Buyers' Guide: Shop Vacuums
A shop vacuum is probably not your favorite tool since it involves cleaning. So if you have to tidy up your shop, why not get a vacuum that will get the job done in a hurry?
Consider a commercial-grade vacuum that is not only more powerful but also offers myriad advances such as quieter operation, better filtration systems, and undercarriages that make transporting them across floors easier. Before heading out to compare vacuums, do some Internet searching to pare down your shopping list. The market for shop vacs is huge. Shop Vac, for example, offers 37 different models.
Also, prices for commercial-grade vacuums can start at around $250 and soar to over $1,200 in short order.
Don’t shop only for horsepower
When rating vacuums, don’t get overly impressed with canister size and horsepower ratings. A canister has little to do with its performance. True, you’ll want a canister large enough (12- to 16-gallon models are common) so you don’t have to be dumping the container all the time on big cleaning jobs.
Likewise, a higher horsepower vacuum doesn’t guarantee it is a dust-sucking fiend. “High-quality commercial brands may have 1- to 2-hp. motors, but they’ll pull more vacuum, do more work, and last longer than an inexpensive brand with a much higher horsepower motor,” explains Russ Battisto of A-1 Vacuum Cleaner Company in St. Paul, Minnesota. “Many inexpensive vacuums are also built to be disposable. They use small but powerful motors with fewer windings, which have short service life and can self-destruct as a result of overheating and low-quality bearings.”
Battisto recommends buying a vacuum that has a good reputation for durability and that provides a medium to high rate of airflow and suction pressure.
Those two characteristics are key to sizing up vacuum performance. Makers of high-quality vacuums aren’t shy to reveal these statistics for their models.
CFM and suction
Vacuum airflow is expressed in cubic feet per minute (cfm). Suction pressure (sometimes called sealed pressure or water lift pressure) is listed in inches.
The two characteristics work hand-in-hand. Basically, suction picks up debris. Airflow moves it down the hose to the canister.
Airflow is a direct result of suction when the hose end is open, says Bob Hunter of Wood magazine (a sister publication to Successful Farming magazine). Wood magazine evaluators conducted an evaluation of 10 different shop vacuums.
“You can have suction without airflow, but you can never have airflow without suction,” Hunter explains.
On the other hand, suction and airflow have an inverse performance relationship when it comes to vacuum design. At a point, suction decreases as airflow increases.
An example of this is a lower-cost vacuum that boasts a high airflow of 120 cfm to 150 cfm. This is created by a high-horsepower motor that is running at a high speed. That higher airflow comes at the cost of lower suction, which, in this case, drops below 60 inches. That compromises the vacuum’s ability to pick up large debris.
Commercial-grade vacuums, on the other hand, deliver a balance of 100+ cfm airflow and 80+ inches of suction. Such vacuums are able to provide this performance balance as they employ two impellers in a series. These vacuums are identified as two-stage models.
The vacuum example mentioned before (the unit with a high airflow rate but low suction) operates with a single impeller.
Two-stage vacuums, on the other hand, can generate higher suction and cfm with less horsepower. Two-stage vacuums typically operate at lower speeds. This results in longer motor life and quieter operation when utilizing a small-horsepower motor. This explains why you should not focus on horsepower alone when buying a vacuum. Instead, inquire about how many stages a model has.
Although horsepower isn’t always indicative of performance, there is one recent motor advance that does impact the ability of some models to work harder. A few commercial-grade vacuums are now being offered with brushless motors that employ a rotor or turning member that has all metal parts and no windings or commutator.
Although more expensive, the advantages of brushless motors are numerous. For starters, they last much longer, as they have fewer components to fail. For example, a 2½-hp. vacuum with a conventional motor can have a lifetime of 400 to 600 hours; a brushless motor can run for 5,000 hours or longer.
Brushless motors also generate more performance in terms of cfm and suction pressure. Shop Vac points out that its 2½-hp., two-stage vacuum operating with a conventional motor can generate 90 inches of suction and 100 cfm. This compares with 125 inches of suction and 110 cfm for its 2½-hp. vacuum operating with a brushless switch reluctance motor.
While shopping around, you will also want to ask about the filtration system used on a shop vacuum. Higher efficiency filters have a direct impact on how much fine dust a vacuum will eject during use.
The best filtration systems employ HEPA medium. Such HEPA filters cost about three times more than disposable ones, but they last up to five times longer, points out Hunter. HEPA filters, he says, remove 99.97% of particles down to .3 microns.
However, Hunter cautions against buying filters labeled “HEPA-type” or “HEPA-style.” These do not provide the same level of air filtration.
During the shop vacuum evaluation, Wood magazine evaluators tested vacuums with dust and chips you’d expect to find in a woodworking shop. They also sucked up chalk-line chalk, because its uniform-size particles are easy to see. Evaluators were surprised to find that as dust cake built up on the filter’s pleats, filtration actually improved.
So while it’s a good idea to occasionally clean the loose dust from the filter, don’t feel the need to blow out every nook and cranny with an air compressor, Hunter says.
Various vacuums come with covers that fit over pleated filters to catch large debris. These bags can be readily removed for a fast cleanup of wood or metal chips.
Some advanced commercial vacuums offer filtration systems that clean themselves.
For example, DeWalt’s DWV012 has an automatic filter cleaning feature that pulses every 30 seconds to remove dust buildup. Bosch offers semiautomatic cleaning on demand through a remote activation button on its model VAC140A.
Another major consideration when sizing up a shop vacuum is its undercarriage.
The traditional undercarriage arrangement is four wheels. However, some vacuums place their wheels farther away from the base, providing for a wider wheel stance that is less apt to tip over. Bear in mind, most of an empty vacuum’s weight is at its top, which makes it top heavy.
A more expensive design features two small wheels out front, two large wheels at the rear, and a push handle at the top of the vacuum. This allows the vacuum to be tipped back and readily moved.