diluant choice

**jmurba** · 26th December 2006, 21:16

Hi all,

I've dived my dolphin ccr "kiss style" for a couple of years on air or normoxic trimix diluant for 2 reasons :

- possibility of rebreathing the diluant without getting a too weak fio2 in the loop in case of electronic failure

- possibility of breathing the dil oc in case of loop floading in normoxic figure

but 4 days ago I was lingering arroung 55m on a normoxic mix and i realized that the ppo2 was far too high,

I've never dived an hypoxic diluant, what does it change ?

is it hazardous ?

what is the best fo2 given that i never get deeper then 60.

regards

RonMicjan · 27th December 2006, 01:25

Hey M8

one should have a diluent that will allow the diver to flush the loop down to your intended setpoint at the target operating depth. If you get any kind of runaway O2 injection, its nice to flush to lower the loop PO2.

jhaaja · 27th December 2006, 05:28

Quote: (Originally Posted by jmurba)

Hi all,

I've dived my dolphin ccr "kiss style" for a couple of years on air or normoxic trimix diluant for 2 reasons :

- possibility of rebreathing the diluant without getting a too weak fio2 in the loop in case of electronic failure

- possibility of breathing the dil oc in case of loop floading in normoxic figure

but 4 days ago I was lingering arroung 55m on a normoxic mix and i realized that the ppo2 was far too high,

I've never dived an hypoxic diluant, what does it change ?

is it hazardous ?

what is the best fo2 given that i never get deeper then 60.

regards

You could start using TX18/45 (or TX18/??) as diluent. Then the ppO2 would not be so high at 60m and you still can breath it OC all the way from surface to surface.

**jmurba** · 27th December 2006, 08:13

Quote: (Originally Posted by jhaaja)

You could start using TX18/45 (or TX18/??) as diluent. Then the ppO2 would not be so high at 60m and you still can breath it OC all the way from surface to surface.

Hem ,

mabye i did not ask the good question then....
Like many I've converted a dolphin ccr kiss style and used the 5 liter tank as the dil tank and the 2 liter bail out as o2 tank.
the consequence is that I had plenty of dil to flush hard and deeply the loop to reduce the ppo2 arround 60m
2 years ago I got rid of the 5 liter dil tank that was destroying my back and replaced it by a 2 liter.
I noticed no difference cause i usualy dive shallow arround 40m
the thing is that i recently decided to dive deeper after 4 years of ccr and then I went down
As a result my deep flushes revealed "expensive" in term of dil pressure making me realize that reducing ppo2 of a rich loop with air or normoxic trimix at 55 m with a 2 liter tank was not really easy.....
what is your experience with 18 O2 mixes , does it drop ppo2 enough during the descent ?
Maybe does it also comes from the way I dive, i start rich to avoid surface hypoxia and get dowm to say 30m and after ward i decend slowly to my max depth following the bottom profile keepping my ppo2 arrounf 1.2 to match my hs explorer fixed set point (i don't use a cell to drive the computer ppo2).
......
well I wil try a 18 fo2 mix and a more direct decent .

mabye 2 dils are not as supid as I thought before

regards

jean mi

decoweenie · 27th December 2006, 08:24

Jean-Michel,

Sounds like you had to flush because you were spiking your loop PO2 on the descent either:

add too much O2 manually
use high fiO2 diluent

Regardless, if you use a lower fiO2 diluent (i.e. hypoxic), you might not have to flush the loop as often to lower your PO2.

And, yes, you could also learn all of this from a CCR Trimix course...

**jmurba** · 27th December 2006, 08:46

Quote: (Originally Posted by decoweenie)

Jean-Michel,

Sounds like you had to flush because you were spiking your loop PO2 on the descent either:

add too much O2 manually

+++++ yes, in fact I had been at 45 m for 20' with a stable 1.2 loop when i decidedthe get deeper down to 55 cause i saw something interresting below,

use high fiO2 diluent

++++ normoxic

Regardless, if you use a lower fiO2 diluent (i.e. hypoxic), you might not have to flush the loop as often to lower your PO2.

++++ yes but how lower for 60m ?

