The pO2 you use

cedricverdier · 18th July 2005, 08:24

Hi all,

A quick poll to know what kind of pO2 you breathe in your loop during deep dives. There are different schools of thought, so every opinion is welcome.

Cheers

***EBT*** · 18th July 2005, 15:31

Depends on depth/length of exposure sequence.

In general my tables are cut for 1.2 bottom and 1.4 from 6m up. Whats in the loop varies according to my intentions etc.

Of course, using VPM i think I'd cut them for 1, so I could get out without niggles

Mark Chase · 18th July 2005, 15:45

Varies according to the planned dive.

A 35m dive on a big wreck I would do the dive on a 1.4 set point bottom phase and stay down as long as I could. I would stay on 1.4 for the ascent then finish the last 15mins of deco on pure 02 rebreather at 4.5m.

A bigger dive to say 80m I might go for 1.2 on the bottom phase of the dive and switch to 1.4 for the ascent ending with pure 02 rebreather for the final 30mins of the deco possibly incorporating OC back gas breaks.

It is totally dive dependant taking into consideration depth duration of dive work load general conditions on the dive site etc etc. Only thing they all will have in common is a period on pure 02 to flush the He out on the last stage of deco.

ATB

Mark Chase

***Decodiver*** · 18th July 2005, 17:14

It really depends on the dive.

Down to 90 metres 1.2 on bottom.

Deeper between 1.0 and 1.2 depending on work rate.

Never deco on more than 1.4

Cheers,

Dave Cooper.

Andyg · 18th July 2005, 18:09

Any reason why you don't deco on anything higher than 1.4 Dave.

Andyg

***Decodiver*** · 18th July 2005, 21:07

Quote: (Originally Posted by Andyg)

Any reason why you don't deco on anything higher than 1.4 Dave.

Andyg

Hi Andy,

I have always been taught that oxygen is not our friend, I am happy to clock some extra deco time and perhaps be not quite as clean as others, however I know of at least one death on the Inspiration that was caused by elevated levels of O2 on deco. It is my choice, I rack it back a little and it works for me.

Cheers,

Dave Cooper.

ROB DAVIE · 18th July 2005, 23:19

0.7 on descent to the switch, 1.3 on the bottom, 0.7 on ascent after the switch per standard YBOD protocol, (1.0 at 3 msw/18 fsw if needed)

Andy M · 18th July 2005, 23:28

Quote: (Originally Posted by cedricverdier)

There are different schools of thought, so every opinion is welcome.

Question for the people who selected 1.0 on the bottom. Why? Seems some people do this, and as far as I know, no training agency teaches this? I dived with someone at the weekend who kept his around 1.0

Yes I can understand doing it for multidive multiday trips where UPTD is likely to be an issue, but for a weekend trip?

Personally I keep mine between 1.3 and 1.2, leave the VR3 on 1.2 for deco and top off the loop to 1.3 every now and again.

Andy

***caveseeker7*** · 19th July 2005, 00:27

Some people select 1.0 ata as their setpoint and fly manually at a higher setpoint.
Others prefer 1.0 ata for safety reasons as that's as much as they can verify at the surface.
Those were the two reasons given when I asked divers who do so, anyway.

cedricverdier · 19th July 2005, 10:31

Quote: (Originally Posted by Andy M)

Question for the people who selected 1.0 on the bottom. Why? Seems some people do this, and as far as I know, no training agency teaches this? I dived with someone at the weekend who kept his around 1.0

Yes I can understand doing it for multidive multiday trips where UPTD is likely to be an issue, but for a weekend trip?

Andy

Hi Andy,

I prefer to use a 1.0 setpoint for all my deep dives for the following reasons:
- Less O2 exposure
- Less risk of CNS oxtox (and on a decompression standpoint, it doesn't make a big difference with a 1.2 or 1.3 setpoint)
- More time to react in case of O2 spike

I need more O2 during the deco phase (so my setpoint is rather 1.3 or 1.4 depending on the tables I use), and I limit my O2 exposure during the bottom phase.

