Barrier

Definition:
Barrier is an older term traditionally used to describe measures preventing or mitigating hazardous events. For modern functional safety terminology, see “Independent Protection Layer (IPL)” for the preferred term.

Key Points:

• Barriers historically have included physical devices, automatic systems, and human interventions.
• In current functional safety practices, the focus is on well-defined IPLs that are auditable and independent.

Example:
A pressure safety valve (PSV) was historically called a barrier and would now be classified as an IPL, if it meets independence and auditability requirements.

See Also: independent protection layer (IPL)

Cited Source:

• CCPS – Guidelines for Initiating Events and Independent Protection Layers.