Possible silly question,

wreckferret · 30th April 2005, 08:21

Hi,

Would it be possible to use a SCR at depth with trimix as the main gas ?

If not why ?

Sorry if this sounds very stupid but I don`t know a lot about the tech side of rebreathers.

decoweenie · 30th April 2005, 10:59

Quote: (Originally Posted by wreckferret)

Would it be possible to use a SCR at depth with trimix as the main gas ?

Short answer is yes.

Long answer is still yes but with certain procedures. The exact procedures will depend on which SCR you are thinking about, but most will require a "travel" gas to get to depth where the bottom mix is safe to breath.

Think of SCR as similar to OC. Even if the trimix is in the normoxic range, going thru the SCR at shallow depth will reduce its fiO2 due to the amount of gas discharged per breath, etc. so might not breathable from surface.

Regardless, you will need to switch to a deco mix on the ascend for deco purpose anyway, thus using the same deco mix as travel mix on the way down.

Pawel · 30th April 2005, 12:53

I believe OMG Azimuth AF is the only recreational SCR designed specifically for trimix. It has two separate flow valves for two on-board mixes. It also has on-board bailout (2x10L) needed for up to 100m dives.

Cheers,

Pawel
www.AliensOfTheSea.com/HDTV

***caveseeker7*** · 30th April 2005, 13:00

Welcome Dave.

In addition to Phi's answer, few SCRs are set up for trimix use when you buy them.
Using mix in passive addition SCRs like the RB80, EDO04 or Tourill is usually not a problem as gas addition is keyed to you RMV, so they add it as needed. The manufacturers of these units all offer gas switchblocks that allow you to switch supply gases as Phi described. Gases can be plugged in UW, so if you need more than two gases that is possible.

The only active addition SCR set up for trimix afaik is the Azimuth AF. It has two gas blocks that each allow you to match the flow rate to the O2 content you use. The Azi AF replaces the two 4 ltr tanks with two 10 ltr tanks. If you need more than two mixes you'll have to modify the unit.

AFAIK training, including the use of trimix, is only offered for the RB80 and Azimuth AF.
On other SCRs you're on your own.

decoweenie · 30th April 2005, 13:08

Quote: (Originally Posted by Pawel)

...recreational SCR designed specifically for trimix...

Is that not an oxymoron ?

Anyway, that's still so not true. What do you think the PVR-BASC and Rebreather-80 were designed for ?

decoweenie · 30th April 2005, 13:16

Quote: (Originally Posted by caveseeker7)

The only active addition SCR set up for trimix afaik is the Azimuth AF...

... from the manufacturer.

However, there are plenty of people diving the Dolphin with trimix. The first one who did that dived the Doria on the modified A1 years ago, AKAIR.

***caveseeker7*** · 30th April 2005, 13:27

Correct, Phi.

Dräger had plans of building an "80 Meter" Dolphin at one point, they made prototypes and ANDI even wrote a few tickets, but Dräger decided to can the project.

They have, however, given some very limited factory support to a few divers that have modified their units for mix use, having their engineers look over the modifications and help out with suggestions and even bits.

**wedivebc** · 30th April 2005, 15:27

Quote: (Originally Posted by caveseeker7)

Correct, Phi.

Dräger had plans of building an "80 Meter" Dolphin at one point, they made prototypes and ANDI even wrote a few tickets, but Dräger decided to can the project.

They have, however, given some very limited factory support to a few divers that have modified their units for mix use, having their engineers look over the modifications and help out with suggestions and even bits.

Do you know of anyone who has pictures or info on this Rebreather? I think they called it the Dolphin 80. I am wondering how they worked.

**wedivebc** · 30th April 2005, 15:29

Quote: (Originally Posted by decoweenie)

Is that not an oxymoron ?

Anyway, that's still so not true. What do you think the PVR-BASC and Rebreather-80 were designed for ?

I think Pawel means recreational as opposed to military/commercial. We tend to forget that what we call technical diving is still recreatonal.

wreckferret · 30th April 2005, 17:08

Thanks.

The main reason for asking this was, when I use twin 12L`s for trimix dives deeper than 70m my bottom gas doesnt last long.

Rather than spend a fortune on a YBOD could I get away with SCR .

I would still carry 10L x 2 of deco gas.

