Interlock and Safety

A protective response which is initiated by an out-of-limit process condition that can cause injury or unacceptable environmental contamination. An instrument, or possibly software, which will not allow one part of a process to function unless another part is already functioning.

Reference: Adapted from CCPS (

A system that detects out-of-limits or abnormal conditions or improper sequences and either halts further action or starts corrective action.

Reference: Interlock System definition by Guidelines for Pressure Relief and Effluent Handling Systems, CCPS, ISBN 978-0-8169-0476-1

Management/Process Safety Information and Knowledge/Instrumentation