Standard Bailout Mixes

UKSteve · 2nd September 2007, 12:11

Quote: (Originally Posted by Decodiver)

The real value of the diluent for me, and for at least one other who died alpine, is that you can flush it to bring down your PPO2 in the event of a stuck openoid solenoid/O2 addition.

Don't I know it....

S.

decoweenie · 2nd September 2007, 12:18

Quote: (Originally Posted by Decodiver)

I just don't get this, if you want to check for a higher PPO2 value, then add oxygen above 1.6 for 10 seconds or so, it ain't gonna kill you...

Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible.

If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify.

kieranu · 2nd September 2007, 12:37

Quote: (Originally Posted by decoweenie)

Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible.

If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify.

I have considered this even at relatively shallow depths of around 10m (leave off ADV and wait to 10m or so until I get a reading of 1.6 on the cells then turn it on and continue descent) but ... exactly, your cells could be reading 1.5 after injecting O2 at 60m to "verify" the cells but the PO2 in the loop could really be at 2.0+++ if they're current limited - this would be a great way to kill yourself.

I'm still MOD1 so if I'm planning a long 30-40m dive I will carry EAN30 bailout in a 40cf cylinder - if I'm bailing I'm not going to be at 1.5+ long enough for it to be an issue even at 40-45m. Of course, provided I've not used up the gas for dry suit inflation I carry it for shallower / shorter dives also. The rest of the time I just top the cylinder up with air until such time as I need bailout for a long / "deep" dive again. After all, its bailout and apart from from running the dry suit, the odd sanity breath and practicing running SCR with my off-board I've never had to use it. I'm not against the idea of having EAN30 as a standardized bailout to 40m for MOD1 trained divers if this is going to increase safety etc.

I've not done MOD2, but carrying dil that will give a maximum PO2 of 1.0 with a flush at max depth sounds like it will give a pretty strong risk of hypoxia when ascending from deeper dives.

***jradomski*** · 2nd September 2007, 12:44

Quote: (Originally Posted by decoweenie)

Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible.

If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify.

My point exactly.. I want to know the accuracy of my cells around the SP.. Just because I can raise the po2 with o2 doesnt mean its accurate.. I have seen cells that I could get up to 1.3 but really needed over 1.6 to reach this, and were spot on at 1.0.. SO if I verified with a dil that gave me a 1.0 I proved NOTHING, other than its ok at a 1.0..

(UKSTEVE)
As to diluent/bailout.. My bottom bailout and onboard diluent are the same gases so its ok from my standpoint where it is..

(decodiver)
I dont want to criticize anyones trechnique, but it doesnt take more than 1 or 2 seconds to do a complete dil flush with OTS lungs when done properly and uses little gas (most of it is your lung volume).. with BM lungs its a bit worse..

with a bottom bailout/diluent around my SP gives me a reasonable SCR or OC bailout for deco.. The last thing I want to do is have to bailout to a gas thats going to make my deco even worse than just baiing to OC with an optimum gas..

As to verifying on descent, cells degrade with exposure, a weak cell at the start of a dive may be fine but can rapidly deteriate (just like a regular battery), the can recover somewhat at a low po2 (low voltage/current) output but will weaken as time progresses..

***jradomski*** · 2nd September 2007, 12:52

Quote: (Originally Posted by decoweenie)

How often do you do a complete diluent flush to test your sensors during the dive ?
.

rarely.. but I HAVE had to verify cells, and even if It only catches a cell once in my lifetinme that it would not have caught using a leaner gas.. I'll be happy since that means I'll probably live to talk about it.. I am very respectful on how unreliable o2 cells are..

***jradomski*** · 2nd September 2007, 12:58

Quote: (Originally Posted by decoweenie)

Since we are talking about bail-out gas, are you going to dump full stages and mix for every dive if you don't standardize your gas ?

Personally, I use the same set of bail-out tanks because of these local-specific reasons (and they might not apply to others):

Our week-end wrecks are in 72m, 85m, 92m and 115m.
It is not 100% guaranty that we will be able to dive a specific wreck until we got out to the primary site (due to local-specific reasons), so must be able to divert to secondary site. Or go home.
Many times we were forced to dive the shallower wrecks using the higher He mix when can't dive the deeper ones. This just meant slightly longer deco.

