Machine safety: Incorporating functional safety, part 1

When considering “functional safety,” look at what differs compared to other safety initiatives, consider U.S. versus international standards, examine conformance responsibilities, and think about what changes are needed, if any, as a manufacturer.

03/13/2013


When considering “functional safety,” look at what differs compared to other safety initiatives, consider U.S. versus international standards, examine conformance responsibilities, and think about what changes are needed, if any, as a manufacturer. 

  1. What is so different about “functional safety”?
  2. Are U.S. domestic standards adopting functional safety requirements from the international standards?
  3. Do the international standards place primary conformance responsibility on manufacturers like with OSHA?
  4. Do we have to change our machine safety program as a manufacturer to meet the compliance requirements?

 

Functional safety can fit with other safety initiativesLet’s take a look at these four questions addressing the first question here in Part 1.

 

Definition from IEC 61508-1 - Functional safety is “part of the overall safety relating to the equipment under control and the equipment under control’s control system which depends on the correct functioning of the Electrical/Electronic/Programmable Electronic safety-related systems, other technology safety-related systems and external risk reduction facilities”.

 

What is so different about “functional safety”?

Who has an answer or supporting comment about this question? From my perspective the major difference in approach is to design in machine safety and to take into consideration the life cycle performance of safety-related functions. This approach therefore brings into consideration factors such as; mean time to fail dangerous, diagnostics, reliable cycles, software and firmware and many more considerations for each component in a given safety-related circuit. A circuit is also considered as electrical, electronic, pneumatic, and hydraulic.

 

Prior methodologies did not take these factors into consideration in my opinion. Also, aren’t functional safety standards intended to encourage designers to focus more on the functions that are necessary to reduce each individual risk, and what performance is required for each function, rather than simply relying on particular components?

 

The primary standard addressing functional safety requirements is ISO 13849-1: 2006 Safety of machinery —Safety-related parts of control systems.

 

J.B. Titus, CFSE

Have you found difficulty understanding any of these issues?  Add your comments or thoughts to the discussion by submitting your ideas, experiences, and challenges in the comments section below.

 

Related articles:

Inside Machines: Does adopting ISO 13849-1:2006 change the U.S. model for compliance and enforcement?

Machine Safety – does OSHA reference consensus standards for compliance?

Machine Safety: Is OSHA okay with my 'acceptable' risk mitigation?

 

Contact: http://www.jbtitus.com for “Solutions for Machine Safety”.



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