More Standards are Coming: What you need to Know

-- Control Engineering, 5/23/2007

The British are coming. So, too, are the Germans and French, with the standards relating to machine and system safety. The new standards, EN62061 and EN ISO 13849-1, signal the advent of the Performance Level (PL), a risk-based assessment that categorizes machine but not process safety. The transition to the new standards will take place over the next two years.

For those original equipment manufacturers exporting to Europe, the changes are important immediately, but the new standards are likely to impact everyone involved in machine safety. For one thing, there are global end users with a worldwide reach, companies with plants around the globe. They don’t like standards divergence and they do like standards harmony. For another, the same can be said for governing bodies in North America or elsewhere. So some version of the new safety standards will probably be adopted worldwide.

That may be some time off but global end users could hasten the de facto adoption of the safety requirements through their suppliers. These vendors sell to others as well, and so market forces may lead to a more rapid implementation of the standards than the pace dictated by standards groups.

As for what’s in the new standards, one of the biggest changes is the replacement of machine safety categories with PLs. The former are determined by a series of yes/no questions, leading to a pegging of a machine as a category 2 or 3 and so on. Problems with this approach are that the answer depends upon who’s asking the question, which makes it difficult to always come up with the same final determination. Another issue is that categories have no relationship to SIL, which is used by manufacturers running a process. Thus there’s no way to answer the question about what’s the SIL rating of a category 2 machine.

The new standards solve these problems by getting rid of categories in favor of Performance Levels that run from a to e. The severity of injury, the frequency and/or duration of exposure, and the possibility of prevention all play a part in determining the PL, in a manner analogous to the way similar variables play a role in finding SIL. By going to PLs, the variability in assessing machine safety is minimized and so the same result can be arrived at by the machine’s maker and its end user. With PLs, it’s also easier for machine makers and machine users to talk to one another since it is possible to translate from SIL to PL and vice versa. So those companies running a process can talk in a quantitative way about safety with those making the processing machines in terms that both can understand – with a bit of translation.

When the widespread adoption of this new way of looking at machine safety might happen isn’t yet known. The transition clearly won’t take place any faster than the one in Europe, which is already underway and due to wrap up by 2009. Past experience suggests it will be some time after that before the new standards will be adopted elsewhere. The gating factor could be the production and adoption cycle of North American standards. If that’s the case, then the maximum time before the new safety approach makes it appearance will be a few years past 2009.

If you would like to learn more about these standards and how they may affect you, Siemens is hosting a series of educational webcasts covering a host of Machine Safety, Risk Assessment and international standards topics.  Please click here to learn more.