Compressed air systems basically consist of four subsystems: compressed air generation, processing, distribution and application. Compressed air is generated in a compressor by air being drawn in and compressed; following processing (filtering, drying) it is fed to the application through pipes and hoses and used herein for technical purposes.
Applications like these are closed systems in which the absolute pressure* has to be measured. The necessary sensors are used in the following devices, for example:
- Pneumatic cylinders
- Proportional valves
Compressors compress the drawn in volume of gas and increase the pressure in the sealed volume. They are usually connected by a valve to a tank which acts as a compressed air buffer and supplies the connected system with compressed air.
- The pressure in a compressor is always measured by relative pressure sensors (< 20 bar) and given as a positive pressure (compared to atmospheric pressure).
These cylinders are work tools where the inflowing compressed air pushes a movable piston rod out of a cylinder housing until it reaches its maximum extension. There are many versions thereof, yet all of them convert the pressure in the cylinder into force.
- Absolute pressure sensors within a range of up to 12 bar are used to measure pressure in pneumatic cylinders.
Proportional valves are used in pneumatic equipment, primarily where adjustable volume flows are required. The internal pressure thereof is measured, making it possible to determine and control the position of the valve spool. This enables energy consumption, reliability and the wear on materials to be considerably improved.
- The pressure is dependent on the required volume flow and is measured by relative pressure sensors of > 100 mbar.