All process industries can benefit from a well-managed alarm system in a variety of ways. The key, however, is to ensure that these systems are correctly configured to keep your plant operating at peak performance. This article will discuss alarm systems, their importance, industry standards, and a guideline for the optimal number of alarms needed to be effective. Then you’ll know whether or not your alarms are working to their full potential.
Alarm systems notify operators and managers about abnormal conditions that require a timely response that occur during a manufacturing process. It warns users to take the appropriate action at the appropriate time, in order to avoid an undesirable outcome.
The following are the top advantages that an effective alarm system can provide manufacturers:
To improve alarm management, the International Society for Automation (ISA) issued standard ANSI/ISA-18.2, “Management of Alarm Systems for the Process Industries.” It establishes a framework for the successful design, implementation, operation, and management of process industry alarm systems.
The core purpose of any alarm is to drive timely operator reaction to an abnormal process event with a cost of inaction.
The ANSI/ISA 18.2 defines alarm as “an audible and/or visual indication to the operator that an equipment malfunction, process deviation or other abnormal condition requires a response.”
A well-architected alarm system aims to have the optimal number of alarms to keep the process within operation range in a safe manner. By implementing the ISA-18.2 standard, plant managers can develop an alarm system with these alarm management goals:
The ISA-18.2 standard defines a set of Key Performance Indicators (KPIs) that plant managers can use to guide their alarm system design philosophy:
|Accumulated Alarms per Day per Operating Position|
|Stale alarms per day (alarms that remain active for extended periods)||Less than 5 present on any day, with action plans to address|
|Percent contribution of top 10 most frequent alarms to overall alarm load||1% to 5%|
The goals of the above KPIs are to provide a benchmark with which to optimize the alarm system to drive operator attention to the right corrective action for the abnormal process.
Unoptimized alarm systems can overwhelm operators with numerous chattering alarms.
To help eliminate inefficient alarms, the ISA-18.2 standard provides some questions that managers and engineers can ask to rationalize each alarm:
Each alarm must be justified and reviewed. In addition, alarms should be prioritized based on the intersection of cost of inaction and time to operator response.
The time to operator response needs to be sufficiently long, so the operator can react efficiently to avoid the cost of inaction.
This cost of inaction can cover many internalized or externalized costs, including plant safety, loss of production or product, and environmental concerns. The ISA-18.2 standard recommends no more than three alarm priority levels.
The ISA-18.2 standard provides plant managers and process engineers with a foundation to architect an alarm system with an optimal number of alerts by providing benchmark KPI’s, an alarm rationalization framework, and prioritization guidelines. Utilizing this standard can increase operational efficiency by reducing nuisance alarms, stale alarms, and alarm flooding, enabling operators to react to process critical events free from distractions, and using alarms to their full potential.