Air particulate counter?

Re: Air particulate counter? *LINK*

Kneale Brownson

Just $5 grand at Grainger's


Click

What are you going to do with the result?

Dick Coers

I really don't understand the idea of getting a number on how dirty your air is. Will you really invest the money to clean the air completely when you get the number, or will you just be pleased with knowing it's just kinda dirty? Sounds like you already know your air is dirty or you wouldn't be thinking of measuring it. I've always kept a fan going somewhere in my shop to create a circulation and more quickly drop the fines out of the air. But recently compressed my old wood pile into a taller pile for more floor space. Man, that pile of lumber was dusty!

Re: What are you going to do with the result?

Barry Irby

I have two Ambient air cleaners running. One home made and the other one a Jet. I also have DC on most of my tools. I use a Festool sander that has excellent dust collection. But there are things like routers and hand sanding. I wear PPG most of the time. So I don't know what else to do. I was pretty happy with it because after a month or more of working with walnut, I have not been blowing black.

Then the news reports the outside air is bad. I live almost in sight of a coal fired power plant. I have lived here for a long time and I know the air is much better than it was when I was a kid. They have all kinds of air cleaners including a bag house with 2900 bags. (I have one) US Gypsum takes the remains and makes Drywall out of it and since they use low sulphur coal, that works.

I was just wondering if I was being too Cavalier about the dust in the air? Could I or should I be doing more? And, like you I am amazed at the places dust finds to accumulate.

Re: Air particulate counter?

John in NM

Most of the counters you see are for clean room evaluation. That makes them expensive, and prone to trouble when used in such a dirty environment as your proposed application.

We have two at work that are used to measure outside dust counts (we don't like getting dust on the telescope mirrors, so there are closure limits set for the night staff). I think the only reason the manufacturer keeps servicing them for us is that they are probably interested in service life data for such an extreme application as ours.

Dylos

John K Jordan

I've had a Dylos laser particle counter for over 6 years now, bought after studying Pentz and reading his recommendation.

https://www.amazon.com/gp/product/B004AWEG0Y

I think this one is a good trade off between cost and function, high quality but not incredibly expensive. (About the cost of a couple of good lathe tools)

I don't think I would ever use it to write down the numbers, plot, analyze, and fret over them. I do make good use of the relative numbers.

I have it in a monitoring mode and note the approximate number before I start cutting and sanding. After working for a while I look again and see just how high the numbers have climbed, if at all. (They often climb just a small amount.) If one machine/operation makes them skyrocket I know there is something wrong. If I don't remember them being high before with the same situation I know that something has gone wrong.

When I make modifications to the dust pickup somewhere, for example at the lathe, comparing the numbers gives me a better idea if I've improved or worsened the situation.

When I do a new operation it's nice to know it's not spreading dust around. When I'm all done it's also nice to see how quick it takes for even small amounts of dust to clear from the air. If I doing something that doesn't have good dust pickup (belt/drum sanding, SCMS) it's a good indicator of when I can take off the respirator.

For even more fun, try turning off the dust collector and do some typical tasks. Makes me glad I put all that money and effort into installing the cyclone.

JKJ

Re: Air particulate counter?

Jesse Cloud

There's a lot of different ideas about where air cleaners should be located for best effect, much of it contradictory.

What you might consider is measuring the shop air, moving a cleaner, and seeing if it makes any difference. Repeat until you are confident you have the best set up.

If you see a Festool router for sale at a good price, snap it up. The dust collection is not as good as on the sander, but its a heck of a lot better than on most routers. I use mostly an OF1400 and very seldom make a lot of dust. With the right accessory, even edge routing can be done pretty cleanly.

Re: Dylos

John K Jordan

Here is something else about the Dylos:

https://woodgears.ca/dust/dylos.html

JKJ

Thank you John, interesting.

Re: Dylos

John in NM

Interesting article, the count numbers strike me as pretty low, but if he was in a humid part of the country that could be the difference. Out here on a dusty day, it is not uncommon to see 300,000 counts at 1 micron, over a million at 0.3 micron - but the air is dry out here.

Given the pictures of the air path & measuring chamber in the unit, I'm not sure I'd trust it's figures, but they would give you a measure of "dusty" vs "not dusty". What he says about air flow through the unit is probably part of the reason the numbers are low.

Its pretty cool that you can find relatively inexpensive dust counters out there. I just wouldn't count on getting a real number from them. If you are careful to always measure in the same way, and to take it apart and clean it frequently, I bet you could get figures that are consistent enough to spot trends, and that could be useful for a couple hundred bucks.

