Machine safety: Does ISO 13849-1: 2006 weight severity, frequency, and probability equally?
New quantitative requirements for designing safety-related parts of the control system (SRP/CS) have created many discussions. Even with new requirements from ISO 13849-1, this updated standard begins with the same old qualitative approach to determine the “goal” (Performance Level required- PLr) for any safety function, asking about severity, frequency, and probability.
New quantitative requirements for designing safety-related parts of the control system (SRP/CS) have created many related discussions about machine safety. Yet, even with these new requirements from ISO 13849-1, this updated standard begins with the same old qualitative approach to determine the “goal” (Performance Level required- PLr) for any safety function. The same three questions are still asked; Severity, Frequency and Probability.
EN954-1 came out in 1996 with an amazing way to put more teeth into determining a hazard level and related mitigation solution for any recognized hazard. In so doing we had to analyze each hazard by evaluating the related potential injury by severity, frequency, and probability according to the graph below.
Ten years later in 2006 ISO 13849-1 was updated and released introducing Performance Levels and the requirement to develop the PLr, which I call the goal. To develop the PLr, we again use the qualitative approach by evaluating the related potential injury by severity, frequency, and probability also shown in the graph. There’s a whole lot more we could get into here but let’s keep it focused at the three questions.
What was the criteria for approaching these three questions in their order of severity, frequency and probability? Is severity weighted the most because it’s the first question? Such as; S = 50%, F = 30% and P = 20%? Or is probability asked last because of its greater impact? Such as; S = 25%, F = 35% and P = 40%? Or, does it matter at all? Can all three questions be equally interchanged?
Can anybody provide some insight and background? Has this presented you with any new perspectives? Add your comments or thoughts to the discussion by submitting your ideas, experiences, and challenges in the comments section below.
Contact: http://www.jbtitus.com for “Solutions for Machine Safety”.
- Events & Awards
- Magazine Archives
- Oil & Gas Engineering
- Salary Survey
- Digital Reports
- Survey Prize Winners
Annual Salary Survey
Before the calendar turned, 2016 already had the makings of a pivotal year for manufacturing, and for the world.
There were the big events for the year, including the United States as Partner Country at Hannover Messe in April and the 2016 International Manufacturing Technology Show in Chicago in September. There's also the matter of the U.S. presidential elections in November, which promise to shape policy in manufacturing for years to come.
But the year started with global economic turmoil, as a slowdown in Chinese manufacturing triggered a worldwide stock hiccup that sent values plummeting. The continued plunge in world oil prices has resulted in a slowdown in exploration and, by extension, the manufacture of exploration equipment.
Read more: 2015 Salary Survey