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Thread: Whole-shop Air Filtration Units Bad?

  1. #31
    Join Date
    Mar 2005
    Ontario, Canada
    Earl said,
    I think alot of people have been pushed towards dust collectors and now cyclones with the findings of the posibility of wood dust being cancerous.
    I would imagine the risk of nasal cancer to be relatively small. My primary reason for pursuing the clean-air-kick is that I have asthma which is triggered by wood dust. I am on a quest to make my time in the shop more enjoyable and asthma-symptom-free.

    George said,
    I found and use this mask from North.
    Do you wear glasses, George? This might work for me if it rides low on the nose.


  2. #32
    Join Date
    Feb 2003
    Leesville, TX (San Antonio/Austin)
    Quote Originally Posted by Ken Salisbury
    I can tell you that the air in my shop can be clouded with dust and within minutes of turning on my air cleaner it is very noticeably cleaner....
    I suspect that the air would be noticeably cleaner within minutes anyway...simply because the dust will settle.

    I've considered an overhead unit, but always been skeptical of the claims. What I DO do is point the fan(s) so it blows past me and 'out' of the shop. That seems to help.


  3. #33
    Join Date
    Apr 2005
    Anywhere it snows....
    I smell a rotten fish or a corporate herring. Here is why.

    The article brings up an excellent point. The most dangerous dust is not the dust you can see. Those big jointer shavings and planer crunchies are not the item causing concern. Not even the fine dust that you wipe off of everything. Its the super small stuff that can stay airborne for a long long time. This is the stuff you can breath into your lungs and it doesnt leave with ease. Kinda like tobacco smoke.

    Now, most dust collectors work on two premises not one. The first stage is to use a macho cyclone to kill off any kinetic energy that these large crunchies have and to drop them into a collection bin whatever that may be... garbage can, rotary air lock and open cannister, or sealed collection bin, etc. The bigger the crunchy, the loader the drop. The smaller the crunchy, the more apt it is to exist the cyclone unphased.

    So now the air passing out of the cyclone contains lots of flour fine dust and tiny particles of that nature. It goes into the bag house or finishing filter unit. In regular designs, this dust actually builds up on the inside of the bag and improves the filter capacity of said bag. So its always good to have some dust inhabiting the inside fibers of the bag. In time, you shake these bags and this fine dust drops into the bucket attached to the bottom of the bag inside the bag house.

    But how good are these bags and where does the bag exhust its air? In most cases, these bags recycle air within the shop. Shops in cold environments really wish to do this as its expensive to exhust the air to the outside. But if that air is being recycled and the bag house is exhusting back into the main shop, your doing the same thing that these hanging air cleaners are doing. Moving Air! How many full shop exchanges does your dust collector do per hour? So unless your installing a hepa filter on your bag house exhust port, it strikes me that this setup is doing the same thing. In actuality, it may be easier to install some form of super filter on one of these box units making them more effective than a full bore DC.

    Now I do know that Onieda has some form of high performance polishing filter inside the central core of its cyclone. Most cyclones do not requiring the use of a bag house. I know that TIP tools offers some really high performance bag house filters for use with their sand blasting gear and they also sell an optional final filter for the bag house filter. It appears that super fine particles are getting through. So it sounds like no matter what you use, these super fine particles will be there to hunt us. Maybe we all need to buy one of those iconic breeze filters and make a guest appearance on The Sharper Image late night infomercials.
    Had the dog not stopped to go to the bathroom, he would have caught the rabbit.

  4. #34
    Join Date
    Sep 2004
    St. Louis
    Quote Originally Posted by Steve Aiken
    The problem is that I can't find any HVAC filters that are independently tested to meet a MERV 13 let alone a MERVE 16 .
    Good job on the research. I went through similar questions when I built my shop filtration system. And I had similar goals. No asthma but RAS (reactive airway syndrome) which basically means if I breath much dust I get congested like a bad cold. It gets to the point where the after effects, make you hesitate to go into the shop. So like you ,I aimed to make my shop enjoyable to use and to eliminate any after effects.

