Yes it’s true, Europe has started a two year phase out of the risk categories; B, 1, 2, 3, & 4 as established by EN 954:1996 and hence referenced in numerous US based standards such as NFPA 79, ANSI B11, S2, ANSI B155.1, etc. to name a few. A  European standard, EN ISO 13849-1:2006, has recently been approved announcing a new system called Performance Level (PL_{a, b, c, d,} & _e) for determining risk levels on a machine replacing the Category system by 2009. So far, it doesn’t seem that any US based standards groups are mustering the troops to update recently modified standards that acknowledged the EN 954 Category system of 1996. The ink has barely dried for gosh sakes! Categories are a product of the task based objective risk assessment process currently still being introduced across the nation for discrete industries.

The PL system, on the other hand, is a quantitative based approach that (if adopted in the US) will require industries across the land to learn or acquire new skills in order to be compliant. One new requirement is calculating MTTF_d (mean time to fail dangerous) and another is PFH_d (probability of dangerous failure per hour). These values will need to be determined for components such as interlock switches and sensors. Does anyone believe that industry is ready for this tidal wave?

Or, will Categories live on………….?