All of the major brand name dust collector and cyclone vendors remain caught in a nasty game of their own making. To appear better than their competitors each badly exaggerates their advertized airflow, filtering and separation. Plus these vendors fail to spend the tiny amounts needed to ensure the workability of their dust collection products. Sadly, our testing badly upset the small shop vendors.
We found only the Jet and Powermatic brands actually advertised airflows that we could get during our testing. All others advertised airflows that were far larger than we could get during testing. A few of the lesser quality imports exaggerated their airflows by as much as 100%.
We found all small shop vendors provide misleading airflow advertising. Almost all small shop vendors advertise maximum airflow which moves enough air for good fine dust collection. Maximum airflow only happens when we have no ducting, no filter or a brand new clean very open filter, and a special test pipe. This means that the advertised maximum airflows are just over double what we get in real use when our systems have to overcome the normal resistance from our hoods, ducting, separators, and filters.
The few firms that share airflow curves falsify their system performance through testing tricks which they convinced magazine editors to continue. Most of the magazine tests measure airflow with no ducting, no filter or a brand new clean very open filter, a special test pipe and oversized ducting much larger than we would use. These changes minimize resistance so the vendors can advertise higher airflow numbers. I reviewed one magazine test and helped conduct another. It sickened me to find that the winning dust collector vendor used an oversized impeller that will make their dust collector burn up if a hose gets knocked loose. With a standard test pipe this winning dust collector overheated and burned up its motor in about twelve minutes of operation. No collectors burned up during that test because it normally only takes about three minutes to do the air volume tests on a dust collector. Likewise, the top rated cyclone vendor demanded that we test their two, three and five hp cyclones with a significantly oversized test pipes. We found all of their motors rapidly overheated from pulling far more than their rated amps and three of their supplied cyclones burned up because these tests take longer to run. When we stopped our testing because the motors reached their maximum rated amperage, all previously top rated dust collector and cyclone vendors except Jet and Powermatic (both part of WMH Tools) lost their top ranking status. In short, running the top rated dust collectors and cyclones at their advertised airflows causes those motors to burn up within minutes.
In spite of the exaggerations, citing maximum airflows and testing tricks all major brand name small shop dust collectors and cyclones sized over 1.5 hp provided the 350 cubic feet per minute (CFM) needed for good chip collection but no dust collector under 3 hp or cyclone under 3.5 hp provided the 1000 CFM airflow that our vendors who guarantee air quality established that we need for good fine dust collection.
Likewise, our small shop vendors consistently advertise improper filtering levels. The American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) set the U.S. standards for indoor filters. As a filter gets used particles get trapped in the filter material that do not come out with normal automated cleaning. This is called seasoning. These particles build until a filter gets saturated and will take in no more particles. Manufactures call this a fully seasoned filter. A fully seasoned filter provides about twenty times better fine filtering than a clean new filter. Because it can take months to years for a filter to fully season, to amply protect our health ASHRAE requires that all filters for indoor use get rated when clean and new. Filter material makers share this clean new filtering level so engineers can comply with the ASHRAE standard for indoor air quality. Filter makers also provide the airflow and filtering levels for fully seasoned filters so air engineers can properly size outdoor filters.
Our small shop vendors claim that shops and garages represent outdoor rather than indoor use so advertise outdoor filtering levels, yet deliver equipment that can only be used in covered indoor areas. This combination makes for dangerously high indoor counts of the unhealthiest invisible particles freely passed by the more open filters even in clean looking shops.
