ISA TR18.2.7 PDF

General considerations

This technical report provides guidance on how to integrate packaged systems (PSs) into a BPCS-based centralized alarm system. The scope includes discussing various issues that can arise when ISA-18.2 work processes are applied to facilities where PSs are used, and providing guidance on how to successfully apply ISA-18.2 in these situations.

Within the context of this report, a packaged system (PS) can be visualized as existing outside of the BPCS. It is a separate entity, usually containing an embedded microprocessor, controller or hardwired logic, which performs specific tasks for a piece of equipment or a process operating within a facility. Most PSs can be configured to send alarm or status information to a BPCS, directly to an alarm annunciation system, or both.

While not the primary emphasis of this report, some discussion is included of PSs that are standalone and also those that are only partially integrated with a BPCS.

PSs can take many forms but have several common characteristics. Typically, PSs combine multiple elements such as process equipment, embedded control systems (typically PLC), and instruments.

Alarm system interfaces

This report includes a focus on alarming-specific issues that can arise when PS interfaces are specified, designed, and implemented. Pros and cons of several design techniques are discussed from an alarm system point of view; the system designer should select the best PS interface option to use for the particular application.

Packaged system design

Within the context of this report, PSs are only considered as sources of possible alarms or of process data for the BPCS to create the alarm. This report does not contain guidance on how to design PSs or how PSs should operate.

Safety instrumented systems

Safety Instrumented Systems (SIS) are considered to be a special case of PSs. While governance of SIS is described by ISA-84, some SISs have the same common attributes as a PS and, in such cases, the guidance in this technical report may apply. SIS design is out of the scope of this document.