Cyclone and Dust Collection Research

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Doc's Orders

  1. Foreword

    This information will make the most sense if you start by reading the Introduction then the Dust Collection Basics page followed by the Medical Risks pages then this Doctor's Orders page.

    My respiratory doctor is considered one of the top people in his field. In addition to his private practice he teaches medicine for the University of California and is a very talented long time fine woodworker. He is the one that pushed me into putting up these pages that became a clearing house for dust collection information. He said he knew quite a few things that would help with the fine dust problem, but left the biggest issue up to me which was how to collect the fine dust as it is made then get rid of this dust. Unless we have good collection and vent the dust away outside, all the other dust collection efforts are not going to be very effective. Over the years he has enhanced his original suggestions plus approved options that other small shop workers suggested. Although countless others, especially my medical air quality inspector added considerable advice, I still call this web page "Doc's Orders" because he laid out most of this information.

  2. Woodworking Environment

    My respiratory doctor used to tell his woodworker patients to always wear a good fine filtered mask and run a large exhaust fan blowing out a side door or window with the main door open a little to clear out the dust. After working with me on this dust collection site and seeing lots of test results he upgraded his recommendations.

    He now tells his patients, meaning those that have already developed respiratory problems, that the only safe way for those who already have problems is to thoroughly cleanup their homes and shops, then capture the fine dust as it is made, then immediately get rid of it so it never gets into our shop air! When we cannot keep from spraying the fine dust into our woodworking environment, he wants his patients to work outside with our masks on.

    For those without problems he has recently changed his recommendation. He now recommends that his patients start by borrowing, renting, or buying a good fine particle meter. The unhealthiest fine dust is invisible without magnification and the only real way to know if we have a problem and how bad it is requires being able to measure. A good particle meter is very inexpensive compared to the loss of our health, hospitalization, or the medications and equipment needed to treat serious respiratory problems. For these reasons he now recommends those with problems start with a way to measure their problems and how well their efforts work to address their problem. He now strongly recommends buying an inexpensive laser particle counter such as the Dylos Products Pro particle counter shown. You can buy one at a discount from Amazon using the link on the right or if you buy directly from Dylos Products please let them know I referred you. For cleanup he recommends that you also start with a thorough cleanup of your home and shop. From then on when making more dust always wear a good NIOSH approved dual cartridge respirator mask while running a strong exhaust fan blowing out a side or back door with the main door open a little for makeup air. Makeup air will also prevent deadly carbon monoxide from getting sucked backward through your flues and vents for your fired stoves, appliances, and heaters. He now says, your mask and strong fan must go on before we start making dust. Our particle counters show both the mask and fan need to stay on for one half hour after we stop making fine dust.

  3. Cleanup

    My doctor recommended that all small shop workers regularly cleanup their shops and their homes if their homes are attached to their shops. For those like me who are already sensitized he recommends having someone else cleanup your shop and home. He said even with a good mask, the cleanup so covers us and out clothing, that it is near impossible to do a good cleanup without getting heavily exposed.

    air cleaner Back in 2000 when I was faced with having to clean up my shop and home to deal with the bad allergy problem that came on so quickly, all had to operate blind. Based on experience my respiratory doctor strongly suspected my problems were caused because my home had become badly contaminated, so I was constantly exposed to the same dust that triggered my allergic reactions. I paid a small fortune to have professional air quality testing which verified my doctor's suspicions. That inspired me to pay for a very costly cleanup, but even with that effort, my health was not getting better. I bought an expensive air quality meter that showed our best efforts were not working. I decided the problem was bad air so bought ever larger and more expensive air cleaners, but the meter showed most barely kept a small area around the cleaner clean. I built my own much more powerful large HEPA filtered Air Cleaner. My particle counter showed it failed to amply stir the air until I added a fitting that let me direct a strong stream of cleaned air throughout my pretty open space home. The particle counter then showed my home air stayed excellent if I intermittently ran that air cleaner for a total of about four or five hours a day. More importantly, my health began to rapidly improve.

