Sensors in the air supply system

For central control of the pneumatics, the air supply has various sensors that monitor different parameters.

Pressure sensors

Pressure sensors monitor compressed air pressure without requiring airflow, making them suitable for nearly every air supply setup. Available types range from simple teach-in sensors with LED indicators to advanced multi-colored LCD variants with programming functionality.

Flow Sensors

Flow sensors measure compressed air volume flow and must be installed in the flow direction within laminar airflow conditions. Proper installation includes placing a component upstream that does not cause disturbances and using a manifold block to ensure accurate measurement.

Valves

Finally, an air preparation system contains various valves to control the relevant application centrally.

Pressure regulator

One of the most important valves is the pressure regulator. With this valve the working pressure is regulated by simply turning a knob. With the help of a pressure gauge (manometer), or pressure sensor, the pressure can be monitored and adjusted if necessary. The operation is shown in the figure: By adjusting the knob, the force on the diaphragm [2] is adjusted via the main spring [1]. The regulating piston [4] moves downwards along with the diaphragm, releasing the lower sealing seat [6]. If the pressure at the working port [5] exceeds the set working pressure, the air can escape through another sealing seat in the diaphragm (secondary venting).

Safety valve

To guarantee the safety of people, machines and the environment, an air supply also has a so-called safety valve. This combines various functions:

• Quick exhaust/dump valve; Due to a relatively large exhaust port the system can be quickly brought to atmospheric pressure and the system pressure is depressurised.
• Slow start-up; With the slow start function, the system can be gradually brought to pressure. This prevents damage caused by actuators ‘jumping’ into the reset position as they start from a pre-exhausted state. The speed of pressurisation is adjustable.
• Redundant operation; In line with machine safety guidelines, redundant valves are available. In these, the coils and position sensors are duplicated in order to be able to cope with possible product failures.

Switch-on/shut-off valve

In addition to regulating the working pressure, the option of a central on/off valve is one of the most desirable features on an air supply. With an on/off valve, the main pressure can be shut off, whereby the pressure on the work side is simultaneously vented [3] to make the system pressure-free. The switching is done manually by means of a rotary knob [1]. A LOTO (Lock Out Tag Out) is also fitted in the knob [2] for safe machine maintenance. In addition to a manual version, the switching valves are also available as an electrical version that can be switched for example from a PLC.