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Why new SIL-rated critical alarms are important in applications that are guided by EEMUA 191 standards.
Obsolescence management of critical alarm systems continues to be a major problem for many businesses, especially those in the petrochemical, oil and gas sectors who are required to use annunciator systems under best practice guidelines like the EEMUA 191 standard. This is made more difficult by the fact that, in many cases, facilities are still equipped with alarm annunciator systems that are no longer supported because the manufacturers went out of business decades ago. Here Gary Bradshaw, director of critical alarm specialist Omniflex, explores the problem of alarm obsolescence and explains why upgrading to new SIL-rated systems might be easier than expected.
Globally, petrochemical, oil and gas facilities follow the best practice for critical safety, health and environmental (SHE) alarms outlined by EEMUA 191, which was developed in 1999 with input from the British Health and Safety Executive to provide comprehensive guidance on designing, managing and procuring effective alarm systems. The international standards for the management of alarm systems for the process industries, ISA 18.2 from the International Society of Automation and IEC 62682:2015, are aligned with EEMUA 191.
One of the key conclusions of the EEMUA 191 guidance is that critical alarms should be easy to understand, promoting quick and effective operator responses. This is where the traditional hardwired alarm annunciators come in.
Alarm annunciators are panel-based alarms that are hardwired directly into relevant safety-critical processes, where each window relates to a fixed alarm point from the sensor. If an abnormal event is detected, the relevant window on the panel lights up and the alarm emits a sound, immediately giving operators the necessary information to act. However, it is common when I conduct site visits to still see alarm annunciators in use that were first installed in the 1980s and 1990s, such as Highland, Rochester, Robinson, Bristol Babcock, Clifford & Snell, Sentry and Londex systems, which are all no longer manufactured or supported. As a result, many sites suffer from obsolescence issues.
Upgrading obsolete alarms
With many former alarm system providers no longer in business, sites haven’t updated the original alarm systems that were installed decades ago. It is vital that physical alarm annunciators are updated in line with current regulations and safety guidance, and display all the critical SHE alarms that operators must respond to.
There are three key considerations for plant managers to consider when it comes to updating their alarm annunciators. Firstly, it is crucial that they determine which alarms are classified as SHE safety alarms and that these are directly hardwired into the processes. This is essential because networked alarms can be susceptible to network or power outages, meaning, if the network goes down, you lose all the alarms on that network. If alarms are individually hardwired, and you lose one wire, you only lose one alarm, and if this alarm is detected from a normally closed open to alarm contact then a wire break would still be seen as an alarm on the annunciator window.
The second consideration is the importance of having each of the alarm windows on the annunciator panel permanently dedicated to a specific process, providing pattern recognition and familiarity for the operator, and, ultimately, improving responsiveness. Operator response times are extremely important, so it is vital that alarm displays maximise the operator’s ability to respond quickly to abnormal events.
Finally, having all the alarms suitably prioritised using an easy-to-understand system, such as colour coding each window to match the priority of the alarm it represents is very important. This means that, in situations where multiple alarms alert, operators can quickly identify their priority, further improving the chances of responding effectively.
Despite what many plant managers might think, upgrading out-of-date alarm systems doesn’t need to be costly or disruptive. Modern industrial alarm specialists can engineer upgrade solutions off-site and design them specifically to fit existing space, reducing installation time and any associated downtime.
For industries like petrochemical, oil and gas, where ongoing operational safety is one of the primary day-to-day considerations, plant managers should reassess the suitability of their alarm systems and how they conform with EEMUA 191 and SIL standards. For those in need of help, Omniflex offers a free consultancy service where one of its specialist engineers will visit your site to perform a free survey and evaluate your existing obsolete and legacy alarm systems before discussing the most suitable replacement options with you.