    Dylos Pro 0.5-micron So now my respiratory doctor strongly recommends not only the same cleanup, but first starting with building one of these air cleaners like I share on my Projects page. He says the air cleaner is vital to have relief while the clean up effort is being done, and the particle counter is vital to know how much and how often to run our air cleaner and to help us find problem areas that need cleaned up. Without a particle counter all you can do is guess. It is far better to be able to see exactly what is going on.

    Shops - To clean our shops my doctor recommends waiting for a breezy day then put on a mask, seal off any house access doors, open all doors and windows, run a big exhaust fan blowing out the side or back working with the wind direction and then thoroughly blow out your shop with an air compressor, leaf blower or strong vacuum on blow. He said to go over and over things until seeing no more dust. After the shop is blown out he said to leave all open and let the big exhaust fan run for at least a half hour. (He originally said four hours but our particle meters show a half hour of strongly venting is enough for almost all shops to get back to normal outdoor air quality). After that fan clears the airborne dust, close all down and let any remaining dust settle for at least a day. Then do it all over again. We carefully tested a few shops with a particle counter and found that two full cleanouts is ample to clear most shops back to ambient air quality, meaning outside air quality.

    Homes - The home cleanup was a pain that required redoing all multiple times. He said to cleanup your home all home floors, ceilings and carpets need washed or vacuumed, all upholstery and drapes need cleaned, and all walls, ceilings, cabinets, closets, and contents need well dusted using a HEPA filtered vacuum or wiped with damp cloths. As my respiratory doctor recommended all in my home was thoroughly dusted. We vacuumed all the walls, cabinets and drawers. All floors were vacuumed and damp mopped. All carpets and drapes were deep cleaned professionally. Even after doing all his suggested cleanup, my particle meter still showed my home rapidly returned to terrible air quality even when I used a really good air cleaner. My doctor suspected the biggest problem was my carpets because it is near impossible to keep contaminated carpets from launching stored fine dust. I replaced almost all of the flooring with tile and that made a huge difference, but my sensitive particle counter showed almost any activity still filled my home air with another round of fine dust. I ended up repainting the entire home inside. Even then my meter still showed problems and I had to repeat HEPA vacuum all my drawers, cupboards, and closets. The problems persisted and we discovered my attic which shares open air with my garage based shop was badly contaminated. I removed and replaced the insulation and HEPA vacuumed it as well, but we still had problems. With continued problems I began wandering the home with my meter looking for problems. It turned out my huge big book collection was a major source of contamination so it had to let it go. I then discovered our ceiling was badly contaminated so I got it repainted. We still had fine dust all over everything, so had to do another whole round of HEPA vacuuming of all before the particle counts started staying down. Throughout all this we had to run my fine air cleaner every day at least three to five hours a day. The good news is the air cleaner pulled the dust down enough that my health which was stuck not improving rapidly improved.

  4. Respirators and Masks
    1. Dust Mask

      My respiratory doctor says every woodworker needs to properly protect themselves from fine dust. Woodworking makes a huge amount of fine dust compared to how little it takes to harm our health and because fine invisible dust lasts nearly forever unless it gets wet, most small shops that vent their dust collection systems inside have such a buildup of fine invisible unhealthy dust that just walking around stirs enough airborne to fail air quality tests without doing any additional woodworking. The best way to protect ourselves from the dust we are making and the fugitive dust we previously made is to own, use and properly maintain a good respirator often called a mask. He says we need to use a good quality fitted respirator mask that meets the NIOSH safety standards. It should have a good silicon-rubber airtight fit with two changeable cartridge filters. Organic cartridges should be readily available to also protect against the various solvents, fiberglass resins, epoxies, and other chemicals we use while doing woodworking. Unless we have thoroughly cleared our shops of the fugitive dust, our mask needs to go on as soon as we enter our shops and should not come off until our shops are properly cleared out. The best way to keep from building unhealthy levels of fugitive fine invisible dust is to use a strong fan blowing out an open side door or window with a large main door open about 5" across the shop to get good flow through ventilation. It takes a large fan about a half hour to clear a normal two-car garage sized shop, so our fan and mask need to stay on during that half hour. If we don't clear our shop, then we need to put on our mask as soon as we enter our shops.