Cheers

18th July 2005, 08:24	#1 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 494	The pO2 you use Hi all, A quick poll to know what kind of pO2 you breathe in your loop during deep dives. There are different schools of thought, so every opinion is welcome. Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
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18th July 2005, 15:31	#2 (permalink)
*EBT* Apprentice Luddite Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: UK, Brighton Posts: 1,902	Depends on depth/length of exposure sequence. In general my tables are cut for 1.2 bottom and 1.4 from 6m up. Whats in the loop varies according to my intentions etc. Of course, using VPM i think I'd cut them for 1, so I could get out without niggles __________________ 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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18th July 2005, 15:45	#3 (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: 2,539	Varies according to the planned dive. A 35m dive on a big wreck I would do the dive on a 1.4 set point bottom phase and stay down as long as I could. I would stay on 1.4 for the ascent then finish the last 15mins of deco on pure 02 rebreather at 4.5m. A bigger dive to say 80m I might go for 1.2 on the bottom phase of the dive and switch to 1.4 for the ascent ending with pure 02 rebreather for the final 30mins of the deco possibly incorporating OC back gas breaks. It is totally dive dependant taking into consideration depth duration of dive work load general conditions on the dive site etc etc. Only thing they all will have in common is a period on pure 02 to flush the He out on the last stage of deco. 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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18th July 2005, 17:14	#4 (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: 2,178	It really depends on the dive. Down to 90 metres 1.2 on bottom. Deeper between 1.0 and 1.2 depending on work rate. Never deco on more than 1.4 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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18th July 2005, 18:09	#5 (permalink)
Andyg New Member Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Mar 2005 Location: Sheffield Posts: 25	po2 Any reason why you don't deco on anything higher than 1.4 Dave. Andyg
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18th July 2005, 21:07	#6 (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: 2,178	Quote: (Originally Posted by Andyg) Any reason why you don't deco on anything higher than 1.4 Dave. Andyg Hi Andy, I have always been taught that oxygen is not our friend, I am happy to clock some extra deco time and perhaps be not quite as clean as others, however I know of at least one death on the Inspiration that was caused by elevated levels of O2 on deco. It is my choice, I rack it back a little and it works for me. 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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18th July 2005, 23:19	#7 (permalink)
ROB DAVIE Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: HOUSTON, REPUBLIC OF TEJAS Posts: 1,120	0.7 on descent to the switch, 1.3 on the bottom, 0.7 on ascent after the switch per standard YBOD protocol, (1.0 at 3 msw/18 fsw if needed)
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18th July 2005, 23:28	#8 (permalink)
Andy M Dude Current Rebreather/s: Home Build Other Rebreather/s: Sport Kiss Home Build Join Date: Mar 2005 Location: Cambridge, UK Posts: 415	Quote: (Originally Posted by cedricverdier) There are different schools of thought, so every opinion is welcome. Question for the people who selected 1.0 on the bottom. Why? Seems some people do this, and as far as I know, no training agency teaches this? I dived with someone at the weekend who kept his around 1.0 Yes I can understand doing it for multidive multiday trips where UPTD is likely to be an issue, but for a weekend trip? Personally I keep mine between 1.3 and 1.2, leave the VR3 on 1.2 for deco and top off the loop to 1.3 every now and again. Andy __________________ Know your PO2 at all times
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19th July 2005, 00:27	#9 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,411	Some people select 1.0 ata as their setpoint and fly manually at a higher setpoint. Others prefer 1.0 ata for safety reasons as that's as much as they can verify at the surface. Those were the two reasons given when I asked divers who do so, anyway. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.'!"
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19th July 2005, 10:31	#10 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 494	Quote: (Originally Posted by Andy M) Question for the people who selected 1.0 on the bottom. Why? Seems some people do this, and as far as I know, no training agency teaches this? I dived with someone at the weekend who kept his around 1.0 Yes I can understand doing it for multidive multiday trips where UPTD is likely to be an issue, but for a weekend trip? Andy Hi Andy, I prefer to use a 1.0 setpoint for all my deep dives for the following reasons: - Less O2 exposure - Less risk of CNS oxtox (and on a decompression standpoint, it doesn't make a big difference with a 1.2 or 1.3 setpoint) - More time to react in case of O2 spike I need more O2 during the deco phase (so my setpoint is rather 1.3 or 1.4 depending on the tables I use), and I limit my O2 exposure during the bottom phase. Cheers __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
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