[HN Gopher] Measuring dust with a Dylos air quality monitor (2012)
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Measuring dust with a Dylos air quality monitor (2012)
Author : walterbell
Score : 25 points
Date : 2022-08-06 06:04 UTC (1 days ago)
(HTM) web link (woodgears.ca)
(TXT) w3m dump (woodgears.ca)
| ahaucnx wrote:
| This article is from 2012. The Dylos was one of the first
| relativelely affordable PM2.5 monitors. Now we have a much higher
| range of pretty accurate fine dust sensors using the laser
| scattering method.
|
| We work a lot with the Plantower PMS5003 model (we use for our
| open-source DIY monitor kits) and its a very reliable module
| which is also used in the purple air and typically cost you
| around USD 15-20.
|
| It is important to know that these sensors are factory calibrated
| for specific kinds of dust, for example the "arizona road dust"
| and thus if you measure different kinds of dust (like the wood
| dust in the article), the accuracy might be off.
|
| Also the measurements are influenced by high humidty so it is
| important to use comprensation algorithms for this or preheat the
| air before measurements to reduce the humidity.
| [deleted]
| ghostpepper wrote:
| Are these sensors factory calibrated? I've recently installed
| some 433 mhz accurite temperature/humidity sensors and
| connected them to Home Assistant. Part of why I went with
| consumer units as opposed to a DIY pcb was because I assumed
| that, while bare chips off Ali Express or DigiKey may be
| precise, I would have no way of knowing if they're actually
| accurate.
| ahaucnx wrote:
| All modules we use in our DIY kits [1] are factory calibrated
| and we use the same sensor modules in our commercial sensor
| that went through the RESET Air certification. So these
| sensors are very good. We compare them side by side and see
| no differences in accuracy.
|
| Another important thing is the PCB and enclosure design to
| ensure accurate air flow to the sensors and also prevent
| internal heat influencing the temperature reading.
|
| In the DIY Pro kit we use a similar design like our
| commercial monitor but as a fully open sourced version. So
| it's very accurate.
|
| [1] https://www.airgradient.com/open-airgradient/kits/
| walterbell wrote:
| Is there a recommended sensor for particles in the range of 0.5
| to 2.5 microns, like the Dylos DC1100 Pro?
| ahaucnx wrote:
| Some low cost sensors are offering data channels down to 0.3
| microns like the Sensirion SPS30 but in my opinion most of
| them are tuned towards delivering the highest accuray at
| around 2.5PM because many standards (e.g. WHO) are based on
| PM2.5.
| walterbell wrote:
| Indeed, looks like most of the PM sensors are focused on
| PM2.5, a few detect PM1.0, and only the Dylos Pro attempts
| PM0.5-2.5, http://www.aqmd.gov/aq-spec/evaluations/summary-
| pm
|
| Workshops and garages are concerned with fine dust from
| cutting or milling metal and wood.
|
| 2020 paper reviewed 50 PM sensors and discussed
| calibration, https://www.mdpi.com/1424-8220/20/23/6819/htm
|
| _> We present an extensive review of the LCPMS currently
| available on the market, their electronic characteristics,
| and their applications in published literature and from
| specific tests. Most of the reviewed LCPMS can accurately
| monitor PM changes in the environment and exhibit good
| performances with accuracy that, in some conditions, can
| reach R2 values up to 0.99. However, such results strongly
| depend on whether the device is calibrated or not (using a
| reference method) in the operative environment; if not, R2
| values lower than 0.5 are observed._
|
| 2021 Lawrence Berkeley paper,
| https://escholarship.org/content/qt2fm3s5zv/qt2fm3s5zv.pdf
|
| _> End-users should be made aware that the PM data from
| the current low-cost sensors needs to be understood as an
| indication of a state change or a rough estimation rather
| than actual concentration in indoor environments._
| walterbell wrote:
| Model with serial port,
| http://www.dylosproducts.com/dcproairqumo.html
|
| http://www.dylosproducts.com/toquabairpue.html
|
| _> The DC1100 is a true Laser Particle Counter that works on the
| same principles as the $8,000 particle counters used in
| pharmaceutical and semiconductor clean rooms. Those guys really
| do need to know how clean their air is and they don't use sensors
| like the one on your air cleaner. Those cheap sensors usually
| have an LED and photodiode arranged at an angle so the photodiode
| will pick up any light scattered back off the particles in the
| air. This design is inexpensive, but suffers from very poor
| signal to noise ratio and can only detect light scattered off
| many particles in a volume of air.
|
| > In contrast, the DC1100 uses a focused laser which results in a
| drastically higher signal to noise ratio. This means that air can
| be flowed through a focused laser beam and the DC1100 is actually
| sensitive enough to detect individual particles. With this
| ability the DC1100 cannot only count the particles, but it can
| also size them based on the amount of light they scatter. For
| convenience sake, the DC1100 displays two particle counts - small
| and large. The large particle count includes pollens, dust mite
| debris, insect feces, coarse dust, etc. The small particle count
| includes most bacteria, mold, fine dust, etc. The small particle
| count can range from many thousands down to zero so the home
| owner can measure air quality with vastly greater resolution than
| is possible with 5 green LEDs._
| falcolas wrote:
| Meta: Jesus, this was 10 years ago? I remember it coming out, and
| it doesn't feel that long ago.
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