      Respirator masks and supplies are available in almost every large hardware or automotive paint store, but most work poorly. My doctor recommends strongly against use of the less expensive readily available disposable paper masks and the inexpensive cartridge or pad filtered masks because even with good filtering, they leak badly exposing us to far too much fine dust. If you see dust trails on your face after wearing your mask you are either using the wrong type of mask or an improperly sized and fit mask. Both my doctor and I tried many different masks then settled on using the exact same units years before we met. In my case I admit bias from over 4,000 hours of flying with a good fitting comfortable oxygen mask. Most masks I tried fit miserably, were uncomfortable and leaked badly. I do woodworking as a hobby to relax. Wearing an uncomfortable mask was anything but relaxing, so I bought a top quality 3M 6000 series respirator mask then upgraded to newer and better 3M 7500 respirator masks as pictured on the left. Mine were fit to me professionally at a paint shop. I bought my 3M 7500 series mask with a dozen R6001 organic filters, P-series particulate filters, and box of cleaning pads. You can click on the picture here to go to to buy that same set. If you buy a small contribution will be made to my web pages. There is a wealth of information on masks, testing for leaks, choices of filters, filter life, etc. If you want more information click here for a Google Search on "dust mask" for an overwhelming amount of good information.

    2. Powered Respirator

      After my initial allergic reaction my doctor told me that if I wanted to continue woodworking, I would always have to work in my respirator mask. Although my 3M was a good mask and fairly comfortable, it was miserable to wear on hot days, plus it provided no eye protection so my eyes became badly swollen from my allergic reactions any time I did turning even when wearing safety glasses or face shield. Following additional respiratory problems with repeated bouts of pneumonia, in 2006 my doctor gave me a choice of permanently giving up woodworking or always using a powered respirator mask like the shown 3M Airstream PAPR here. A Powered Air Purifying Respirator (PAPR) uses a blower to pull air through a course then fine filter then blow it into a covered face area so we have clean filtered air to breathe. I did a lot of homework and talked to many woodworkers who have long used the different powered respirator masks. Most wood turners including my doctor like the older Racal PAPR. 3M bought Racal long ago but continues to sell supplies, so my doctor said he will keep using his Racal as long as he can, but when it needs replaced he will buy the 3M PAPR shown. 3M made their own PAPR that is near identical to the Racal and is now the favorite of most serious wood turners.

      I was not at all excited about the high cost for upgrading to a 3M PAPR, so I did all pretty much wrong. My research showed the Triton PAPR mask is the most frequently purchased by woodworkers, and the one my local woodshop experts recommended. At less than half the price of the 3M my doctor recommended I bought their full system with extra filters, face shields, shield protectors, spare battery pack, on and on. With my sensitivity to wood dust I am the best meter around and the first time I used that mask I immediately had an allergic reaction. It clearly did not provide ample protection. I initially thought it was just too underpowered so dusty air was leaking in around my beard. Groaning over the additional cost and under time constraints to get some gifts done, I bought the only other PAPR immediately available locally, a Trend Air Shield PAPR. It had the same problems as the Triton meaning the first time I used it, I had another allergic reaction due to poor protection. I called my doctor friend. He said I should learn to either listen to him or at least carefully read the product literature. Detailed reading of the product literature disclosed both of these PAPR units came with filters that freely passed the under 5-micron sized particles. With almost no protection from the finest dust that explained why my allergic reactions. Further research showed almost every available woodworking powered respirator has terrible filters that freely pass the unhealthiest 5-micron and smaller particles. The problem is it takes a much stronger blower which needs a far more expensive and larger battery pack to push the air through the fine NIOSH approved filters that operate at HEPA levels (99.99% effective down to 0.5-microns). We might as not even bother to wear one of these typical powered masks except they get rid of the larger nuisance dust particles.

