Regenerative blowers are low-pressure, high-volume blowers that generate centrifugal airflow. Regenerative blowers are capable of both pressure (or compression) and vacuum (or suction) service.  Some products are geared toward either pressure or vacuum service, while others are suitable for both.  Compression blowers are often configured for use as air supply units or compressors, while vacuum blowers are frequently used as vacuum pumps or fume exhausters.  

The construction and operation principles of a regenerative blower gives the product its name.  All regenerative blowers consist of an impeller that spins within a housing compartment.  The housing contains both an inboard (or intake) channel and an outboard channel; for this reason regenerative blowers are also known as side channel blowers.  When the impeller spins past the intake port, air is drawn in and trapped between the impeller blades.  As the impeller continues to spin, the air is pushed both inward and outward through both channels, and this process continues until the impeller stops rotating.  It is this regenerative process that allows the blower to function as both a pressure blower and a vacuum blower.  While the air trapped between two impeller blades represents only a small pressure increase, the sum total of the blades, from intake to outlet, is capable of powerful continuous operating pressures.

For the purpose of this selection guide, the blue spheres represent air molecules traveling through the blower. A regenerative blower may feature an integral OEM controller or control panel with multiple adjustment controls in addition to a simple regulator knob. Additionally, vacuum blowers may or may not include a vacuum gauge to provide a pressure readout.

Specifications

Specifications for blowers with compression service include maximum pressure and free air delivery.

Maximum pressure refers to the maximum level of air pressure generated by the compressor.  This specification is typically expressed as gauge pressure and is referenced against ambient air pressure.  Common pressure units include pounds per square inch (psi), torr, bars, pascals, or atmospheres.  It is important to note that maximum air flow may not occur at maximum pressure.

Free air delivery, or FAD, simply refers to the actual amount of air produced by the compressor at its maximum rated pressure. It is expressed as the volume of air produced in a given time period, such as cubic feet per minute (CFM) or metric equivalent.

Specifications for vacuum or suction blowers include vacuum pressure, pumping speed, and vacuum stages.

Ultimate vacuum pressure is typically measured in torr or millimeters of mercury (mm Hg) referenced above absolute zero pressure. The following reference terms are sometimes used to classify vacuum pressure:

• Rough vacuum:  1 Torr and above
• Medium vacuum:  0.001 to 1 Torr
• High vacuum:  less than 0.001 Torr

Pumping speed, also known as displacement, is similar to free air delivery and refers to the air volume capacity of the vacuum pump. 

A vacuum pump may also be specified according to stage.  The number of stages is determined either by the number of sequential impeller assemblies or the number of separate pumps packaged together.  Vacuum pumps with more than one stage can achieve lower absolute pressure by moving air through the several stages.  The blower below is an example of a two stage blower, as evidenced by the two in-line housing assemblies, both of which contain separate impellers.

A double stage blower.  Image credit:  Direct Industry

The Engineering360 SpecSearch database contains information about a blower's power source, lubrication, mounting, and applications.

Power Source

A regenerative blower may be powered using a number of different methods, including compressed air, an engine, or electric power.

In a compressed air/fluid system, the blower is driven by nonelectric media such as motive fluid.  While compressed air systems are most common, some blowers are powered by hydraulic media or a similar power source.  Compressed air systems are most effective in factory applications.

DC power sources include batteries and power supplies.  Blowers designed to be used in remote or field applications are often DC powered.

Single phase AC power voltages include 115 V and 230 V.  This power source is applicable to lighter industrial uses, as well as laboratory and HVAC use.

Three phase AC power is often used to power heavy industrial machinery, using voltages such as 208 V and 377 V.

Some blowers are powered by a gasoline or diesel engine.  Like DC powered equipment, they are useful in field applications. 

Lubrication

A blower's lubrication style is very important when selecting based on its intended application or use. 

Dry or oil-less equipment uses permanently sealed bearings in order to eliminate the need for oil.  A regenerative blower's impeller is its only moving part, therefore making it well-suited for oil-less operation.  Oil-less blowers are advantageous for several different uses:

High purity applications, in which use of a lubricant could contaminate semiconductor, pharmaceutical, or optical components with critical cleaning requirements.

If the blower will be built into another product or system, and cannot be accessed for periodic re-lubrication.

Explosion-proof applications where oil may cause fires or other hazardous conditions.

Mounting

A blower may be mounted according to several different methods.

Benchtop blowers are small enough to be affixed or placed on a bench or other flat surface.  They may be portable.

Blowers mounted on a cart include wheels or casters to enable frequent relocating

Floor/skid mount devices rest on the floor or a skid, and are typically used for large pumps.

Permanent blowers are used with very large systems and are permanently mounted in one location.

Applications

Buyers are able to specify one or many regenerative blower applications.

General purpose uses cover a wide range of manufacturing and industrial applications.

Blowers may be suitable for use with chemicals or corrosive gases and vapors.

Manufacturing applications include plastics vacuum forming, degassing, vacuum sintering and casting.

Vacuum blowers may be used in packaging applications, including shrink-wrapping, food packaging, and medical device packaging.

References

Pneumatics Online - Regenerative Blowers

Image credit: ANVER Corporation