And, yes, you could also learn all of this from a CCR Trimix course...

++++ you are right...but there are no kiss courses in france... and i don't want to do a yellow box course the only r course available down there...

regards

jean mi

decoweenie · 27th December 2006, 09:04

Quote: (Originally Posted by jmurba)

++++ you are right...but there are no kiss courses in france...

I believe that I have read there were KISS courses conducted in southern France from time to time. As well as Switzerland.

Personally, I use 10/50 for almost everything down to 90m when I am lazy. When I am not, I blend 10/70 for the local 90m wreck dive.

ADDited:

Trying to avoid The Shit-stirrer, I just have to mention this again but it has been mentioned many times in the past.

The shallowest wreck we dive locally on the week-end is 72m, and the deepest is 120m. It is not unusual for us to come out to the 72m wreck and see a US warship anchors within 3km (no dive zone), and have to divert to the next deeper wreck (92m). This obviously negates using best-mix-diluent for a dive.

And I said "almost" is because I use air diluent when teaching.

Moray Brown · 27th December 2006, 13:30

I believe Decodiver runs courses out of France and Switzerland! Covering the KISS

You can find him here

http://www.rebreatherworld.com/members/decodiver.html

All the best

dive2dive2000 · 27th December 2006, 14:08

Quote: (Originally Posted by decoweenie)

I am assuming you mean when teaching

And I said "almost" is because I use air diluent when teaching.

I am assuming you mean when teaching CCR and not Trimix CCR

decoweenie · 27th December 2006, 14:33

Quote: (Originally Posted by dive2dive2000)

I am assuming you mean when teaching CCR and not Trimix CCR

Jeez, what do you think ?

Even Trimix CCR course has a shallow diving portion, but of course, everyone is on trimix diluent (% defined by the agency) on the deep diving portion.

26th December 2006, 21:16	#1 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 672	diluant choice Hi all, I've dived my dolphin ccr "kiss style" for a couple of years on air or normoxic trimix diluant for 2 reasons : - possibility of rebreathing the diluant without getting a too weak fio2 in the loop in case of electronic failure - possibility of breathing the dil oc in case of loop floading in normoxic figure but 4 days ago I was lingering arroung 55m on a normoxic mix and i realized that the ppo2 was far too high, I've never dived an hypoxic diluant, what does it change ? is it hazardous ? what is the best fo2 given that i never get deeper then 60. regards
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27th December 2006, 01:25	#2 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,082	Re: diluant choise Hey M8 one should have a diluent that will allow the diver to flush the loop down to your intended setpoint at the target operating depth. If you get any kind of runaway O2 injection, its nice to flush to lower the loop PO2. __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
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27th December 2006, 05:28	#3 (permalink)
jhaaja Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Mar 2005 Location: Finland Posts: 867	Re: diluant choice Quote: (Originally Posted by jmurba) Hi all, I've dived my dolphin ccr "kiss style" for a couple of years on air or normoxic trimix diluant for 2 reasons : - possibility of rebreathing the diluant without getting a too weak fio2 in the loop in case of electronic failure - possibility of breathing the dil oc in case of loop floading in normoxic figure but 4 days ago I was lingering arroung 55m on a normoxic mix and i realized that the ppo2 was far too high, I've never dived an hypoxic diluant, what does it change ? is it hazardous ? what is the best fo2 given that i never get deeper then 60. regards You could start using TX18/45 (or TX18/??) as diluent. Then the ppO2 would not be so high at 60m and you still can breath it OC all the way from surface to surface.
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27th December 2006, 08:13	#4 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 672	Re: diluant choice Quote: (Originally Posted by jhaaja) You could start using TX18/45 (or TX18/??) as diluent. Then the ppO2 would not be so high at 60m and you still can breath it OC all the way from surface to surface. Hem , mabye i did not ask the good question then.... Like many I've converted a dolphin ccr kiss style and used the 5 liter tank as the dil tank and the 2 liter bail out as o2 tank. the consequence is that I had plenty of dil to flush hard and deeply the loop to reduce the ppo2 arround 60m 2 years ago I got rid of the 5 liter dil tank that was destroying my back and replaced it by a 2 liter. I noticed no difference cause i usualy dive shallow arround 40m the thing is that i recently decided to dive deeper after 4 years of ccr and then I went down As a result my deep flushes revealed "expensive" in term of dil pressure making me realize that reducing ppo2 of a rich loop with air or normoxic trimix at 55 m with a 2 liter tank was not really easy..... what is your experience with 18 O2 mixes , does it drop ppo2 enough during the descent ? Maybe does it also comes from the way I dive, i start rich to avoid surface hypoxia and get dowm to say 30m and after ward i decend slowly to my max depth following the bottom profile keepping my ppo2 arrounf 1.2 to match my hs explorer fixed set point (i don't use a cell to drive the computer ppo2). ...... well I wil try a 18 fo2 mix and a more direct decent . mabye 2 dils are not as supid as I thought before regards jean mi
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27th December 2006, 08:24	#5 (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: diluant choice Jean-Michel, Sounds like you had to flush because you were spiking your loop PO2 on the descent either: add too much O2 manually use high fiO2 diluent Regardless, if you use a lower fiO2 diluent (i.e. hypoxic), you might not have to flush the loop as often to lower your PO2. And, yes, you could also learn all of this from a CCR Trimix course... __________________ "...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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27th December 2006, 08:46	#6 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 672	Re: diluant choice Quote: (Originally Posted by decoweenie) Jean-Michel, Sounds like you had to flush because you were spiking your loop PO2 on the descent either: add too much O2 manually +++++ yes, in fact I had been at 45 m for 20' with a stable 1.2 loop when i decidedthe get deeper down to 55 cause i saw something interresting below, use high fiO2 diluent ++++ normoxic Regardless, if you use a lower fiO2 diluent (i.e. hypoxic), you might not have to flush the loop as often to lower your PO2. ++++ yes but how lower for 60m ? And, yes, you could also learn all of this from a CCR Trimix course... ++++ you are right...but there are no kiss courses in france... and i don't want to do a yellow box course the only r course available down there... regards jean mi
(Offline)

