Dylos and dust collection

[Jim Dwight]

Matthias Wendel (woodworking for engineers) has some good data on dylos readings with various dust collectors on his website. His views are pretty different from Bill Pentz, however. Big question is how good do we need. Bill's level is definitely low enough - much cleaner than most houses. I tend to think that getting the shop down to the level Dylos would call good is good enough. Like most things, the air movement to drive the value lower is exponential, not linear. It takes a lot more hp to get to Bill's recommended level.

The other important parameter is the significance of an excursion for a few minutes to a higher level - like a moderate level. Since those levels are not unusual for outside air and even inside under some circumstances, I cannot see why it is worth another 3hp in the DC.

In other words, as Bill Pentz says you need 5hp to get the air as clean as he thinks we need. If you accept something like the Dylos good level, possibly with an occasional excursion something like a 1.5-2hp DC should work - correctly set up with a good filter (or discharging outside).

The worst DC is one with big leaky bags rated at greater than 1 micron. They will help you reduce sweeping but just throw the fine stuff up for you to breathe. I had one but never will again.

[Mark Daily]

Thanks for the info Jim- I’ll read up on what Matthias has to say.

[Mark Daily]

I haven’t had a chance to do any detailed testing yet but I did check a couple of things in my shop.

My shop is 10’x20’, the 3rd car stall of a 3 car garage. I have the large door taped shut and it is partitioned off with an insulated wall to allow it to be air conditioned.

When in the shop but not working, the small particle reading fluctuates around 150 or so.

I have a single stage 1.5 HP Grizzly DC with a cloth aftermarket upper filter bag that claims to filter down around .5 microns, if I remember right. I put the Dylos on a shelf next to the bag and turned on the DC while I sanded at the other end of the shop on my bench top belt sander which is connected to the DC.

The small particle reading hovered around 100 the entire time. I expected it to go up while sanding but it did not. I turned on my AFS1000B and after an hour the reading was 4. My AFS1000B has the original, 10 yr old inner filter. The outer filter is a washable one with a metal frame that I bought with the air cleaner.

Apparently, the DC bag is working pretty well and the Jet air cleaner hanging from the ceiling is filtering well also.

More later as I can get it done.😎

[Jim Dwight]

Great data Mark. I used to have a 1hp Delta DC (AP400) that was single stage. I used it with the stock bags but that was a terrible idea. Then I put on shaker felt bags and it didn't seem to be too bad. But I had no real data. I later added a Wynn cartridge filter which seemed to work well. The filter the Grey house studios used in their build are about half as expensive, however.

I will have a super dust deputy on my new system when I get it set up because I do not like cleaning filters. Bags work best with dust on them but the more dust they collect, the less airflow they permit. I use a dust deputy on my shop vac and it greatly reduces filter cleaning.

[Mark Daily]

Great data Mark. I used to have a 1hp Delta DC (AP400) that was single stage. I used it with the stock bags but that was a terrible idea. Then I put on shaker felt bags and it didn't seem to be too bad. But I had no real data. I later added a Wynn cartridge filter which seemed to work well. The filter the Grey house studios used in their build are about half as expensive, however.

I will have a super dust deputy on my new system when I get it set up because I do not like cleaning filters. Bags work best with dust on them but the more dust they collect, the less airflow they permit. I use a dust deputy on my shop vac and it greatly reduces filter cleaning.

“Shaker felt bag” is what I wanted to say but couldn’t remember- thanks Jim!

I have one on top and a plastic bag on the bottom.

I cut some wood on the table saw without using the over arm DC, just the cabinet mounted dust port which is terrible. Particle counts shot up to 3800-500- yikes! I turned the air cleaner on high (1044CFM per Jet) and in 15 minutes it was down to 150-20. Noisy but really effective!

Inside the tablesaw is a dust deflector/chute mounted in front of the blade. It deflects the dust straight down to the bottom of the cabinet where it just sits there instead of being sucked out the port. So, I’m working on a mod to connect the dust deflector to a new port mounted on the opposite side of the cabinet which makes for a much shorter hose run.

Stay tuned- same Bat time- same Bat channel!

[Mark Daily]

A few days ago we made microwave popcorn which is guaranteed to smell up the entire house. But this time I replaced the A/C filters with Filtrete 1200 MPR odor reduction filters which use activated charcoal.

I turned on the A/C fans before cooking the popcorn to circulate the air. Afterwards, we could barely smell just a hint of popcorn anywhere in the house. I went outside for a short time and when I came back inside I couldn’t smell any popcorn.

Before, I was skeptical about these filters but not any more. The Dylos does however show they don’t filter quite as well as the 1900 MPR filters I put in recently. The 1200’s got the small particle count down to around 100 at best while the 1900’s will bring it down to 5-10 easily.

[Jim Dwight]

If I decide I need overarm dust collection I will probably get a shark guard. SawStop offers a setup but the hose is really small and it costs more than the sharkguard. The Shark Guard is available with a 2.5 or a 4 inch hose attachment. I think that will be much more effective.

My old Ryobi BT3100 and my new SawStop both have chutes around the blade to get the dust to the dust port. The SawStop uses a hose, however, so I think it will be less effective. But I think chutes help since they direct the suction up around the blade.

I did some simple photographic tests on various sized openings around the blade. I took pictures, in other words, with different throat plate designs of the dust left on the top of the saw. As you might expect, I found that opening up the slot on the back side of the blade reduced dust on the top of the saw. Makes sense, I just added some picture evidence to what you would expect. I tried holes in the throat plate but that did not seem to do anything. I will try that on the SawStop before adding overarm dust collection.

