MACHINE SAFETY
ISO 13855:2024 – NEW GUIDELINES FOR SAFER SENSOR POSITIONING A
t the end of 2024, the new version of ISO 13855 on the positioning of protective devices on machines was published. The revised version contains amendments and additions to reflect the developments of recent years and the current state of the art. Markus Erdorf, senior safety consultant at Leuze, explains what we need to know about the updated standard.
ISO 13855 HAS BEEN A PROVEN REFERENCE FOR THE DESIGN OF PROTECTIVE DEVICES FOR MORE THAN A
DECADE. WHY WAS THE REVISION NECESSARY? Markus Erdorf: The last valid version was published in 2010, around 15 years ago. That is a long time in industrial automation, and a lot has changed in the meantime: Today, we are dealing with more flexible production systems, more mobile robots and new operating concepts. The previous standard could only reflect this to a limited extent. We also looked at the incidence of accidents at work and derived normative consequences from this. ISO 13855:2024 is better suited to current technologies
because it provides more precise specifications for the calculation of safety distances and, accordingly, for the positioning of protective devices. It also addresses topics that were missing from the previous standard and adjusts existing values.
WHAT ARE THE MOST IMPORTANT NEW FEATURES OF ISO 13855:2024?
The calculation of the safety distance, previously referred to as the minimum distance, has been revised and extended for the orthogonal, i.e. right- angled, approach of a person. This allows the safety distance to be determined more precisely. Specifically, the range DDS - previously referred to as safety distance C - is now determined on the basis of three criteria: Reaching over, reaching through and reaching under the protective field. The DDU (reaching under the detection zone) has been added and the DDT (reaching through the detection zone) has been extended by a formula. For the parallel approach of a person, the calculation has been simplified by the use of
The value for DDO is a maximum of 1,200mm and results from the ratio of the upper edge of the protective field to the height of the hazard area. The values in the associated “Reaching over” table in ISO 13855 are unchanged from the previous version.
Leuze’s Markus Erdorf explains how the updated standard changes the game in sensor positioning and machine safety planning.
flat-rate values. The Z supplements, which result, for example, from the measurement inaccuracy of safety laser scanners or brake wear on vehicles, have also now been included. Another very interesting topic is “distances to safety-related manual control devices “ - referred to as SRMCDs in the standards. The distances must now be calculated to enable installation in a safe position. The introduction of the dynamic safety distance is intended for the future. This makes it possible, for example, to dynamically adjust the safety distance during robot movements depending on external conditions such as speed, braking distance and direction of movement. It has therefore become somewhat more complex to calculate the safety distance. On the one hand, this means more accuracy, but on the other hand it also means more responsibility for the users of the standard.
WHAT IMPACT DOES THE UPDATED STANDARD
HAVE FOR MACHINE MANUFACTURERS? The Machinery Directive (MD) applies to manufacturers of machinery. This states that only safe machines may be placed on the market. Standards or harmonized standards exist to make this easier to prove. Even though the new EN ISO 13855 has not yet been harmonized, it reflects the state of the art and thus states how machines are correctly safeguarded today. It is
16 AUTUMN 2025 | INDUSTRIAL COMPLIANCE
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