Rebreather newbie questions

spacemanspiff1974 · 3rd April 2006, 17:27

Hello everyone.

I have never experienced the fun of rebreather diving, but I have been reading about it a lot here and on various web pages.

I do have a couple of questions to which some of you may have an answer.

1) Is it possible to have a mechanical device to monitor PO2? (without electronics).

2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics)

3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle?

4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants?

***Beanie*** · 3rd April 2006, 18:11

Quote: (Originally Posted by spacemanspiff1974)

Hello everyone.

I have never experienced the fun of rebreather diving, but I have been reading about it a lot here and on various web pages.

I do have a couple of questions to which some of you may have an answer.

1) Is it possible to have a mechanical device to monitor PO2? (without electronics).

erm I don't beleive that it is, well I suppose you could use chemical tubes but not going to be very useful really

Quote:

2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics)

Well you could add at a constant rate see KISS

Quote:

3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle?

No this is a very bad idea

Quote:

4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants?

Hmm I think you might need a rather large case to put that lot in me thinks

**wedivebc** · 3rd April 2006, 18:40

Quote: (Originally Posted by Beanie)

No this is a very bad idea

Actually the Canadian Navy does it with their CUMA units.
HE for dil

***caveseeker7*** · 3rd April 2006, 18:46

Hi Spiffy, welcome to Rebreather World.

Quote: (Originally Posted by spacemanspiff1974)

1) Is it possible to have a mechanical device to monitor PO2? (without electronics).

The closest you'll probably get to that is a mechanical analog gauge as used on the CCR1000/MK15, MK15.5 and PRISM Topaz.

It still involves sensors, cables and the gauge, but the sensor output drives the gauge and it does not have a battery to fail.

Quote:

2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics)

Yes, some units like the beforementioned MK15.5 and PRISM Topaz have auto setpoint switching, with setpoint selection before the dive. Other electronics, like the Vision used on Inspiration and Evolution offer a choice of automatic or manual setpoint switching (as well as selection while diving).

Quote:

3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle?

Possible, but you want to be able to perform a loop flush with a breathable diluent, hence a really bad idea. Furthermore, most CCRs also have a second stage hooked up to the diluent tank for OC bailout.

Quote:

4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants?

Not that I'm aware of, at least not in publicly available rebreathers.

gathan · 3rd April 2006, 20:54

Quote: (Originally Posted by wedivebc)

Actually the Canadian Navy does it with their CUMA units.
HE for dil

We have also recently experimented with a mixture of 50/50 HeN2 as a dil.

Andre

diverrob · 3rd April 2006, 21:46

Quote: (Originally Posted by wedivebc)

Actually the Canadian Navy does it with their CUMA units.
HE for dil

We do use 100% He for our dil in our CUMA/SIVA+/VIPER set. We are unable to perform a dil flush on our sets and if we need to flush we have a bypass that gives us a breathable mixture at any depth. We are looking at Trimix as well as a redundant Rebreather on our down line for bailout. Remember that when we dive we have all the support that we may need if things go bad (ie: chamber, doctor, DMT, dressed standby diver, evacuation plan....). Most would highly discourage using a pure gas in the dil for many reasons as were listed above. We are able to maintain a constant PPO2 in our sets without using electronics but we run a semi closed system and have the flow regulated by depth.