30th April 2005, 08:21	#1 (permalink)
wreckferret New Member Current Rebreather/s: Other Rebreather/s: Join Date: Apr 2005 Location: Belfast, N.Ireland Posts: 8	Possible silly question, Hi, Would it be possible to use a SCR at depth with trimix as the main gas ? If not why ? Sorry if this sounds very stupid but I don`t know a lot about the tech side of rebreathers. __________________ *wreckferret ( Dave )*
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30th April 2005, 10:59	#2 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Quote: (Originally Posted by wreckferret) Would it be possible to use a SCR at depth with trimix as the main gas ? Short answer is yes. Long answer is still yes but with certain procedures. The exact procedures will depend on which SCR you are thinking about, but most will require a "travel" gas to get to depth where the bottom mix is safe to breath. Think of SCR as similar to OC. Even if the trimix is in the normoxic range, going thru the SCR at shallow depth will reduce its fiO2 due to the amount of gas discharged per breath, etc. so might not breathable from surface. Regardless, you will need to switch to a deco mix on the ascend for deco purpose anyway, thus using the same deco mix as travel mix on the way down.
(Offline)

30th April 2005, 12:53	#3 (permalink)
Pawel New Member Current Rebreather/s: Other Rebreather/s: Join Date: Apr 2005 Location: Sydney, Australia Posts: 68	I believe OMG Azimuth AF is the only recreational SCR designed specifically for trimix. It has two separate flow valves for two on-board mixes. It also has on-board bailout (2x10L) needed for up to 100m dives. Cheers, Pawel www.AliensOfTheSea.com/HDTV
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30th April 2005, 13:00	#4 (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: 5,287	Welcome Dave. In addition to Phi's answer, few SCRs are set up for trimix use when you buy them. Using mix in passive addition SCRs like the RB80, EDO04 or Tourill is usually not a problem as gas addition is keyed to you RMV, so they add it as needed. The manufacturers of these units all offer gas switchblocks that allow you to switch supply gases as Phi described. Gases can be plugged in UW, so if you need more than two gases that is possible. The only active addition SCR set up for trimix afaik is the Azimuth AF. It has two gas blocks that each allow you to match the flow rate to the O2 content you use. The Azi AF replaces the two 4 ltr tanks with two 10 ltr tanks. If you need more than two mixes you'll have to modify the unit. AFAIK training, including the use of trimix, is only offered for the RB80 and Azimuth AF. On other SCRs you're on your own. __________________ Cheers Stefan Be Water, My Friend - Bruce Lee Sponsor Lou in Race For Life!
(Offline)

30th April 2005, 13:08	#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	Quote: (Originally Posted by Pawel) ...recreational SCR designed specifically for trimix... Is that not an oxymoron ? Anyway, that's still so not true. What do you think the PVR-BASC and Rebreather-80 were designed for ?
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30th April 2005, 13:16	#6 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,510	Quote: (Originally Posted by caveseeker7) The only active addition SCR set up for trimix afaik is the Azimuth AF... ... from the manufacturer. However, there are plenty of people diving the Dolphin with trimix. The first one who did that dived the Doria on the modified A1 years ago, AKAIR.
(Offline)

30th April 2005, 13:27	#7 (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: 5,287	Correct, Phi. Dräger had plans of building an "80 Meter" Dolphin at one point, they made prototypes and ANDI even wrote a few tickets, but Dräger decided to can the project. They have, however, given some very limited factory support to a few divers that have modified their units for mix use, having their engineers look over the modifications and help out with suggestions and even bits. __________________ Cheers Stefan Be Water, My Friend - Bruce Lee Sponsor Lou in Race For Life!
(Offline)

30th April 2005, 15:27	#8 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,339	Quote: (Originally Posted by caveseeker7) Correct, Phi. Dräger had plans of building an "80 Meter" Dolphin at one point, they made prototypes and ANDI even wrote a few tickets, but Dräger decided to can the project. They have, however, given some very limited factory support to a few divers that have modified their units for mix use, having their engineers look over the modifications and help out with suggestions and even bits. Do you know of anyone who has pictures or info on this Rebreather? I think they called it the Dolphin 80. I am wondering how they worked. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
(Online)

30th April 2005, 15:29	#9 (permalink)
wedivebc FIGJAM Current Rebreather/s: Megalodon Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Other CCR Join Date: Feb 2005 Location: Vancouver Island BC Canada Posts: 1,339	Quote: (Originally Posted by decoweenie) Is that not an oxymoron ? Anyway, that's still so not true. What do you think the PVR-BASC and Rebreather-80 were designed for ? I think Pawel means recreational as opposed to military/commercial. We tend to forget that what we call technical diving is still recreatonal. __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die
(Online)

30th April 2005, 17:08	#10 (permalink)
wreckferret New Member Current Rebreather/s: Other Rebreather/s: Join Date: Apr 2005 Location: Belfast, N.Ireland Posts: 8	Thanks. The main reason for asking this was, when I use twin 12L`s for trimix dives deeper than 70m my bottom gas doesnt last long. Rather than spend a fortune on a YBOD could I get away with SCR . I would still carry 10L x 2 of deco gas. __________________ *wreckferret ( Dave )*
(Offline)

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