      My needs differed from most wood turners because I have a full beard and too many metal working toys including different welders, so I needed more than normal protections. The higher end 3M PAPR could be purchased with a different face mask that allows using it for welding plus it had an optional secondary belt type filter system that let this mask be powered by a clean air compressor rather than having to put up with the battery packs. Unfortunately, the cost setup as I wanted was too expensive. Likewise, the less costly 3M that my doctor recommended no longer made sense either because repeated bouts of pneumonia moved my doctor to instead recommend that I totally give up woodworking. As a very stubborn person with three generations of tools, that was not the answer I wanted, so I went to work trying to find a more affordable solution. I finally stumbled on a dealer who was closing out his new but old stock Racal inventory on eBay and put in a bid for the works. While waiting for the results of that bid, I came across another interesting eBay deal for one of the very expensive 3M PAPR masks with welding, woodworking and spray painting face shields, plus both the air compressor and belt fan options. I put in ridiculously low bids on each and won both auctions and both turned out to be my size. I got lucky all the way around with a full Racal setup and full 3M PAPR woodworking, painting and welding setup. All were brand new in unopened packages with all the goodies including extra filters and very dead battery packs. I took those dead battery packs to my local Batteries Plus outlet store who upgraded to high end Ni-MiH cells that last far longer but did require a different charger. I now use the Racal for wood turning because it is lighter and has better visibility. I really like my 3M welder mask as pictured as it works great and came with both the 3M belt pack plus the compressor setup. You can click on these mask pictures if you want one, but be prepared for some serious sticker shock.

      So enough of my bragging, what would I recommend to somebody today? I like and mostly use my 3M 7500 series non-powered mask pictured above with dual cartridge filters, pre-filters, and organic vapor cartridges. If you are a turner or are sensitive to dust then you should seriously consider the 3M Powered Air Purifying Respirator (PAPR) with face shield which are expensive but worth the cost. I continue to hear many recommend the latest versions of the same two PAPR masks I tried, but my most recent visit to the woodworking store showed even their newer units still came with the far too open filters.

    3. Dust Mask Fitting

      Wearing a dust mask that leaks is near useless, so we have to make sure our mask is properly fit to our faces. The better brand respirator masks such as the 3M 7500 units referenced above come in small, medium, large, and extra large. I was surprised when in spite of my being a pretty big guy, I needed either a small or medium sized mask. It all has to do with the width and curves on our faces. I was fortunate enough to be professional fit by our safety officer at the university where I taught, plus also fit by the Air Force where I flew for many years. Most professional paint shop suppliers can fit you with a mask as can safety officers, but you can also do a good job of fitting yourself. The secret is to make sure you don't have to pull the mask too tight to avoid air leaks, plus having a clean shaven beard. My 3M respirator manual does share how to make sure it fits and is properly adjusted. Cover the intake ports and inhale slightly. The mask should pull in and not leak. Likewise, if you cover the exhaust and exhale slightly it also should inflate a bit and not leak. This self test will let you know if your mask fits and works but is not as good as using the 3M fit tester. There are numerous hints on mask fitting on the Internet, but I think one of the better discussions and videos including fit tester information is the 3M Dust Mask Fitting Video.

    4. Dust Mask Care

      Whether we own a dust mask or powered respirator we must regularly wipe them out with a non-alcohol pad to keep them clean. We also must change the cartridge filters when needed. Activated charcoal filters and many other types of mask filters lose effectiveness when exposed to air whether we are wearing them or not, so my doctor recommends storing our masks in a Ziploc airtight bag. When he puts his mask in its bag he sucks most of the air out to maximize filter life.

  5. Dust Fan

    My respiratory doctor said even when working outside, whenever I made fine dust that was not being immediately captured I needed to use a fan. He recommended using a good heavy duty stand mounted oscillating fan with the oscillation feature turned off. This fan must be set to blow the dust away from me as I worked to keep me from breathing it and to help keep my clothing clean. My respiratory doctor also recommended I use this good sized fan in the back doorway of my shop with the garage door open a little whenever making fine dust to keep that dust from building in my shop. I have to sometimes make the fan in the doorway blow outward and other times blow in depending upon the local wind direction. In the few instances where I mess up and fill my shop with fine dust he recommended I use that fan on high with all doors open wide while also running my air cleaner and cyclone with fine filters, then after all settles vacuum all with my HEPA filtered vacuum.

  6. Exhaust Fan

    A few of my friends also recommend using in every shop that is attached to our homes an exhaust fan wired to turn on whenever we turn on the lights. If we have all doors and windows closed and run that exhaust fan to the outside it will create a negative pressure. This fan does not have to exhaust any air. A small bathroom exhaust fan creates enough negative pressure to keep a blast of dust filled air from contaminating our homes when we open a connecting door between our shop and home.

