New edition of standards for safeguards

According to CEN, the responsible publisher, both standards have ‘Approved’ status, with ratification due to take place in mid-July 2024. Following publication by CEN, the standards will then be distributed to the national standardisation organisations for publication. It is expected that users will be able to obtain the final editions at the beginning of 2025.

The CEN website shows that these are ‘only’ harmonised standards for the Machinery Directive. This is also evident in the two draft standards: the documents only have an Annex ZA, which documents the conformity of the standard sections with the essential health and safety requirements of the Machinery Directive 2006/42/EC. A listing in the EU Official Journal for the directive is expected in the months following the final publication in the event of a positive HAS assessment.

It is likely that the two new standards will also be published in the EU Official Journal for the new Machinery Regulation (EU) 2023/1230 as part of an implementing decision with restrictions. Details of the planned procedure can be found in our technical article ‘New Machinery Regulation – status of harmonised standards’.
 

Essentially, the scope of the standard has increased significantly. The current draft standard has grown from 78 pages in the 2013 version to 109 pages. The essential health and safety requirements, which were already very well covered, have been adapted to the new state of the art in the new standard. In addition, the scope has been extended to include instructions for measures to minimise the possibility of bypassing interlocking devices in a reasonably foreseeable manner.

Some terminology has been added to reflect current developments, such as type 5 interlocking system: Trapped key interlocking system. This type is also described in detail later in Section 5 ‘Requirements for the design and the arrangements of interlocking devices with and without guard locking’ and in Annex K 'Trapped key interlocking systems'. If a key interlocking system of this kind is used, requirements for a key transfer plan are to be set out under point 7.4. A key transfer plan is to be created for each key interlocking system, which must subsequently describe the key path in detail. Based on the safety-related specifications, key coding must be defined, which must be included in the operating instructions with an appropriate description.

Another new point is point 4, Symbols and Abbreviations. Symbols and abbreviations are presented here and show general operating principles for the locking devices.

In section 6.2, there are new points regarding the ‘Arrangement and fastening of position switches, bolt locks and access locks’. In this case, for example, when designing the access points, prevention of defeat in reasonably foreseeable modes shall also be considered and the switches mentioned shall not be used as a mechanical stop unless this is the intended use of the position switch.
If the device cannot be used as a mechanical stop, it must be ensured that additional mechanical stops are available for the application. This is to prevent the device from being exposed to excessive impact energy in excess of that specified by the manufacturer. Additional requirements for interlocking devices.

The scope of the new EN ISO 13855 will also almost double. At 87 pages (previously 50 pages), this edition is significantly more extensive and also more complex.

The formula for calculating the minimum distance is new and has now been renamed ‘Principles for calculating the safety distance’:

S = K x T + D_DS + Z

S describes the separation distance between the safeguard and the hazard zone [mm]. The term ‘minimum distance’ has now become ‘separation distance’ S, which describes the minimum distance between the safeguard and the hazard zone [mm].

K defines the approach speed 2000 [mm/s] or 1600 [mm/s], depending on the application.

Changed:T: System response time of the safety function after the relevant part of the body enters the protective field [ms]. The determination of the system response time T was described in point 5.4 ‘Overall system response time T’ and is considerably more complex than before.

NEW is D_DS: This describes the reaching distance associated with a protective device in millimeters. Here, too, the level of complexity has been increased and extended to include the addition depending on the detection capability and installation situation [mm]. The previous penetration range C_RT, C_RO has been replaced by the range D^DS (consisting of D_RT, D_RO, D_RU), the surcharge depending on the detection capability and installation situation.

NEW is Z:An supplemental distance factor, e.g. due to measurement inaccuracies or brake wear [mm].

In addition, numerous new terminologies have been added, including, for example:

• whole body access: situation where a person can be completely inside a safeguarded space
• safeguarded space: area or volume enclosing a hazard zone(s) where guards and/or protective devices are intended to protect persons
• reference plane: level at which persons would normally stand during the use of the machine or access to the hazard zone or safety-related manual control device
• Distance factor Z: a supplement depending on the application, machine and protective device, e.g. due to measurement inaccuracies or brake wear.
• SRMCD – safety-related manual control device: control device which requires deliberate human action and whose actuation can result in an immediate increase of the risk(s)

Other noteworthy innovations in the future standardised version of EN ISO 13855 include the following points:

• If access of a person below the protective field is to be prevented, the distance may be ≤ 200 mm from the reference plane. In an industrial environment, a maximum height of 300 mm is permissible for the lower edge of the protective field, provided that the results of the risk assessment show that this is sufficient. Here, too, the importance of the risk assessment is emphasised.
• For ESPE mounted vertically to the reference plane, the distance G_D, which defines the possibility of walking behind, must be calculated according to the formula in number 4.3.3.2.
• Examples for calculating the opening width for applications with hinge switches have been added.
• The additional distance for two-hand controls without a cover has been increased from C = 250 mm to D_DS = 550 mm.
• A great deal of attention has been paid to the subject of ‘Reaching through a vertical detection zone’ and ‘Reaching through a detection zone’, which is illustrated by a number of images and tables.