[Mark Daily]

I made my overarm collector based on Justin Dephew’s design. Right now I’m using it with my shop vac and it works great- enough suction to lift wood off the table!

Hopefully the following link works:

https://youtu.be/DA-O-1qUDh4

Holes in the throat plate are too small and are usually covered up by what you are cutting.

[Alan Lightstone]

OK. This one has me baffled. For the past several days, when I go into my shop in the morning, the Dylos readings are far higher than I've seen. About 1100 for small particles. I have been working in the shop all week, and was thinking, maybe I wasn't vacuuming enough at the end of the day, but it repeats every day.

So I took the meter outside, and it's reading 3500.

We've had a huge dry spell here, but it's been on and off raining for the past few days. My question is, do Dylos meters read incorrectly high when the relative humidity is very high? If not, suddenly the air to breath in Tampa Bay has gotten dangerous. It's hard to imagine where I live - I'm less than a mile to the Gulf of Mexico, and the wind has been coming off the Gulf for the past week.

Now this morning, it went down to 518 in the house, and 734 in the shop with the AC unit presumably running overnight. 2315 outside. Clear, sunny day outside. No forest fires, factories nearby.

So, does high humidity make the Dylos read high?

[Doug Dawson]

OK. This one has me baffled. For the past several days, when I go into my shop in the morning, the Dylos readings are far higher than I've seen. About 1100 for small particles. I have been working in the shop all week, and was thinking, maybe I wasn't vacuuming enough at the end of the day, but it repeats every day.

So I took the meter outside, and it's reading 3500.

We've had a huge dry spell here, but it's been on and off raining for the past few days. My question is, do Dylos meters read incorrectly high when the relative humidity is very high? If not, suddenly the air to breath in Tampa Bay has gotten dangerous. It's hard to imagine where I live - I'm less than a mile to the Gulf of Mexico, and the wind has been coming off the Gulf for the past week.

Now this morning, it went down to 518 in the house, and 734 in the shop with the AC unit presumably running overnight. 2315 outside. Clear, sunny day outside. No forest fires, factories nearby.

So, does high humidity make the Dylos read high?

You may (or in Tampa may not) have noticed that when you turn on the humidifier in your shop, the Dylos small-particle readings spike pretty hard, because of the fine mist of water droplets in the air, which get registered as particles.

[David L Morse]

Alan, you can easily check your local conditions at either the EPA site or Florida's site. The EPA reports an overall AQI for the Tampa area of 57 (moderate) due to PM2.5 right now. That works backwards to a difference of about 1500 between the Dylos large and small numbers. The Florida site lets you look at a number of monitoring stations in your area. Pick the closest upwind station or look at several of the surrounding ones.

I've seen studies comparing low cost particle counters with actual PM numbers. In general, the Dylos included, they seem to read high at lower particulate levels They all suffer from large particles blocking the small counts at very high levels, but those levels are way outside the range we're talking about here.

It would help if everyone reports both Dylos numbers. The number on the left is actually the total number of particles counted. The number on the right is the amount larger than 2.5micron. That means that the number of small particles is really the difference between the two.

In your case, the difference might be a bit over 2000. That overage compared to a 1500 reading is about what would be expected based on the data I've seen, and of course there's a lot of variation depending on where you are relative to the measuring stations. I would say your readings look about right.

[Doug Dawson]

Alan, you can easily check your local conditions at either the EPA site or Florida's site. The EPA reports an overall AQI for the Tampa area of 57 (moderate) due to PM2.5 right now.

Do you know specifically how the EPA measures this? Just for the record.

Specific to Alan, I'm calling it sea breeze, most likely.

[David L Morse]

Do you know specifically how the EPA measures this?...

AQI or PM2.5?

I linked to the AQI calculation in a previous reply to this thread. There are a variety a ways to measure PM2.5 but I think the most common one currently is Beta Attenuation Monitoring (BAM).

(edit) Oh, are you maybe asking how they come up with only one number when there are so many measuring stations in the area? That I certainly don't know. Some kind of data analysis magic I presume.

[Mark Daily]

Alan, you can easily check your local conditions at either the EPA site or Florida's site. The EPA reports an overall AQI for the Tampa area of 57 (moderate) due to PM2.5 right now. That works backwards to a difference of about 1500 between the Dylos large and small numbers. The Florida site lets you look at a number of monitoring stations in your area. Pick the closest upwind station or look at several of the surrounding ones.

I've seen studies comparing low cost particle counters with actual PM numbers. In general, the Dylos included, they seem to read high at lower particulate levels They all suffer from large particles blocking the small counts at very high levels, but those levels are way outside the range we're talking about here.

It would help if everyone reports both Dylos numbers. The number on the left is actually the total number of particles counted. The number on the right is the amount larger than 2.5micron. That means that the number of small particles is really the difference between the two.

In your case, the difference might be a bit over 2000. That overage compared to a 1500 reading is about what would be expected based on the data I've seen, and of course there's a lot of variation depending on where you are relative to the measuring stations. I would say your readings look about right.

David, my Dylos manual states “small particle concentration is always displayed to the left and large particle concentration to the right.” No mention that the left is the total large & small.

[David L Morse]

David, my Dylos manual states “small particle concentration is always displayed to the left and large particle concentration to the right.” No mention that the left is the total large & small.

Check page 12 of the manual:
DylosDef.JPG

Also look at this on the Pentz site.

This is standard reporting practice for particle monitors, probably because of their heritage as industrial process control instruments.