CO2 Sensor/Alarm

[gianaameri]

Finally a working CO2 sensor!

I have put 100s of MBs of pics. and videos of internals and various tests on land and in use here: http://www.rebreathermallorca.com/forum/index.php?topic=100.msg211#new .

[rookers]

The site requires registration and administrator approval. Hopefully this is forthcoming.

[gianaameri]

The site requires registration and administrator approval. Hopefully this is forthcoming.

All polite persons are generally welcome to view the data/info.

[Slüdge]

Well, that leaves me out!

[WEPIV]

Well, that leaves me out!

What do you mean...? You're a Southern gentleman.

[Slüdge]

What do you mean...? You're a Southern gentleman.

Yeah, in person.

On the internet I'm a gooberhead.

[Puttzer]

Recognizing the letters for registration is not worth 4 tries.

[gianaameri]

Recognizing the letters for registration is not worth 4 tries.

I hate it when that happens too and I give up pretty quickly... the noise in the verification image has now been reduced.

[w ripley]

My registration went thru OK, but don't know any more about it now than I did before. Can the OP give us a narrative, especially how his/their sensor works? Would really like to know what makes it tick.

[Art Greenberg]

Careful, Bill. You'll be branded as "impolite".

[gianaameri]

My registration went thru OK, but don't know any more about it now than I did before. Can the OP give us a narrative, especially how his/their sensor works? Would really like to know what makes it tick.

There is a CO2 sensor connected to a circuit board connected to the batteries. There is also a red LED connected to a normally open digital switch. The circuit board LCD display gives you the % CO2 in the breathing loop (unadjusted for pressure or N or He). So, 1.000 on the LCD means 1% CO2. That is where I set the alarm to go off in the video. In use, I set the alarm at 0.4999% (inhale monitoring). The alarm triggers a buzzer and the LED. I am adding a HUD and will use a housing half the height with two batteries only (good for 10 hrs.). Material probably Lexan.

Sent from my HTC Desire using Tapatalk

[w ripley]

What are you using for the CO2 sensor, itself?

[gianaameri]

What are you using for the CO2 sensor, itself?

It is a patented sensor. I have the patent number (if you open the sensor it is inscribed inside it), but in order not to hurt any third-party commercial sensitivities I cannot post it. I can only discuss my experience as an end-user.

[jlillest]

There is a CO2 sensor connected to a circuit board connected to the batteries. There is also a red LED connected to a normally open digital switch. The circuit board LCD display gives you the % CO2 in the breathing loop (unadjusted for pressure or N or He).....

What's the technology behind the sensor? Is it IR or chemical?

-Jon

[gianaameri]

What's the technology behind the sensor? Is it IR or chemical?

-Jon

IR.

You can see the little orange light inside the sensor glow through the hydrophobic membrane. It is not constant ON to save battery, but pulses.

[w ripley]

I think everyone sincerely hopes you've solved the CO2-monitoring problem, that you have full patent protection, and that you make a fortune as the result of your effort. It's just that many of us have a good handle on existing CO2 sensors and why they don't work, so well, in an underwater/CC environment + why where they are located in the loop is so important.

Sooner or later you're going to have to publish the science behind what makes your sensor work in a breathing loop, or no one's going to buy them. As everyone reading this knows, there's no "trust" me in cave diving or with RBs. So, what does that little orange light inside do when it glows?

[gianaameri]

I think everyone sincerely hopes you've solved the CO2-monitoring problem, that you have full patent protection, and that you make a fortune as the result of your effort. It's just that many of us have a good handle on existing CO2 sensors and why they don't work, so well, in an underwater/CC environment + why where they are located in the loop is so important.

Sooner or later you're going to have to publish the science behind what makes your sensor work in a breathing loop, or no one's going to buy them. As everyone reading this knows, there's no "trust" me in cave diving or with RBs. So, what does that little orange light inside do when it glows?

I am just the guinea pig and I have no commercial interest or patents.

This guinea pig says it works and you can see the data and more will come in due course.

I suspect the people that say it cannot be done is because they can't do it, but it does not mean it cannot be done.

For one thing, I think sensor location in the current rebreathers is in the worst possible place, most humid and hot and condensing area.

