Compressed air is widely used as a power source because of its many advantages. Among these, compressed air is recognized as a clean and harmless resource. It is also suitable for a wide variety of applications.

Its cleanliness and multi-purpose nature make compressed air a popular choice. However, to generate compressed air, an external power source is required. Most compressors run on electric or combustion engines. So, how does this process work?

To understand the working principle of air compressors, we need to distinguish between two main types: reciprocating (piston) compressors and rotary (screw) compressors.

Reciprocating compressors compress air using cylinders, pistons, and cranks, powered by an electric or combustion engine. Here’s how they work:

Stage 1 - Air enters the cylinder.

Stage 2 - Pistons compress the air in one or multiple stages until the desired pressure is reached.

Stage 3 - Compressed air passes through a cooler and into the air tank.

In this case, lubrication is essential because these compressors have many moving parts. The latter are oil-lubricated, which means the compressed air contains oil residue

(typically 10–15 mg/m³). If oil contamination is an issue, an oil filter can be added to remove particles.

These compressors are mainly used in gas industry, in chemical plants, oil refineries and for refrigeration technology.

Screw compressors operate differently. Instead of pistons, they use rotating screws to compress air:

Stage 1 - Air is trapped between two rotating screw elements.

Stage 2 - Compression generates heat, so a cooling liquid (usually oil) is injected into the compression chamber.

Stage 3 - The cooling liquid circulates through tanks and coolers to maintain an operating temperature of about 80°C.

Stage 4 - After compression, oil is separated from the air in an oil separator.

Stage 5 - Compressed air passes through an after-cooler and then into the air tank.

These compressors are mainly used in industries such as food processing, packaging, automotive and automated manufacturing. They are ideal for applications requiring a constant flow of compressed air.