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Pneumatics refers to the technique in which mechanical movement is generated with the help of pressurised gas. Like hydraulics, pneumatic systems belong to the field of fluid dynamics. However, whereas pure hydraulics uses liquids as the working material, pneumatics works with compressed air.
The areas of application are therefore very diverse and using air as a drive medium is also cheap and comparatively environmentally friendly. This is why compressed air and pneumatic tools are so popular.
Pneumatics – the basics
The word pneumatics is derived from the Greek word pneuma, which translated means ‘wind’ or ‘breath’. It refers to a diverse field of technology in which work is carried out with compressed air or compressed air-driven systems.
Pneumatics provides movement and drive, and usually pneumatic cylinders are the first thing associated with this technology. But more specialised and complex systems are also available, such as vacuum systems, grippers or even air springs which are ideal for damping shocks.
Pneumatic systems, also called control systems, work with compressed air. In most systems, this has an overpressure of 6 bar. High-pressure systems, which are used for gas pipelines, work with up to 18 bar. However, the highest pressure needed for the production of products like plastic bottles is up to 40 bar.
How does pneumatics work?
In basic pneumatic systems, air is compressed and fed via valves to the desired location. The energy stored in the compressed air is then converted into kinetic energy and used in specific ways, for example, to move a cylinder piston in a specific direction.
Basically, every pneumatic control system consists of four components:
- Compressed air generation: The required ambient air is drawn in by one or more compressors and then compressed to between 6 and 40 bar depending on requirements. For high air pressures that are only needed for a certain period of time, a compressor with speed control is used. Compressing air generates heat that can also be used as a source of heat energy.
- Compressed air treatment: The compressed air is freed from impurities such as dust or pollen using various filter systems. This is important to ensure that the pneumatic systems have the longest possible service life.
- Compressed air distribution: Compressed air is distributed via pipes. To prevent the air from becoming contaminated again, the pipes must be leak-proof and emit as little rust or water as possible. In most cases, storage facilities are also integrated into the pipe networks.
- Application/performance of work: Compressed air is supplied to the respective work processes via valves or actuators. The number of pneumatic switching positions and connections varies depending on the application and the device. The mechanical work is performed with the help of compressed air by so-called working elements – mainly pneumatic cylinders.
The way in which pneumatic circuits must be constructed is specified for the various systems and devices through corresponding safety standards.
Where is pneumatics used?
Pneumatic systems are used in a wide variety of industries and areas, from hazardous material handling to robotics and medical technology. Other areas of application are drive and transport. For example, systems are installed in air brakes of trucks or buses.
They are also used in air-filled tyres, various lift trucks and other industrial trucks. Pneumatic tube systems can also be used to transport smaller unit loads or liquids. Some special pneumatic tools only work with compressed air – for example in spray painting and other surface treatments.
Advantages of pneumatic systems
Pneumatic systems have several advantages. The source material used, namely air, is environmentally friendly, cheap and available everywhere. Air can be used in any quantity and can also be transported easily over long distances.
Other advantages of pneumatics are:
- Storage capability: Compressed air can be stored in the appropriate pressure vessels.
- Temperature resistance: Compressed air is insensitive to temperature fluctuations.
- Safety: There is no danger of explosion or fire with compressed air.
- Environmental friendliness: Compressed air that escapes does not cause any environmental damage.
- Simple design: This makes low-cost solutions possible.
- Speed: Compressed air is a very fast working medium.
- Stepless adjustability of forces and speeds: The pressure level can be adjusted to the respective application.
- Force: High forces are possible in a comparatively small installation space.
- Robust against overload
- No additional cooling necessary: The air itself already provides sufficient cooling for the individual drive components.
One of the possible disadvantages of pneumatics is the low level of efficiency. Even if the heat generated during compression is reused, some energy is lost. However, cold temperatures can also become a problem. When compressed air flows through equipment and machines, it can cool them down considerably and can cause ice to build up. Working with pneumatic circuits also generates noise, but this can be reduced by using silencers. It should also be taken into account that the power of compressed air systems is limited.
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