  7. Exhausting Outside

    My respiratory doctor says ideally we would all do just like commercial shops and just blow the finest dust away outside. Although most small shop woodworkers should exhaust their shop air outside, most do not. Venting indoors even with fine filters is bad news. Woodworking just makes far too much fine dust. Every twenty pounds of sawdust that we create contains enough fine dust to cause over 15,000 two-car garage sized shops to fail their EPA air quality test. Most dust collectors miss collecting 40% or more of the fine airborne dust. If we just miss collecting 1% of the fine dust each twenty pounds of sawdust adds another one hundred and fifty times more fine dust than it takes for a typical two-car garage sized shop to fail an EPA air quality test. Because this dust does not go away unless it gets wet and breaks down, most shops that vent inside rapidly build dangerously large amounts of fine dust. Venting inside also increases our fire risks as most dust collectors and even cyclones come with collection bins that are not fire proof.

    My doctor said there are many bad excuses to not vent outdoors, the main one being that it is easier. Most wrongly claim that they cannot vent outside because it costs too much to heat their shops. My surgeon friend lives in Canada where minus twenty is not unusual. He says he vents outside and stays comfortable with a pair of IR heat dishes even in the coldest weather.

    The only valid reasons to not vent outside is venting outside is not permitted or you air condition. If you vent inside then he recommends you should setup your shop with really good fine dust collection or only work in your mask, then thoroughly clean out your shop before you take that mask off.

    1. In some areas like mine venting outside is illegal. Although this is what I heard from my County building inspector's office, it turns out that it is illegal only if I have a large commercial firm with many employees, so is not enforced for small and home based shops. This is one of those things that upset me considerably because I tried to do all right, got bad advice and spent a lot of time and money to avoid venting outside then found I could and should have vented outside.

    2. The noise can upset neighbors. Adding a little sound proofing either around our dust collection equipment or storage shed, plus using a good muffler, homemade or commercial will address most of the noise issue.

    3. Too many small shop owners foolishly worry about blowing the heated air out of their shops when commercial firms have shown that doing so really is not as expensive as trying to filter the air. Large commercial shops with huge blowers that turn over the entire air volume many times every hour have known for years a good infrared heater will leave us feeling little discomfort unless it is below freezing outside.

    4. Our small shop dust collectors and cyclones are built for indoor use. Repair is as easy as providing their own shed or covering to place our dust collectors and cyclones outside. Many simply choose to keep their cyclones inside and vent outside.

    5. Also, a good many of the woods used in woodworking today can kill our landscaping plants, and can harm our pets and children when they play outside. Repair is fairly simple, use a cyclone separator to remove the heavier sawdust and chips. The remaining fine dust will dissipate in the outdoor air without causing problems.

    6. Finally, Unless we provide a way for makeup air to enter our shop, blowing the air outside can suck deadly carbon monoxide backward through our fired appliance vents such as water heaters, stoves, and gas driers. Most need to just open a door or window and they the risks of pulling the carbon monoxide out of our fired appliances vanishes.

  8. Carbon Monoxide Monitor

    My respiratory doctor and many safety organizations warn our dust fans, exhaust fans, dust collectors, and cyclones can pull deadly carbon monoxide backward through the vents from our gas water heaters, heaters, fireplaces, furnaces, stoves, and other fired appliances. My carbon monoxide detector showed my shop exhaust fan and dust collection blower both pulled carbon monoxide from my attached home furnace and gas water heater. Carbon monoxide kills and hurts more people than any other kind of poisoning. My doctor strongly recommends every small shop woodworker install good quality carbon monoxide detectors in their home and shop to immediately know if we have a problem.

  9. Air Filtering

    My respiratory doctor recommends we buy filters with enough surface area and ample fine filtering. Unfortunately, most small shop filters provided with dust collectors, cyclones, air cleaners, and even shop vacuums are too open so pass most of the unhealthiest invisible dust plus have too little surface area so clog constantly requiring frequent cleaning and quickly wear out. Moreover, our testing showed that most air cleaners fail to stir the air very well, so they just keep cleaning the same bit of air over and over needing a very long time to fully clear our shop air.

