This recommended practice is provided for the benefit of design engineers and, ultimately, plant operators. Use of this recommended practice will result in a more coherent and useful application of plant alarms for operations personnel. The goal of this recommended practice is to reduce alarm discrepancies, clutter, excessive noise levels, and information overload, but it is not intended for postfactum analysis of events.

This recommended practice will address the following alarm-related issues.

a) Functional grouping

b) Prioritization

c) Order and consistency

d) Colors

e) Formats and displays

f) Audio tone and pitch

g) Acknowledge, reset, and test functions

h) Nuisance alarms

These items are addressed both individually and with respect to their relationships with one another.

This recommended practice pertains to alarms displayed using lights or light boxes, but not softwarebased alarms (e.g., CRP-based alarms) and is intended to supplement the information provided by ISA-18.1-1979 (R2004), Annunciator Sequences and Specifications.

Purpose

The purpose of this recommended practice is to provide advice and guidance in the development and design of plant alarm systems. The primary application for this recommended practice is fossil power plants; however, these guidelines are generic in nature and suitable for use in other process industries.