    If you build your own you have more flexibility in filters and you can design it around non-standard sizes. You won't find much in the way of fliters rated above MERV 12 in the typical furnace sizes at H. depot and the like. If you try industrial suppliers (I'll use Grainger as an example) you can find several MERV 13 and 14. You don't have to worry about restricting the air flow as they are made with various capacities (CFM). They get expensive, but you can consider it a one time buy. Use lower rated prefilters so only the fine stuff gets to these and it takes a long time to fill them up. Many are washable.

    Here are a couple of examples, but you can find plenty more with a bit of searching:

    Also realize that the first pass numbers actually improve with use as the dust that gets trapped actually helps to filter more and more dust (resistance does increase, so there comes a point where you need to clean them to maintain enough CFM)

    I think getting above MERV 14 is pretty tough and expensive and true HEPA can be prohibitive. These are largely applied in hospital and clean-room situations.

    I don't know your shop setting, but if you can think in terms of a whole shop system you can get far better result than a box. Your main cost is probably the filter. You can get a furnace blower 2000 to 4000 CFM and ducting free from a HVAC shop. The construction is similar in effort you just need a bigger box to house the fan and filter. If you do a box, do two. For 2x the job you'll get 8x the efficiency of circulation (rough estimates from an article). See my earlier post for reasoning. See the pictures below for an idea of my whole shop system.

    I hope some of this helps in some way. Good luck in finding a solution that makes your shop enjoyable and healthy!
    Attached Images Attached Images
    Last edited by Ken Waag; 05-06-2005 at 8:33 AM. Reason: additions
    Ken Waag

  5. Lightbulb

    Hi All,

    .... Has anyone thought to ask Bill Pentz about this. He certainly has devoted a lot of time and done a tremendous amount of work in his life time on dust collection. I, for one, would be very much interested in his point of view, especially on this critical health subject. He is our only real expert here at the creek and I think perhaps he should be consulted .


    Every manís work is always a portrait of himself.

  6. #36


    I have an 1100 dust collectoer with an home made cyclone+an jet 1000 air filter and I still wear a mask. Mike

  7. #37
    Join Date
    Mar 2004
    Toronto, Ontario, Canada
    Thnaks for starting this post Steve and thanks to all those who have contributed.

    I have a cyclone system but I don't (yet?) have a whole room filter. I am thinking of buting one, so am following this thread with lots of interest.

  8. #38
    Join Date
    Mar 2005
    Ontario, Canada
    Well thought out system you've got their, Ken, looks like it does a great job a recirculating every square inch of air in that shop. The only limitation is the quality of the air filter(s). What combination of filters do you use?


  9. #39
    Join Date
    Jul 2004
    Tacoma, WA
    Here is a link to the one section of Bill Pentz' web site that mentions air cleaners.

    Simple gist is that they don't do much for your health while working but they do clean the air so the next time you go in the shop you don't have to deal with the dust from the last session.

  10. #40
    Join Date
    Sep 2004
    St. Louis
    Quote Originally Posted by Steve Aiken
    Well thought out system you've got their, Ken, looks like it does a great job a recirculating every square inch of air in that shop. The only limitation is the quality of the air filter(s). What combination of filters do you use?

    I got a roll of washable electrostatc filter material at HD and made my own pleated section to match my finer filter. Its MERV 10 and can be washed for a lifetime (I think it was $25). Then I have a V bank as per the link in my post above. Merv 14 very high efficiency and capacity. Listed there at $182, I got one while they were on "sale" for $120. Pricey, but it will take a long time to fill up and you can vacuum or blow it out, so it should last many years/lifetime.

    The system works well. With the exhaust vents in the middle of the front wall and the intakes high along both side walls I get to circles that move pretty quick. I did a smoke test and cleared the space in 4 minutes.
    Ken Waag

  11. #41
    Ken, thanks for the additional details on your post. You have the best air filtration unit I have seen in a home shop!
    Jeff Sudmeier

    "It's not the quality of the tool being used, it's the skills of the craftsman using the tool that really matter. Unfortunately, I don't have high quality in either"

  12. #42
    Great thread. I WAS planning on buying a Baleigh Industrial air filtration system... then the shiupping cost on a $380 unit came out to $180... no thanks... I'll just die... but seriously- I am now thinking of a totally different method of attacking this issue.
    Last edited by Lee Schierer; 11-27-2017 at 6:47 PM. Reason: fixed wonky text
    Ryan Higgins Financial Advisor by day... Amateur woodworker/ Batman by night

  13. #43
    I have to somewhat agree with Oneida, all of the commercial air shop cleaners are garbage and probably do more harm than good. They might keep dust nibs off your finish but they won't clean the ultra fine particles from the air. Nobody makes a woodworking shop air cleaner that actually works for the harmful stuff and if you try to build one out of an old furnace motor and filters from home depot it's really no different.