    1. Shop Vacuum Filter Upgrade

      My respiratory doctor said to immediately change my vacuum filter from their paper and cloth bags to HEPA air filters. Luckily both of my vacuums are name brand units for which good quality HEPA fine filters are readily available. Early on the cost of one of these fine filters for a shop vacuum came close to the cost for a smaller vacuum. Now that there is far more interest, prices have fallen far below the somewhat painful $30 each I had to pay.

    2. Dust Collector & Cyclones

      My respiratory doctor remains pretty strongly against upgrading to finer filters on our dust collectors and cyclones because even fine filters work poorly. The medical air quality testing he has seen show regardless of vendor advertising claims almost all small shop cyclone and dust collector fine bag and cartridge filters freely pass the finest unhealthiest dust. This at best creates a false sense of security because these so called fine filters get rid of the visible dust while allowing the finest unhealthiest invisible dust to just keep building. He instead recommends venting these units outside into standard open 30-micron filters and letting the fine dust blow away into the outside air. He said venting outside also helps get rid of the fugitive dust that escapes collection from these too open filters, dust collectors and cyclones that move too little air for good fine dust collection and tool hoods that allow the fine dust to spray all over.

      I thought I could do air filtering by just letting my cyclone or dust collector run as both had upgraded commercial finer filters. An air engineer friend said that AAF had done extensive testing and found both dust collectors and cyclones make poor air cleaners and their use as air cleaners can be expensive. An air cleaner stirs the whole volume of air in a room. Without that stirring, much of the fine dust will be missed. Unless you setup the air coming out of your filters to blow in a wide stream at close to ceiling height, the air simply creates a narrow racetrack between the open gate and your filters without doing a good job of cleaning the rest of the air. Moreover, a good air cleaner uses a small motor. Running the huge blower motor for the roughly four hours it would take to clean my shop air could create some costly electric bills.

    3. Air Cleaner

      My respiratory doctor says he likes and regularly uses his air cleaner but does not rely on it for anything except keeping his finishes from being spoiled with dust contamination. He explained that it takes a typical small shop air cleaner four to six hours to clear the larger airborne dust particles, but most of these come with such open filters they never really do clear the finest unhealthiest dust. He also recommends against trying to upgrade these units with finer filters as most don't have the air pressure to work against the finer filters as these filters become dirty. Plus upgrading to finer filters makes for a constant cleaning chore and cleaning quickly wears out the fine filters.

      He said the magazines rated Jet, Delta, JDS, and Penn State all pretty close, but he bought a Jet for himself because he likes Jet tools. In looking at many woodworker posts and some magazine reviews, it appears that he did pick one of the best. He now says we either capture the fine dust at the source as it is made or work outside.

  10. Downdraft Table

    My respiratory doctor next told me to go buy or build a good quality down draft table and always use it when sanding. I looked at him kind of funny because he has been bugging me for years for a set of plans for the down draft table I built ages ago. We both have long known that there are no good affordable hobbyist downdraft tables. I teased him back saying he was the one who made the big bucks. After looking suitably hurt, he smiled and said if I built another, he could have my old downdraft table and I would get a new one. The projects area of my index gives directions on how to size and build your own downdraft table.

  11. Portable Hood

    Years after putting up these web pages my respiratory doctor now recommends every woodworker have and use a good portable hood connected to our dust collector. Too many large tools, smaller power tools, and even hand operations generate lots of fine dust. Often even a downdraft table is not enough to provide good fine dust collection unless we also use a portable dust collection hood placed right next to the dust source. He recommends buying or building a stand that supports this hood and permits positioning it right next to our woodworking operations. I found having both a stand and gluing a few powerful rare earth neodymium magnets to my hood lets me cover almost any need firmly holding the hood right where it is needed without slipping.

  12. Clothing

    My doctor also reminded me to not only wear my apron, but also when making fine dust to wear a cap, light jump suit, and bandanna that I take off before going into my home. This keeps the fine dust from being tracked all over. He also recommends wearing wear gloves and good skin protective clothing when working with the more toxic woods.

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Copyright 2000-2015, by William F. Pentz. All rights reserved.