scope:

General

This technical report was written in support of the standard ANSI/ISA-18.2-2016, Management of Alarm Systems for the Process Industries (March 2016), commonly referred to as ISA-18.2.

This technical report provides guidance, rationale, and examples for the identification and rationalization life cycle stages from ISA-18.2.

a) Identification - Identification is a general term for the different methods that can be used to determine the possible need for an alarm or a change to an alarm. The identification stage is the input point of the alarm lifecycle for recommended alarms or alarm changes. Identified alarms are an input to rationalization.

b) Rationalization - Rationalization encompasses several significant activities, including alarm justification, documentation, prioritization, and classification. In justification, existing or potential alarms are systematically compared to the criteria for alarms set forth in the alarm philosophy. If the proposed alarm meets the criteria, then the alarm type, setpoint, cause, consequence, and operator action are documented. The alarm is prioritized and classified according to the philosophy. Classification encompasses assigning alarms to a group or class defining certain administrative requirements. These activities are often combined into a single rationalization activity. They do not need to be conducted in separate sessions.