The addition of other gasses would be useful i think. The MICS6814, on the Enviro+, is for instance an analog gas sensor that can detect three different groups of gases that they refer to in the datasheet as reducing, oxidising, and NH3.
Hi Michel,
I think the problem with that particular sensor is that it is uncalibrated and won’t be very useful on the macro scale since the different readings on the map from every sensor won’t have any reliable point of reference.
Having said that I would also like to see gas sensors supported on sensor community. I noticed that some commercial sensors offer that function. I am not sure why it is so difficult to do that here as well. Is it the sensitivity? Is it the calibration? If it is the latter wouldn’t it be possible to make mass orders as a community and then calibrate them by co-locating them with some reference design?
There is only a limited count of gases that would be interesting for outdoor measurements. I would say that these are NO2 and O3. But i.e. for NO3 there is only one sensor at the moment that would measure concentrations low enough for useful data. If I remember it correctly the official annual average limit for NO2 is 40µg/m3 or 21 ppb.
We have tested the AlphaSense NO2 sensor (around 150 Euro per sensor). The result of this test was that there is a dependency on temperature, humidity AND the “speed” of change in humidity. This isn’t really solveable for a citizen science project.
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Why only those two? There are others as well, SO2 and HCl for example which might become a serious problem due to policies such as waste incineration.
Now about those issues with the NO2 sensor, is the speed of change something none of the cheaply available sensors can measure?
Please send us all the datasheets of all these sensors (if they are Open source…) for us to check the specs.
But for now, there are always problems…
I am not that knowledgable, it is just that I have seen products from airly and others that incorporate sensors of this kind.
Of course they don’t mention what sensor they’ve been using, and I wouldn’t except them to be honest them being for profit only, but I’ve been able to find a couple of sensors from, I think, reputable manufucturers. Please take a look here (Alphasense) and here (SGX).
I understand that there might be problems (I suspect humidity and condensation is one of them), my point is that being able to detect these kinds of gases is relevant to the goals of this community and a real issue. There are commercial products available but it would be better if this community can come up with a solution. Might not be as simple as plugging a few parts together in a pipe or as cheap as the pm2.5 sensor, but it would be open.
Far more interesting would be standard weather gear. Windspeed and direction. There are (yes/no) rain sensors too. Many of these are under $20 from the integrator. Less expensive AliExpress.
https://www.argentdata.com/catalog/index.php?cPath=29&osCsid=yJrx,D04wIweWxTvHo89e3
I would be interessted in CH4/CO/H2, something like this sensor:
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