A preliminary air quality analysis of my shop

[Phil Thien]

[Note: I know dust collection and the safety of dust is a contentious topic around here. I was concerned about using a shop vac instead of a dust collector with my tools and set out to try to figure out how much of a price I may be paying by not having room to setup a larger dust collector and giant air scrubber. I do not wish to start any wars, just report my findings which I find somewhat reassuring and may be reassuring to those of you using shop vacs as well.]

Background: My shop is in my basement. I have a Ryobi BT3K, a small Inca (8-5/8" wide but short bed) jointer/planer, Inca 9-1/2" bandsaw, A Ridgid oscillating belt sander, and a router table with downdraft box. I use a Ridgid shop vac with 2-1/2" flex hose network for "dust" collection (along with a separator).

All my tools have 2-1/2" or smaller ports. I have a couple of different dust collectors but I don't use them because I just can't run 4" piping (perhaps some day I will figure out a way to do this--my shop is TINY). My shop vac gets about 150-160 CFM w/o separator. With the separator and network I get about 125-CFM. Absolutely not enough for collection of fine dust.

So the more I read Bill Pentz's site (among others) the more concerned I've gotten that I'm breathing boxcar loads of super-fine dust. That, this dust never settles and every time I enter the shop I breath more of it.

I realize my setup is sub-optimum, but the question is, how much of a price am I paying for it?

Recently I stumbled upon a particle counter that is really geared towards homeowners. It uses a laser to count particles in two sizes.

From the manual:

"Small particles are all particles detected by the DC1100 right down to its detection limit--typically below 1-micron. Large particles are all particles detected above the large particle threshold which is typically around 5 microns."

The meter comes with a table to help interpret the readings:

0 - 25 Excellent Air Quality
25 - 50 Very Good
50 - 100 Good
100 - 350 Fair
350 - 1000 Poor
1000 + Very Poor

So I got this thing and plugged it in in my basement and let it settle for a half hour or so. I had not used any tools for at least 24-hours.

On returning to the shop, it was reading 53/4. You have to add "00" to the end of the readings, so 53/4 translates to 5300 particles total (per cubic foot), with 400 of them being larger than about 5 microns. So far, so good (looking at the table my reading was considered good).

So I switched on the vac and started to cut some MDF. I basically cut the edge off a 3/4" thick piece of 24" long MDF, taking about six swipes. This type of cut (where the blade isn't buried in the wood but rather the left edge of the blade is exposed) seems to generate the largest amount of visible dust above the saw.

I then switched off the saw and watched the meter spike. Approx. one minute after I was done cutting, the meter hit a max of 1955/515. So 195,500 particles (down to 1-micron) and 51,500 larger than 5.0 microns. Nearly twice the 1000+ reading that garners a "poor" rating from their table.

Subsequent readings:

+3 minutes (from peak): 1001/223
+9 minutes (from peak): 499/91
+46 minutes (from peak): 54/2 (now, it could have been low for a while, I had to go upstairs and wasn't paying super-close attention to the meter).

I'm taking for granted that the meter does, in fact, measure down to under 1-micron. However, I will say that the meter is extremely sensitive. Just moving around in the area (within six feet of the meter) causes readings to climb.

Some interesting factors: Above the saw is a vent from the furnace. The furnace has a Honeywell electronic air cleaner. When I close this vent, and let the [new] fine dust air cleaner (down to .3-micron) filter run for just fifteen or so minutes, the meter gets down to 18/1. With the vent reopened the meter almost immediately climbs to 50ish/3-4ish. So my take on this is that, with the vent open, the air from the rest of the house dilutes the super dirty air the table saw creates as I cut. So after cutting the #'s peak, but then fairly quickly start to drop again.

It is too early to make any real generalizations. I hope to use the meter to improve dust collection/filtering in my shop, home, and office (where we service PC's that are full of dust--similar issues to home wood shop).

BTW, the black thing is the meter, the big thing sitting on the floor is my new fine air filter.

