Check this CO2 sensor out.

diveoceanos

Gas Sensors

Would something like this possibly be a solution for CO2 detection somewhere before the inhalation counterlung?

Have a look at the link. It costs only 20 USD and it can detects CO2 at a range between 0 and 10,000. Check the data sheet. it is electronic component. It is much smaller than an infrared gas analyser which has a size of a refrigerator. It is only 16mm diameter by 21mm height!

CO2 is an ungly thing and it would be nice to have a sensor in our loop.

Any folks with electronic knowledge that could possibly give us some more information?

fin

There are at least two solid electrolyte CO2 sensors in the market. TMG811 by Hanwei Electronics and CDM4161 or CDM4161A by Figaro. I will be experimenting with the second from now on but it is very early to say anything.
That is if Tom Rose will not come to a final product (using IR absorption measuring) until then. Mr Rose is far ahead on this (see http://www.rebreatherworld.com/cells...at-dema-4.html ).
Only time will tell.

osiris

Have you checked out Laguna Research? They offer a CO2 sensor as part of the eCCR suite.......I should think thay will alos understand the electronics. lagunaresearch.com.

Pacman

Sorry but roughly 60 secs response time and 200mA supply current are quite
unacceptable.
The first one because if breaktrough reached you could be almost dead after such time.
The second one because of battery capacity unless you would like to carry a speleo light battery pack to supply the reb.

My two cents

Pacman

AD_ward9

The Deep Life CO2 sensor that is fitted to the commercial rebreathers and is proven in underwater trials on rebreathers, has a 150ms response, but power consumption is an issue: to handle that we switch it on once every 10s, for 0.5s, then off again. It is 38mm x 20mm, and protected from moisture using heat from the scrubber stick, and by a hydrophobic membrane: it is sufficient. We have not had a single instance of losing a CO2 sensor due to moisture.

On the solid gel and heated wire type CO2 sensors, none of these that we tested worked in helium.

Alex

Hk101gr

Hi Alex
I'm not sure if this has been discussed before, but are there any plans to put your sensor on the market as an aftermarket part for existing Rebreather's?

Dive safe
Dimitris

AD_ward9

It is on the professional rebreathers that we have done already as a standard feature: these are eCCRs.

For sports use, we concluded that mCCR is more appropriate but with very good monitoring and auto loop shut off as safeguards.

We plan to offer the mCCR monitor with the same CO2 sensor as we use currently in the commercial diving rebreather.

As to when you can have it: we have it now using CNC parts, but plastic mouldings etc all take time ....

We were accurate in delivering the working commercial rebreather for DEMA 2007, and suggest that DEMA 2008 will have the mCCR monitor, though there is some risk the monitor could stretch to spring 2009. We do not see the point in bringing CNC sports parts to DEMA: it should be production parts or nothing.

Alex

PhilSiswick

So, I can't buy your sensor/electronics for my existing eCCR? What is the rationale, other than the ongoing mCCR vs eCCR debate? Why not sell the sensor/electronics separately to the PO2 monitoring?

Cheers,

__________________
Phil

No comment on open circuit... it's an evolutionary dead end not really worth discussing here. Dave Sutton, 2007

I have always felt that the dive I am on is not nearly important as the dives I plan to be on the rest of my life. Tom Rose, 2007

www.hugsac.org.uk

York

diveoceanos,
this sensor has been discussed before:
http://www.rebreatherworld.com/home-...seen-this.html

Joerg

AD_ward9

You may want the O2 monitoring as well for your eCCR!

There is just not enough existing eCCRs out there, and the owners still in spending money for it, to warrant a CO2 only add on. At least thats the sums we did. For a combined O2 and CO2 monitor, as part of a low cost mCCR the numbers look better.

Alex