    True HEPA filters are very fine and require a good amount of pressure to force air through them, as such a fan that is designed to deliver high pressure is necessary. There's really 3 main aspects that make a good filter unit, the fan, the filter, and air sealing the assembly. Its quite simple and yet all of these woodworking companies (JET, King, Steel City, Delta, etc) have it wrong.

    The Fan:
    If you are building your own filter and want to purchase a fan, the CFM alone means nothing, ignore it unless you have a fan curve. Looking at the fan curve, look at where it says "1" w.g." and read the air flow, that's the air flow you will get with a typical brand new HEPA filter. As the filter gets dirty the pressure drop across it goes up, usually the filter is changed when it gets to "2" w.g.", so read this off the fan curve and this will be the minimum flow. I have not been able to find a furnace fan that will go to this high of pressure and still have air flow, this is why you should look at a fan curve and know what you are getting before purchasing a fan. Note that this is just a rule of thumb starting point, the fan should be selected based on the filter pressure and capacity requried.

    The Filter:

    Look for true HEPA filters that filter 99.97%+ of particles under 0.3 microns. This is the gold standard for construction clean up, asbestos abatement, and most industrial applications, therefore i think this should also be applied to woodworking dust if you want the best protection. If you want to build your own, Camfil makes excellent HEPA filters.

    The assembly:
    The key to a good assembly, at least as far as performance is concerned, is getting a tight air seal around the filter. The filter itself needs to be designed with integral gaskets and the filter housing needs to compress this gasket to make a tight seal and ensure that there is zero air leakage going around the filter rather than through it.

    A good air cleaner doesn't need to be complicated but using good quality filters and a proper fan isn't exactly cheap. Fortunately the asbestos abatement industry is doing it right and there are a lot of commercial air cleaners to choose from if you are looking for something off the shelf. I've dealt with Abatement Technologies and Novatek, both great to deal with so i would look into what they have to offer. I think having two of the PRED750's (from Abatement Technologies) or two of the Novair 700's (from Novatek) would be ideal for an average size shop. I don't have any affiliation with the mentioned companies, and there are more to choose from, I would encourage everyone to do their own research on the matter. It might even be better to call up a local asbestos abatement company to see what products they are using and there might be a company closer to home where its easier to get replacement filters.

  14. #44
    Join Date
    Feb 2017
    Northern Illinois
    I have never believed that there is a single answer to dust collection in the shop and, for many years, have used the following combination:

    1. An Oneida cyclone for at source collection for my tablesaw, planer, jointer, bandsaw, router table and, most recently via a hood, my lathe (For the past 2 years it's been a cyclone with a HEPA filter.);
    2. A HEPA filter vac for small power tools like sanders, handheld routers, sometimes the drill press;
    3. A ceiling hung air cleaner which is on the entire time I'm in the shop and usually for at least 30 minutes after I leave the shop;
    4. A powered dust mask which I wear when I am working for extended periods.

    Since I upgraded my cyclone to an Oneida HEPA V Series, I do sometimes leave that running for awhile after using the tablesaw or bandsaw or router table and let it circulate air via the opened gate for my lathe hood. That cleans most of remaining dust out of the air quickly and the air cleaner can handle the rest.

    I have read the articles indicating that air cleaners don't really improve air quality. I'm not convinced. At any rate, they certainly do remove dust from the air because there is very little settled on any flat surface in the shop. I have always thought that alone is an improvement because there is very little dust to be stirred up into the air when walking or using benches or tables.

    I don't believe that any of the methods I use in and of themselves will do the job. Together, for me, it has worked.

  15. #45
    Twelve. Year. Old. Thread.

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