Parts I and II of this article provide a framework for when it is appropriate to make the transition from qualitative analysis to more quantitative during the hazard review work process. It further illustrates that LOPA can be used as part of what is considered more qualitative analysis…
exida explains Blog
- by Michael Medoff , CFSE, CISA
- Wednesday, August 10, 2011
- Industrial Cybersecurity
Keeping “Dancing Monkeys” out of your PLC
Last week a security researcher, Dillon Beresford of NSS Labs, presented at the Blackhat conference on the security vulnerabilities he found in Siemens PLC firmware. One of many stories on Dillon’s findings can be found here. Among other things, Dillon found “dancing monkeys” in the code! Actually,…
- by Dr. William Goble, CFSE
- Thursday, August 04, 2011
- Certification
Not Perfect? Not Good
Over the years I have heard good ideas rejected. We have all done this and observed others doing the same. As far as safety equipment, I recall when the first safety certified pressure transmitter, the Moore 345, was released to the market. Several potential customers said “it doesn’t…
- by John Yozallinas, CFSE
- Tuesday, June 21, 2011
- Certification
How does CMMI help my safety assessment?
We have CMMI processes at CL3; does that help us get IEC 61508 certification for SIL 3?
Companies that deliver a product or service do so by following a sequence of processes. High quality deliverables are a result of high quality processes and continuous improvement in…
- by Dr. William Goble, CFSE
- Tuesday, June 07, 2011
- Certification
The Weakest Link
One of the objectives of new performance based standards like IEC 61508 is to allow performance metrics (like PFDavg for low demand systems) to identify the weak links in any proposed design. Obviously, it is not necessary to put effort into design and spend money on areas…
- by Michael Medoff , CFSE, CISA
- Wednesday, June 01, 2011
- Industrial Cybersecurity
Industrial automation is in the cross hairs of the hacker
As the details of STUXNET’s design unfolded last fall, like many, I was truly impressed by the pin-point precision that the malware authors used to ensure that their target, and only their target, was impacted by the virus. In this regard, STUXNET may be one of the…
- by Dr. William Goble, CFSE
- Thursday, May 26, 2011
- Functional Safety
Keep Risk Personal
We are fortunate that Risk Analysts have developed a logical framework of quantitative and semi-quantitative analysis techniques that allow us to assess and optimally mediate risk. And we all know that this is part of the Safety Lifecycle, a series of engineering steps/procedures that represent best safety practices. These…
- by Hal Thomas, CFSE
- Tuesday, May 24, 2011
- Functional Safety
When is a Variable Frequency Drive a SIS?
It used to be that a pump would operate at a single speed dictated by a motor, thus fixing the pump curve. As the discharge flow decreased due to a restriction downstream, the pump outlet pressure would increase reaching its deadhead pressure. If the downstream piping and vessels were…
- by Dr. William Goble, CFSE
- Thursday, May 12, 2011
- Certification
Buy Certified Equipment, Meet the Standard, Right? WRONG!
While correcting a CFSP exam, I read a question which went something like this:
If you purchase all IEC 61508 certified equipment for a low demand safety instrumented function, then to meet the requirements of IEC 61511:
A. No other design verification is needed
B.…
- by John Yozallinas, CFSE
- Thursday, April 28, 2011
- Certification
What is So Important About Derating?
Some designs push their operating specifications right up to the limit of the components in the system or device. (let’s not talk about the designs that try to spec a limit that is beyond the capability of one or more components… phooey on them!) And if you make a…
- by Dr. Eric Scharpf, CFSE
- Monday, April 18, 2011
- Functional Safety
Lifecycle Analysis: It’s Worth the Effort
Performing a risk analysis as part of an IEC61508 / 61511 / ISA 84.01 safety lifecycle process can be quite challenging. How can you be sure you get what you need within budget and how can your team provide the best value for money?…
- by Iwan van Beurden, CFSE
- Friday, April 15, 2011
- Certification
Functional Safety and Taxes: Are you an expert?
Today, April 15th, is tax-day in the US. Ok, the Internal Revenue Service (IRS) has given us a few extra days this year (the tax filing deadline is not until April 18th).
There are a lot of similarities between how you do your taxes and how you handle…
- by John Yozallinas, CFSE
- Thursday, April 14, 2011
- Certification
Stepping stones to SIL 3
Imagine. Marketing has just approached the engineering department and says your new safety product must have SIL 3 Capable certification instead of SIL 2 to be successful. You are in the engineering group developing this new product. Now what?
Let’s assume that the “change request” makes…
- by Dr. William Goble, CFSE
- Saturday, April 09, 2011
- Functional Safety
Driving with Blinders
Imagine: An automobile that has only one window in the front. No side windows. The driver can see to steer the auto forward and turn, but cannot see completely from side to side. What happens when the driver reaches an intersection with no traffic lights? The driver cannot see…
- by Dr. William Goble, CFSE
- Thursday, April 07, 2011
- Functional Safety
Certified to SIL 4 - Cycle Test Failure Data is Dangerous
I got a copy of the IEC 61508 certificate for a solenoid valve today from an engineer who thought something was wrong. Although the certificate was from a well known certification company, the certificate gave a “Dangerous Failure Rate” of 1.7 FITS (1.7 * 10-9 failures per…