11/3/19 - Zoro Staff
Wet/dry vacuums are powerful, versatile tools that can help you clean anything—from your car interior to your entire workshop. Here, we’ll take a look at the factors you’ll want to consider when shopping for a wet/dry vacuum.
What is a wet/dry vacuum?
Although a wet/dry vacuum isn’t so different from any other vacuum in its basic operation, the incredible versatility of these tools means they’re commonly found in homes, offices, garages, workshops, and more. Their unique design allows them to pick up a wide range of debris in both wet and dry environments with powerful suction and without damage to the vacuum or its motor.
Essentially, wet/dry vacuums are used for tough jobs that a standard vacuum couldn’t easily handle—anything from cleaning out your car to picking up wood chips, sawdust, heavy dirt, and liquids.
Is a wet/dry vacuum different from a shop vacuum or shop-vac?
These names are generally used interchangeably, although it’s important to note that Shop-Vac™ is actually a brand of wet/dry vacuum. There are several competing brands that offer similar products without the Shop-Vac™ name.
What do I need to know about the different types of wet/dry vacuums?
When shopping for wet/dry vacuums, you’ll encounter an extremely wide range of products, which can make choosing the right one difficult or even intimidating. These vacuums may vary by everything from their size or brand to the included nozzles and accessories. Pricing also varies considerably, with some products costing less than $100 and others priced in the thousands of dollars.
However, the most important consideration is how you’ll be using the wet/dry vacuum; every other choice will flow from that decision. For example, industrial applications may require a vacuum with wheels, handles, and a much larger capacity, while certain jobs may require a HEPA rating for dealing with fine particles or hazardous materials. And while some vacuums offer the same power and filtration at lower prices, these models may be noisier and less reliable over the long term.
What sizes are available?
Wet/dry vacuums range in size from handheld models with a capacity of less than 2 gallons to industrial sump cleaners that can hold 100 gallons. In workshops and industrial applications, drum-shaped wet/dry vacuums that hold at least 14 gallons are commonly used.
What do I need to know about wet/dry vacuum motors?
Wet/dry vacuums will use one of two motor systems in their construction.
Bypass motor systems use a separate cooling fan to draw air in and cool the motor. The air drawn into the tank to create suction bypasses the electrical components of the motor, allowing a bypass system to pick up wet debris and liquid.
Flow-through systems use the same air drawn through the tank to cool the vacuum motor. Because the suction air flows through the motor, flow-through units should be used for dry debris only. Exposure to wet debris or liquid can quickly short circuit the vacuum.
Wet/dry vacuum motors can also be either single-stage or two-stage, which refers to the number of fans used.
Single-stage motors use a single impeller to create suction pressure at a fairly high air flow volume. Single-stage units are adequate for applications like workshops, home, and auto, as well as light industrial use.
Two-stage motors use two impellers to produce a significantly higher suction pressure. This higher suction pressure makes the two-stage vacuums ideal for heavy-duty and commercial maintenance applications.
What terms or measurements or specs do I need to consider when shopping for a wet/dry vacuum?
The size of a wet/dry vacuum is generally measured in gallons. The power of a wet/dry vacuum may be measured by its sealed pressure, cubic feet per minute, and/or peak horsepower. These measurements mean different things, so you may want to take all of them into consideration.
Sealed pressure (SP), sometimes listed as static pressure, is a measure of how far a vacuum motor can lift a column of water up a glass tube, as measured in inches of water column. Maximum suction pressure (also referred to as sealed water lift) is obtained at zero air flow, meaning the water column is lifted by the suction pressure with no external air flow through the hose.
Cubic feet per minute (CFM) is a measurement of the amount of air moved by the vacuum at a particular load. The actual system load is determined by the type, size, and length of the hose, as well as the accessories and filtration system used.
Peak horsepower (HP) is the maximum horsepower output of a motor, as determined in a laboratory test. Because the test is done outside of the motor’s normal operating range, this is generally not the best specification to use when comparing vacuums.
What type of filters do I need for my wet/dry vacuum?
Just like a furnace or a humidifier, a wet/dry vacuum requires a filter for optimal performance with dry debris. However, most filters will need to be removed for wet applications. Check your specific unit’s manual for confirmation.
For dry filtration, vacuums use a centrally located filter to capture dust and debris. This is the filter that comes with your vacuum, but it’s often removable.
To improve filtration, many manufacturers and aftermarket brands offer bags that can be placed inside the vacuum tank. This is called multiple-level filtration, where the bag becomes the primary filter, capturing large dust and debris, and the standard filter captures additional dust particles before the air is exhausted. The type of bag used for dry pickups can also depend on the size of the debris, from large items (such as gravel) to fine debris (such as dust).
The majority of commercial wet/dry vacuums will have standard multi-level filtration, but smaller units may offer filter bags as an option.
Also, keep in mind that while HEPA filters can be useful for capturing fine particles and dust, a standard wet/dry vacuum is not sufficient for use with lead, asbestos, or other hazardous materials. For these applications, a HEPA rated vacuum is necessary.
A wet/dry vacuum with a HEPA filter type
What about nozzles? What other features and accessories are available?
Many wet/dry vacuums are sold with interchangeable nozzles targeted at specific functions, such as picking up liquids or cleaning out car interiors; some wet/dry vacuums also include caddies designed to hold these accessories on the vacuum body. Specially designed nozzles for other purposes are also sold separately.
Many larger wet/dry vacuums also have built-in casters that allow you to wheel them from space to space. Others may be equipped with handles that make it easier to transport the vacuums around your shop, especially when you’re moving up and down staircases. Wet/dry vacuums can also be very noisy, and for some models, mufflers are available as an additional accessory.
Wet/dry vacuums can hold up in conditions and environments that would be far too tough on a traditional vacuum cleaner, which makes them extremely useful in the workplace and even at home. Once you’re ready to shop around, don’t forget to check out Zoro’s excellent selection of wet/dry and shop vacuums. You’ll also find a wide variety of vacuum filters, vacuum bags, and vacuum accessories.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.