If you were to put the CO2 Sensor same place you put the O2 Sensors in most rebreathers, I doubt it will take the harsh environment.

Mid-section of the inhale counterlung is by far the kindest and driest environment for a sensor (O2 or CO2).

As you say, the proof is in the pudding, and it does work (so far I could not fault it).

[Art Greenberg]

It is a patented sensor. I have the patent number (if you open the sensor it is inscribed inside it), but in order not to hurt any third-party commercial sensitivities I cannot post it. I can only discuss my experience as an end-user.

Patents are public documents. I don't understand why there would be any "commercial sensitivities" to be concerned with. If you post the patent number and jurisdiction, we can find out for ourselves all we want to know about the technology.

[gianaameri]

Patents are public documents. I don't understand why there would be any "commercial sensitivities" to be concerned with. If you post the patent number and jurisdiction, we can find out for ourselves all we want to know about the technology.

I understand, but I am not at liberty of providing the particulars of the components.

You have to wait for a commercial announcement of this application of this particular sensor and circuit board and logic, if it will go in production and distribution. I suspect it will, at some point (all I did is to prove the concept works when the sensor is located in the mid-section of the inhale counterlung, but I presume there will be some need for ANSTI tests and simulations of the configuration to confirm my personal experience).

I only noted there is a patent number inscribed on the sensor when I opened it, but I did not make a note of it.

[w ripley]

I am just the guinea pig and I have no commercial interest or patents. . . For one thing, I think sensor location in the current rebreathers is in the worst possible place, most humid and hot and condensing area.

OK, now I understand and will ask no more questions. Agree with your sensor location comment, but the best place for sensors may not always be the best place for the divers.

We're obviously very interested, so please keep us in the loop on the development, and thanks for the post.

[FW]

...so please keep us in the loop on the development...
Pun intended?

[w ripley]

Pun intended?

No, not that clever.

[gianaameri]

OK, now I understand and will ask no more questions. Agree with your sensor location comment, but the best place for sensors may not always be the best place for the divers.

We're obviously very interested, so please keep us in the loop on the development, and thanks for the post.

Remind me closer to DEMA and if there has been no formal announcements before then I may be able to give you a Booth number to go and ask questions direct and there may be a few sensors and boards floating around... we could use more guinea pigs.

[w ripley]

Remind me closer to DEMA . . . I may be able to give you a Booth number. . .

That would be great. Or, if you can pass along the mfgr's name we can look up the booth number.

[gianaameri]

That would be great. Or, if you can pass along the mfgr's name we can look up the booth number.

Booth 717

[FW]

Booth 717
I will stop by there :-)

[gianaameri]

I will stop by there :-)

I won't... so please post what is going on there and the latest, and in particular it would be nice if more end-users can get hold of a unit/components (either final or beta prototype) and try/test it and post here first impressions/results.

Rebreathermallorca.com will make available storage and bandwith for the data (should it not be possible to host it elsewhere) and we can compare notes and continue the discussions here.

We need more user impressions/results to create a wide enough database of experience and dive/test conditions for this very promising CO2 Sensor/Alarm.

[FW]

I won't... so please post what is going on there and the latest, and in particular it would be nice if more end-users can get hold of a unit/components (either final or beta prototype) and try/test it and post here first impressions/results.

Rebreathermallorca.com will make available storage and bandwith for the data (should it not be possible to host it elsewhere) and we can compare notes and continue the discussions here.

We need more user impressions/results to create a wide enough database of experience and dive/test conditions for this very promising CO2 Sensor/Alarm.
OK.

[ntheath]

It is a patented sensor. I have the patent number (if you open the sensor it is inscribed inside it), but in order not to hurt any third-party commercial sensitivities I cannot post it. I can only discuss my experience as an end-user.

This sounds fishy to me. If you have a patent number then the information is public already and its only a matter of doing enough searching and having the time to find it on the USPTO's website. If you provide the information, then more of us will be able to learn about it and this will increase any chances of a commercialization of the product. Why not take advantage of the initial interest to drum up more ? By withholding the information, you lose credibility in my opinion/view.

[gianaameri]

This sounds fishy to me. If you have a patent number then the information is public already and its only a matter of doing enough searching and having the time to find it on the USPTO's website. If you provide the information, then more of us will be able to learn about it and this will increase any chances of a commercialization of the product. Why not take advantage of the initial interest to drum up more ? By withholding the information, you lose credibility in my opinion/view.

