March/April 2010

A standard grows up: The evolution of ISA's standard on alarm management (ISA-18.2)

By Todd Stauffer

On 23 June 2009, ANSI/ISA-18.2, "Management of Alarm Systems for the Process Industries" (ISA-18.2), was released. As with many standards, completion of ISA-18.2 entailed significant effort from a cross-functional team of volunteers representing end users, suppliers, consultants, integrators, and the government. The ISA18 committee labored for more than five years, turning out eight drafts of the standard and reviewing/resolving almost 4,000 comments. Release of a standard, however, is just one stage in its life. Performance-based standards define the "what," but not the "how." Application guidelines and examples, the "how," are needed to support wide-spread adoption by industry.

Overview of ISA-18.2

ISA-18.2 provides a framework for the successful design, implementation, operation, and management of alarm systems. It contains guidance to help prevent and eliminate the most common alarm management problems, as well as a methodology for measuring and analyzing performance of an alarm system. The standard is organized around the alarm management lifecycle. The key activities of alarm management are executed in the different stages of the lifecycle. The products of each stage are the inputs for the activities of the next stage.

Defining an alarm

Several of the most important principles of alarm management are highlighted in the definition provided by ISA-18.2.

An alarm is …

  • An audible and/or visible means of indicating-There must be an indication of the alarm. An alarm limit can be configured to generate control actions or log data without it being an alarm.
  • To the operator-The indication must be targeted to the operator to be an alarm, not to provide information to an engineer, maintenance technician, or manager.
  • An equipment malfunction, process deviation, or abnormal condition-The alarm must indicate a problem, not a normal process condition.
  • Requiring a response-There must be a defined operator response to correct the condition. If the operator does not need to respond, then there should not be an alarm.

Benefits of ISA-18.2

A well-functioning alarm system can help a process run closer to its ideal operating point, prevent unplanned downtime, and keep the process running safely. Poor alarm management can affect an operators' performance by making it more difficult for them to detect, diagnose, and respond to each alarm correctly and within the appropriate timeframe. Following the alarm management lifecycle of ISA-18.2 can go a long way toward eliminating and preventing common alarm management problems such as:

  • Nuisance alarms
  • Chattering & fleeting alarms
  • Stale alarms
  • Alarms with no response
  • Alarms with the wrong priority
  • Redundant alarms
  • Alarm floods

Next steps

As part of the continuing evolution of ISA-18.2, a series of ISA18 technical reports (TRs) is being developed to help alarm management practitioners put the requirements and recommendations of ISA-18.2 into practice.

Alarm Philosophy (Technical Report 1): The cornerstone of an effective alarm management program is the alarm philosophy document, which defines how a company or site will execute alarm management. TR1 will define roles and responsibilities, how to classify and prioritize alarms, what colors will be used to indicate an alarm in the HMI, and management of change procedures. It will also establish key performance benchmarks (e.g., acceptable alarm load for the operator).

Alarm Identification & Rationalization (TR2): This TR will describe how to evaluate whether something should be an alarm, and how to set its priority, classification, and limit by considering time to respond, process dynamics, and potential consequences.

Basic Alarm Design (TR3): This TR will provide guidance and application examples covering the selection and configuration of alarm attributes (types, deadbands, and delay time).

Enhanced and Advanced Alarm Design (TR4): This TR will describe how to deliver information to the operator to help formulate a response, to modify alarm attributes dynamically based on operating state, to address events that trigger multiple alarms, to use model-based predictive alarming, and to redirect alarms outside of the control room.

Alarm Monitoring, Assessment, and Audit (TR5): This TR will provide guidance on how to measure, analyze, and improve alarm system performance through evaluation of key performance indicators.

Alarm Systems for Batch and Discrete Processes (TR6): This TR will specifically address how the standard applies to batch and discrete processes. It will provide guidance on how to deal with the nuances of managing alarms associated with batch and discrete processes.

Looking for good men, women

If you are interested in contributing your knowledge and experience to the TR development effort-and in gaining from the knowledge and experience of your professional colleagues at the same time-please contact ISA18 co-chairs Nicholas Sands (Nicholas.P.Sands@USA.dupont.com) or Donald Dunn (Donald.Dunn@aramcoservices.com).

ABOUT THE AUTHOR

Todd Stauffer (tstauffer@exida.com) is an alarm management consultant for exida and a voting member of the ISA18 committee. He is co-chairing the development of TR3 on basic alarm design.