Thread: Opinions on IKEA air quality sensor?

Originally Posted by toni_k

I will get into dust collection hardware separately but I thought a good starting point would be to make some measurements of air quality at the moment so I can see if I'm making improvements as I go along.

...

Couple of questions if I may:

1. Any experiences or thoughts on the IKEA sensor?
2. Any sugestions for a decent sensor up to around AUD $200 mark?

An excellent strategy, IMO.

These economy AQ sensors may not be as accurate as the very expensive industrial units, but they are more than adequate for indicating any step up in improvement from any changes in your DE setup.

I can't comment on the IKEA model, but I expect it has the same sensor unit inside as all of the economy models. From my experience, you are not going to get more accurate readings by paying $200. I've purchaded various models and, when placed side by side , they have all given the same reading.

At that IKEA price I would be buying two of them. One for inside and one for outside the workshop. That way you get a background reading of the AQ on the day so you can take that into account when interpreting the readings you are getting inside the workshop.

Well put Neil - my thoughts almost to the letter.

One caveat is that these and most other budget end units use sensors that for readings <10 µg/m^3 will have reading errors approaching 100% so making decisions about changing DC setups at those levels may lead to you simply chasing your tail.

Thank you both for your advice!

Originally Posted by NeilS

At that IKEA price I would be buying two of them. One for inside and one for outside the workshop. That way you get a background reading of the AQ on the day so you can take that into account when interpreting the readings you are getting inside the workshop.

@NeilS What is the reason behind recommending 2 sensors rather than just moving the same sensor from inside to outside? Is it because of averaging the PM values over the same time period for inside and outside? My only thought was that a single sensor would avoid any difference from unit-to-unit but I guess that could be checked by taking a reading with both units side by side.

Thanks,
Toni

I have one of these IKEA sensors in my workshop and have checked the readings from it against a cheapo unit from Amazon. I found quite a large difference in the PM2.5 figure, with the IKEA unit consistently reading lower. Not sure what to make of it honestly.

Originally Posted by toni_k

@NeilS What is the reason behind recommending 2 sensors rather than just moving the same sensor from inside to outside? Is it because of averaging the PM values over the same time period for inside and outside? My only thought was that a single sensor would avoid any difference from unit-to-unit but I guess that could be checked by taking a reading with both units side by side.

Thanks,
Toni

If ever I get an unexpected reading inside the workshop I check to see if the outside reading can explain it. Having one located outside that I can see through the window saves me having to be going in and out and also unplugging and plugging in again several times. Having a spare one in case you manage to kill or maim one, which I have managed to do with several of mine, is also a good idea for me...

Originally Posted by NeilS

If ever I get an unexpected reading inside the workshop I check to see if the outside reading can explain it. Having one located outside that I can see through the window saves me having to be going in and out and also unplugging and plugging in again several times. Having a spare one in case you manage to kill or maim one, which I have managed to do with several of mine, is also a good idea for me...

Ok, thanks! I'll probably pick one or two up tomorrow and let you know how it goes.

The pic request was accidental btw

Originally Posted by SteveSaysHi

I have one of these IKEA sensors in my workshop and have checked the readings from it against a cheapo unit from Amazon. I found quite a large difference in the PM2.5 figure, with the IKEA unit consistently reading lower. Not sure what to make of it honestly.

Is it possible for these things to become clogged and under-read? Or do they over-read when clogged? I don't imagine they are designed to cope with the dust load generated in a woodwork shop.

Originally Posted by jack620

Is it possible for these things to become clogged and under-read? Or do they over-read when clogged? I don't imagine they are designed to cope with the dust load generated in a woodwork shop.

None of mine have become 'clogged' from use in the dry dust that I generate in my workshop. But, I do run a fairly clean (not necessarily tidy) workshop.

They work a bit like counting a mob of sheep going through a narrow run, but not so narrow that the sheep get jammed in there. That's the untechnical explanation.

Anyway, Bob (BobL) worked professionally with this technology in cleanroom settings, so best to leave it until he comes back to give us a more technical explanation of how these particle counters work.

Originally Posted by jack620

Is it possible for these things to become clogged and under-read? Or do they over-read when clogged? I don't imagine they are designed to cope with the dust load generated in a woodwork shop.

These detectors work fine in a DIY woodwork shop provided you don't poke them direct into a direct sawdust stream or leave them on for too long because eventually they will clog. The time taken to clog depends on the amount and type of dust you make and how good your DC system is.

The way these things work is the dust is pumped as a small stream past a IR laser beam. As the particle stream pass past the beam the particles "reflect-twinkle" a "pulse" to an off axis detector. The size of the pulse is related to the size of the particles and the number of pulses = the number of particles. On the more upmarket sensors A couple of fast chips sort the pulses into size ranges or "bins", typically 0.3-0.5, 0.5-1.0, 1.0-2.5, and 2.5, 2.5-5.0 and >5 microns.