[Mark Carlson]

Very interesting. I wonder if a $140 dollar dust particle counter is reliable? I was able to find the dylos site from your description and picture.

I would love to test my shop in the morning after not using any equipment for a couple of days. Turn on my canister style dust collector and see what the reading are. My guess is that my dust collector is really a dust pump and I should be thinking about a cyclone and a respirator.

~mark

[Andrew Nemeth]

Phil, Very interesting post. Where did you happen to pick up the meter and how much did it set you back? I did not used to worry too much about sawdust but recently I have begun to take it more seriously. I know dust collection is kinda the hot thing lately (I can't remember it being much of an issue 10 years ago). I recently jumped on the bandwagon and invested in an air filter and have become much more accustom to hooking up my shopvac when I can't use my DC. After spending so much time and money on a arsenal of dust collecting equipment I wonder how much good it really does. If it's affordable I would be interested in doing some test myself.

[Phil Thien]

Oh yeah, I'm sorry, it is a Dylos DC1100. You can make it out from the picture but I should have said something.

I do suspect it is pretty accurate. I kinda suspect there is some LSI circuit under the cover. Just like digital calipers were once expensive and somewhat obscure but became cheap and plentiful, I suspect the same thing is happening with this technology.

BTW, I believe Dylos is coming out with a .5 micron version (but it will be more expensive).

[Phil Thien]

Phil, Very interesting post. Where did you happen to pick up the meter and how much did it set you back? I did not used to worry too much about sawdust but recently I have begun to take it more seriously. I know dust collection is kinda the hot thing lately (I can't remember it being much of an issue 10 years ago). I recently jumped on the bandwagon and invested in an air filter and have become much more accustom to hooking up my shopvac when I can't use my DC. After spending so much time and money on a arsenal of dust collecting equipment I wonder how much good it really does. If it's affordable I would be interested in doing some test myself.

You can get them direct from the manufacturer:
www.dylosproducts.com.

They run about $150.

You can also get 'em from www.americanallergysupply.com (where I got mine--and Sandy has an interesting write-up about cleaning air with box fans and and pleated filters).

[Sam Yerardi]

Phil,

Is there a local university in your area? Sometimes they have people/equipment to do air quality analysis for biological studies, etc. They could help but I would make sure if there's a cost involved.

[Phil Thien]

Phil,

Is there a local university in your area? Sometimes they have people/equipment to do air quality analysis for biological studies, etc. They could help but I would make sure if there's a cost involved.

I'm done relying on others for this information. I purchased the equipment so I could see for myself how my shop measures up. By some accounts, using a shop vac for dust collection should have put me squarely in the "get out of that house" category. My meter tells me my air quality (at least down to .9 or .8 microns) is as good as it gets (in normal houses) within less than an hour of cutting MDF. I suppose it is possible that my .5 micron count is out of whack, but I kinda doubt it.

In retrospect, the single thing that could easily and economically be done to improve my picture would probably be to add a Shark Guard and dust pickup above the table saw. I can't say that for sure, but I suspect that investing $100 or $200 in a SG would do more to improve the situation than any gigantic DC or any type of filtering.

Need to do more research.

[Peter Quadarella]

There is an interesting thread in which the designer of the Dylos chimes in. The .5 micron unit is already available but you have to ask for it (although I would think 1 micron is good enough).

To find it, just search for Dylos DC1100 on Google and check out the link to the hvac-talk forum. It sounds like a pretty good unit.

[Phil Thien]

There is an interesting thread in which the designer of the Dylos chimes in. The .5 micron unit is already available but you have to ask for it (although I would think 1 micron is good enough).

To find it, just search for Dylos DC1100 on Google and check out the link to the hvac-talk forum. It sounds like a pretty good unit.

Thanks for the info Peter.

[Al Willits]

""""""""
So my take on this is that, with the vent open, the air from the rest of the house dilutes the super dirty air the table saw creates as I cut.
"""""""""

fwiw while the house air is diluting your shop area, your dirty shop air is polluting your house air.

