I was recently asked how the PFDavg value in an exida FMEDA report was calculated. Those PFDavg values are calculated using the exSILentiaTM program. The person who posed the question was using the equations from Part 6 of IEC 61508 and got a different value. Why?
exida explains Blog
- by Ted Stewart, CFSP, exidaCSP
- Friday, February 22, 2013
- Certification
Why Personnel Functional Safety Certification Programs are Needed
The publication of the international functional safety standards IEC 61508 (1999), IEC 61511 / ISA-84 (2004) and IEC 62061 (2005) were significant milestones in the effort to increase equipment and process safety. 1,2,3 Unfortunately, the release of safety standards does not by itself make the world a safer place.…
- by John Yozallinas, CFSE
- Tuesday, February 19, 2013
- Certification
It’s Just a Little Change…
Once there was a laundry room with old, worn-out linoleum floor. It was functional but did not have the look and feel of newer homes. The lady of the house decided to replace the flooring with new ceramic tile. She engaged her husband with the idea, outlining the benefits…
- by Loren Stewart, CFSE
- Thursday, February 14, 2013
- Functional Safety
Stiction: Fact or Fiction & Start Time Prediction
Click here to read the blog “What is Stiction?”
Stiction is a phenomenon that is beginning to become an accepted theory among engineers. It…
- by Loren Stewart, CFSE
- Tuesday, February 12, 2013
- Functional Safety
How Does Stiction Affect Me?
Click here to read the blog “What is Stiction?”
In normal operation of a solenoid valve, the O-rings in the valve create a smooth transition while the plunger or spool is in motion. Because the O-rings are in direct…
- by Loren Stewart, CFSE
- Thursday, February 07, 2013
- Functional Safety
What is Stiction?
Many studies and organizations have defined stiction, or static friction, in different ways. A few examples of the various definitions are as follows:
- According to Entech [1], “stiction is a tendency to stick-slip due to high static friction. The phenomenon causes a limited resolution of the resulting…
- by Chris O'Brien, CFSE
- Tuesday, February 05, 2013
- Software
How Do You Handle Interposing Relays?
Many times in the design of a safety instrumented system it is necessary to utilize an interposing relay. Typically there is not a certified relay available. Since no certified product is being used it is important to follow the requirements to justify prior use and also to design…
- by Todd Stauffer
- Wednesday, January 30, 2013
- Alarm Management
New Working Group (WG7) Formed for Alarm Management
The ISA-18.2 committee on alarm management has launched a new working group (WG7) that is focused on developing a standard, recommended practice, or technical report on the application of alarm management to process plants utilizing multiple packaged equipment systems. The work will be based on and complement the existing…
- by Ted Stewart, CFSP, exidaCSP
- Monday, January 28, 2013
- Functional Safety
Understanding Our Customers – One Step Closer to Excellence
Customer service isn’t about slashing prices or offering great rates. Sure these types of strategies can promote new customers and generate business, but how often do the “new customers” return if the service or product didn’t meet their expectations? It’s always said that a great sales person can sell…
- by Dr. William Goble, CFSE
- Thursday, December 20, 2012
- CertificationIndustrial Cybersecurity
2012 - Good Progress for Cybersecurity and Functional Safety
Product Certification
Over 60 new products received functional safety or cybersecurity certification this year. Those products and more…
- by Dr. William Goble, CFSE
- Thursday, December 13, 2012
- Functional Safety
Replace Before Failure
The solenoid valve manufacturer provides an FMEDA report that lists “useful life = 12 years.” Useful life is a reliability engineering term that indicates a point in time when the failure rate of a device will begin increasing rather rapidly. Why do we care about this time interval? That…
- by John Yozallinas, CFSE
- Thursday, December 06, 2012
- Software
Spaces and Braces and Comments – Oh My!
What constitutes a good coding guideline?
Serious software development for functional safety requires a coding standard or coding guideline. Most organizations have one, but how do you know if it’s good?
You need to look beyond the boilerplate and physical code layout that are often defined in a coding…
- by Michael Medoff , CFSE, CISA
- Thursday, November 29, 2012
- Certification
Tool Qualification and Safety Standards
When building a product such as an anti-lock braking system for an automobile, or a railroad, or process control safety system, making sure that the product works as specified is a big part of functional safety. When it is time for the system to engage to prevent an accident,…
- by Todd Stauffer
- Monday, November 26, 2012
- Alarm Management
Alarm Rationalization is “Going Green (field)”
- by Dr. William Goble, CFSE
- Thursday, November 15, 2012
- Certification
Certification Accreditation
I am often asked “who says exida can certify a product?” The best answer is of course “the marketplace.” End user owner/operators ask for an exida certificate because they understand why technical competency is so important when evaluating design quality. Then instrumentation manufacturers get an exida certificate because exida…