The term safety control refers to the design of control loops with a certain safety integrity level (SIL); this is achieved using certified controller/measurement hardware in suitable loop architecture. In a HAZOP session, a set of parameters is identified as having relevance to compressor hazards and operability. In the subsequent SIL-classification session, each of these predefined parameters is assigned a SIL. Hence, the output of the SIL-classification session is a list of parameters with assigned SILs; the SIL can vary among different parameters.

The following is a list of important considerations:

  • The SIL is an attribute of a single loop, not an attribute of a compressor.
  • The same parameter on identical machines in different plants may receive different SILs, depending on the risk-management guidelines of the end user.
  • The majority of compressor parameters are unclassified, i.e. no SIL.
  • A loop SIL is not necessarily achieved simply by using a TÜV-certified SIL3 PLC without taking field devices into account.
  • The implementation of compressor safety controls on the plant ESD system is not a free service.


AviComp has full capabilities for supporting clients in the establishment of a design framework for safety controls on their compressors through the participation of AviComp engineers in HAZOP sessions and SIL-classification sessions and through the development of alternative concepts for system architectures.

Following the conceptual-engineering and basic design phase, AviComp has the in-house capabilities required to perform not only detail engineering for the implementation and commissioning of safety controls but also SIL verification.

Over the past 15 years, AviComp has successfully engineered, supplied, and commissioned 1,200 rotating-machinery control systems all over the world. Our customers worldwide, which include machinery manufacturers and end-users, as well as EPC contractors, trust in AviComp’s unique capabilities.