How effective are air filtration systems?

[Greg Book]

In my shop, I have a 1 micron dust collector, and a couple of 20" box fans with furnace filters taped to the back. However, I still have a fine layer of dust in the shop and I wear a respirator to help my allergies.

How effective are the air filtration systems that hang from the ceiling, compared to a box fan, or other methods? I'm looking at the Jet 1000 CFM model.

[glenn bradley]

Ambient cleaners can be a nice add-on assist for fine dust. The downside is that for them to catch the stuff it already has to be in the air so you are breathing it. If your DC bag/filter is "dusting" your shop I would look to improve that. If you are trying for hand held power tool spoil assistance beyond hooking them to the vac an ambient can provide a good assist. Mine usually gets turned on as I leave the shop if the air gets to where I need it ;-) My point is that the ambient cleaner does scrub a lot (if my filters are any indicator) but, they are not able to keep up with dust being created by power sanding and so forth. A more focused collection is better for that.

[Thomas Bank]

As Glenn says, they’re only going to catch the stuff that you’re already breathing. I still wear a respirator when kicking up a lot of fine dust, but see the ambient cleaner as more quickly clearing the air so that it reaches the point I can take my respirator off sooner. It’s probably a bit more effective than the box fan with a furnace filter, but it is essentially the same basic idea.

[John K Jordan]

...How effective are the air filtration systems that hang from the ceiling, compared to a box fan, or other methods? I'm looking at the Jet 1000 CFM model.

Greg,

I have found them both ineffective and very effective. To explain: I put a Jet in my garage shop and tested it after making a lot of fine dust sanding on the lathe (with no dust collector). It is too much to expect one to completely clean the air while you are making the dust so a good dust mask is still important. However, if you make a lot of dust then run the cleaner while you are out of the shop or a while the air will be far cleaner when you return. Of course, running it constantly while working and wearing a dust mask will clear the air the quickest.

How long does it take? It's been a while since I tested it but it seems like 1/2 hour to an hour was enough to get the particle levels down to a safe level. I have not yet moved it to my newly built shop so I cannot test it again until then.

It is probably extremely important to set it up properly for best results with the air circulation. There are instructions with the unit and on the web. What is mostly recommended is to put close to a long wall. Note that you can mount it hanging from the ceiling or turn it 90 degrees and fasten it to the wall, blowing sideways. It will, of course, only catch the particles it can move into it's filter so dust outside of the moving air stream will settle as before.

A better way to postion effectively is to use smoke sticks to watch the actual air movement. The idea is direct the air into a big loop, hopefully one that will pass through the areas of high dust generation. My plan for my new shop is to temporarily position the unit by the ceiling using a panel jack and test the air flow. In my case I don't have a suitable long wall where I need one so I will first try positioning it near the center of the main work area and slightly angled. It might be possible to supplement the air movement with carefully placed fans. I do have a good 5hp cyclone DC in the new shop.

To monitor the air quality in the shop I bought a Dylos air particulate monitor from Amazon:
https://www.amazon.com/gp/product/B004AWEG0Y
Bill Pentz recommends this. It's not cheap but what is the value of health? It is good for checking the various rooms in your house too. Is especially useful if anyone in the family has asthma, allergies, or breathing issues.

One think an air quality monitor will convince you of is the need to continue wearing a dust mask even after you are done making the dust.

BTW, I use this in the shop, for shearing llamas, etc. Comfortable, light weight, quick to put on/take off, fits under the face shield, industrial strength particulate filters.

respirator.jpg

I know several of people now who had to give up woodworking and woodturning completely due to developed wood sensitivity and breathing problems. To breathe freely one guy sold his entire shop contents and house and took up metal working at his new place.

Oh, I forgot to mention a better way one friend used: he mounted a huge industrial fan in the wall behind his lathe. It blew all the chips and dust and probably small woodturnings and sandpaper out into the yard.

