Update to BS EN ISO 13849-1, third edition 2015 – standard for safety related controls on machines

The latest 2015 edition is now harmonised to the Machinery Directive. David Collier of Pilz UK shares his observations of the impact the significant changes will have.

The capping of MTTFD to 100 years has been raised to 2500 years in Category 4 subsystems, allowing more Category 4 subsystems to be connected without a degradation in Performance Level.

Test frequencies for Category 2 systems are further clarified.

In the Risk Analysis to determine the Performance Level required (PL r) for a safety function, possibility of occurrence is now included (previously this was assumed to be 100%) and the standard states “where the probability of occurrence of the hazardous event can be justified as low, the PLr may be reduced by one level”. This is highly contentious as it could be used to justify a lower cost system potentially at the expense of safety.

Further detail of addressing these changes is discussed in the full article on the Pilz website.