177 / 648
Safety and environmental standards for fuel storage sites
Final report
175
Guidance on alarm systems
248 Management of abnormal situations often concerns the effectiveness of the alarm system.
Increased automation provides a relatively calm operating scenario when the plant is in a steady
state. However, given the importance of alarms in times of upset, the display of alarm information
has to be given high priority. Even if there are relatively few alarms on the system and the system
is not a distributed control system (DCS) the same principles apply, to ensure a reliable response
to alarms.
249 Dutyholders should proactively monitor control systems, such as the tank gauge system, so
that designated level alarms etc do not routinely sound. (This does not exclude the use of properly
managed variable alarms or warnings set below the established alarm levels).
250 The Energy Institute’s
Alarm handling
,
113
and HSE’s
Alarm handling
114
and
Better alarm
handling
115
provide useful summaries of alarm handling issues with case studies.
251 EEMUA 191 covers the topic fully, and is referenced as good practice guidance in each of
the above summaries. It identifies the following characteristics of a good alarm:
Relevant: not spurious or of low operational value.
■
■
Unique: not duplicating another alarm.
■
■
Timely: not long before response needed, or too late.
■
■
Prioritised: indicating importance to the operator.
■
■
Understandable: message clear and easy to understand.
■
■
Diagnostic: identifying the problem that has occurred.
■
■
Advisory: indicative of action to be taken.
■
■
Focusing: drawing attention to the most important issues.
■
■
252 EEMUA 191 provides a roadmap to direct different users to different parts of the guide,
relevant to their particular needs. There are separate roadmaps for:
where an alarm system is already in operation; and
■
■
where an alarm system is in the conceptual phase.
■
■
253 For situations where an alarm system is already in operation, users are provided with
guidance on how to review:
the alarm system philosophy;
■
■
the principles of alarm system design, especially:
■
■
the design process;
––
generation of alarms;
––
structuring of alarms;
––
designing for operability;
––
implementation issues, especially:
■
■
training;
––
procedures;
––
testing;
––
alarm system improvement.
■
■
Summary
254 Dutyholders should ensure that their control room information displays, including human-
computer interfaces and alarm systems, are reviewed in relation to recognised good industry
practice.
255 Where reasonably practicable, dutyholders should put plans in place to upgrade control room
information displays, including human–computer interfaces and alarm systems, to recognised
good industry practice.