So I use 10/50 + 50% for bail-out, except 10/70 + 50% for the 115m site. Same trimix for on-board.

I usually penetrate the wrecks so using a hot-mix to save deco isn't ideal as I wouldn't be able to commence the ascend immediately upon bailing out.

First team hangs a spare trimix stage at bottom of anchor line, last team removes it. There are plenty more of safety stages on the boat to drop when an yellow DSMB is sent up.

Phi,
for dives that I can drive to a bring my choice of gear, I carry 2 different diluent bottles one lean, 1 richer) and carry 2 different bottom bailout mixes and 50%.. This way once If the deep plans get blown I just switch out 1 bottle on my rig, and move one bailout regulator over to a richer bailout..

***jradomski*** · 2nd September 2007, 13:03

Quote: (Originally Posted by Hanssing)

How do you then select your bottom bailout?
At setpoint or above?

Nicolai

I try and select a gas that will give me a flush between 1.2 and 1.6 as the worse case on bottom (not reaching target depth or having to go a bit beyond initially planned depth).. The gases I choose usually fall in the range of 1.3-1.4 for most of the depths I will use the mix at..

**fireman** · 2nd September 2007, 14:02

I think it obvious that one must avoid hypoxic mixes until absolutely necessary. So 18/50 gives pp0=1.6 at 267'; 16/50 at 300'. So normoxic down to at least 250'...

So
100% because you have it on the breather

Air or richer nitrox because its easy as on board dil
Very deep or very shallow= richer nitrox
Shallow You can flush with richer on board nitrox. Deeper so you are carring more O2 in case of mishap.

Stage :Air Shallow
Normoxic trimix 18/50 Deep

I haven't had to dive deeper than 250' yet...

I would use 16/50 or 16/74 down to 350 or so depending upon the specific situation (overhead etc)

Abbo · 2nd September 2007, 14:43

I might have had a Sake or 2 too many (cheers), but here goes: I was taught recently to use a maximum PO2 of 2.0 for bailout.
Initially, I thought that a little rash, but in an emergency bailout, my first absolutely necessary deco stop is around half the maximum depth. I'm likely to blow out my deep stops and go for the first deco stop. The amount of time on a PO2 of 2.0 is therefore not very long.
The percentage of my dive at maximum depth is small, so the probability of needing to bailout at that depth is commensurately small.
I'm also likely to be breathing like a racehorse when I bail out, and a high PO2 may be just what the doctor ordered.
It would be best to have a regulator on the diluent gas, though, to give me a lower PO2 for the start of the ascent.
So, for an 85m dive I have one sling tank of air and one of pure O2.
At least with this method, the bailout gas has a chance of being rich enough to get me all of the way through deco.
Flameproof suit is ON

UKSteve · 2nd September 2007, 14:53

Quote: (Originally Posted by Abbo)

I was taught recently to use a maximum PO2 of 2.0 for bailout. <snip>
So, for an 85m dive I have one sling tank of air and one of pure O2.
At least with this method, the bailout gas has a chance of being rich enough to get me all of the way through deco.
Flameproof suit is ON

Wow.. air at 85m... have you tried to breath air at that depth coming off trimix? I would imagine it would feel like treacle... and quite a belt from the ppN2 I presume...

... or are you assuming you will be above 60m or so by then breathing off the diluent?

Don't get me wrong... not saying its wrong...but have you tested it?

