As discussed in Part I, bow tie diagrams provide an easy-to-understand visual representation of risk management information (hazards, potential consequences, barriers, degradation factors and controls). In this article we examine the applicability of bow ties to alarm management.
According to the CCPS book “Bow Ties in Risk Management”,…
Creating an alarm philosophy document is often the entry point into the ISA-18.2/IEC 62682 alarm management lifecycle. Many tasked with developing one are discouraged by its length and the barriers it creates. When it comes to using the philosophy document, a common concern is that if the…
From an operations point of view, one of the significant parts of the ISA-18.2 and IEC 62682 alarm management standards is the endorsement of alarm response procedures. An alarm response procedure, otherwise known as “Alarm Help” or “Alarm Response Manual”, is defined as guidance for response to an alarm (e.g., operator…
US Chemical Safety Board cites lack of Alarm Philosophy, Alarm Rationalization, and State-Based Alarming as Contributing Factors to Blowout in Oklahoma
On January 22, 2018, a blowout and rig fire at the Pryor Trust gas well killed five workers, who were inside the…
Alarm floods are periods of alarm activity during which the alarm rate is greater than the operator can effectively manage (e.g., when the operator receives ≥10 alarms in 10 minutes). During a flood situation awareness is compromised and alarms are likely to be missed. In the eleven minutes prior to the explosion…
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…
The ISA-18.2 and IEC 62682 standards define an alarm as an “audible and/or visible means of indicating to the operator an equipment malfunction, process deviation, or abnormal condition requiring a timely response”. One of the reasons why alarm systems are out of control (alarm overload, nuisance alarms)…
As the name implies, the purpose of Safe Operating Limits (SOL) is to define the limits beyond which a process will not intentionally be operated and at which troubleshooting ceases, replaced by pre-determined actions to bring the process to a safe state. Pretty important information. I am sure this is…
As discussed in What do Nuisance Alarms, the 80-20 Rule, and Mental Models Have in Common?, there are typically a handful of alarm points (10 to 20) that create the majority of notifications (50-80%) to the operator (referencing the 80-20 rule). These nuisance alarms are affectionately called “bad…
In an ideal world, every alarm in a process control system would indicate a malfunction or abnormal condition that required operator action. In the real world, alarms that are irrelevant or annunciate excessively—otherwise known as nuisance alarms—can pop up occasionally to quite frequently. They pose a risk to the…
Which one of these layers of protection (operator response to alarm, relief valves, dikes, and safety instrumented systems) is not like the other?
Operator response to alarm (Operator Intervention), because of the “Human” factor.
It is very difficult to calculate the probability…
Throughout history, total solar eclipses have been a significant event. In primitive societies, eclipses were viewed with fear or as important omens. In the US, the upcoming “Great American Solar Eclipse” is creating much excitement. From buying “official” eclipse-viewing glasses, to paying $1500 or more…
Most everyone has heard of the “80-20 rule”. It asserts that for many situations, roughly 80% of the effects (outcomes) come from 20% of the causes (inputs). This rule was first proposed in the early 1900s by Vilfredo Pareto, who was an Italian engineer, sociologist, economist, political scientist, philosopher,…
The purpose of an alarm is pretty straightforward - to draw the operator’s attention to an abnormal situation that requires action in order to prevent an undesired consequence. Alarms that don’t meet this principle often become nuisance alarms. A nuisance alarm is defined as:
“an alarm that annunciates excessively,…
In the book “Outliers”, Malcolm Gladwell popularized the notion that to become an expert in a field requires putting in 10,000 hours of practice.
The emerging picture from studies of expertise is that ten thousand hours of practice is required to reach the level of mastery associated with being…