Technology

Knowledge

Understanding
key technologies

Compressed air and vacuum technologies have evolved significantly over many decades, providing today’s industrial users with an extensive range of highly efficient, reliable, and cost-effective equipment solutions.

From reciprocating, piston, rotary screw, and centrifugal compressors to claw, vane, and side-channel vacuum pumps, there is a wide variety of technologies available to suit different applications and operational requirements. In addition, a broad selection of downstream air treatment and system enhancement equipment is available, including desiccant and refrigerant dryers, heat recovery systems, and nitrogen generators.

With so many options on the market, selecting the most appropriate equipment can be a challenge.

To help you make informed decisions, BCAS has brought together a range of practical resources covering the key technologies used in compressed air and vacuum systems. Whether you are specifying a new installation or seeking to optimise the performance and efficiency of an existing system, our guidance provides an excellent starting point.

Compressed Air at a glance

Compressed air is air that has been pressurised and stored for use as a versatile source of power. The equipment used to generate compressed air is known as an air compressor.

Compressed air plays a vital role in modern industry and automation. It is estimated that around 70% of manufacturing and industrial businesses use compressed air in some part of their operations, making it one of the most widely used forms of utility energy. From production lines and process control systems to specialist applications in healthcare and transportation, compressed air delivers a safe, reliable, and flexible power source.

How Does a Compressor Work?

An air compressor draws in atmospheric air and reduces its volume by compressing it within a confined space. As pressure increases, the compressed air is then cooled and stored in an air receiver or storage vessel, ready for use when required.

The stored energy can be distributed throughout a facility via pipework to power equipment, machinery, and processes. Unlike many other energy sources, compressed air can be stored efficiently and delivered to locations where direct electrical power may be impractical or unsuitable. It is particularly valuable in environments where there is a risk of fire, explosion, or contamination.

Applications of Compressed Air

Compressed air is used to power a wide range of pneumatic equipment and systems. Its reliability, safety, and ease of use make it suitable for numerous industrial and commercial applications, including:

Pneumatic tools and machinery
Automated production systems
Process control valves and actuators
Vehicle braking systems
Dental and medical equipment
Packaging and bottling lines
Cleaning and dust removal systems
Diving and breathing air equipment

Types of Air Compressors

There are a number of compressor technologies available, each designed to meet different operational requirements, flow demands, and air quality specifications.

Reciprocating Compressors

Reciprocating compressors utilise a piston moving within a cylinder to compress air. Pressure can be generated on one or both sides of the piston.

Available in both lubricated and oil-free designs, reciprocating compressors are commonly used for smaller air demand applications. While they generally require more maintenance and can produce higher levels of noise and vibration, they often provide a cost-effective solution for lower-capacity systems.

Oil-Injected Rotary Screw Compressors

Rotary screw compressors use two intermeshing helical rotors that rotate in opposite directions to compress air continuously.

They are widely used in industrial applications due to their reliability, efficiency, and ability to deliver large volumes of compressed air. Variable speed drive (VSD) options are commonly available to improve energy efficiency during fluctuating demand.

Oil-Free Rotary Screw Compressors

Oil-free screw compressors operate on a similar principle to oil-injected machines but prevent lubricant from coming into contact with the compressed air.

These compressors are often selected for applications requiring high air purity, such as food production, pharmaceuticals, electronics manufacturing, and healthcare. Water-injected oil-free variants are also available.

Sliding Vane Compressors

Sliding vane compressors feature a rotor fitted with movable vanes within an eccentric housing. As the rotor turns, pockets of air are progressively compressed until discharged.

Available in both lubricated and non-lubricated versions, vane compressors are known for their smooth, pulse-free airflow and compact design.

Rotary Lobe Blowers and Compressors

These positive displacement machines use high-speed, non-contacting lobed rotors to move and compress air.

Although precision-engineered and often more expensive to purchase, they offer low installation costs, oil-free operation, and reliable performance for specialist applications.

Scroll Compressors

Scroll compressors use two interlocking spiral elements, one stationary and one orbiting, to compress air gradually and efficiently.

Compact, quiet, and vibration-free, scroll compressors are frequently used where low noise levels and high air quality are important.

Dynamic Compressors

Dynamic compressors generate pressure by accelerating air through rapidly rotating components before converting velocity into pressure energy.

These continuous-flow machines are typically used for larger industrial applications where significant air volumes are required.

Centrifugal Compressors

Centrifugal compressors use one or more rotating impellers to accelerate and compress air.

They provide oil-free, pulse-free air at high flow rates and are commonly found in large industrial facilities with substantial compressed air demands.

Axial Compressors

Axial compressors use rows of rotating and stationary blades to accelerate air along the axis of the machine.

Capable of delivering extremely high volumes of air, they operate at very high rotational speeds and are typically used in specialist industrial and aerospace applications.

Understanding Compressed Air System Requirements

A compressed air system consists of four key elements:

Production – generating compressed air.
Treatment – removing contaminants and conditioning the air.
Distribution – transporting air throughout the facility.
Consumption – delivering compressed air to end-use equipment.

For maximum efficiency and performance, these components must be carefully matched to the application’s requirements for pressure, flow, air quality, and energy consumption.

A thorough understanding of air demand is essential. Conducting a compressed air audit can provide valuable insight into actual system usage, identify operating patterns, detect leaks and pressure losses, and evaluate overall system efficiency. The results can help organisations reduce energy costs, improve reliability, and optimise air quality.