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ISO 13849-1 Machine Guarding adoption, part 2
August 24, 2011
The scope statement in this standard reads, “This part of ISO 13849 provides safety requirements and guidance on the principles for the design and integration of safety-related parts of control systems (SRP/CS), including the design of software. For these parts of SRP/CS, it specifies characteristics that include the performance level required for carrying out safety functions. It applies to SRP/CS, regardless of the type of technology and energy used (electrical, hydraulic, pneumatic, mechanical, etc.), for all kinds of machinery.” Good stuff, right?
And, according to the European Machinery Directive, at the end of December 2011 EN 954-1; 1996 will be withdrawn and can no longer be used to demonstrate conformity.
Over the last 15 years EN 954-1 did a great job of helping OEMs, systems integrators, and end users understand categories of hazards and the importance of mitigating those hazards to acceptable levels and improve overall safety. Also, over the last fifteen years automation suppliers have stepped to the plate bringing a lot of new products to market designed, tested and certified for safety applications. Many of these new products are hardware and software based offering complicated new sources of possible failures and potential hazards. In my opinion, this transition in innovation for safety technology to a large part has driven the need for a quantitative approach to evaluate the performance level of safety circuits and to include the evaluation of software. Specifically, the level of diagnostics included in the software.
The system designers from the OEM’s and systems integrators will use EN ISO 13849-1 and the quantitative analysis of the safety circuits to determine the performance levels to achieve required safety functions during the design phase. This gives the designers the flexibility to modify the design in order to meet the acceptable hazard levels determined in the risk assessment. So, life is good – right?
Well, in my mind the transition for the end user is a little bit different. Under the qualitative approach of EN 954-1 the OEM, systems integrator, and end user all likely had the competencies to demonstrate conformance. Under EN ISO 13849-1 do all of the end users have the competencies to demonstrate conformance when compared to the system designers of the OEM’s and systems integrators? Only you can answer this question. According to a Control Engineering survey via Webex in April of this year respondents were asked if they needed outside help or tools in order to meet the compliance requirements. A full 38% indicated they needed help and 42% indicated maybe or unsure!(See pie graph, above.)
I’m not sure how many of these respondents were end users, but we’d sure like to know your opinions, questions, or experiences and what you can add to this discussion?
Your comments or suggestion are always welcome so please let us know your thoughts. Submit your ideas, experiences, and challenges on this subject in the comments section below. Click on the following text if you don't see a comments box, then scroll down: ISO 13849-1 Machine Guarding Adoption, Part 2.
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For more than 30 years, J.B. Titus has advised a wide range of clients on machine functional safety solutions, including Johnson + Johnson, Siemens, General Motors, Disney, Rockwell Automation, Bridgestone Firestone, and Samsung Heavy Industries. He holds a Bachelor of Business Administration degree from Oklahoma University in industrial management and an MBA from Case Western Reserve University in marketing and finance. He is a professional member of the American Society of Safety Engineers and is OSHA-certified in machine guarding. Titus is also TUV-certified as a Functional Safety Expert and serves on several American National Standards Institute, National Fire Protection Association, and National Electrical Manufacturers Association national safety and health standards committees. Reach him at jb(at)jbtitus.com and via www.jbtitus.com.