Helium in the Isnp.

Pierre Farrugia · 2nd June 2005, 09:42

Hello all,

I in the process of starting using some helium mix diluent, for the 40m range dives! What things I should be looking at, as compared to air diluent ? Should it be just straight foward as changing dil and Vr3 settins and bailout plans ? All info is welcome.

decoweenie · 2nd June 2005, 09:48

Are you trained in CC mix or even OC mix, or are you planning to learn to dive CC mix via Internet only ?

Pierre Farrugia · 2nd June 2005, 10:10

Hello,

I am TDI adv trimix trained. What I had in mind to start diving some mix now. Also I never learned from internet but normally get reassured on what I know, if people are willing to help.

Mark Chase · 2nd June 2005, 21:08

Quote: (Originally Posted by Pierre Farrugia)

Hello all,

I in the process of starting using some helium mix diluents, for the 40m range dives! What things I should be looking at, as compared to air diluent ? Should it be just straight forward as changing dil and Vr3 settings and bailout plans ? All info is welcome.

Hi M8

I ran normoxic mix from day one on my Mod 1 cert but obviously I got the Mod3 and I was TDI Full Trimix certified on OC prior to that.

If there is a big difference to diving it on CCR I am not sure what it is (even after Mod3). Mind you getting accurate Mix into a 3ltr is a bugger I can tell you that for a start

All the usual issues of heat loss, normoxic / hypoxic at what depth, must do deep stops and controlled ascents, etc etc apply. A new thought process is perhaps having mix to bailout to rather than air or nitrox to avoid increasing the PPof nitrogen on bailout.

Personally I found it essential to flush all the He out of the loop and go 02 rebreather for a good portion of the last stop. Prior to this I was decoing out on 1.3 @ final stop depth of 6m and I was buggered after the dive running my favourite deco schedules. Going pure 02 flush brought me back to feeling good for a chat after the dive

Apart from that its just trimix but amazingly cheep to run

ATB

Mark Chase

Pierre Farrugia · 2nd June 2005, 22:37

Mark ,

What profiles are you speaking of, time at depth ? Also what where you using for deco planning ? Or just used Vr3 and if so what settings ? Did anyone here had same problem as opposed to OC trimix diving?

Quote: (Originally Posted by Mark Chase)

Hi M8

I ran normoxic mix from day one on my Mod 1 cert but obviously I got the Mod3 and I was TDI Full Trimix certified on OC prior to that.

If there is a big difference to diving it on CCR I am not sure what it is (even after Mod3). Mind you getting accurate Mix into a 3ltr is a bugger I can tell you that for a start

All the usual issues of heat loss, normoxic / hypoxic at what depth, must do deep stops and controlled ascents, etc etc apply. A new thought process is perhaps having mix to bailout to rather than air or nitrox to avoid increasing the PPof nitrogen on bailout.

Personally I found it essential to flush all the He out of the loop and go 02 rebreather for a good portion of the last stop. Prior to this I was decoing out on 1.3 @ final stop depth of 6m and I was buggered after the dive running my favourite deco schedules. Going pure 02 flush brought me back to feeling good for a chat after the dive

Apart from that its just trimix but amazingly cheep to run

ATB

Mark Chase

***schford*** · 2nd June 2005, 22:59

Hi Pierre,

I think Mark is referring to the fact that as you don't / shouldn't change your diluent (to avoid increasing gradient of ongassed v off gassing via your breathing mix) there is a need to ensure you purge all ongassed He from your tissues effectivly.

Imagine you were doing OC you were not be breathing He at your 6m stop where as on a Rebreather you would be if you didn;t purge and repeat regularly (to eliminate He that you have off gassed from loop).

Please note there is no right or wrong answer for this and decodiver who is very experinced advocates the opposite of this eg dont O2 flush and a constant set point through out dive.

You have to work out what works for you!

