Most engineers who design and verify safety instrumented functions (SIFs) understand how hard it is to design a manual proof test with high effectiveness (also called high proof test coverage). Those folks who understand that a proof test is not likely to detect all failures never use simplified equations…
exida explains Blog
Entries tagged with: FMEDA
- by Dr. William Goble, CFSE
- Thursday, October 16, 2014
- Certification
How to Calculate Proof Test Coverage
- by Michael Medoff , CFSE, CISA
- Thursday, October 29, 2020
- Industrial Cybersecurity
IEC 62443 Cybersecurity Certification for Medical Devices
exida has traditionally been involved in industries such as oil and gas, chemicals, power generation and automotive. While these are a diverse set of industries, many of the techniques that we use such as FMEDA (Failure Modes Effects and Diagnostic Analysis), Risk Assessment, Threat Modelling, etc.…
- by Dr. William Goble, CFSE
- Wednesday, February 16, 2022
- Certification
Most Failures are Systematic - NOT!
At exida we have studied hundreds of sets of field failure data from various sources. Some of these data sets have indicated differences in failure rates by two orders of magnitude for the same product type! After tracing through the data collection process for many of these field failure data sets,…
- by Dr. William Goble, CFSE
- Tuesday, July 07, 2020
- Functional Safety
OLD component data = Bad FMEDAs
When we first invented the FMEDA technique in the late 1980s the biggest problem was the component failure rate and failure mode data. Still is. I picked up a well-known standard for component failure rates and saw a date of 2010. The technology world has gone through an order of…
- by Chris O'Brien, CFSE
- Friday, January 17, 2014
- Certification
Product Stewardship and Engineering Ethics
Recently I witnessed something I never thought I would in the engineering profession: I was told by a system designer that even though they knew the safety reliability data for one device was too optimistic, they were going to use it because it meant they didn’t need to…
- by Dr. William Goble, CFSE
- Wednesday, May 07, 2014
- Certification
Random vs. Systematic?
Most of you know that exida gathers field failure data from many sources including manufacturers’ warranty return data and end user maintenance/failure records. At this point we have nearly 100 billion unit operating hours of data. This is probably the largest process industry data set in the world. And…
- by Dr. William Goble, CFSE
- Thursday, November 17, 2016
- Functional Safety
Realistic Failure Rate Data – Necessary
Reliability engineers have known for decades that realistic data must ultimately come from one source, quality field failure data for devices operating in a similar application.
Perhaps that is why IEC 61511:2016, Clause 11.9.3 states
“The reliability data used when quantifying the effect of random failures shall…
- by Loren Stewart, CFSE
- Tuesday, December 22, 2015
- Functional Safety
SILSafe Data Website
exida has launched the web site www.silsafedata.com. SILSafe Data is a web site listing a number of product categories used in process control and the expected range of failure rates for process industry applications. The use of realistic and application appropriate failure rate data has a significant…
- by Dr. William Goble, CFSE
- Monday, April 11, 2016
- Certification
Site Safety Index™ (SSI) – A Simple Model for Site Variations in Safety
In several of our technical papers over the years, we have noticed that failure rates for the manufacturer, model number are different at different sites, even when the processes were quite similar. When I have mentioned this to end users and manufacturers, often the response is “Yes, I have…
- by Dr. William Goble, CFSE
- Tuesday, January 27, 2015
- Functional Safety
The exida FMEDA Process - Accurate Failure Data for the Process Industries
In this blog, I will talk about the FMEDA method and how it can generate realistically accurate failure rate data.
The first question we have to ask is “why do you need failure rate data ?”
One of the fundamental concepts in today’s functional safety standard, IEC 61508 and…
- by Dr. William Goble, CFSE
- Monday, October 29, 2018
- Certification
Using SILSafeData to Check Your Failure Data Source
www.SILSafeData.com is a complimentary resource that contains the upper and lower bounds failure rates for many categories of automation equipment, as well as the methodology used by exida to derive the numbers.
Many of you have asked how to…
- by Paddy Healy
- Tuesday, April 18, 2023
- Functional Safety
What is a FMEDA?
In the 1980’s, there was a raging debate in the functional safety committee about redundancy versus diagnostics. Some said functional safety could only be achieved with redundant systems. This was strongly supported by Triple Modular Redundant (2oo3) safety PLC vendors.
Others argued that diagnostics would be an equal or…
- by Jonathan Moore
- Tuesday, October 29, 2019
- Certification
Why Does My Risk Assessment Require an FMEDA?
If you find yourself faced with this question you might be wondering why it is that having successfully used risk assessments without FMEDA your team are suddenly faced with the complexity of executing FMEDAs.
Maybe us safety people answer with a follow…
- by Todd Stauffer
- Thursday, August 12, 2021
- Software
“Data is King” – Introducing the Sovereign of Component Reliability Databases
With the drive for digitalization and the Internet of Things the expression “Content is King”, coined by Bill Gates, has now been replaced by “Data is King”. This is especially TRUE in functional safety where the safety and reliability predictions generated from a Failure Modes, Effects & Diagnostics Analysis…
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