In an ideal world, every alarm would indicate a malfunction or abnormal condition that required operator action. In the real world, alarms that are irrelevant or annunciate excessively—otherwise known as nuisance alarms— can overload operators with nonessential noise and desensitize them to the importance of alarms (“I can ignore this alarm….”). The presence of nuisance alarms is a common contributor to alarm management incidents.
Alarm shelving provides a way for the operator to manage these nuisance alarms safely and securely. Shelving provides a controlled mechanism for the operator to temporarily remove a nuisance alarm from view until the underlying problem can be addressed. It is such an important tool for alarm handling that it is now required control system functionality per ISA-18.2-2016 and IEC 62682 (Management of Alarm Systems for the Process Industries). As a result, more and more control systems have added this as a standard feature.