Editing Alarm management (section)

==Some improvement methods==
The techniques for achieving rate reduction range from the extremely simple ones of reducing nuisance and low value alarms to redesigning the alarm system in a [[holistic]] way that considers the relationships among individual alarms.

===Design guide===
This step involves documenting the methodology or [[philosophy]] of how to design alarms.  It can include things such as what to alarm, [[standardization|standard]]s for alarm annunciation and text messages, how the operator will interact with the alarms.

===Rationalization and Documentation===
This phase is a detailed review of all alarms to [[documentation|document]] their design purpose, and to ensure that they are selected and set properly and meet the design criteria.  Ideally this stage will result in a reduction of alarms, but doesn't always.

===Advanced methods===
The above steps will often still fail to prevent an alarm flood in an operational upset, so advanced methods such as alarm suppression under certain circumstances are then necessary.  As an example, shutting down a [[pump]] will always cause a low flow alarm on the pump outlet flow, so the low flow alarm may be suppressed if the pump was shut down since it adds no value for the operator, because he or she already knows it was caused by the pump being shut down.  This technique can of course get very complicated and requires considerable care in design. In the above case for instance, it can be argued that the low flow alarm does add value as it confirms to the operator that the pump has indeed stopped.  Process boundaries (Boundary Management) must also be taken into account.

Alarm management becomes more and more necessary as the [[complexity]] and size of manufacturing systems increases.  A lot of the need for alarm management also arises because alarms can be configured on a DCS at nearly zero incremental cost, whereas in the past on physical [[control panel (engineering)|control panel]] systems that consisted of individual [[pneumatic]] or [[electronics|electronic]] [[analog signal|analogue]] [[Measuring instrument|instruments]], each alarm required expenditure and control panel area, so more thought usually went into the need for an alarm.  Numerous disasters such as [[Three Mile Island accident|Three Mile Island]], [[Chernobyl accident]] and the ''[[Deepwater Horizon]]'' have established a clear need for alarm management.