Packaging automation professionals tend to be very aware of safety, knowing that safety failures can have both human and business costs. They are typically less aware, though, of the seeming avalanche of safety standards that are increasingly affecting both automation vendors and users, or of the changed assumptions that underlie those standards.

Certainly the fact that there are a number of relevant standards, each with their own code-like set of letters and numbers, can make the subject a bit confusing. Still, it’s important to have a basic understanding of the standards: In part because of the effect they are having on machine and system design and implementation, and in part because of the effect they can have on your bottom line.

That last statement may seem a bit cryptic, but as the inimitable Charlie Chan might have observed, “Have patience… all will become clear momentarily.” First it is necessary to sort out the standards themselves, and most observers agree that the place to start is IEC 61508.

As Stephan Stricker, product manager for automation supplier B&R Industrial Automation Corp. ( www.br-automation.com), Roswell. Ga., points out, “IEC 61508 is a broad standard from which several newer, more targeted standards have been derived.” This generic standard marked a drastic shift in the approach to safety. Previous safety standards had always been prescriptive: You must do this; you must not do that. With IEC 61508 and the subsequent standards derived from it, the approach became more functional. Functional safety evaluates the safety of a system or piece of equipment in relation to a broad range of “real-world” inputs, including the operation of upstream and downstream systems, as well as likely operator errors and environmental disruptions.

Importantly, functional safety is a holistic, or end-to-end approach, one that employs the concept of safety lifecycles. This looks at a component or system over its complete lifespan, from the design stage all the way to final decommissioning. The goal is to improve the overall level of safety, with an added benefit of improving the functional operation of the machine or system as well.

The claim that safety standards can improve machine operation seems counterintuitive to many of us who often tend to think of safety strictly in terms of signs saying things like ”Keep hands away from moving parts.” However, Dave Kirklen, business developer for the packaging industry for automation vendor Siemens Industry Inc. ( www.sea.siemens.com) , Alpharetta, Ga., provides some insight into one of the ways that can happen.

“In the past, the machine builders would simply point guard everything; that is, put a barrier between the person and the machine.” That, says Kirklen, came with a cost in terms of productivity, as operators will need to interact with the machine at some point. If they need to shut the machine down to disable the barrier in order to get at the machine, it’s like a very expensive taxi ride with the cost rising every minute.

Improved access, greater uptime

What we’ve seen over the past few years, Kirklen says, “is that companies are coming up with ways to achieve the required levels of safety and not have to barrier guard the machine from the operator. The idea is to minimize the number of times the machine must be shut down, thus maintaining productivity while still safeguarding the operator.”
Going forward, he maintains, safety is going to be viewed as more of an enabler for production machines, as a factor in building “a net positive ROI, an aid in building better machines that increase reliability and availability.”

The main reason that today’s functional safety standards allow this type of nuanced response to nonstandard conditions, rather than the blunt on/off, go/no go response of former days, is that they embody risk assessment. Risk assessment uses specified models contained within the standard to permit risk levels to be determined for every component in a safety system. That is, you can quantify the possibility that any particular component in that system will fail to perform its function. Put all those numbers together and you’ve got a picture of the risk level of the system as a whole. Now comes the tricky part: How much risk are you willing to accept?

That’s not an invitation to skimp on safety; rather, it’s an acknowledgment that the levels and quality of risk vary. For instance, you could accept a greater level of risk from a component whose failure could lead, at worst, to a minor injury than you could ...