Is there such a thing as a nitrogen sensor?

[Woz]

How IIRC from school chemistry nitrogen is pretty unreactive. So is there such a thing as a sensor to measure the PN2, just like a PO2 sensor?

[manganui222]

Not sure if there is one and why would you want one?

If using nitrox just use o2 analyser and the difference is the nitrogen

If using nitrox use a trimix analyser which has an o2 analyser and he analyser so the difference will again be nitrogen

o2 analyser works using a fuel cell and he analyser uses resistance and conductivity of he (i think)

[Woz]

This isn't for nitrox or trimix but for something different. Exactly what may or may not be revealed depending on how silly I think I'll look.

[Dave Crampton]

Hi Woz

Analox make Trimix analysers so presumably they make or buy in helium sensors so I would expect them to supply sensors for there analysers.

Dave C

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[Duncan Price]

Originally Posted by Woz

How IIRC from school chemistry nitrogen is pretty unreactive. So is there such a thing as a sensor to measure the PN2, just like a PO2 sensor?

Nitrogen can be done by Raman spectroscopy or mass spectrometry - both techniques are not cheap. For trimix, ppO2 is done using electrochemically and He is done using thermal conductivity.

Duncan

[Mark Powell]

A Nitrogen sensor would need some physical property to measure in order measure the amount of Nitrogen. An O2 Sensor measures oxidisation, a Helium sensor measures thermal condustance (at least the Analox one does).

I'm not aware of any property of Nitrogen that would allow suitable measurement and so have never seen a Nitrogen sensor in a diving context.

I'd be interested to see if there is anyone from the wider world of enginering who knows differently.

"for something different" sounds intriguing, and don't worry about looking silly, we wont tell.

[Woz]

OK if you promise not to tell- I was just tossing and turning the other night thinking of the old 'how do I measure the CO2 in my loop' problem when I thought if you add up the O2, He (if used) and N2 the rest will be either very little (water vapour and a few bits and bobs) or a rising % of CO2 if your scrubber is channelled or spent.

But if you need an inconveniently large mass spectrometer on your wrist next to the VR3 then I believe that is this idea's handbag well and truly crapped in.

[nigelH]

Originally Posted by Woz

But if you need an inconveniently large mass spectrometer on your wrist next to the VR3 then I believe that is this idea's handbag well and truly crapped in.

I can do mass spectrometry very small if you can provide a reasonable amount of hard vacuum. However if you could do that I know some were we could make a lot of money with it so forget the diving application.

nigelH