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Which Measure (Rationalized or Annunciated) is More Important?
Apr 14, 2020[:en][vc_row][vc_column][vc_column_text]Get your priorities (distribution) straight A very common question is posed during alarm management training. Does the recommended alarm priority distribution of ~5% / ~15% / ~80% for high / medium / low priority alarms apply to the rationalized alarm priority distribution (as configured in the control system) or to the annunciatedalarm priority distribution (those […]
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Back to Basics: Failure Rates – λD
Apr 02, 2020[:en][vc_row][vc_column][vc_column_text] The Greek symbol λD represents dangerous failure rates in functional safety, usually expressed in the unit of measurement of FITs, and can be determined through FMEDAs. (FITs (λ) are failures per billion hours, expressed by 10-9 hours). λD is the number of dangerous failures per unit time for a piece of equipment. This would be a time when the failure […]
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The Benefits of exida’s Site Safety Index (SSI)
Nov 21, 2019[:en][vc_row][vc_column][vc_column_text]New reports out now are claiming that an aging, failed elbow pipe appears to be the initial cause of a June 21 fire and subsequent explosions that injured five people at the largest oil refinery on the East Coast, federal investigators said. The U.S. Chemical Safety and Hazard Investigation Board released a preliminary factual findings […]
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Back to Basics 17 – PFH (Probability of Failure on Demand per Hour)
Nov 19, 2019[:en][vc_row][vc_column][vc_column_text]PFH (The Probability of Failure on Demand per Hour) is the probability that a system will fail dangerously, and not be able to perform its safety function when required. PFH can be determined as a probability or maximum probability over a time period of an hour. IEC 61508 and IEC 61511 use PFH as the system metric upon which […]
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Evaluating Alarm System Performance in a Multi-Operator Control Room
Nov 14, 2019[:en][vc_row][vc_column][vc_column_text] Situation: There are three operator consoles (positions) in the same control room. There is one general alarm horn that goes off whenever a new alarm comes in from any one of the three consoles. The horn draws the attention of each of the three operators. Question: How are the ISA-18.2 KPIs for alarm system performance applied […]
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Why Proof Test Coverage Is So Important For A SIF to Achieve Its Target SIL?
Aug 24, 2017[:en][vc_row][vc_column][vc_column_text]This is a question I often get asked when I’m teaching our FSE100 course on Functional Safety, when we discuss the purpose of Proof Testing and coverage. It’s amazing how many end users assume perfect proof testing (i.e. 100% coverage), that is capable of finding, all the potential dangerous undetected failures. It just isn’t the case. There […]