27th December 2006, 09:04	#7 (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: diluant choice Quote: (Originally Posted by jmurba) ++++ you are right...but there are no kiss courses in france... I believe that I have read there were KISS courses conducted in southern France from time to time. As well as Switzerland. Personally, I use 10/50 for almost everything down to 90m when I am lazy. When I am not, I blend 10/70 for the local 90m wreck dive. ADDited: Trying to avoid The Shit-stirrer, I just have to mention this again but it has been mentioned many times in the past. The shallowest wreck we dive locally on the week-end is 72m, and the deepest is 120m. It is not unusual for us to come out to the 72m wreck and see a US warship anchors within 3km (no dive zone), and have to divert to the next deeper wreck (92m). This obviously negates using best-mix-diluent for a dive. And I said "almost" is because I use air diluent when teaching. __________________ "...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 Last edited by decoweenie : 27th December 2006 at 13:37.
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27th December 2006, 13:30	#8 (permalink)
Moray Brown Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2006 Location: WMUK Posts: 227	Re: diluant choice (calling Decodiver) I believe Decodiver runs courses out of France and Switzerland! Covering the KISS You can find him here http://www.rebreatherworld.com/members/decodiver.html All the best Last edited by Moray Brown : 27th December 2006 at 14:08.
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27th December 2006, 14:08	#9 (permalink)
dive2dive2000 PRISM DIVER & LUVIN IT! Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: Feb 2005 Location: Long Island, NY Posts: 784	Re: diluant choice Quote: (Originally Posted by decoweenie) I am assuming you mean when teaching And I said "almost" is because I use air diluent when teaching. I am assuming you mean when teaching CCR and not Trimix CCR __________________ Safe Diving, Martin "but what's the fun of getting what you need, instead of what you want?"
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27th December 2006, 14:33	#10 (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: diluant choice Quote: (Originally Posted by dive2dive2000) I am assuming you mean when teaching CCR and not Trimix CCR Jeez, what do you think ? Even Trimix CCR course has a shallow diving portion, but of course, everyone is on trimix diluent (% defined by the agency) on the deep diving portion. __________________ "...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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