Machinery Directive standard delayed
September 14th 2009 The European Committee for Standardisation has postponed the date of cessation of presumption of conformity of EN 954-1 until the 31st Dec 2012. Derek Jones of Rockwell Automation explains some of the implications of this.
From the perspective of the many parts of industry that have expended time and effort to be ready for the transition away from the old standard this decision will be seen as disappointing. However it is very important to understand the real intent and implication of the decision, The wording makes it very clear that, whilst it is understood that some parts of industry may still have issues in moving to the new standard, this is a final extension and the extra time allowed should definitely be used to move to the new standards.
Caution should be counselled for anyone who may think this is an extended opportunity to ignore the impending changes. It will not be clear for some time exactly what the full implication might be. Perhaps some of the best clarification will be given in the forthcoming official EU guidance document on the new Machinery Directive. That is still under preparation but it is likely to set the preference for following EN ISO 13849-1 (or EN 62061)wherever possible, as opposed to the old EN 954-1.
We must remember that these later standards were introduced for a reason, one of the most significant of which was the fact that the old standard was no longer suitable for use with complex safety functions and complex technology. That is a fact that bears some consideration.
Also, some of the machine specific C type standards have already been updated to reference only the later standards. In these cases, if the old standard is used, it is not immediately clear what the implications are. The decision to extend the presumption of conformity of EN 954-1 is one thing but that does not necessarily mean that a requirement for PLd can be met by a system that only satisfies the old requirements for Category 3.
Also some less obvious but important implication arise when the later standards alone are referenced in another standard. One of the most significant and universally applied standards is EN 60204-1: Safety of Machinery – Electrical equipment of Machines. The latest amendment and annex to this standard state that the requirements of EN ISO 13849-1 or EN 62061 shall be applied. Again it is not immediately clear what the implications will be of using the old EN 954-1.
It is also an unfortunate fact that, after all the movement towards global machinery safety standards with common texts between EN and ISO/IEC, we will now have the situation where EN 954-1 will only be recognised within Europe.
The equivalent old 1999 version of ISO 13849-1 has already been withdrawn and replaced by the later version. Again, it is not yet clear how machinery customers outside Europe will react to a machinery control system that is designed to a standard that is only relevant in Europe.
It is understood, of course, that the extension to EN 954-1 also has good and positive aspects when used intelligently. It may help with some technology, notably low complexity hydraulic or pneumatic devices where suitable data may still be hard to find. It is also a good thing if the transition from old to new has more time to be digested. Haste in safety cannot be a good thing. It must be agreed that the relatively recent availability of data for safety products has meant too short a transition time for some machine builders.
It would seem that one of the greatest needs is for education and, looking on the positive side, this extension now provides more time for a properly structured and focused training and information transfer. The fact that the extension to EN 9654-1 probably raises even more grey areas makes this doubly important.
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