Co2 Sensor At Dema

**jepuskar** · 21st November 2007, 14:33

I'm curious as well..

Tom Rose · 21st November 2007, 15:12

[quote=divetheworld;82825]

Quote: (Originally Posted by Tom Rose)

Question, am I missing something?
If you are using an IR absorb sensor then it will be specific to a frequency, but that frequency will change with pressure.
So as the pressure increases so will the error. IR is usually only accurate over a specific range.

Brent

Absolutely right....there is more going on than discussed before. Without going into details, there are ways of handling that issue.

Tom

Tom Rose · 21st November 2007, 15:27

Quote: (Originally Posted by RZEP17)

Hi again
Some more questions for Tom Rose.
Being so informative, about your device, I hope you don't mind few more questions, Tom.

The O2 drying flow - you have to find a compromise between drawing adequate gas sample for monitoring CO2 and still not affecting to much the PPO2 in the loop. Is there a potential for the hyperoxia in certain situation like rapid decent? And again my understanding is you are using some kind of orifice/ venturi tube in your aspirator. Is there potential, pardon my language, for sucking in some sorb dust and plugging it? Finally the mysterious(for me) membrane open for water vapors and impenetrable for the CO2 molecules. Can you say something more about it or it is a trade secret?
rgrds
Tomek

The flow volume through the sensor path is very small compared to the flow volume through the loop such that the effect on concentration in the loop is indetectable.

The issue of plugging came up early in my discussions with other divers....it actually came up in those discussions at the DEMA Rebreather Party in Los Vegas when I was describing the concept...(it always helps to have some other eyes on a project)...I frankly had not even thought that far in advance. Placement of the filter became an interesting problem that was solved when I devised the retrofit package I showed at DEMA. As soon as the Holidays are over and my life gets back to normal (or as normal as my life would be to most observers) I will post a picture and a description of the retrofit package as shown at DEMA.

Tom

Tom Rose · 21st November 2007, 15:31

[quote=Tom Mount;83788]

Quote: (Originally Posted by Tom Rose)

Hi Tom

You know that Tomar (Titan- bubbleseekers) also had a co2 sensor at DEMA plus waterproof o2 sensors- not sure how or if your designs are similar

Hi Tom

No I did not have a chance to see it? Did not know Tomar was even working on one. Wish I had. If Tomar did have a working unit, thats great. Like everything else, nothing advances by one persons effort alone. Multiple solutions mean multiple options.

Tom Rose

Tom Rose · 21st November 2007, 15:34

[quote=Tom Rose;152374][quote=Tom Mount;83788]

Since I have dominated this thread with three posts in a row...I wish everyone a great Thanksgiving day if you celebrate it tomorrow, If not I'll be thinking about you guys as we chow down...sure I will.

Tom

onetime · 21st November 2007, 15:56

[quote=Tom Rose;152375][quote=Tom Rose;152374]

Quote: (Originally Posted by Tom Mount)

Since I have dominated this thread with three posts in a row...I wish everyone a great Thanksgiving day if you celebrate it tomorrow, If not I'll be thinking about you guys as we chow down...sure I will.

Tom

Just so you're not just talking to yourself

, you have a happy Thanksgiving too. Thanks for all your posts on the subject. It's definitely an interesting one.

Jorma · 21st November 2007, 17:31

Hello and Happy Thanksgiving for you over there.
Thanks indeed of the interesting subject which I just stumbled unintentionally.
I was working years ago with manned submersibles, and there a CO2-monitor was standard equip to monitor scrubber life.
Without knowing much of the technical details of CO2-sensors, was wondering if any of commercially available bell or submersible CO2 monitors could be modified for the CCR-purpose?
Kind Regards, Jorma Savolainen

jdicediver · 22nd November 2007, 00:15

[quote=Tom Rose;152375][quote=Tom Rose;152374]

Quote: (Originally Posted by Tom Mount)

Since I have dominated this thread with three posts in a row...

Tom

AMAZING, best of luck with the design, let me know if you need an investor. Sounds like some old-timers know a thing or two about a thing or two.

Now...THAT'S not Vaporware...

Tom Rose · 20th December 2007, 16:31

[quote=jdicediver;152483][quote=Tom Rose;152375]

Quote: (Originally Posted by Tom Rose)

AMAZING, best of luck with the design, let me know if you need an investor. Sounds like some old-timers know a thing or two about a thing or two.

Now...THAT'S not Vaporware...

Well the vapor is condensing...and that is good news for me and hopefully for all.

As promised...

Here is a picture of the working monitor I showed at DEMA.

The unit was set up to flash green when CO2 was below .5%, Green/Red above .5% and Red above ~2%.

This version is powered by 4 AA cells and contains a charging circuit for the batteries.

So you can see the board, I have left off some of the hardware parts. The US Quarter (now worth almost nothing) does not come with it but is there for scale. (If US money does continue to drop in value, I may include one)

Happy Holidays,

Tom

Ben Field · 20th December 2007, 19:02

Thanks for the update, its looking good.

Would be interesting to see how long before the red/green light comes on in some typical rebreathers and then how long to red only?

also how it compares to things like the ap tempstik on calling time for the scrubber.

