exida explains Blog

Entries tagged with: SAEL

A Ball Valve with Safe Failures! Really?

Look at the photo. What do you see? I see a ball valve with:

  • a valve body
  • a ball
  • a stem that can turn the ball

What are the high level potential failures for a ball valve?

A Spring Return Scotch-Yoke Actuator with No Safe Failures! Really?

scotch yoke

Look at the picture. What do you see? I see a spring return actuator with

  • a diaphragm chamber
  • a spring chamber
  • the scotch-yoke mechanism

What are the high level potential failures for a ball valve?

  • Scotch-yoke mechanism breaks, can no longer operate valve…


  • by Dr. William Goble, CFSE
  • Thursday, May 09, 2013
  • Certification

Certificate Forgery!

exida has discovered yet another forged functional safety certificate.  You can read about another occurrence in a previous blog entry.

False Certificate

The company name on the forged certificate is ISP SA DE CV, Cunduacan, Tab., Mex.  How could someone…


The exida Certificate Explained

The exida Certificate Explained

A manufacturer whose product passes the exida IEC 61508 Assessment Scheme will receive a certificate based on IEC 61508 and perhaps other functional safety standards. There is a significant amount of information on a certificate that may not be always trivial for a novice. This document explains how one…