Steve

2nd September 2007, 12:11	#21 (permalink)
UKSteve Still a novice... Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jul 2005 Location: Weymouth, UK Posts: 577	Re: Standard Bailout Mixes Quote: (Originally Posted by Decodiver) The real value of the diluent for me, and for at least one other who died alpine, is that you can flush it to bring down your PPO2 in the event of a stuck openoid solenoid/O2 addition. Don't I know it.... S.
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2nd September 2007, 12:18	#22 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Re: Standard Bailout Mixes Quote: (Originally Posted by Decodiver) I just don't get this, if you want to check for a higher PPO2 value, then add oxygen above 1.6 for 10 seconds or so, it ain't gonna kill you... Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible. If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify. __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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2nd September 2007, 12:37	#23 (permalink)
kieranu Apprentice Meg Pilot Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: WA, Australia Posts: 236	Re: Standard Bailout Mixes Quote: (Originally Posted by decoweenie) Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible. If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify. I have considered this even at relatively shallow depths of around 10m (leave off ADV and wait to 10m or so until I get a reading of 1.6 on the cells then turn it on and continue descent) but ... exactly, your cells could be reading 1.5 after injecting O2 at 60m to "verify" the cells but the PO2 in the loop could really be at 2.0+++ if they're current limited - this would be a great way to kill yourself. I'm still MOD1 so if I'm planning a long 30-40m dive I will carry EAN30 bailout in a 40cf cylinder - if I'm bailing I'm not going to be at 1.5+ long enough for it to be an issue even at 40-45m. Of course, provided I've not used up the gas for dry suit inflation I carry it for shallower / shorter dives also. The rest of the time I just top the cylinder up with air until such time as I need bailout for a long / "deep" dive again. After all, its bailout and apart from from running the dry suit, the odd sanity breath and practicing running SCR with my off-board I've never had to use it. I'm not against the idea of having EAN30 as a standardized bailout to 40m for MOD1 trained divers if this is going to increase safety etc. I've not done MOD2, but carrying dil that will give a maximum PO2 of 1.0 with a flush at max depth sounds like it will give a pretty strong risk of hypoxia when ascending from deeper dives.
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2nd September 2007, 12:44	#24 (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: 2,890	Re: Standard Bailout Mixes Quote: (Originally Posted by decoweenie) Joe will clarify, but the way I understand his comment was... using a known gas at a known depth to test the cells to a PO2 as close to SP as possible. If adding O2, then you no longer know the actual PO2 in the loop other than what the cells are telling you - which you are trying to verify. My point exactly.. I want to know the accuracy of my cells around the SP.. Just because I can raise the po2 with o2 doesnt mean its accurate.. I have seen cells that I could get up to 1.3 but really needed over 1.6 to reach this, and were spot on at 1.0.. SO if I verified with a dil that gave me a 1.0 I proved NOTHING, other than its ok at a 1.0.. (UKSTEVE) As to diluent/bailout.. My bottom bailout and onboard diluent are the same gases so its ok from my standpoint where it is.. (decodiver) I dont want to criticize anyones trechnique, but it doesnt take more than 1 or 2 seconds to do a complete dil flush with OTS lungs when done properly and uses little gas (most of it is your lung volume).. with BM lungs its a bit worse.. with a bottom bailout/diluent around my SP gives me a reasonable SCR or OC bailout for deco.. The last thing I want to do is have to bailout to a gas thats going to make my deco even worse than just baiing to OC with an optimum gas.. As to verifying on descent, cells degrade with exposure, a weak cell at the start of a dive may be fine but can rapidly deteriate (just like a regular battery), the can recover somewhat at a low po2 (low voltage/current) output but will weaken as time progresses.. __________________ 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. Last edited by jradomski : 2nd September 2007 at 12:47.
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2nd September 2007, 12:52	#25 (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: 2,890	Re: Standard Bailout Mixes Quote: (Originally Posted by decoweenie) How often do you do a complete diluent flush to test your sensors during the dive ? . rarely.. but I HAVE had to verify cells, and even if It only catches a cell once in my lifetinme that it would not have caught using a leaner gas.. I'll be happy since that means I'll probably live to talk about it.. I am very respectful on how unreliable o2 cells are.. __________________ 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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2nd September 2007, 12:58	#26 (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: 2,890	Re: Standard Bailout Mixes Quote: (Originally