Go to Booth 717 at DEMA and ask the patent number of the sensor (or buy one there if it is for sale and take it apart and read out the patent number). I am not at liberty to publish it as it is not my product and it is a beta I am testing.

I did not make a note of it myself. I only saw it was there when I stripped the sensor as the sensor circuit board was a bit oversized and I had to sandpaper it down to fit it in the p-port sensor holder.

There is nothing fishy whatsoever.

[jlillest]

Go to Booth 717 at DEMA ....

A quick google search shows these guys: http://www.temc.it/

They have some gas analyzers and whatnot, but I don't see any C02 sensor technology on the website. It'll be interesting to see what they come up with.

-Jon

[FW]

A quick google search shows these guys: http://www.temc.it/

They have some gas analyzers and whatnot, but I don't see any C02 sensor technology on the website. It'll be interesting to see what they come up with.

-Jon
Are you going to DEMA?

[gianaameri]

According to the specs. :

The sensor outputs actual CO2 readings, compensated for temperature in the range -20C and +50C.
Typical resolution for 0 5000 ppm sensor is 50 ppm from 0 to 2500 ppm, then 100 ppm up to full scale
Temperature & Humidity working range

-20 °C to 50 °C (-4°F to 122°F)
Temperature performance:
± 10% of reading up to 50% FSD and ± 15% of reading from 50% to 100% FSD over the range -20°C to +50°C (-4°F to 122°F)
Storage temperature range: -20°C to +50°C (-4°F to 122°F)
0 to 95% RH, non-condensing

Warm-up Time

To final zero ± 0.2% of range : 1 minute @ 20°C (68°F) ambient (operational)
10 minutes (for maximum accuracy)

Accuracy at ambient pressure (tipical 1013 mbar)

sensor linearity at ambient temperature is ± 2% FSD or ± 10% of the reading which ever is greater.
Response Time T90: <30s @ 20°C (68°F) ambient
gas flow rates kept below 600 cc/minute
Zero Repeatability: ± 2% of full scale @ 20°C (68°F) ambient
Span Repeatability: ± 2% of full scale @ 20°C (68°F) ambient
Long term zero drift: ± 1% of full scale / month @ 20°C (68°F) ambient

[Squirrel Girl]

A quick google search shows these guys: http://www.temc.it/

They have some gas analyzers and whatnot, but I don't see any C02 sensor technology on the website. It'll be interesting to see what they come up with.

-Jon
http://www.temc.it/index.php?option=com_content&view=article&id=100%3Ade-ox-bio-carbon-dioxide-analyzer&catid=29%3Adiving&Itemid=56&lang=en

[gianaameri]

Any news on this CO2 Sensor at DEMA?

[Dave1981]

To me it was one of the more interesting things at the show, I'd say it needs refined though.

Right now you need the full electronics package which doesn't seem up to task, a big clunky set of gear there, that doesn't look very 'scuba'

The sensor its self looked promising, same dimensions as an o2 sensor. From what I gathered tested at 100% humidity for 4 hours before it would start to read badly, digital output so couldn't be just used as a millivolt input on anything instead of a spare O2 sensor.

If the electronics companies get on top of this I'd be all over it, for me it needs to be connected up to shearwater and could be plugged into the inhale side of the head. I suspect we'll see that in the next year or two.

[gianaameri]

I love the electronics as they are. They work.

Plus CO2 Monitor and pPO2 Montitor I prefer to run separate and independent from each other and separate and independent from any dive computer.

If they are separate, there is less to go wrong (and boy do integrated "tech" dive computers go wrong).

Was there no offering at Booth 717 of a fully working out-of-the box CO2 Rebreather Monitoring package based on that CO2 Sensor?

[FW]

I love the electronics as they are. They work.

Plus CO2 Monitor and pPO2 Montitor I prefer to run separate and independent from each other and separate and independent from any dive computer.

If they are separate, there is less to go wrong (and boy do integrated "tech" dive computers go wrong).

Was there no offering at Booth 717 of a fully working out-of-the box CO2 Rebreather Monitoring package based on that CO2 Sensor?
Yes there was, but it looked like Draeger fittings on it. All in all, pretty neat idea. I know of at least two rebreather manufacturers looking at it now.