JKJ

[Ben Rivel]

Greg, does your 1 micron dust collector use a cloth bag for the filter?

[Stan Calow]

I have read, and it makes sense to me, that the filtration unit should be at the level of you head (that is, at the height you are breathing) versus hanging from the ceiling.

[John K Jordan]

I have read, and it makes sense to me, that the filtration unit should be at the level of you head (that is, at the height you are breathing) versus hanging from the ceiling.

The chains can be long. But yikes, a head banger. Better pad the corners. I tried to work my own plans to put it flat against the wall over a bench but no go.

It's not clear to me that it would matter if it was nose height since it is not going to clean the air enough to breathe safely in real time. Seems a few baffles or fans could have the same effect. A study of how dust of different particle size moves and settles in air currents would be interesting. Perhaps the optimum position for a filter would be bench or floor height.

That makes me imagine the future of dust collection: a shop designed with an air filtering system built-in with nothing but vents at critical positions in the shop, forced air and return ducts behind the walls or between the studs, centralized self-cleaning electrostatic filters. Software could model and optimize air flow and vents in the space, taking the tool and usage layout into consideration. Something else to spend money on.

Best to collect as much as possible at the source. I was amazed watching fine sanding dust from the lathe travel sideways at least a foot to get sucked up by my DC inlet positioned behind the lathe. I had expected it to only pick up dust directly in line with the port.

JKJ

[Stan Calow]

I think the point was that if you think of a room full of floating dust, a filter up high will be catching dust that had already gone up past the breathing zone. The vertical room circulation would then be propelling more dust up past you to the filter. I have no expertise in the subject just passing on for consideration.

[Jim Dwight]

I think a box fan with filter can be effective but only if the filter is a good one - high MERV rating. The kind of filter that goes for at least $10 if not $20. If you use a $5 filter, it isn't going to do much. You need to catch the really fine stuff, which you may not see.

I currently believe that Bill Pentz is a good source for how to do dust collection but not a great source for how good is good enough DC. Bill has allergies. If you have allergies then you need to listen closely to what he says. He shares that household air with no wood dust bothers him. But that isn't where I am, fortunately. Even dusty environments do not bother me. I don't want to develop problems either but I don't see where my shop needs to be less dusty than other environments I am in for extended periods of time. Wood dust is not either the worst kind of dust or completely without irritation issues.

Currently I use a shop vac with a dust deputy discharging through a quasi HEPA filter (HEPA fabric). It doesn't work on my planner or jointer but does OK with my little BT3100 table saw although I still get a lot of dust out the top on some cuts. I open both doors on the shop for air movement (no AC) and to help move any dust I generate out.

I think our goal with DC and airfiltering should be to get to dust levels we would otherwise be breathing. The Woodworking for Engineers website has some interesting comments on dust collection that are supported by a medical opinion where the doctor talks about the fact our lungs clean the air we breath.

Please don't take this that I am anti-Bill Pentz, I like his site, but I think his idea that everybody essentially needs a 5hp DC is not completely supportable. If you want one and can afford it I have no problem with that. But I don't think most people need to get all the wood dust to be healthy. Most of our bodies can deal with higher levels and do from other sources. We should collect as much as is reasonably possible at the source and possibly filter the air to get some of the rest (or let the breeze blow it away).

Another idea I've read about but not tried is to use a yard type blower to blow the fine stuff out of the shop periodically. I initially thought that wasn't a great idea because it could just redeposit but if you do it right, it might be the best way to clean out what gets through the filter on your DC and not captured by your box fan or other ambient filter.

Last thought, a DC without a fine filter is just a dust circulator. It will get the big pieces but will let the potentially more harmful fine dust blow around for you to believe. Worse than nothing literally. My old 1hp DC came with terrible bags. I upgraded to better bags and then a cartridge filter. If I put a DC back into the shop, it will likely blow outside (an idea Bill supports). Part of my logic is I hate cleaning filters. Trapping fine dust, even inside the filter, still leaves it inside the shop to potentially leak back out (like when you change the bag). Getting it out seems like a better idea.

