Pros: inexpensive, portable, major brand support
Cons: No HEPA filter, small capacity, need a screw driver to change filters
The amateur woodworker is often confronted with, but frequently ignores, two significant environmental contaminants: (1) fumes and gaseous by-products from the application of oil or cyano based finishes (shellac, cyanoacetate, "varnish", polyurethane), and (2) airborne particulates, typically from saw dust.
The first contaminant (fumes and vaporized oil-based or cyano finishes) can pose a profound health risk for the woodworker and his or her family, particularly if the finishing area is in a basement or enclosed workshop that shares airflow with the household. Moreover, the fumes generated by the application of oil-based or cyano finishes are highly flammable and, if allowed to accumulate, can be detonated by the spark caused by operation of an electric motor, including a house fan used to vent the space. These risks are even greater if the finish is applied with a spray gun that atomizes the material being applied. Many of us who live in the north (I live in Minnesota) have little alternative but to apply finishes indoors during the winter months, since it is too difficult or expensive to maintain an adequate temperature in a garage or outdoor workshop. Further, many outdoor or garage shops, unless equipped with a dust-free spray booth that is properly vented with a dedicated spray-booth fan, will have enough dust circulating in the atmosphere that the resulting finish will be imperfect, especially if one is trying to apply a high-gloss finish. This form of air contamination, and ventilation systems and air cleaners used to treat it, is typically the subject of local building code and fire regulations, particularly as they relate to multiple family dwellings.
The second contaminant (airborne particulates), also poses a significant, though seemingly less immediate, threat to health and safety. Like the first category of contaminants, local building and fire codes routinely contain extensive ventilation requirements (apart from requirements for dust collection by vacuums, etc.) for wood shops located in multiple family dwellings. This is due to concerns about the health effects of long term exposure to airborne wood dust and its combustibility. In addition to these problems, dust generated in a basement wood shop can be a real mess, spreading quickly throughout a house, especially those equipped with forced air heat or central air conditioning. I was recently alerted to the health problems resulting from dust exposure by a local wood-floor refinisher who does not smoke but suffers from debilitating emphysema. He has worked for years behind a floor sander, typically with a dust mask. Nevertheless, the steady accumulation of wood dust has ruined his lungs. His experience illustrates the long term risk to ones health from the particulates generated by wood work.
Like many amateur woodworkers, I have an indoor wood shop. Although I routinely use a vacuum dust collector on all of my power tools, I was nevertheless finally persuaded to take this air quality issue seriously by the phlegmatic floor refinisher and my wife. The Shop Vac air cleaner reviewed here, and all other similar air cleaners (Jet, etc) are only intended to deal with the second type of contaminants (particulates), and are not intended (or even recommended) for the filtration of fumes and other by-products of staining or varnishing.
After researching several larger air cleaners, (particularly the Jet AFS 1000B and a JDS model) I decided to purchase the ShopVac portable air cleaner. It is advertised as a two stage air cleaner that will recycle the air in a 17 x 17 area room 10 times per hour, at a rate of 235 cfm. Since my indoor, winter shop is relatively small (about 17 x 12), I hoped this would be adequate for my space and dust requirements. The ShopVac is also relatively light weight (15 lbs) and portable. It is clearly not in the same league as the Jet of JDS air cleaners, and lacks many of the features and capacity of those machines. Nevertheless, for a smaller area it is reasonably adequate.
The ShopVac is advertised as a two stage air cleaner. That is true, in the sense that it has two filter elements, although some may argue it really only has a single filtering mechanism, and is therefore a single filter cleaner. The first stage air cleaner is a cylindrical foam tube, similar to that used for wet vacuuming on other Shop Vac products. The second stage air cleaner, over which the foam filter is placed, is a cylindrical, pleated filter with rubber gaskets at the top and bottom. Again, this filter is essentially the same (although about four inches longer) than the filters shipped on other Shop Vac vacuums. The filter materials supplied by Shop Vac trap (according to the manufacturer) particles as small as 5 microns. No other filter media is available at this time, so far as I am aware. This is not as efficient as a HEPA. To qualify as a HEPA filter under regulations promulgated by the Dept of Energy, the filter media must remove 99.97% of particles 0.3 microns in size. Other air cleaners, such as the JET, remove smaller particles, but are not otherwise HEPA filters because their overall efficiency does not meet this standard. The JET and JDS air cleaners both have electrostatically charged filter elements that are unavailable for the Shop Vac.
The Jet, JDS and other air cleaners utilize a more efficient turbine fan to move the air through the filter and have multiple speed settings, and (depending on the model) timers and remote controls. They also have an air flow that is (at maximum speed) about three times greater. The Shop Vac moves the air through the filter media with a fan blade, and operates at only one speed. In general, the Shop Vac filters are relatively secure and do not permit unfiltered air to pass through the air chamber. Over a period of about one month of regular use, I have not observed any indication of significant blow by, as would be suggested by dust streaks on the exhaust side.
The principal advantage of the Shop Vac is its portability. The Jet and JDS air cleaners are considerably heavier and, although they can be floor or table mounted, are really intended to be permanently mounted on one location. The Shop Vac, although relatively large (about 2 feet long and one foot in diameter), can easily be moved to the source of the dust, and set on a floor or table. It is also handy when working on sheet rock or other projects in other rooms of our house, where I can set it near my work area. The unit can also be hung from a ceiling. Although some pictures of the Shop Vac show it with a pull chain, mine is equipped only with a rocker switch. I simply suspended the unit upside down. Since my ceiling is only 8 feet, it is within easy reach (for this six footer).
One annoying feature of the Shop Vac is the need to use a phillips screw driver to remove two screws from the filter grate to inspect or remove the filters. Given Shop Vacs tendency to enclose all of their other products with snap fittings, this is a bit of a surprise. Nevertheless,
considering its relatively cheap price, the Shop Vac is a reasonable air cleaner for a small shop. For larger shops, or those with heavier filtering needs, look at the Jet, and read Gamblin_mans review of the same.