21st November 2007, 14:33	#21 (permalink)
jepuskar NA Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2005 Location: Chicago, IL Posts: 391	Re: Co2 Sensor At Dema I'm curious as well..
(Offline)

21st November 2007, 15:12	#22 (permalink)
Tom Rose Still Learning Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Prism Topaz Other CCR Home Build Join Date: Oct 2005 Location: USA,North Carolina Posts: 329	Re: Co2 Sensor At Dema [quote=divetheworld;82825] Quote: (Originally Posted by Tom Rose) Question, am I missing something? If you are using an IR absorb sensor then it will be specific to a frequency, but that frequency will change with pressure. So as the pressure increases so will the error. IR is usually only accurate over a specific range. Brent Absolutely right....there is more going on than discussed before. Without going into details, there are ways of handling that issue. Tom __________________ The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time. www.atlimp.com
(Offline)

21st November 2007, 15:27	#23 (permalink)
Tom Rose Still Learning Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Prism Topaz Other CCR Home Build Join Date: Oct 2005 Location: USA,North Carolina Posts: 329	Re: Co2 Sensor At Dema Quote: (Originally Posted by RZEP17) Hi again Some more questions for Tom Rose. Being so informative, about your device, I hope you don't mind few more questions, Tom. The O2 drying flow - you have to find a compromise between drawing adequate gas sample for monitoring CO2 and still not affecting to much the PPO2 in the loop. Is there a potential for the hyperoxia in certain situation like rapid decent? And again my understanding is you are using some kind of orifice/ venturi tube in your aspirator. Is there potential, pardon my language, for sucking in some sorb dust and plugging it? Finally the mysterious(for me) membrane open for water vapors and impenetrable for the CO2 molecules. Can you say something more about it or it is a trade secret? rgrds Tomek The flow volume through the sensor path is very small compared to the flow volume through the loop such that the effect on concentration in the loop is indetectable. The issue of plugging came up early in my discussions with other divers....it actually came up in those discussions at the DEMA Rebreather Party in Los Vegas when I was describing the concept...(it always helps to have some other eyes on a project)...I frankly had not even thought that far in advance. Placement of the filter became an interesting problem that was solved when I devised the retrofit package I showed at DEMA. As soon as the Holidays are over and my life gets back to normal (or as normal as my life would be to most observers) I will post a picture and a description of the retrofit package as shown at DEMA. Tom __________________ The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time. www.atlimp.com
(Offline)

21st November 2007, 15:31	#24 (permalink)
Tom Rose Still Learning Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Prism Topaz Other CCR Home Build Join Date: Oct 2005 Location: USA,North Carolina Posts: 329	Re: Co2 Sensor At Dema [quote=Tom Mount;83788] Quote: (Originally Posted by Tom Rose) Hi Tom You know that Tomar (Titan- bubbleseekers) also had a co2 sensor at DEMA plus waterproof o2 sensors- not sure how or if your designs are similar Hi Tom No I did not have a chance to see it? Did not know Tomar was even working on one. Wish I had. If Tomar did have a working unit, thats great. Like everything else, nothing advances by one persons effort alone. Multiple solutions mean multiple options. Tom Rose __________________ The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time. www.atlimp.com
(Offline)

21st November 2007, 15:34	#25 (permalink)
Tom Rose Still Learning Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Prism Topaz Other CCR Home Build Join Date: Oct 2005 Location: USA,North Carolina Posts: 329	Re: Co2 Sensor At Dema [quote=Tom Rose;152374][quote=Tom Mount;83788] Since I have dominated this thread with three posts in a row...I wish everyone a great Thanksgiving day if you celebrate it tomorrow, If not I'll be thinking about you guys as we chow down...sure I will. Tom __________________ The 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong the first time. www.atlimp.com
(Offline)

21st November 2007, 15:56	#26 (permalink)
onetime Classic KISSer #138 Current Rebreather/s: Classic Kiss Other Rebreather/s: Join Date: Mar 2005 Location: US, NJ Posts: 655	Re: Co2 Sensor At Dema [quote=Tom Rose;152375][quote=Tom Rose;152374] Quote: (Originally Posted by Tom Mount) Since I have dominated this thread with three posts in a row...I wish everyone a great Thanksgiving day if you celebrate it tomorrow, If not I'll be thinking about you guys as we chow down...sure I will. Tom Just so you're not just talking to yourself , you have a happy Thanksgiving too. Thanks for all your posts on the subject. It's definitely an interesting one.
(Online)

21st November 2007, 17:31	#27 (permalink)
Jorma New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Nov 2007 Location: Finland, Inkoo Posts: 10	Re: Co2 Sensor At Dema Hello and Happy Thanksgiving for you over there. Thanks indeed of the interesting subject which I just stumbled unintentionally. I was working years ago with manned submersibles, and there a CO2-monitor was standard equip to monitor scrubber life. Without knowing much of the technical details of CO2-sensors, was wondering if any of commercially available bell or submersible CO2 monitors could be modified for the CCR-purpose? Kind Regards, Jorma Savolainen
(Offline)

22nd November 2007, 00:15	#28 (permalink)
jdicediver Single/burdened with cash Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Jun 2006 Location: Calgary, Alberta Posts: 253	Re: Co2 Sensor At Dema [quote=Tom Rose;152375][quote=Tom Rose;152374] Quote: (Originally Posted by Tom Mount) Since I have dominated this thread with three posts in a row... Tom AMAZING, best of luck with the design, let me know if you need an investor. Sounds like some old-timers know a thing or two about a thing or two. Now...THAT'S not Vaporware... __________________ Regards; "Alterations performed under controlled conditions, on a closed course by a qualified Closed Circuit Diver" "Some people shouldn't dive...others shouldn't even get wet".
(Offline)

20th December 2007, 19:02	#30 (permalink)
Ben Field CK+Shearwater Current Rebreather/s: Classic Kiss Other Rebreather/s: Sport Kiss Join Date: Aug 2005 Location: London, England Posts: 1,485	Re: Co2 Sensor At Dema Thanks for the update, its looking good. Would be interesting to see how long before the red/green light comes on in some typical rebreathers and then how long to red only? also how it compares to things like the ap tempstik on calling time for the scrubber. __________________ www.hugsac.org.uk Beware Fridge Suck
(Online)

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