[deepairmike]

I have one now and I will be putting it to the test to see how well it works.

[gianaameri]

I have one now and I will be putting it to the test to see how well it works.

You may want to get yourself some 1%CO2 99%N Bump test gas (certified) to check periodically the factory calibration. It should not drift like the other sensors which require frequent re-calibration.

When is your first test dive planned so that we can compare notes?

I have a series of cave dives coming up end of the month.

[gianaameri]

Here is a video from the manufracturer of the CO2 Sensor Kit. Mine differs insofar I use a 1 ATA box and HUD: http://vimeo.com/31914685

[gianaameri]

I have done some accuracy and linearity test and pressure tests of the unit finally assembled ready to dive. With 1% CO2 99%N (calibrated/certified bump test gas) the sensor reads 1.066% (quite accurate). Linearity so so, at surface the CO2 was 0.045% and at 90 meters the sensor read 0.612% (when it shoud have read 0.45%), which is still quite acceptable - BUT bear in mind the battery went low during the test and then it died while I was depressurising... so the linearity error maybe due to that as well. One thing I noted is that if the sensor and board are pressurised fast, at about 40 meters the board turns itself off as if the OFF button had been pushed (or maybe something else is causing this, but I think fast pressurization pushes the ON/OFF button and the unit turns itself OFF). In a a 1 ATA case no such porblem. I have posted a couple of pictures of the test unit final assembly with HUD ready for diving tomorrow and will upload overnight the test videos here: http://www.rebreathermallorca.com/forum/index.php?topic=100.msg219%3Bboardseen#new (http://www.rebreathermallorca.com/forum/index.php?topic=100.msg219%3Bboardseen#new) . Hopefully can make some videos tomorrow of the test dive with the display in clear view through the Lexan 1 ATA tube.

[gianaameri]

The CO2 Sensor performed well during the dive as well (cave, scooter, 60 min., max. depth 17 meters, distance 2.5 km., max. penetration 800 meters).

No false alarm and the reading was stable throughout the dive around 0.15% CO2 (off the top of my head) including during frequent and rapid ascents and descent.

If the video came out (no idea yet) it may be more precise.

[plazma]

The CO2 Sensor performed well during the dive as well (cave, scooter, 60 min., max. depth 17 meters, distance 2.5 km., max. penetration 800 meters).

No false alarm and the reading was stable throughout the dive around 0.15% CO2 (off the top of my head) including during frequent and rapid ascents and descent.

If the video came out (no idea yet) it may be more precise.

Have you tested the sensor with trimix?

[gianaameri]

Have you tested the sensor with trimix?

I did, but only in the pressure chamber, not diving. No problem in that test.

I learned something interesting the last couple of days diving the sensor.

It is essential to keep it off the rebreather until just before pre-dive and take it out the rebreather immediately post-dive.

If you don't, you prolongue the exposure to humidity, and if you leave it say overnight in the rebreather in storage in a very wet counterlung and loop the readings will drift up by as much as 40%.

After about 10 - 15 hours in air it will all return to normal, back to the original calibration.

It is really important NOT to re-calibrate CO2 sensors if they look off the mark because it may be just due to exposure to humidity, and it may correct itself given enough time.

I had constant reading of about 0.02% on the dive today (3.5 hours of scrubber use total) compared to 0.15% yesterday (same scrubber fill as today's), and yesterday the reading was high because I had left the CO2 sensor overnight in the rebreather (dry counterlung, but wet can and scrubber) and with the humidity it had drifted up a little.

[gianaameri]

I uploaded the full CO2 Sensor test dive video (2GB) here: http://www.rebreathermallorca.com/forum/index.php?topic=74.msg228#new

[gianaameri]

Been doing some longer dives (2 hours) and no problem whatsoever. The CO2 sensor was placed in the rebreather before pre-breathe and removed at the end of the dive. Max. CO2 was 0.05% (scrubber total use time 3.5 hours).

[gianaameri]

Nice to see that the CO2 Sensor I have been using is moving into commercial distribution in a nice 1 ATA case. Too bad the commercial version does not have an HUD.

See: http://vimeo.com/42380836