EN ISO 13849-1; 2008 - Are We Ready? - Part 2
Does anyone have an easy answer on how a safety application proof test can be accomplished with dissimilar tools and without the skilled resources for analysis? See table.
Does anyone have an easy answer on how a safety application proof test can be accomplished with dissimilar tools and without the skilled resources for analysis?
In January 2010 I blogged on this subject and talked about the kinds of companies that might encounter the need to comply with EN ISO 13849-1; 2008 and its new requirements for quantitative skills within your company. One year later this new standard is appearing more and more in our updated domestic standards and I believe it will soon become our basis for machine safety compliance. As this happens I further believe we will need some additional tools to bridge the compliance applications for the majority of our manufacturing industry. Could it be that in order to fully apply EN ISO 13849-1; 2008, your company will need to proof test safety certified products in your safety related circuits on your machine in order to fully mitigate the safety hazards identified by your risk assessment? I believe the answer is, Yes!
This issue potentially exists across industry here in the U.S. so let’s take a hypothetical walk through an example in real life industry. Let’s say the owner of a manufacturing company decides that they need to retrofit a forty year old machine with a new control system and machine guards. He asks one of his salaried employees to do the risk assessment according to an ANSI B11 standard and one of the hazards is identified as a Category 3 hazard. Separately his maintenance technician meets with their local electrical distributor and they select some parts off the shelf including the required safety rated controls and devices. These controls and devices used to be safety certified to SIL (Safety Integrity Levels) and Cat. (Category Levels), however, they are now safety certified to SIL and PL (Performance Levels) according to EN ISO 13849-1; 2008. Furthermore, these safety certified controls and devices also include basic wiring application drawings for their safety certified level of application for use.
Don’t worry, we’re quickly getting to the problem/opportunity. You see, in the past the maintenance technician simply applied the category certified product to the safety related circuit on his machine per the product’s wiring documentation. And, life was simple because he could show the business owner how he mitigated the Category 3 hazard from the risk assessment using a Category 3 safety certified product per the supplier’s documentation for use. Table 2 from EN ISO 13849-1; 2008 below shows a direct comparison between PL and SIL, however, that does not relate to this example. With Performance Level safety certified products how will the technician be able to convince his business owner that the applied PLc safety certified product fully and totally mitigates the Category 3 identified hazard from the risk assessment? I don’t see the US moving away from Category based hazards in risk assessments any time soon.
I believe this situation is resolvable at the OEM and engineering firm level where there are tools from suppliers and loads of engineers on staff to perform the required design and related mathematical analysis. However, does anyone have an easy answer on how a safety application proof test can be accomplished with dissimilar tools (PLc safety certified control/device and related documentation for use vs the Category 3 hazard from the risk assessment) and without the skilled resources for analysis?
Doesn’t US industry need training for the transition to EN ISO 13849-1; 2008 and tools and training to apply this standard while maintaining Category based hazards per the risk assessment? Where’s the proof test plan?
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