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Management of control room alarms

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Introduction to the management of control room alarms including guidance from EEMUA 191.
Control Room Operators receive alarms from the systems they use to monitor and control
Alarms should warn about situations that require a prompt response
There are many problems with alarms.

Publié dans : Ingénierie
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Management of control room alarms

  1. 1. Tel: (+44) 01492 879813 Mob: (+44) 07984 284642 andy@abrisk.co.uk www.abrisk.co.uk 1 Management of Control Room Alarms Andy Brazier
  2. 2. A bit about me Chemical engineer 22 years working as Human Factors Engineering (HFE) consultant 13 years self-employed Chartered member of the Chartered Institute of Ergonomics and Human Factors Associate member of Institute of Chemical Engineers. 2
  3. 3. Clients UK – Shell, BP, Tata, Syngenta, Total, Centrica, Scottish and Southern Energy etc. Middle East – PDO, KNPC, ADMA, Saudi Aramco India – Larson and Toubro (projects for PDO and Farabi). 3
  4. 4. Human Factors Engineering A multidisciplinary science that focuses on the interaction between the human and the work system Optimise human and system performance Thinking about how people will interact with plant and equipment during design Making sure it will be easy to operate and maintain Reduce health and safety risks Reduce the likelihood of human error and improve efficiency. 4
  5. 5. Why apply HFE to the design of work systems, workplaces and products? Improve HSE performance Reduce operational HSE risk Reduce the likelihood or mitigate the consequences of human error Improve human efficiency and productivity. Contribute to more efficient design and avoiding re-work/changes later on. Reduce life cycle costs of operating and maintaining facilities. 5
  6. 6. HFE Activities Critical task analysis Plant/piping layout & access (valve analysis) Control room design Human machine interfaces Process graphics Alarms Operational controls Staffing arrangements Procedures, training and competence 6
  7. 7. Introduction Control Room Operators receive alarms from the systems they use to monitor and control Alarms should warn about situations that require a prompt response There are many problems with alarms. 7
  8. 8. 1994 – Fire & Explosion at Texaco’s Milford Haven Refinery Too many alarms Poorly prioritised Displays did not help Inadequate training. 8
  9. 9. Typical problems with alarms Nuisance alarms during normal operations - do not require a response Floods of alarms during process upsets and emergencies Too many standing alarms Priorities not helpful to Operators Operators do not understand alarm descriptions or don’t know how to respond Too many alarms configured. 9
  10. 10. Not consistent with human capability 10
  11. 11. Improving alarms Alarm definition and philosophy Prioritisation Alarm review and rationalisation Performance measurement. 11
  12. 12. Definition and philosophy An alarm is “a means of directing an Operator’s attention to something that requires their timely assessment and action” Audible signal Visual identification Applied to situations with potential for Safety hazard Environmental emissions Major equipment damage. 12
  13. 13. Definition and philosophy Part of an overall risk management system Part of the hierarchy of control in this order Inherent safety Engineering controls Effective Human Machine Interface (HMI) allowing Operators to act proactively Main role of alarms is to avoid activation of automated protection Safety Instrument Systems (SIS) or ‘trips.’ 13
  14. 14. ISA 18.2 14
  15. 15. Every alarm matters Key design principles Attract, inform and guide Useful and relevant to the Operator Have a defined response Allows the operator enough time to respond. 15
  16. 16. Alerts – not alarms Indication that something has happened but Operator does not have to respond No safety or environmental consequence if Operator does not respond Useful way of reducing alarm count without losing interesting or useful information No audible signal Listed separately. 16
  17. 17. Not alarms Status indications Normal or expected status changes Activation of SIS or trip Duplicate signals Signals confirming successful Operator action. 17
  18. 18. Alarm priorities All alarms are important Operator must respond to every alarm when it occurs Low priority does not mean unimportant Prioritisation used to assist operator if more than one alarm occurs at the same time Use 3 or 4 levels of priority Low – advisory Medium – may not need this level of priority High – warning Critical – special case (see below). 18
  19. 19. Determining priority 19 Potential consequence Possible alarm Time available Time available Low priority High Priority No alarm (or alert) Major <20 minutes >20 minutes <4 hours >4 hours <Major
  20. 20. Critical alarms Operator action required to avoid an immediate hazard No automatic protection in place Avoid wherever possible and engineer out If needed Alarm annunciator must be very reliable Alarm must be clearly differentiated from others Response must be documented fully Operators must be assessed as competent. 20
  21. 21. Our aim 20% high priority 80% low priority No critical alarms (or very few) 21
  22. 22. Logical processing Every alarm received needs to be useful to the operator May depend on mode of operation Making alarms conditional can ensure this Example – low flow alarm is only active when a pump is running More sophisticated methods available but must be used with great care. 22
  23. 23. Alarm review and rationalisation Existing alarms or new project Clear definition, policy & priority guide Review every alarm Confirm it is an alarm (or an alert) Review alarm identifier/description Define operator response Assign priority Consider conditional alarm Review alarm set-point. 23
  24. 24. Example 24 90% Trip & alarm 30% = normal 100% = overflow 70% Alarm
  25. 25. Alarm review method 25 ID. Avoiding what? Operator action Consequence of no action Time available Priority LH1 High level Vessel overfill Reduce inlet flow Plant trip 20 minutes High LHH1 High High level Vessel overfill None None N/A Alert LH1 High level Vessel overfill Reduce inlet flow Plant trip 40 minutes Low
  26. 26. Monitoring performance Criteria Benchmark per operator Average rate <6 alarms per hour Maximum rate (upset event) 10 alarms in 10 minutes Standing alarms 0 Supressed/shelved alarms 0 26
  27. 27. Final comments Alarms are only part of the HMI – think about graphics as well Alarms are a tool for people – need a HFE solution The aim is to reduce demands on safety systems If the operator does not need to (or cannot) respond promptly – it is not an alarm. 27
  28. 28. Final comments For new projects Define the philosophy as soon as possible Schedule alarm review workshops like other safety studies Review performance as soon as operational For existing plants Define the philosophy to include continual improvement Carry out alarm rationalisation Monitor performance. 28
  29. 29. Pertinent requirements (EEMUA 191) Each alarm should attract, inform and guide Every alarm presented to the operator should be useful and relevant to the operator Every alarm should have a defined response Adequate time should be allowed for the Operator to carry out a defined response Every alarm should be relevant, unique, timely, prioritised, understandable, diagnostic and advisory. 29
  30. 30. References Free, simple guide to better alarm handling http://www.hse.gov.uk/pubns/chis6.pdf Paid for guides/standards EEMUA 191 IEC 62682 ISA 18.2 30
  31. 31. I hope you found that useful If you would like any more information you can contact me as follows: Email – andy@abrisk.co.uk Phone – +44 1492 879813 Mobile – +44 7984 284642 31