Vacuum FAQ

How do Guardair compressed air-powered vacuums work?

Compressed air-powered vacuums (also known as pneumatic vacuums) work on the venturi principle. Compressed air, via the air supply hose, enters the venturi box and travels through the injector. As the air continues through the surrounding venturi, it accelerates, thereby creating low pressure inside the venturi box. This low pressure induces vacuum flow inside the adjacent canister, and in turn through the attached vacuum hose. Click here for a compressed air-powered vacuum diagram.

What are the advantages of compressed air-powered vacuums over electrical powered vacuums?

Compressed air-powered vacuums offer a number of significant advantages. First, they have no electric motor, or any moving parts for that matter. Therefore, they shine in heavy duty-cycle (on-off-on-off) applications conducive to burning out electric vacs. Second, because there is no electric motor, sparking at the brushes is eliminated, and no electric fields are present. Third, they require no dangerous, high voltage electrical cords, an important feature for wet and/or hazardous environments. Fourth, they provide significantly more vacuum lift than electric vacs. Finally, compressed air is often more readily available than electric power in some mobile, and in many in-plant locations.

What is the difference between Vacuum Flow and Vacuum Lift?

Vacuum Flow is the volume of air that passes through a vacuum hose during a given period of time. Vacuum flow is expressed in cubic feet per minute (cfm). With any given diameter vacuum hose, the higher the vacuum flow, the higher the air velocity traveling through that vacuum hose, and the more effective the vacuum unit will be at sucking up and transporting debris.

Vacuum Lift is the height that a vacuum unit can raise a given material or liquid. Vacuum lift (sometimes referred to as vacuum head) is expressed in inches of mercury (in Hg), or inches of water (in H2O). Thus a vacuum with a rating of say 120 inches of water would be able to suck up water from a tank buried 120 inches (10 feet) underground.

What is the definition of Vacuum Suction?

Vacuum suction is a non-scientific term referring to the general cleaning power of a vacuum unit. Vacuum suction is an off-hand way to describe a vacuum unit's ability to generate vacuum flow, vacuum lift, and its overall effectiveness.

With respect to compressed air used to power vacuums, what is the difference between Pressure and Flow?

Pressure is the measure of potential energy stored within compressed air. Pressure is measured in pounds per square inch (psi). The higher the pressure, the more energy is stored, and the more work can be performed. In general, most industrial compressed air systems operate at pressures between 80 and 120 psi. The electrical equivalent of pressure is voltage.

Flow is the volume of air traveling through an air supply line, or through a vacuum line, during a given period of time. Flow is measured in cubic feet per minute (cfm). The electrical equivalent of flow is amperage.

What size (capacity) air compressor do I need to operate my Guardair vacuum?

A good rule of thumb states that air compressors generate approximately 4 cubic feet per minute (cfm) of compressed air per horsepower (HP) on a continuous basis. To size a compressor in HP, divide the air requirement (cfm) of the vacuum by 4. Refer to the specification on your compressor for more information.

How does tank size effect vacuum performance?

Tank size can also effect the operation of the vacuum. The larger the tank, the longer the period of time the vacuum can run without calling upon the air compressor to cycle "on" and refill the tank.

What is the recommended operating air pressure for my Guardair vacuum?

Most in-plant air compressors operate at pressures between 80 and 120 psi. This is the air pressure range we recommend for Guardair vacuums.

What size air supply line do I need to run my Guardair vacuum?

Guardair vacuums require air supply lines that range from 3/8"ID up to 3/4"ID in size, depending upon the model. Please refer to the Guardair product catalog or website for recommended air supply line size. To ensure adequate performance, a larger size than required air supply line can always be employed, but never a smaller size.

What about connectors and fittings?

Be sure that fittings and/or connectors do not restrict the air supply flow in any manner. Use fittings that are rated the same size, or larger, for a given air supply line. Whenever recommended, use "high flow" connectors.

How often do I need to replace the filter and/or muffler?

Filters should be inspected regularly. Shake out and clean, or replace, clogged filters. Immediately replace ripped or torn filters.

Mufflers should also be inspected regularly. Mufflers do not normally need to be replaced unless dust/dirt is getting past the filter. Shake out the muffler if covered with dirt/dust and replace if necessary.

Can I use any 55 gallon drum with my Guardair vacuum generating head?

Guardair vacuum generating heads produce extremely powerful suction. Generating vacuum lift of up to 213 inches of water at 100 psi, they have been known to implode 55 gallon steel drums. Therefore, Guardair recommends that drums be constructed of 19 gauge steel or heavier.

Does Guardair offer HEPA and ULPA filters?


What is the maximum ambient temperature in which I can operate my Guardair vacuum?


How do vacuums generate static electricity?

Both electric and compressed air-powered and electric have the potential to generate static electricity. Static electricity is generated by the movement of air over the internal surface of a vacuum hose. The amount generated is a function of the composition and humidity of the air, air velocity, and the vacuum hose material.

Why doesn't my vacuum seem to have any suction?

By far the most common problem is undersized air supply lines, or restrictions due to undersized fittings and/or connectors. Some combination of these two issues will result in inadequate air being supplied to the vacuum. In addition, other things to look for include low plant air pressure (less than 80 psi), a dirty filter, a clogged vacuum hose, or a faulty vacuum head gasket.

When initially turned on, my Guardair vacuum operates fine. After a relatively short period of time, the performance begins to degrade. What's the cause?

Your air compressor probably does not have enough capacity and is undersized. Please refer to the compressed air requirements for each vacuum and the minimum recommended size air compressor.

Does Guardair offer replacement parts and/or repair kits for vacuums?

We carry replacement parts for the vast majority of our vacuums.