"calibrate" or verify values of SDS011 (PM2.5 and PM10)

senseBox:edu
#1

Hello experts,

Just today I have completed assembling my Sensebox:home.
After some initial connectivity issues with the SSL cert that needed importing (thinking of doing a newbie write-up to save others some time) all works like an absolute charm.

The only think I am wondering: I have the unit outside for couple of hours now, and my readouts seem WAY lower than other units in (relative) close proximity.

Can some folks chime in with „experience and notes from the field“?

AND what I noticed is that the PM2.5 and PM10 values are ALWAYS the same.
This does not really sound „normal“?

btw, it is perfectly ok to react in German if that is easier. I can read German quite well, but would make a complete fool of myself trying to write it. :rofl:

#2

Ok, answering my own question. I think I have found the issue where the PM10 and the PM2.5 give a constant same value.
I removed the lid of the box the sensor is build into and immediate all started working "as expected. Also values are now quit „similar“ to the other station close-by.

I was re-thinking the mechanics of how an SDS011 works (it passes air between a sensor and an LED source) and figured that having the sensor in an enclosure that is 100% airtight has several issues:

  1. There would be a (very tiny) over-pressure, disabling the sensor from getting in „fresh air“.
  2. I guess that over time (probably long time, but still) the internal of the housing could get contaminated with all the particles it „offloads“ there.

So will have to see how I modify the box so it also allows air to escape and have a „real flow“.