31-​​December-​​2011 marks a key mile­stone for machine builders mar­ket­ing their prod­ucts in the European Union, the EEA and many of the Candidate States. Functional Safety takes a pos­i­tive step for­ward with the manda­tory appli­ca­tion of EN ISO 13849–1 and –2. As of 1-​​January-​​2012, the safety–related parts of the con­trol sys­tems on all machin­ery bear­ing a CE Mark will be required to meet these standards.

This change started six years ago, when these stan­dards were first har­mo­nized under the Machinery Directive. The EC Machinery Committee gave machine builders an addi­tional three years to make the tran­si­tion to these stan­dards, after much oppo­si­tion to the orig­i­nal manda­tory imple­men­ta­tion date of 31-​​Dec-​​08 was announced.

If you aren’t aware of these stan­dards, or if you aren’t famil­iar with the con­cept of func­tional safety, you need to get up to speed, and fast.

Under EN 954–1:1995 and the 1^st Edition of ISO 13849–1, pub­lished in 1999, a designer needed to select a design Category or archi­tec­ture, that would pro­vide the degree of fault tol­er­ance and reli­a­bil­ity needed based on the out­come of the risk assess­ment for the machin­ery. The Categories, B, 1–4, remain unchanged in the 2^nd Edition. I’ve talked about the Categories in detail in other posts, so I won’t spend any time on them here.

The 2^nd Edition brings Mean Time to Failure into the pic­ture, along with Diagnostic Coverage and Common Cause Failures. These new con­cepts require design­ers to use more ana­lyt­i­cal tech­niques in devel­op­ing their designs, and also require addi­tional doc­u­men­ta­tion (as usual!).

One of the main fail­ings with EN 954–1 was Validation. This topic was sup­posed to have been cov­ered by EN 954–2, but this stan­dard was never pub­lished. This has led machine builders to make design deci­sions with­out keep­ing the nec­es­sary design doc­u­men­ta­tion trail, and fur­ther­more, to skip the Validation step entirely in many cases.

The miss­ing Validation stan­dard was finally pub­lished in 2003 as ISO 13849–2:2003, and sub­se­quently adopted and har­mo­nized in 2009 as EN ISO 13849–2:2003. While no manda­tory imple­men­ta­tion date for this stan­dard is given in the cur­rent list of stan­dards har­mo­nized under 2006/​42/​EC-​​Machinery, use of Part 1 of the stan­dard man­dates use of Part 2, so this stan­dard is effec­tively manda­tory at the same time.

Part 2 brings a num­ber of key annexes that are nec­es­sary for the imple­men­ta­tion of Part 1, and also out­lines the com­plete doc­u­men­ta­tion trail needed for val­i­da­tion, and coin­ci­den­tally, audit. Notified bpdies will be look­ing for this infor­ma­tion when eval­u­at­ing the con­tent of Technical Files used in CE Marking.

From a North American per­spec­tive, these two stan­dards gain access through ANSI’s adop­tion of ISO 10218 for Industrial Robots. Part 1 of this stan­dard, cov­er­ing the robot itself, was adopted last year. Part 2 of the stan­dard will be adopted in 2012, and RIA R15.06 will be with­drawn. At the same time, CSA will be adopt­ing the ISO stan­dards and with­draw­ing CSA Z434.

These changes will finally bring North America, the International Community and the EU onto the same foot­ing when it comes to Functional Safety in indus­trial machin­ery appli­ca­tions. The days of “SIMPLE, SINGLE CHANNEL, SINGLE CHANNEL-​​MONITORED and CONTROL RELIABLE” are numbered.

Are you ready?

Compliance InSight Consulting will be offer­ing a series of train­ing events in 2012 on this topic. For more infor­ma­tion, con­tact Doug Nix.

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