3rd April 2006, 17:27	#1 (permalink)
spacemanspiff1974 New Member Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Mar 2006 Location: Houston Posts: 13	Rebreather newbie questions Hello everyone. I have never experienced the fun of rebreather diving, but I have been reading about it a lot here and on various web pages. I do have a couple of questions to which some of you may have an answer. 1) Is it possible to have a mechanical device to monitor PO2? (without electronics). 2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics) 3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle? 4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants?
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3rd April 2006, 18:11	#2 (permalink)
*Beanie* Cheif tea maker Current Rebreather/s: Inspiration Classic Other Rebreather/s: Inspiration Vision Join Date: Jan 2005 Location: In da house! yeah baby! Posts: 3,133	Re: Rebreather newbie questions Quote: (Originally Posted by spacemanspiff1974) Hello everyone. I have never experienced the fun of rebreather diving, but I have been reading about it a lot here and on various web pages. I do have a couple of questions to which some of you may have an answer. 1) Is it possible to have a mechanical device to monitor PO2? (without electronics). erm I don't beleive that it is, well I suppose you could use chemical tubes but not going to be very useful really Quote: 2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics) Well you could add at a constant rate see KISS Quote: 3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle? No this is a very bad idea Quote: 4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants? Hmm I think you might need a rather large case to put that lot in me thinks __________________ Beanie Gallery Admin & Library Assistant. www.outlawdivers.org.uk www.beandiving.co.uk www.beanengineering.co.uk www.divelife.co.uk
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3rd April 2006, 18:40	#3 (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: 1,336	Re: Rebreather newbie questions Quote: (Originally Posted by Beanie) No this is a very bad idea Actually the Canadian Navy does it with their CUMA units. HE for dil __________________ Cheers, Dave.... Man is the only animal burdened with the knowledge he will eventually die Last edited by wedivebc : 3rd April 2006 at 18:44.
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3rd April 2006, 18:46	#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: 5,281	Re: Rebreather newbie questions Hi Spiffy, welcome to Rebreather World. Quote: (Originally Posted by spacemanspiff1974) 1) Is it possible to have a mechanical device to monitor PO2? (without electronics). The closest you'll probably get to that is a mechanical analog gauge as used on the CCR1000/MK15, MK15.5 and PRISM Topaz. It still involves sensors, cables and the gauge, but the sensor output drives the gauge and it does not have a battery to fail. Quote: 2) Is it possible to have a device which automatically adjusts for a pre-set PO2? (Without electronics) Yes, some units like the beforementioned MK15.5 and PRISM Topaz have auto setpoint switching, with setpoint selection before the dive. Other electronics, like the Vision used on Inspiration and Evolution offer a choice of automatic or manual setpoint switching (as well as selection while diving). Quote: 3) On a CCR, does anyone use an oxygen-free diluent and have the O2 only from the oxygen bottle? Possible, but you want to be able to perform a loop flush with a breathable diluent, hence a really bad idea. Furthermore, most CCRs also have a second stage hooked up to the diluent tank for OC bailout. Quote: 4) Has anyone designed a liquid scrubber (enzymatic with the appropriate buffer) as a replacement for the lime scrubber? I would think that an enzyme scrubber might be more efficient - perhaps utilizing a carbon fixation pathway of cyanobacteria or plants? Not that I'm aware of, at least not in publicly available rebreathers. __________________ Cheers Stefan Be Water, My Friend - Bruce Lee Sponsor Lou in Race For Life!
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3rd April 2006, 20:54	#5 (permalink)
gathan MixedGas Current Rebreather/s: Classic Kiss Other SCR Other Rebreather/s: Other SCR Join Date: Sep 2005 Location: Tottenham, Ontario, Canada Posts: 199	Re: Rebreather newbie questions Quote: (Originally Posted by wedivebc) Actually the Canadian Navy does it with their CUMA units. HE for dil We have also recently experimented with a mixture of 50/50 HeN2 as a dil. Andre
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3rd April 2006, 21:46	#6 (permalink)
diverrob The Evolution of Diving Current Rebreather/s: Evolution Other SCR Other Rebreather/s: Not Bought Yet Other SCR Join Date: May 2005 Location: Victoria BC Canada Posts: 315	Re: Rebreather newbie questions Quote: (Originally Posted by wedivebc) Actually the Canadian Navy does it with their CUMA units. HE for dil We do use 100% He for our dil in our CUMA/SIVA+/VIPER set. We are unable to perform a dil flush on our sets and if we need to flush we have a bypass that gives us a breathable mixture at any depth. We are looking at Trimix as well as a redundant Rebreather on our down line for bailout. Remember that when we dive we have all the support that we may need if things go bad (ie: chamber, doctor, DMT, dressed standby diver, evacuation plan....). Most would highly discourage using a pure gas in the dil for many reasons as were listed above. We are able to maintain a constant PPO2 in our sets without using electronics but we run a semi closed system and have the flow regulated by depth.
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