MEASUREMENT & MONITORING
MAXILARM
OMNIFLEX
How distributed alarm annunciator systems can help nuclear , petrochemical and oil and gas facilities comply with strict safety standards
Businesses in the nuclear , petrochemical and oil and gas sectors generally follow best practice guidelines like the EEMUA 191 standard when it comes to safety-critical alarm systems . However , as regulations increasingly require data acquisition and sequence of events capabilities for critical alarm systems , many plant managers are struggling to find a cost-effective way of keeping up . Here Gary Bradshaw , director of remote monitoring specialist Omniflex , discusses why installing a distributed alarm annunciator system might provide the solution to plant managers ’ problems .
In high-consequence risk environments like the nuclear , petrochemical and oil and gas industries , the use of safety , health and environmental ( SHE ) alarms is a key part of best practice guidelines like the EEMUA 191 standard . One of the key requirements of the EEMUA 191 standard is that critical alarms must be easy to understand , promoting quick and effective operator responses . This is where traditional hardwired alarm annunciators come in as they promote easy of use and rapid responses .
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 .
It is common 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 and do not meet the current safety requirements . As a result , many sites suffer from obsolescence and support issues and must now upgrade their critical alarm systems .
Considerations for updating alarm systems
There are three key considerations for plant managers when updating their alarm annunciators . Firstly , it is crucial that they determine what alarms are classified as SHE alarms and that these are directly hardwired into the processes . This is essential because networked alarms can be susceptible to 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 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 operators . This improves operator responsive times , which is an important part of safety standards .
Finally , all alarms should be suitably prioritised using an easy-to-understand system , such as colour coding each window to match the severity of the alarm it represents .
This means that allows operators to have a clear order of priority in place for situations where multiple alarms go off , further aiding their chances of responding quickly and effectively .
Maximum flexibility
Omniflex ’ s Maxilarm alarm annunciator system offers a complete distributed modular alarm management system for critical plants . It incorporates features such as submillisecond time stamping at source , integrated analogue logging and remote Omni X LED alarm fascias , to meet EEMUA 191 guidelines . These features allow the Maxilarm system to provide a dependable layer of plant protection and early diagnostics of faults in real time .
The Maxilarm system can be configured using standard 24 vdc and 48 vdc input modules and has specialist sequence of event digital input modules . These ensure all the digital inputs are time stamped in real time to a resolution of sub one millisecond , which is the fastest on the market . This is ideal in facilities where the potential for multiple simultaneous alarms is high and it is important for operators to know the chronological order of alarm alerts . This also improves data auditing and event analysis capabilities .
To find out more about Maxilarm , visit www . omniflex . com / products / M1264A .
Issue 61 PECM 119