Air quality meter, what make model, what do they cost?

[John K Jordan]

Thanks.

JKJ

The Plantower(1) based monitor displays particle densities in the metric unit particles per deciliter. The Dylos display is imperial, particles per one hundredth cubic foot.

28 liters per cubic foot is .28 liters per one hundredth cubic foot. 10 deciliters per liter then makes 2.8 deciliters per one hundredth cubic foot. So, 2.8 times as many particles in .01 cubic foot as there are in one deciliter at the same particle density. Or, Dylos count = 2.8 x Plantower count.


(1) Plantower is the manufacturer of the sensor used in this and many other air quality monitors.

[Scott Winners]

the conversion formula for the particle count to AQI so I never really did that. One of these days I'll get around to it.

I think I got this one. EPA regulates (outdoor) air quality based on particle counts. I am in a city that gets regularly spanked on our PM 2.5 counts. The PM 2.5 count to EPA regulated Air Quality Index (AQI) in repeated on this page:

http://data.fnsb.us/airquality/AQNearRealTime , FWIW I live kinda near the "oa" in Broadmoor towards the left side of the 'rectangle of death' aka non attainment area.

There are probably similar EPA regs for PM10 and so on, outdoor PM2.5 is the thing EPA is spending tax dollars on here.

[Alan Lightstone]

David:

I had previously used the Dylos formula for calculating AQI from their meter (at your suggestion in our previous thread). This is the explanation on Bill Pentz's website:
http://billpentz.com/woodworking/cyclone/dylos.php

In essence, it is PM 2.5 = (Small Particles - Large Particles) /100

Now the units may be wrong here, and David please correct me if that is the case. I believe this gives the number in mcg/m3 which is the typical units for PM 2.5.

Alan

The next time I run my wide belt, I'll put both meters next to each other, and look at the readings.

[David L Morse]

David:

I had previously used the Dylos formula for calculating AQI from their meter (at your suggestion in our previous thread). This is the explanation on Bill Pentz's website:
http://billpentz.com/woodworking/cyclone/dylos.php

In essence, it is PM 2.5 = (Small Particles - Large Particles) /100

Now the units may be wrong here, and David please correct me if that is the case. I believe this gives the number in mcg/m3 which is the typical units for PM 2.5.

Alan

The next time I run my wide belt, I'll put both meters next to each other, and look at the readings.

Yes, that formula provides a rough estimate of PM2.5 and the units are indeed mictogram per cubic meter. If you want to trudge through the math the assumptions are a particle diameter of 1.5 micron and density of 1.6 g/ml.

Obviously there's a lot of room for uncertainty when you have to assume an average particle diameter for a distribution that ranges over a 5:1 range. That's actually a 125:1 range for the mass per particle. Size distribution varies a lot for different materials and generating processes as well as distance from the source.

For more details on using particle counts to estimate PM levels see this paper.

[Frank Pratt]

Yes, that formula provides a rough estimate of PM2.5 and the units are indeed mictogram per cubic meter. If you want to trudge through the math the assumptions are a particle diameter of 1.5 micron and density of 1.6 g/ml.

Obviously there's a lot of room for uncertainty when you have to assume an average particle diameter for a distribution that ranges over a 5:1 range. That's actually a 125:1 range for the mass per particle. Size distribution varies a lot for different materials and generating processes as well as distance from the source.

For more details on using particle counts to estimate PM levels see this paper.

There's a little light reading For now I'll stick to my simple relative method of monitoring air quality.

Thanks for offering those explanations David. It's nice that you have put your brain to work so that some of the rest of us don't have to.

[John K Jordan]

Thanks for offering those explanations David. It's nice that you have put your brain to work so that some of the rest of us don't have to.

David is my new hero.

JKJ

[Alan Lightstone]

My old hero.

[Ben Ellenberger]

The air quality agency for the Los Angeles region has done a lot of work testing consumer sensors against lab-quality equipment. They have evaluations for many popular models. http://www.aqmd.gov/aq-spec/evaluations/summary-pm

I was involved with a project a few years back where we decided to use purple air sensors, as much for their interface as for their accuracy/precision.

[Steve Engelschall]

Found what appears to be the same product on Amazon:https://www.amazon.com/Digital-Quali...2319002&sr=8-3

Costs more, but free returns if you have Amazon Prime and you can avoid the spam from Banggood everybody is warning about.

[Frank Pratt]

Found what appears to be the same product on Amazon:https://www.amazon.com/Digital-Quali...2319002&sr=8-3

Costs more, but free returns if you have Amazon Prime and you can avoid the spam from Banggood everybody is warning about.

The easy return is definitely an advantage. But calling their email marketing 'spam' is just plain wrong. It is something you sign up for when making a purchase, but you can easily opt out. Takes about 3 clicks to do so.

[John K Jordan]

The easy return is definitely an advantage. But calling their email marketing 'spam' is just plain wrong. It is something you sign up for when making a purchase, but you can easily opt out. Takes about 3 clicks to do so.

I didn't buy it from Amazon since at the time it said "not in stock" and the projected delivery time was so long.

How long does it take to quit getting emails from Banggood? I clicked to get off their list but 4 days later I still get several promotional emails a day.
BTW, I didn't see anywhere I signed up for emails when purchasing. Maybe it was in their Terms of Service or Privacy notice (which I did read or try to) but clicking that was required for the purchase. Did I miss something or were they being sneaky?

JKJ

[Jim Becker]

Found what appears to be the same product on Amazon:https://www.amazon.com/Digital-Quali...2319002&sr=8-3

Costs more, but free returns if you have Amazon Prime and you can avoid the spam from Banggood everybody is warning about.

That does appear to be same unit. Nice find.

[Alan Lightstone]

I didn't buy it from Amazon since at the time it said "not in stock" and the projected delivery time was so long.

How long does it take to quit getting emails from Banggood? I clicked to get off their list but 4 days later I still get several promotional emails a day.
BTW, I didn't see anywhere I signed up for emails when purchasing. Maybe it was in their Terms of Service or Privacy notice (which I did read or try to) but clicking that was required for the purchase. Did I miss something or were they being sneaky?

JKJ

I’m still getting them months later, and I never signed up for them, and clicked on the unsubscribe link several times So yes I consider that spam.

[John K Jordan]

I’m still getting them months later, and I never signed up for them, and clicked on the unsubscribe link several times So yes I consider that spam.

Fortunately gmail can send them all to never never land.

[Matthew Hills]

At this point, is there a prefered air-quality measurement tool for the shop?
Are the purple air sensors useful for shop measurements?

(I'd bought a dylos years back, but it recently stopped working--shows all 0 after a few minutes)

Matt