Pneumatics

What is pneumatics?

Pneumatics is a drive technology that uses compressed air, usually at a working pressure of around 6 bar, to generate mechanical motion and force through cylinders, valves and grippers. Within industrial automation, pneumatics is the default choice for fast, repetitive and relatively simple movements such as clamping, positioning, ejecting, sorting and operating valves. You will find it in packaging lines, assembly machines, robot cells, the food industry and process plants.

Modern pneumatics is no longer stand-alone mechanics. Valve terminals sit on Industrial Ethernet, are driven by a PLC, measured with sensors and supply data to SCADA, condition monitoring and predictive maintenance. That makes pneumatics part of the OT you need to secure.

⚙️ How does a pneumatic system work?

A pneumatic system converts electrical energy into motion in four stages: a compressor compresses ambient air, air treatment cleans and dries it, a pipe network distributes it, and valves direct it to cylinders or other actuators.

Cylinder force follows from F = p × A: pressure times piston area. A cylinder with a 50 mm bore has an area of about 1,963 mm². At 6 bar (0.6 N/mm²) it theoretically delivers about 1,180 N when extending. When retracting, the area of a 20 mm piston rod is lost, giving about 990 N. Friction costs roughly another 10 percent in practice, and for dynamic movements designers typically choose a cylinder that is loaded to only 50-70 percent of its theoretical force.

Because air is compressible, a pneumatic cylinder gives way under load. That makes pneumatics forgiving in a collision, but less precise than hydraulics or an electric servo motor.

🔩 Which valves and cylinders are there?

Valves are named after their number of ports and switching positions. A 5/2 valve has five ports and two positions.

Cylinders come as single-acting (spring return), double-acting, compact and guided cylinders, plus rotary actuators for quarter-turn operation of shut-off valves and control valves. Standard cylinders to ISO 15552 (bores of 32 to 320 mm) and ISO 6432 (mini cylinders of 8 to 25 mm) are interchangeable between manufacturers. End positions are usually detected by magnetic cylinder sensors (reed or electronic) that sense a magnet in the piston, and sometimes by proximity sensors or a linear encoder.

🏭 Where is pneumatics used?

In the process industry pneumatics remains dominant for valves: a spring-return pneumatic actuator moves to a safe position by itself when air or power fails. That fail-safe behaviour is harder to achieve with an electric actuator. Pneumatics is also attractive in potentially explosive atmospheres (ATEX), because the actuator itself produces no sparks; the electrical valve coils and sensors must still be certified.

Pneumatics is often combined with motion control for precise axes and PID control in a closed loop for pressure or position.

💨 Why does air quality matter so much?

Compressed air contains water, oil and dust particles. Untreated, these cause corrosion in pipes, sticking valves, accelerated seal wear and unreliable motion. The standard ISO 8573-1:2010 specifies air quality with a purity class for each of three contaminants, written as [particles:water:oil], for example [1:4:1].

A refrigerant dryer typically achieves a pressure dew point of about +3 °C, sufficient for general pneumatics in a heated hall. Pipework outdoors or in cold stores, and air that contacts food, call for a desiccant dryer and stricter oil classes. Modern components are lubricated for life: adding oil mist is usually unnecessary and can even wash out the original grease.

⚡ How much energy does compressed air cost?

Compressed air is an expensive energy carrier. A Fraunhofer ISI study for the European Commission (2001) estimated that up to about 10 percent of industrial electricity in the EU, more than 80 TWh a year, goes into generating compressed air, and most of the electrical energy fed into a compressor ends up as heat. Typical savings opportunities:

• Find leaks - a poorly maintained network can lose 20-30 percent of the air produced, while a well-maintained one stays below 10 percent; ultrasonic leak detection finds leaks even during production
• Lower the network pressure - every bar less saves roughly 6-8 percent of compressor energy and also reduces leakage
• Variable-speed compressor - a VSD compressor follows demand instead of cycling between load and unload
• Heat recovery - compressor heat can warm buildings or process water
• Shut off at standstill - a 2/2 valve per machine stops leaks from running outside production hours

A systematic approach fits within an energy management system to ISO 50001. Flow and pressure metering per machine makes compressed-air consumption visible in SCADA or a historian.

🌐 How does pneumatics integrate with OT networks?

The valve terminal is the link between pneumatics and OT convergence: dozens of valves on one manifold with a single network connection instead of a cable per coil. Common interfaces are ProfiNET, IP, EtherCAT, Modbus TCP and IO-Link, alongside classic fieldbuses and O.

