Pneumatic Systems and Components Explained

Introduction to Pneumatics

Pneumatics studies the behavior of air compressed by mechanical pressure and its effects. The fundamental formulas include pressure, P = F / S (where P is pressure, F is force, and S is surface area), and flow rate, Q = V / t in m³/s (where Q is flow rate, V is volume, and t is time). A pneumatic circuit is a device consisting of a set of interconnected elements through which compressed air can circulate.

Pneumatic Circuit Components

A standard pneumatic system with a compressor includes the following essential components:

• Compressor: Increases the atmospheric air pressure up to 6 to 7 bars.
• Auxiliary engine: Communicates the rotary motion of the shaft to the compressor.
• Refrigerator: Diminishes the air temperature at the exit to 25 °C and eliminates up to 80% of water content.
• Repository (Receiver): Stores the compressed air to be used when needed, equipped with pressure gauges and exhaust valves.
• Maintenance unit: Prepares the air through filtration, pressure regulation, and lubrication.

Pneumatic Actuators and Cylinders

Actuators (Drives): Transform the energy accumulated in compressed air into mechanical energy, resulting in rectilinear or swinging movement.

A cylinder is a tube of constant circular section, closed at its ends. A piston slides inside, solidary with a stem that passes through a base. The piston divides the cylinder into two chambers, which have openings through which air enters and exits.

• Single-acting cylinder: Transforms pneumatic energy into mechanical energy, performing work only in the forward direction. The return stroke is achieved thanks to a built-in return spring.
• Double-acting cylinder: The displacement of the piston occurs in both directions. To achieve this, air must feed each of the holes of the two chambers.

Advantages of Double-Acting Cylinders

• They can develop work in both directions.
• There is no loss of effort due to the compression of a return spring.
• The stroke can be adjusted very precisely along the entire length of the cylinder.

Applications: Transfer, pressing, stopping, ejecting, assembly, marking, shaping, and pivoting.

Distribution Valves

A pneumatic valve is a distribution element that directs and regulates the flow of compressed air.

• 2/2 Valve: Features 2 ports for air and 2 working positions.
• 3/2 Valve: Features 3 ports for air and 2 working positions.
• 5/2 Valve: Features 5 ports for air and 2 working positions.

Auxiliary Pneumatic Valves

• Non-return (check) valves: Allow air circulation through ducts in one direction and prevent it in the opposite direction, using a spring attached to a sealing element.
• Shuttle valve (double-effect or selector circuit): Features 3 ports and a small internal shuttle that moves to block one inlet or another. It is used to select one power source or another.
• Flow control valves: Feature a screw that increases or decreases the flow section. They are usually installed at the exit of the cylinder chambers to regulate the speed of the piston's movement.