[Alan Lightstone]

I've been impressed how well my Jet Air Cleaner works, as measured by my Dylos particle counter.

That being said, I always wear a very good P100 respirator (the one above, actually) while kicking up fine dust, and continue wearing it until the particle count goes below ambient (yes, the air cleaner very quickly cleans the air in my shop to better than ambient.)

[David Kumm]

Interesting comments on placement. I've always been told to keep the ambient well above the breathing zone. 10 ft or so to keep dust moving above your head and keep it from dropping back down. More information would be good here. As to bags vs cartridges, it is more about getting the dirty air to the filter than what comes out. A good quality 1 micron filter of either type, properly sized gets you to the same place. The key is moving enough air to pull the dust cloud around the machine into the filter as quickly as possible. If you use a Dylos you will find that even a large 5-7.5 hp collector won't stop the monitor from spiking. It is more a matter of how fast the air cleans during and after the machine is used. Watching a Dylos gives you a whole new appreciation for how air cleaners work and how long it takes. Dave

[mreza Salav]

I have a home made air filtration system (an old furnace cage blower/motor inside a box with furnace filters on two opposite sides where air goes in and blower blowing from a 3rd side). When I had a 1.5HP (small) DC I measured using a Dylos the air quality. There were times when working in the shop that the particle count really shot up (especially when hand sanding) but with the air filtration running it would come down quickly.
With me doing minimal work and not hand sanding the air quality was actually not bad. If I had the filtration running for a while and not working there (say half an hour) the quality would be better than inside the house.
I think it does help a lot in (at least) reducing the air borne dust very quickly.

[Jim Finn]

I have a small shop (13'x23') and a small Grizzly ceiling hung air cleaner. It cleans up the dust in the air in six minutes. I leave it running much of the time I am in there. I put my dust collector that goes to each piece of equipment, outside in a closet I built for it, so any leakage is not in my shop. I also have a fan or two, at head level, circulating air in the shop. Still, I have a dusty shop floor.

[John K Jordan]

I have a small shop (13'x23') and a small Grizzly ceiling hung air cleaner. It cleans up the dust in the air in six minutes. I leave it running much of the time I am in there. I put my dust collector that goes to each piece of equipment, outside in a closet I built for it, so any leakage is not in my shop. I also have a fan or two, at head level, circulating air in the shop. Still, I have a dusty shop floor.

Jim,

That is encouraging! In my old shop with no dust collector the air cleaner took muck longer to clean up after sanding. Your experience make me anxious to install it in my new shop with the good cyclone (also in a closet.)

Did you mount yours along a side wall? What are your biggest sources of dust?

My new shop is 24x62 but flat wood and turning space is only about 24x30 and with an odd shape. The TS is in the center and everything else is more-or-less around the walls. Dust from the lathe, drum sander, bandsaw and table saw is removed fairly well by the DC but my biggest offender is a 6x10 belt/disk sander and a 1" belt sander. Do you have any advise about positioning the air cleaner - seems like the sanders should be somewhat downstream from the air cleaner intake, right?

Do you position the fans to blow dust from a source towards the air cleaner? I'm not opposed to buying a second air cleaner if that would help. I don't mind a dusty floor so much.

Thanks for any advice you can offer.

JKJ

[Greg Book]

Thanks for the responses. I'm thinking that what I have now isn't much different than a $300 air cleaner. The only difference being the packaging of the filter and fan, and a timer. Maybe I'll just build a box for my fan and filter. Also, checking the specs on a 20" box fan, it says up to 2500 CFM of airflow, so... that 2.5x as much as the Jet air cleaner. Just keeping better control of how the dust collector is connected, and maybe building a sanding table, should keep the dust under better control.

Basically I got a gift card to the big orange box store and was deciding between an air filtration unit and a new jointer. I think I will go with the jointer.