5 Key Safety Functions in a Pneumatic System

Machine building has become more complex with the introduction of more automated systems, and designers must devote more careful attention to the newer safety standards that apply. Mechanical safety standards had to be supplemented with new procedures for functional safety and performance reliability. In 2006, ISO 13849 was revised to incorporate safety functions for machine control systems, reflecting the move towards more software-based architecture.

Designers must anticipate every possible eventuality for the system, whether it is operational, not operating or being serviced. Incorporating standards like ISO 13849 will ensure the maximum possible safety of pneumatic circuits and components, based on risk assessment and performance level (PL) parameters. Using factors such as MTTFd (mean time to dangerous failure), CCF (common cause failures) and DC (diagnostic coverage), the PL can be calculated for each individual safety function, and a required level of performance stipulated (PLr).

5 Key Safety Functions in a Pneumatic System

When designing a pneumatic system, there are five key safety functions that must be considered.

1. Protection against unplanned start-up
2. Exhausting
3. Holding, blocking and stopping
4. Reversing the movement
5. Reducing speed