Maybe something for those with basement shops to consider??
Al

[Todd Franks]

Phil,

Excellent post!! It is so refreshing to see actual data.

I'm done relying on others for this information. I purchased the equipment so I could see for myself how my shop measures up.

I'm with you on this point. I've researched and read this topic to death and as a result I decided to upgrade from a canister style DC to a cyclone. I have been wondering how much improvement I get for all the extra expense. We can discuss CFM, SP, Amps, filter efficiency, separation efficiency, etc but ultimately the number of particles in the air in your shop is the spec that matters most. I have also been wanting to do a before and after air quality measurement but didn't want to spend the bucks for a professional meter. Even if the absolute accuracy of this meter is off, it should be good enough for relative measurements. Thanks so much for this post.

Another interesting experiment would be to rerun your MDF test but put the meter somewhere else in your house. I'm curious how the air quality of the rest of the house is affected by a basement workshop.

Now, I can't believe I am really talking about spending $150 on a meter instead of a real tool.

-Todd

[Steve Leverich]

Todd, if you go to the Dylos site and click on the "com" option, there's a comparison between the expensive and the Dylos results - IMO, the diff isn't worth $4000 (although I do think I'll opt for the .5 micron version) HTH... Steve

[Brad Shipton]

This detector peaked my interest, so I sent an email to the manuf. Very quick to respond. Thought I would share with the other members.

Hi Brad:

The forum was brought to our attention today...and we like that different industries are interest in their air quality. What the DC1100 can do is provide you with a baseline of what the particle saturation is when you are not using any equipment and when you are not in the shop. Once that is established, you can run your equipment the way you normally would (you will see the counts increase significantly), then turn on your dust collectors and see if the counts go down. If they do, then they are doing their job, if not...then they may have a clog somewhere in the tubing or the filters/bags need to be replaced. Our DC1100 Air Quality Monitor was primarily designed for home/office use, however, it can be used in a woodworking shop, you just need to remember that the counts are going to be significantly higher as this type of environment has significant dust. As far as the question of accuracy is concerned it is...yes. If you go to our website you will see a graph inwhich a $4500 particle counter was compared against the DC1100, they almost track identically. If you have any additional questions, please feel free to email me again or call at the phone number below.

Thank you,

Kimberly Unger
Dylos Corporation
9825 Magnolia Avenue, #B327
Riverside, CA 92503
PH: 877.351.2730
FX: 951.351.1765
www.dylosproducts.com

----- Original Message -----
From: Brad Shipton
To: support@dylosproducts.com
Sent: Saturday, January 12, 2008 1:25 AM
Subject: DC1100 for Woodworking Shop


A number of members on a forum are discussing the use of the DC1100 for monitoring the air quality in a Woodworking shop. All have installed some form of a dust collector (cyclone or single stage machines), but we cannot quantify the effectiveness of our systems. Would you recommend the DC1100 for evaluating a woodworking shop? What is the accuracy of this device?

Thank you
Brad Shipton

[Phil Thien]

I have spoken to Dylos and they have agreed to a group purchase. Kim will even individually ship the units to each purchaser for 2% above actual UPS (doesn't get any better than that).

The discounts are substantial and will depend on the size of the group (obviously), 25 being the minimum.

Here is some pricing:
Qty. 1, 1-micron, $159.95 each (MSRP)
Qty. 25, 1-micron, $103.99 each.
Qry. 50, 1-micron, $99.19 each.

Qty. 1, .5-micron, $219.00 each (MSRP)
Qty. 25, .5-micron, $142.99 each.
Qty. 50, .5-micron, $136.99 each.

Roger (developer) has agreed to go to Home Depot for me and pickup some MDF. He will saw/sand some MDF and some pine and compare and contrast the .5 and 1-micron units to each other. Either he or I will post the results.

Still some details to be worked out, but not a bad deal overall.

Looks promising.

[Greg Funk]

Put me down for one (either the .5 or 1 micron) depending on the test results.

Greg