Stuart

Mark Chase · 3rd June 2005, 11:22

Quote: (Originally Posted by Pierre Farrugia)

Mark ,

What profiles are you speaking of, time at depth ? Also what where you using for deco planning ? Or just used Vr3 and if so what settings ? Did anyone here had same problem as opposed to OC trimix diving?

Hi Pierre

These were nothing special 35 - 40m dives with very conservitave deco using VR3 set to 0 plus my own V slow ascent rate additional stops and 5min from 6m to the surface. I was using 16/45 diluient.

30mins bottom time multi level between 32 and 40m 25mins of deco

ATB

Mark Chase

decoweenie · 3rd June 2005, 12:02

Quote: (Originally Posted by Mark Chase)

30mins bottom time multi level between 32 and 40m 25mins of deco

Just curious, which program gives you this deco profile ?

AndyP · 3rd June 2005, 14:12

Quote: (Originally Posted by decoweenie)

Just curious, which program gives you this deco profile ?

I was with im, the bottom times are approximate as is the deco time. The feeling ropey was a puzzel, so much so we played with deco times, assent rates etc. In the end we found an O2 flush at 6M and occaisional loop cleanups on the last stop got rid of it entirely. The conclusion (since we had never felt like this on OC) was that it was caused bu the He in the mix and deco was leaving us sub-clinical.

Added that cos it amuses me.

Andrew

decoweenie · 3rd June 2005, 14:22

Quote: (Originally Posted by AndyP)

I was with im, the bottom times are approximate as is the deco time.

Understood. I was curious since it looked conservative to me.

2nd June 2005, 09:42	#1 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Helium in the Isnp. Hello all, I in the process of starting using some helium mix diluent, for the 40m range dives! What things I should be looking at, as compared to air diluent ? Should it be just straight foward as changing dil and Vr3 settins and bailout plans ? All info is welcome. __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
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2nd June 2005, 09:48	#2 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Are you trained in CC mix or even OC mix, or are you planning to learn to dive CC mix via Internet only ?
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2nd June 2005, 10:10	#3 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Hello, I am TDI adv trimix trained. What I had in mind to start diving some mix now. Also I never learned from internet but normally get reassured on what I know, if people are willing to help. __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
(Offline)

2nd June 2005, 21:08	#4 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,821	Quote: (Originally Posted by Pierre Farrugia) Hello all, I in the process of starting using some helium mix diluents, for the 40m range dives! What things I should be looking at, as compared to air diluent ? Should it be just straight forward as changing dil and Vr3 settings and bailout plans ? All info is welcome. Hi M8 I ran normoxic mix from day one on my Mod 1 cert but obviously I got the Mod3 and I was TDI Full Trimix certified on OC prior to that. If there is a big difference to diving it on CCR I am not sure what it is (even after Mod3). Mind you getting accurate Mix into a 3ltr is a bugger I can tell you that for a start All the usual issues of heat loss, normoxic / hypoxic at what depth, must do deep stops and controlled ascents, etc etc apply. A new thought process is perhaps having mix to bailout to rather than air or nitrox to avoid increasing the PPof nitrogen on bailout. Personally I found it essential to flush all the He out of the loop and go 02 rebreather for a good portion of the last stop. Prior to this I was decoing out on 1.3 @ final stop depth of 6m and I was buggered after the dive running my favourite deco schedules. Going pure 02 flush brought me back to feeling good for a chat after the dive Apart from that its just trimix but amazingly cheep to run ATB Mark Chase __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
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2nd June 2005, 22:37	#5 (permalink)
Pierre Farrugia Custom Title Allowed! Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Malta Posts: 636	Mark , What profiles are you speaking of, time at depth ? Also what where you using for deco planning ? Or just used Vr3 and if so what settings ? Did anyone here had same problem as opposed to OC trimix diving? Quote: (Originally Posted by Mark Chase) Hi M8 I ran normoxic mix from day one on my Mod 1 cert but obviously I got the Mod3 and I was TDI Full Trimix certified on OC prior to that. If there is a big difference to diving it on CCR I am not sure what it is (even after Mod3). Mind you getting accurate Mix into a 3ltr is a bugger I can tell you that for a start All the usual issues of heat loss, normoxic / hypoxic at what depth, must do deep stops and controlled ascents, etc etc apply. A new thought process is perhaps having mix to bailout to rather than air or nitrox to avoid increasing the PPof nitrogen on bailout. Personally I found it essential to flush all the He out of the loop and go 02 rebreather for a good portion of the last stop. Prior to this I was decoing out on 1.3 @ final stop depth of 6m and I was buggered after the dive running my favourite deco schedules. Going pure 02 flush brought me back to feeling good for a chat after the dive Apart from that its just trimix but amazingly cheep to run ATB Mark Chase __________________ Pierre Farrugia My wife told me " If you don't quit diving I'm going to leave you" My reply " God, I'll miss you" www.atlam.org www.divemed.com
(Offline)