Almost all small shop vendors sell much smaller filters than filter makers recommend which depends upon airflow and dust loading. This results in our filters constantly needing cleaning which kills our needed airflow and over cleaning quickly ruins fine filters. The typical small shop dust collector or cyclone vendor generally provides about one square foot of filter material for every ten cubic feet per minute (CFM) of airflow. This is the normal for a 30-micron filter that lets the airborne dust blow away outdoors. Sadly, most vendors now sell 10 and 20-micron filters that they claim as either 0.5 or 1-micron filters and size them the same. The actual sizing according to the top filter makers should be at least one square foot of 0.5 or 1-micron fine filter material for every two CFM of airflow. This means a typical 1.5 hp dust collector with a maximum airflow of 1100 CFM and real airflow of about 550 CFM needs at least 275 square feet of fine filter area if we use a real fine filter. Rather than provide this much expensive fine filter material, most small shop vendors instead provide roughly thirty square feet of far more open filter material. The more open filters appear to work just as well as they filter off the visible dust but they freely pass the invisible dust. This makes for terrible air quality but avoids the upset of customers having to constantly clean and replace fine filters.
During the one to three years it takes a small shop filter to fully season the filter freely passes the fine unhealthiest dust leaving our lungs to do the fine filtering. Although some vendors claim much faster seasoning, the truth is seasoned filters provide little health protection. Every time a seasoned filter gets hit with a blast of air from starting our blowers it sprays dangerously high amounts of fine dust into our shop air. Likewise, after every thorough cleaning these too open filters freely pass the fine unhealthiest invisible dust.
Worse, most filters contain large amounts of polymer materials that build up large amounts of static as we run air through the filters. This static charge causes lots of the fine airborne dust to build and collect on the filter exterior surface then get blown all over our shops when we turn on our dust collectors or cyclones.
In summary we did not find one single small shop dust collector or cyclone with advertised fine filter that did not freely pass through a majority of the finest invisible unhealthiest dust.
We also tested the separation ability of the various dust collectors and cyclones. As a baseline we first tested the two most popular trashcan separator lids. These trashcan separator lids work well and separate off almost all but the airborne dust. This means they captured about 85% of the dust created by weight and sent that remaining 15% airborne dust into the filters saving lots of time and trouble emptying dust bags and collection bins. When we stepped up the airflow from the 350 CFM needed for good chip collection to the 1000 CFM needed for good fine dust collection the trashcan separator lids became useless. The additional airflow scoured the cans clean of all but larger blocks and chunks.
At 350 CFM all but one small shop cyclone separated almost identically well as the trashcan separator lids. That one cyclone was so dismal that it put close to one third of the material it collected right into its filters. I had that firm identified on these pages and was quickly hit with a threat of a law suit demanding I remove that information. They did not care about how well their product works, only that nobody know how bad it works. They made no effort to improve this product and it continues to be sold exactly as was still being advertised as one of the best and most efficient. The magazine tests also found this one unit dismal and gave it their lowest possible rating without outright saying it was dismal. In defense of the magazines they do get considerable revenue from this vendor.
All other small shop cyclones except for my design separated little better than the trashcan separator lids. The only real advantage of these cyclones is at higher airflows than needed for “chip collection” all these cyclones continued to provide the same separation meaning close to 100% of the airborne dust went right into the filters. Independent medical school testing on my cyclone design found the same results as our testing. Instead of passing close to 100% of the airborne dust right through my cyclone design separates much better. It separates off over 82% of the airborne dust that other cyclones pass right through, plus it provides 99.9% separation of the unhealthiest invisible dust down to 4.7-microns. At this level of separation typical fine filters can go months instead of minutes between cleanings and these fine filters we need to amply protect our health will last years instead of the typical three months.
Unlike air from a compressor or vacuum cleaner, at typical dust collection pressures air is little more compressible than water, so just about any tiny opening, small hose, small duct, rough duct, poorly made fitting, or bad ducting design will seriously harm the airflow we need for good fine dust collection. We found every small shop vendor who offered a ducting design service used professional shop ducting designs that presume no blast gates and full time collection from all machines at the same time. Because air at typical dust collection pressures will not compress, this requires that each main and branch be sized large enough to carry all air coming from downstream. This creates very impressive graduated ducting designs which work terribly in small shops that only use one machine at a time. The oversized mains end up with too little airspeed to keep from building up piles and plugging.
The fine invisible fugitive dust we miss collecting just keeps building in shops that vent inside. Almost any airflow is enough to launch this dust airborne and keep it airborne as long as we are working.
