Pneumatic Vacuum FAQ
TECHNICAL
How do PowerQUAD™ compressed air-powered vacuums work?
Compressed air-powered vacuums (also known as pneumatic vacuums) work on the venturi principle. Compressed air, via the compressed air supply hose, enters the venturi box and travels through the injector nozzle. 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.
What are the advantages of compressed air-powered vacuums over electric vacuums?
Compressed air-powered vacuums offer a number of significant advantages over electric vacuums. These include:
- Compressed air-powered vacuums have no electric motor to wear out or burnout. Motor failure most often occurs in high demand applications where a motor is strained for long periods of time, for example when vacuuming heavy liquids or operating with a clogged filter.
- With no electric motor, sparking at the brushes is eliminated, and no electric fields are present. This is important in hazardous locations, for example when combustible fumes are present.
- Compressed air-powered vacuums require no dangerous, high voltage electric cords. Over time cords often become frayed as they are dragged across shop floors, or run over by mobile equipment, such as carts or forklift trucks. This is an important safety feature particularly on steel surfaces or where floors are wet.
- Compressed air-powered vacuums generate significantly more vacuum lift than electric vacuums. This enables them to suck up heavier materials a higher vertical distance.
- Compressed air is often more readily available than electric power in most in-plant and many remote or mobile locations.
- And finally, since compressed air-powered vacuums feature an unlimited lifespan, their Total Cost of Ownership (TCO) is often lower than equivalent electric vacuums.
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 120 inches of water can 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 to clean.
With respect to compressed air, 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 hose, during a given period of time. Flow is measured in cubic feet per minute (cfm). The electrical equivalent of flow is amperage.
How do vacuums generate static electricity?
Both electric and compressed air-powered vacuums 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, vacuum hose material, and material being vacuumed.
OPERATION AND MAINTENANCE
What size (capacity) air compressor do I need to operate my PowerQUAD™ 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. For example, a 50 HP air compressor will generate approximately 200 cfm (4 x 50) on a continuous basis. Refer to the specifications on your air compressor for more information. For a given injector nozzle set, the table below shows the minimum size air compressor required (when run continuously) to supply compressed air to the vacuum.
How do I optimize the performance of my PowerQUAD™ Vacuum?
PowerQUAD™ vacuums can be configured to maximize compressed air savings, maximize vacuum performance, or a balance between the two. PowerQUAD™ vacuums come with three (3) sets of injector nozzles, all of which provide industry leading vacuum efficiency (vacuum performance per cfm of compressed air consumed). To maximize compressed air savings, install the lowest flowing injector nozzles (Green) and then test the vacuum. If higher vacuum performance is desired, install the next higher flowing injector nozzles (Blue) and test again. To maximize vacuum performance, install highest flowing injector nozzles (Yellow) and test the vacuum.
If PowerQUAD™ vacuum performance is not as expected, the capacity of the compressed air system may not be sufficient. With the vacuum running, check the pressure gauge which should read between 80 and 90 psi. If the gauge measures lower than 80 psi, considering installing lower flowing injector nozzles. Since vacuum performance is directly related to compressed air consumption, make sure the air supply hose is delivering adequate compressed air to the vacuum for a given injector nozzle set. Refer to the PowerQUAD™ Vacuum Performance Table for compressed air consumption, vacuum performance specifications, and recommended minimum size of the compressed air supply line.
What is the recommended operating air pressure for my PowerQUAD™ vacuum?
Most in-plant air compressors operate at pressures, or are regulated to between 80-120 psi. PowerQUAD™ vacuum are engineered to offer optimal performance at 80-90 psi as read on the pressure gauge located on the rear manifold of the vacuum while the vacuum is running.
What size compressed air supply line do I need to run my PowerQUAD™ vacuum?
PowerQUAD™ vacuums require compressed air supply lines that range from 3/8" ID up to 1/2" ID depending upon the injector nozzles that have been installed within the vacuum generating head. Refer to the PowerQUAD™ Vacuum Performance Table for recommended compressed air supply line size. To ensure adequate performance, a larger 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. For optimal operation, use "High Flow" connectors.
How does the size of my compressed air receiver size in combination with my air compressor effect vacuum performance?
Receiver size can also affect the operation of the vacuum. The larger the receiver, the longer the period of time the vacuum can run without calling upon the air compressor to cycle "on" and refill the receiver.
Can I use any steel drum with my PowerQUAD™ vacuum generating head?
No. PowerQUAD™ vacuum generating heads produce extremely high head. Generating vacuum lift of up to 255 inches of H2O running on 80-90 psi of compressed air, they have been known to implode. Therefore, Guardair recommends that steel drums meet the following necessary wall thickness:
What is the maximum ambient temperature in which I can operate my PowerQUAD™ vacuum?
150˚ F
How often do I need to replace the filter and/or Silencer Foam?
Filters should be inspected regularly. Shake out and clean, or replace, clogged filters. Immediately replace ripped or torn filters. Silencer foam should also be inspected regularly and does not normally need to be replaced unless dust/dirt is getting past the filter. Shake out the foam if covered with dirt/dust and replace if necessary.
Does Guardair also offer HEPA and ULPA filters?
In addition to offering Standard filters, Guardair offers HEPA and ULPA filters for PowerQUAD™ Vacuums.
Why does my PowerQUAD™ vacuum seem to have inadequate suction?
By far the most common problem is undersized compressed air supply lines, or restrictions due to undersized fittings and/or connectors. Some combination of these two issues often results in inadequate compressed air being supplied to the vacuum. When the vacuum is operating, the pressure gage should read between 80 and 90 psi. If the pressure is lower, check for compressed air restrictions. If no restrictions are found, consider changing out the injectors. See the CHANGING INJECTOR NOZZLES section of the operating instructions. In addition, other things to look for include low plant compressed air pressure (less than 80 psi), a dirty filter, a clogged vacuum hose, or a leaky vacuum head gasket.
What is the definition of "Air Watts"?
Air Watts are a measure of a vacuum's suction power and is a function of Vacuum Flow (cfm) and Vacuum Lift (inches H2O). The higher the Air Watt rating, the better the vacuum performance. Published Air Watt ratings for PowerQUAD™ Pneumatic Vacuums also account for air resistance within filters and vacuum hose to provide an accurate measurement of their actual suction power.