Pneumatic Circuit Components and Compressor Systems

Compressor Group Components

To use the air in a pneumatic circuit, it is necessary to increase the pressure, and this is achieved by the compressor group:

1. The compressor: This is the basic element, and its function is to increase the pressure of the air sucked from the atmosphere. The simplest is the single-phase piston compressor, and the pressure is usually between 6 and 7 bar.
2. The auxiliary engine: This communicates rotary motion to the compressor shaft. It can be a combustion engine or an electric motor.
3. The cooler: This reduces the temperature to 25ºC and eliminates up to 80% of the water it contains.
4. The tank: This stores the compressed air for use when needed.
5. The maintenance unit: This is responsible for achieving good air quality, and for this, it must perform these three operations:
   • 5.1 Filtering: The air is subjected to a spinning process where impurities stick to the wall and fall by gravity into a chamber.
   • 5.2 Regulator: This ensures a stable pressure of air in the pneumatic circuit, which is indicated by the manometer.
   • 5.3 Lubricator: This adds oil to the compressed air so there is no oxidation and there is a smooth slip of the moving parts.

Pipes and Distribution

These are the pipes that form the network of compressed air distribution.

Pneumatic Actuators

Pneumatic actuators transform the energy stored in compressed air into mechanical energy through a rectilinear back-and-forth movement. They are called cylinders. The cylinder is a tube of constant circular section, closed at its ends, inside which slides a piston integral with a rod running through an end cap. The piston divides the cylinder into two chambers and has openings through which air enters and leaves.

Cylinder Working Capacity

The working capacity of the cylinders is determined by two magnitudes: stroke (race) and diameter.

• Stroke (e): This is the piston displacement within the cylinder. It depends on the length (L) of the stem displacement.
• Diameter (D): This determines the surface of the plunger. Given a certain air pressure, the greater the surface of the piston, the greater the force exerted by the stem.

Pneumatic actuators are classified into two groups: single-acting cylinders and double-acting cylinders.