DIY Nitrox Analyzer (Arduino based)

[Pao]

Nice project and thanks for sharing. What about the next step ? A trimix/oxy analyser, for example ? Seen one done, arduino based, on a French forum.

No plan for a Trimix analyzer at this time. :-D Maybe some more improvements and making a metered sampler suitable for blending.

 

[dm9876]

Very cool! I am considering a similar project (commercial ones are way overpriced and offer less than this one). While the simplicity of the traditional style with LCD panel meter + 9V battery is hard to beat. I do think that the ability to display the actual sensor voltage, as well as the battery voltage, is a good advantage. perhaps also nice option is to do the PPO2 calcs for 1.4 and 1.6

 

[dm9876]

@JMBL do you have a link to the Trimix analyser DIY? would be very interesting to see what method they use (Acoustic perhaps?)

 

[Pao]

Yes

@JMBL do you have a link to the Trimix analyser DIY? would be very interesting to see what method they use (Acoustic perhaps?)

Yes. Link please. Pretty please?

 

[dm9876]

As for Carbon Monoxide I did do some research into that too. the typical ones for DIY (MQ7) is not very suitable, but there is this brand which looks good for the job (SPEC). However using the raw sensor (~$20) you are needing to measure in the nano Amp range. very difficult to design a suitable analog front end that is accurate near zero and to manage the compensation / drift etc very close to zero (we're interested in 0 to maybe 20 pmm). However they also offer one with a ADC and all the hard work done (Digital CO Sensor Module for Carbon Monoxide - Spec Sensors) $75.. you could integrate this with a display and microcontroller for not much extra. Seems to be the way to go for a one off

 

[Pao]

Very cool! I am considering a similar project (commercial ones are way overpriced and offer less than this one). While the simplicity of the traditional style with LCD panel meter + 9V battery is hard to beat. I do think that the ability to display the actual sensor voltage, as well as the battery voltage, is a good advantage. perhaps also nice option is to do the PPO2 calcs for 1.4 and 1.6

It is easily done via software, but I like the simpler/cleaner interface.

 

[dm9876]

@Pao out of interest can I ask where did you get the blue cap? Thanks

 

[Pao]

That is very i

As for Carbon Monoxide I did do some research into that too. the typical ones for DIY (MQ7) is not very suitable, but there is this brand which looks good for the job (SPEC). However using the raw sensor (~$20) you are needing to measure in the nano Amp range. very difficult to design a suitable analog front end that is accurate near zero and to manage the compensation / drift etc very close to zero (we're interested in 0 to maybe 20 pmm). However they also offer one with a ADC and all the hard work done (Digital CO Sensor Module for Carbon Monoxide - Spec Sensors) $75.. you could integrate this with a display and microcontroller for not much extra. Seems to be the way to go for a one off

The sensor module is very interesting and looks usable and uses a serial interface; however settling/calibration time is one hour.

 

[Pao]

@Pao out of interest can I ask where did you get the blue cap? Thanks

It is a uPVC fitting. A 1" unthreaded end cap. https://www.amazon.com/NIBCO-Pipe-F...+inch+end+cap&qid=1555240837&s=gateway&sr=8-4

 

[JMBL]

Keep cool guys ! I live in a different time zone on the other side of the pond, and I'm not glued to my computer, ok ?

The link is down below (in French). Helium sensor is not acoustic but thermic.

Analyseur Trimix :. - ppt télécharger