P6: The average probability of dangerous failure per hour (PFH)
In the previous articles we explored the Parameter PFDavg: Average Probability of Failure on Demand. It is used to indicate the reliability of a Safety Instrumented System operating in Low demand. We will now explore the domain of Safety-related Cont...
Process Safety
Proof Test and Diagnostic Coverage
THE DOUBT: What is the difference between a Proof Test and a Diagnostic Test?
CONSIDERATIONS: The Proof Test concept is coming from IEC 61508 and it is im...
Process Safety
High versus Low Demand
THE DOUBT : What does it mean that a Safety Control Systems is operating in High or in Low Demand and why is it important to know it?
CONSIDERATIONS:...
Process Safety
Safety Contactors and their usage
THE DOUBT: What is a safety contactor and is their usage compulsory in a Safety related control circuit?
CONSIDERATION 1: There are 2 main types of contac...
Functional Safety
Well-tried components
THE DOUBT
Why are well-tried components important in Machinery Safety?
CONSIDERATIONS
The concept is defined in both ISO 13849-1 and IEC 62061. Those...
Functional Safety
What standards to follow in USA and Canada?
THE DOUBT: If you are a machinery manufacturer, you may be lost by the so many standards mentioned when discussing export to USA or Canada. The question yo...
UL and CSA Conformity
Assembly of Machinery
THE DOUBT: Shall a group of machinery be CE Marked? When can I say a certain group of machinery constitute an Assembly of Machinery and therefore, it must be CE...
Machinery Directive
The importance of layout analysis in risk assessment
EN ISO 11161 is the reference standard regarding the safety of the Integrated Machinery System (which henceforth in the article will be simply called IMS).
The...
Machinery Safety
The concept of SPAN-OF-CONTROL
The standard ISO 11161 of May 2007 introduces the concept of span of control, which identifies the predetermined portion of a machine under control of a specifi...
Machinery Safety
TABRA: A task based approach to risk assessement in Machinery
When applying ISO 12100 we tend to focus on the hazards that result form situations an operator or the maintenance team can incur to, while in North America the...
Machinery Safety
Short-circuit aspects: NEC vs IEC
There are several differences between the North American and International electrical standards (published by IEC).
One of those differences is the way...
UL and CSA Conformity
