PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 3, Number 2, 2017
The planned merger of EN ISO 13849-1 and EN 62061 into IEC/ISO 17305 by the Joint Working Group JWG1 did not eventually come to pass, however, during the attempt an official request was made to alter the existing version of EN ISO 13849-1 which did take place in December 2015. The latest 2015 edition is now harmonised to the Machinery Directive. The modifications are in some cases purely editorial (such as the suffix “d” used in MTTF d , B10 d and elsewhere being replaced by “D”), however, some importan t clarifications and shifts have been included, and it is now the case that EN ISO 13849-1:2015 is the go-to standard for safety-related controls on machines since the previous edition is no longer harmonised to the Machinery Directive 2006/42/EC. In section 1 the table comparing the recommended application of EN ISO 13849-1 and EN 62061 has been removed, but EN 62061 is still mentioned. In section 2 normative references to other standards have been updated, such as ISO 12100:2010 for risk assessment and risk reduction. In section 3 (terms and definitions) one addition is the me ntion of “proven in use” which means demonstration, based upon operation experience for a specific configuration of a component that a likelihood of a dangerous failure is low enough not to impact the Performance Level of all safety functions incorporating that component. Later in the standard it becomes clear in 4.5.5 that this is only “allowed” for mechanical, hydraulic and pneumatic elements where omission of MTTF D is to be justified, and proven in use would need to be stated by the manufacturer of the component. Quite a lot of change has happened in section 4 Design Considerations. In section 4.5.2 the limitation of MTTF D to 100 years (capping) was previously applicable to all subsystems regardless of category, which had the undesirable effect of limiting the number of category 4 subsystems which could be combined without a drop in Performance Level from PL e to PL d. This was thought to be too conservative, therefore, for category 4 subsystems the capping limit has been raised to 2500 years which means later in the informative annex K the table K1 now covers this extended range instead of 100 years. This higher value is justified because in Category 4 other quantifiable aspects (structure and Diagnostic Coverage) are at their maximum point. As a result of this there is no longer a need to combine input and actuator elements as one subsystem in some cases, which was previously sometimes needed especially for hydraulic and pneumatic components.
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Article 10 – Pilz on Safety Controls
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