2nd June 2005, 22:59	#6 (permalink)
*schford* RBW Founder Current Rebreather/s: Megalodon Sport Kiss Other Rebreather/s: Join Date: Jan 2005 Location: UK Posts: 3,564	Hi Pierre, I think Mark is referring to the fact that as you don't / shouldn't change your diluent (to avoid increasing gradient of ongassed v off gassing via your breathing mix) there is a need to ensure you purge all ongassed He from your tissues effectivly. Imagine you were doing OC you were not be breathing He at your 6m stop where as on a Rebreather you would be if you didn;t purge and repeat regularly (to eliminate He that you have off gassed from loop). Please note there is no right or wrong answer for this and decodiver who is very experinced advocates the opposite of this eg dont O2 flush and a constant set point through out dive. You have to work out what works for you! Stuart
(Offline)

3rd June 2005, 11:22	#7 (permalink)
Mark Chase RBW Member Current Rebreather/s: Classic Kiss Other Rebreather/s: Inspiration Classic Join Date: Jan 2005 Location: Kent Posts: 2,821	Quote: (Originally Posted by Pierre Farrugia) Mark , What profiles are you speaking of, time at depth ? Also what where you using for deco planning ? Or just used Vr3 and if so what settings ? Did anyone here had same problem as opposed to OC trimix diving? Hi Pierre These were nothing special 35 - 40m dives with very conservitave deco using VR3 set to 0 plus my own V slow ascent rate additional stops and 5min from 6m to the surface. I was using 16/45 diluient. 30mins bottom time multi level between 32 and 40m 25mins of deco ATB Mark Chase __________________ See my "Doing It Chasey" video where I'm locked into a padded room, naked, with two ball bearings and within an Hour, I manage to lose one and break the other!!! Kevin Juergensen 16/11/08 [/quote]
(Offline)

3rd June 2005, 12:02	#8 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Quote: (Originally Posted by Mark Chase) 30mins bottom time multi level between 32 and 40m 25mins of deco Just curious, which program gives you this deco profile ?
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3rd June 2005, 14:12	#9 (permalink)
AndyP Mutter Grumble Groan Moan Current Rebreather/s: Inspiration Classic rEvo Other Rebreather/s: rEvo Join Date: Feb 2005 Location: UK Posts: 93	Quote: (Originally Posted by decoweenie) Just curious, which program gives you this deco profile ? I was with im, the bottom times are approximate as is the deco time. The feeling ropey was a puzzel, so much so we played with deco times, assent rates etc. In the end we found an O2 flush at 6M and occaisional loop cleanups on the last stop got rid of it entirely. The conclusion (since we had never felt like this on OC) was that it was caused bu the He in the mix and deco was leaving us sub-clinical. Added that cos it amuses me. Andrew
(Offline)

3rd June 2005, 14:22	#10 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Quote: (Originally Posted by AndyP) I was with im, the bottom times are approximate as is the deco time. Understood. I was curious since it looked conservative to me.
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