200 bar O2 so am not too worried, however I do manually control my setpoint so it is rare for my solenoid to fire. Also on the Meg the manual O2 injector is on the inhale side and the dump is on the exhale side, so I'm damned either way. Cheers, Dave __________________ 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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3rd May 2005, 02:12	#50 (permalink)
dteubner Pedant Current Rebreather/s: Sport Kiss Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: Adelaide, Australia Posts: 217	Quote: (Originally Posted by jradomski) Your spreadsheet is a nice idea, the problem is the HT doesn't give an accurate display of whats going on.. for example a ccr dive to 100m for 20min using 50%he, 13% oxygen, the controlling compartment is compartment 8 (yours is close to 7 which does still have significant loading) compartments 8 + 9 have significant gas loading and are much slower to release so it will have an effect for a longer period of time.. the fast compartments do have a gas load, but they will be taken care of pretty quickly,, even compartment 5 is still less than 30m HT.. The way you see the offgassing into the loop makes sense, early on the fast compartents are causing the po2 drop, once these drop they have less of an effect and the slow compartments take over, since they take longer to ogffgas they have less an effect on the loop. Different tissues has different capacities to hold various gases... I have re written the spread sheet so it now uses a nine compartment model and includes a graph. It still makes a lot of assumptions (for a start it doesn't include any stops - just rate of offgassing with a Haldanian model at 1ATA) but it does address Joe's points above. http://www.davidteubner.com/images/G...calculator.xls Dave T
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