Re: Dylos

Barry Irby

I was thinking of using it in some sort of comparative sense. My DC dumps the air outside. So it would be interesting to know what the count is outside and see if the count inside is nearly as good.

300,000 what? In what quantity of air? Sort of unimaginable.

I grew up on a dairy. We used to have the milk tested and bacteria count per CC was one of the measurements. I don't remember the actual numbers, but you don't want to know.

Re: Dylos

John in NM

Sorry, volume is 0.1 ft^3 for ours. I don't remember the sampling interval - that much particulate in that volume over X time - maybe 10 seconds in 5 minutes sounds about right. I can look it up if you want to know, I have the manual on my computer at work. For mirrors we integrate the sample interval over the time open per night and end up with X dust-hours, which is a different figure than the raw counts.

Right now, on a moderately breezy spring day, dust counts are at 4k for 0.3 micron and 224 for 1 micron (I'm actually a bit surprised its not 10x those values given how windy it is at my house 15 miles north of the site). The 1 micron value is the one we use for open/close standards, usually around 10k to 20k depending on other factors like humidity. The 0.3 micron is very useful for spotting smoke spikes (from forest fire in our case), but you also see a bit of that in the article John linked - don't use the kitchen for comparison, especially on fried catfish night.

That kind of comparative figure you're thinking of is what those inexpensive counters would be good for - measure in the shop, the house, and outdoors and compare those (within a few minutes of each other). Comparing measurements from 6 months ago to now is where I would expect a counter like that to fall flat. Probably would be ok if it was not used between longer interval measurements, but if it took one a day it would be way off after just a few months.

I have a pretty good idea how "dirty" milk is - we had a couple dairy cows for several years. Most of that bacteria is harmless, but not all. A friend of mine has a daughter who is and epidemiologist, and had some pretty horrifying observations on how the population is reacting to chickenpox now that kids generally don't get it (and thus aren't re-vaccinating their parents' immune systems by exposing them to it).

As long as we're on the subject, dust counters are somewhat useless unless you know that the particle you are interested in is within the range of the counter you are using. These counters work by timing the interruption of a beam of light, given a known airflow rate. But hardly any of them are calibrated for the air path, and usually they are useless over 30 microns or so because the particles above that tend not to stay entrained in the air flowing through the counter. The ~40 micron particle we're most interested in at work is pollen from pine trees, and in spring time we still have to go out and look at windshields rather than count on the counters - they miss the pollen spikes. Part of this is that pollen is also horribly sticky, but size and flow path is also a contributing factor.

The point of that is that if the bulk of the dust you see in your shop is 100 micron, the counter is likely to miss it.

Now we know who to blame!!

David Yoho

Dang, Barry, the outside air here in VA is bad and you're dumping your dust collector outside??? It's all your fault

Yeah but!,,,,

Barry Irby

I filter it first, through that bag with the dust caked on the inside.

I was just wondering if the air I am drawing back in is just as dirty.

David, you live near Richmond, right? That power plant on the side of the river in Chesterfield burn 100 train car loads of coal a day. Not only that, they use the water from a sewage treatment plant to produce steam in their boilers, because it's cleaner than the James river water. Kinda makes you go Eeau!! doesn't it?

Re: Dylos

Barry Irby

I am confounded. Are you saying there are sometimes 300,000 particles in a cube .1' X .1' x .1'? Sort of unimaginable. Sounds like the atmospheric version of mud.

Not really

John in NM

0.1 cubic foot is 2.8 million cubic millimeters. Each cubic millimeter would hold 1 billion 1 micron particles packed tight.

So that 300k count is about 0.1 parts per billion.

Why we don't do it in metric to begin with is beyond me, but since this observatory has 0 degrees AZ pointing south I stopped questioning their historical judgement several years ago (in the rest of the engineering world 0 degrees is north - so this place is a lost cause in my book).

size...

John in NM

0.1 cubic feet is 0.464'x0.464'x0.464' of course....

Re: size...

Barry Irby

Oh! .1 cubic foot, not .1 of a foot cubed.

I have read the regulations on mold. (Wait for it, there is a tenuous relationship) It says it's acceptable to clean up ten square feet of moldy surface without hiring professional mitigaters. I have heard it argued that that's ten square feet and it could ten feet squared (100SF). It just depends on who you ask as to which one is correct. And, I have heard it argued that you only count the area that actually has mold on it.

Re: size...

John in NM

Yeah, it gets tricky when dimensions are less than one as the volume seems to shrink rather than grow.

On the other hand, ten square feet is never the same as ten feet squared. Run from a contractor who mixes words in that way, they are simply not honest people. Counting the actual treated area seems like a legit dodge, even though it is clearly dodging the intent of the rule. Man I'm glad I'm not in that business!