Posted by decoweenie) Since we are talking about bail-out gas, are you going to dump full stages and mix for every dive if you don't standardize your gas ? Personally, I use the same set of bail-out tanks because of these local-specific reasons (and they might not apply to others): Our week-end wrecks are in 72m, 85m, 92m and 115m. It is not 100% guaranty that we will be able to dive a specific wreck until we got out to the primary site (due to local-specific reasons), so must be able to divert to secondary site. Or go home. Many times we were forced to dive the shallower wrecks using the higher He mix when can't dive the deeper ones. This just meant slightly longer deco. So I use 10/50 + 50% for bail-out, except 10/70 + 50% for the 115m site. Same trimix for on-board. I usually penetrate the wrecks so using a hot-mix to save deco isn't ideal as I wouldn't be able to commence the ascend immediately upon bailing out. First team hangs a spare trimix stage at bottom of anchor line, last team removes it. There are plenty more of safety stages on the boat to drop when an yellow DSMB is sent up. Phi, for dives that I can drive to a bring my choice of gear, I carry 2 different diluent bottles one lean, 1 richer) and carry 2 different bottom bailout mixes and 50%.. This way once If the deep plans get blown I just switch out 1 bottle on my rig, and move one bailout regulator over to a richer bailout.. __________________ 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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2nd September 2007, 13:03	#27 (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: 2,890	Re: Standard Bailout Mixes Quote: (Originally Posted by Hanssing) How do you then select your bottom bailout? At setpoint or above? Nicolai I try and select a gas that will give me a flush between 1.2 and 1.6 as the worse case on bottom (not reaching target depth or having to go a bit beyond initially planned depth).. The gases I choose usually fall in the range of 1.3-1.4 for most of the depths I will use the mix at.. __________________ 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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2nd September 2007, 14:02	#28 (permalink)
fireman rEvo combat swimmer Current Rebreather/s: rEvo Other CCR Other Rebreather/s: rEvo Other CCR Join Date: Nov 2006 Location: chicago Posts: 497	Re: Standard Bailout Mixes I think it obvious that one must avoid hypoxic mixes until absolutely necessary. So 18/50 gives pp0=1.6 at 267'; 16/50 at 300'. So normoxic down to at least 250'... So 100% because you have it on the breather Air or richer nitrox because its easy as on board dil Very deep or very shallow= richer nitrox Shallow You can flush with richer on board nitrox. Deeper so you are carring more O2 in case of mishap. Stage :Air Shallow Normoxic trimix 18/50 Deep I haven't had to dive deeper than 250' yet... I would use 16/50 or 16/74 down to 350 or so depending upon the specific situation (overhead etc) __________________ Heres to you Capt. Bill Never Forget, and stay safe everyone. Last edited by fireman : 2nd September 2007 at 14:12. Reason: answere original question
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2nd September 2007, 14:43	#29 (permalink)
Abbo Going down on Meg Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: Tokyo Posts: 422	Re: Standard Bailout Mixes I might have had a Sake or 2 too many (cheers), but here goes: I was taught recently to use a maximum PO2 of 2.0 for bailout. Initially, I thought that a little rash, but in an emergency bailout, my first absolutely necessary deco stop is around half the maximum depth. I'm likely to blow out my deep stops and go for the first deco stop. The amount of time on a PO2 of 2.0 is therefore not very long. The percentage of my dive at maximum depth is small, so the probability of needing to bailout at that depth is commensurately small. I'm also likely to be breathing like a racehorse when I bail out, and a high PO2 may be just what the doctor ordered. It would be best to have a regulator on the diluent gas, though, to give me a lower PO2 for the start of the ascent. So, for an 85m dive I have one sling tank of air and one of pure O2. At least with this method, the bailout gas has a chance of being rich enough to get me all of the way through deco. Flameproof suit is ON Last edited by Abbo : 2nd September 2007 at 14:46.
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2nd September 2007, 14:53	#30 (permalink)
UKSteve Still a novice... Current Rebreather/s: Inspiration Vision Other Rebreather/s: Join Date: Jul 2005 Location: Weymouth, UK Posts: 577	Re: Standard Bailout Mixes Quote: (Originally Posted by Abbo) I was taught recently to use a maximum PO2 of 2.0 for bailout. <snip> So, for an 85m dive I have one sling tank of air and one of pure O2. At least with this method, the bailout gas has a chance of being rich enough to get me all of the way through deco. Flameproof suit is ON Wow.. air at 85m... have you tried to breath air at that depth coming off trimix? I would imagine it would feel like treacle... and quite a belt from the ppN2 I presume... ... or are you assuming you will be above 60m or so by then breathing off the diluent? Don't get me wrong... not saying its wrong...but have you tested it? Steve
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