If they become clogged they usually read zero because no air is going thru them.
BUT
they can also read Zero because something has broken
Also
have seen the display on some sitting on a constant very high number - I suspect that is sticky damp (ie conductive) dust coating and short circuiting bits of the internal circuitry.
Also
have seen the display showing variable numbers which suggests intermittent shorting of internal circuitry

Very gently blowing dry air into the inlet (IE NOT direct compressed air) may unclog/clean them. I use my dried compressed air with a low pressure nozzle. It's just a 150mm length of 6mm ID PVC tube with 3mm holes drilled in the sides. The holes reduce the pressure so what comes out is much lower pressure.

These should occasionally be tested to make sure the readings drop to zero (eg inside a sealed clear container, ie dust will eventually drop out of the air inside the container) and then ideally checked against another one you know is working.

Here the particle counter that runs more or less 24/7 in the study/electronics workshop in the house.
The dust crusting the edges of the inlet and outlets is the build up resulting from ~18 months when it was last cleaned.
HopusePC.jpg

Here the one in the shed.
Apart from the wisp of dust (purple arrow) it's pretty clean for about 12 months continuous use.
This shows how little I have used the shed since SWMBO passed, and the very little I have done in there has been mainly machining metal.
ShedPC.jpg

I picked up one of the IKEA sensors last night and did some testing at home. Haven't taken it to the workshop yet but hoping to do that later this week.

All the measurements are μg/m³ of PM2.5 particles as that's the only measurement this sensor can make.

3rd April 7:30pm

• 2 - reading inside the house
• 3 - reading outisde in the backyard
• 3.2 - reading from Melbourne CBD as per EPA website (I'm 5.1km north of the EPA station)

4th April 8:00am

• 2 - reading inside the house
• 6 - outside in the backyard
• 4.8 - reading from Melbourne CBD as per EPA website

I know this is a fairly crude comparison but it's given me some confidence as the sensor appears to get similar values to the EPA station which is about 5km away. I will keep measuring and hopefully get some more data points as the air quality gets worse and perhaps even drive down to near the EPA station and take couple of measurements.

I also did some cooking on a gas stove in the evening and created some smoke on purpose. The sensor showed a reading of about 300 - 350 and at one point briefly spiked to about 650. After wenting the house for about half an hour the reading came down to about 100. Another hour later is was down to about 40 and then next morning it had settled back down to 2. From what I've read on the forum it is quite normal to get these high PM levels when cooking.

I'll try and take some measurements in the workshop this week and see how that compares.

Originally Posted by toni_k

I also did some cooking on a gas stove in the evening and created some smoke on purpose. The sensor showed a reading of about 300 - 350 and at one point briefly spiked to about 650. After wenting the house for about half an hour the reading came down to about 100. Another hour later is was down to about 40 and then next morning it had settled back down to 2. From what I've read on the forum it is quite normal to get these high PM levels when cooking.

Be careful using it when cooking. Baking is usually OK but any sort of grilling/frying will make oily/sticky smoke and if too much of that get inside the sensor this may kill int,

Getting a local outside reading rom your EPA website will be helpful for getting an area background readings. But, if you are getting unexpected readings inside your workshop, stick your head outside in case a neighbour is having a burnoff, as I have had at times. The EPA site may be too far away or upwind to pick that up.

Some measurements from the shop taken in the evening. It's a fairly small place 6m x 3m with ceiling that slopes from 3m to 3.5m. I placed the meter on my bench which is roughly in the middle of the shop. All measurements are μg/m³ of PM2.5 particles and are generally peak values I was able to observe. In all cases the readings would settle down relatively quickly. Usually around 4-5min after a machine was turned off.

No tools or machines on, door closed, shop generally very dusty	2
Turning the extractor on (1HP Sherwood unit with pleated filter, about 1 year old)	4
5-6 cuts about 50cm in length in 35mm thick pine with a Dewalt 7491 table saw with standard dust extraction below and above table	9
5-6 cross cuts in 90x35 pine on the mitre saw, no dust extraction at all	90
Sweeping the floor with a broom	280
Vacuuming around the shop for couple of minutes using M class Ryobi vac	16
Planing a 90x35 piece of pine about 50cm long down to 5mm on Dewalt DW735 with standard dust extraction hooked up to the 1HP Sherwood DC	3

So in conclusion, don't sweep up the floors in you shop

On a serious note, the numbers were generally lower than I would have expected. I'm concious of lulling myself into a false sense of security so I took some more measurements couple of days later during the day.

No tools or machines on, door closed, shop relatively dusty and messy	3
Moving around the shop, using hand tools etc	52
Using drll press to make about 20 holes in 20mm pine	126

The 2nd set of measurements was more in line with what I expected. My guess is that there was bit more air circulation that day. The shop is not very well sealed and has couple of vents in the windows that are always open.

Originally Posted by toni_k

So in conclusion, don't sweep up the floors in you shop

That is what I tell them at our local men's shed, but I'm yet to completely win that battle.

I had to take some friends to the airport a few days ago and took the opportunity to drop into the nearby IKEA to pick up one of their particle counters. I'm yet to do a side by side with my current counters to see how closely they calibrate. Of course, if they closely calibrate that can just mean that they are equally way off any reliable number.