Smart valve terminals count switching cycles, measure switching times and report coil faults. A cylinder that takes longer and longer to reach its end position points to a leaking seal or low pressure. With anomaly detection, machine learning or Industrial AI you can spot such trends before the machine stops, and a digital twin uses the same data to simulate cycle times. Pneumatics thus becomes part of Industry 4.0 and of the cyber-physical systems on the shop floor, and feeds KPIs such as MTBF.

🔐 How do you secure smart pneumatics?

A networked valve terminal is a full OT asset with embedded firmware, sometimes with a web interface and its own on-board controller. CVE-2022-3079 (CVSS 7.5, high) showed that this risk is real: Festo’s CPX-CEC-C1 and CPX-CMXX control blocks gave unauthenticated access to critical web functions such as a reboot, causing a denial of service. No patch was released; Festo advised replacing them with the successors CPX-CEC-C1-V3 and CPX-CEC-M1-V3.

Baseline controls are network segmentation with zones according to IEC 62443, a firewall between the machine and office networks, hardening (web interface and unused services off, default passwords removed), controlled remote access for suppliers and monitoring of the OT network. Zero Trust principles and proper segmentation limit the damage if one device is compromised. Importantly, safety functions such as depressurising on an emergency stop must never depend on the ordinary network, but on a certified safety circuit. General cybersecurity and machinery safety meet here.

⚠️ Which safety risks and standards apply?

Pneumatics works at lower pressures than hydraulics, but stored energy remains dangerous: whipping hoses, unexpected motion when air is restored, trapping by grippers, compressed-air injection into the skin and noise from exhaust air. Measures include safety exhaust valves, soft-start valves that build up pressure gradually, lockable shut-off valves for lockout/tagout, silencers and guarding. An emergency stop must define what happens to the air: exhaust it, or hold a load-bearing cylinder in place.

The Machinery Regulation also requires protection of control systems against corruption, which makes the cybersecurity of networked pneumatics part of the CE assessment.

🔄 What is the difference between pneumatics, hydraulics and electric drives?

Pneumatics wins for simple two-position movements with limited force and low purchase cost. For many intermediate positions or high precision an electric axis wins, and for very high forces hydraulics. On continuously running machines, the higher energy consumption of compressed air can make an electric solution cheaper over its lifetime.

❓ Frequently asked questions

What pressure is used in pneumatics?

Industrial pneumatic systems usually operate at a working pressure of around 6 bar, while the compressor delivers 7-10 bar to compensate for pressure drop in the pipe network. Most pneumatic components are rated for a maximum of 10 bar. Lowering the network pressure saves roughly 6-8 percent of compressor energy per bar.

How do I calculate the force of a pneumatic cylinder?

The force of a pneumatic cylinder is pressure times piston area (F = p × A). A 50 mm bore cylinder at 6 bar theoretically gives about 1,180 N when extending and, with a 20 mm rod, about 990 N when retracting. To allow for friction and dynamics, size the cylinder for a load of no more than 50-70 percent of that value.

What is a valve terminal?

A valve terminal is a manifold carrying several pneumatic valves with one shared electrical and network connection, for example via PROFINET, EtherNet/IP or IO-Link. It replaces individual wiring per valve and delivers diagnostic data such as switching cycles and coil faults to the PLC. That also makes a valve terminal a network device that you must include in your OT security.

Why is compressed air so expensive?

Compressed air is expensive because most of the electrical energy fed into a compressor is lost as heat and leaks waste a substantial share of the air produced. European estimates put the share of industrial electricity in the EU used for compressed air at up to about 10 percent. Leak detection, lower pressure and a variable-speed compressor are the quickest savings.

Is pneumatics safer than hydraulics?

Pneumatics works at much lower pressures than hydraulics and produces no sparks itself, which makes it suitable for potentially explosive atmospheres. Still, pneumatics is not inherently safe: stored pressure, whipping hoses and unexpected motion when air is restored cause accidents. Pneumatic safety functions should therefore be designed and validated to ISO 13849-1.

Can a pneumatic system be hacked?

A purely mechanical pneumatic system cannot be hacked, but a networked valve terminal or smart sensor can. Vulnerabilities such as CVE-2022-3079 in Festo control blocks show that an unprotected web interface can let an attacker reboot the controller without a password and so stop the machine. Segmentation according to IEC 62443, hardening and monitoring reduce that risk.

📌 In summary

Pneumatics uses compressed air at around 6 bar for fast, low-cost and robust movements, making it a staple of industrial automation. The downside is low energy efficiency and, now that valve terminals sit on the network, a new attack surface: control leaks and air quality, design safety functions to ISO 13849-1 and secure smart pneumatics like any other OT asset.