Key takeaways:
The article discusses the design of guards and barriers in accordance with EN ISO 13857, including reaching over, around, and through openings in guards. It emphasizes the importance of selecting solutions appropriate to the level of risk and of regularly monitoring and maintaining protective structures.
- EN ISO 13857 specifies the minimum safety distances required to prevent access to a machine’s hazardous zones.
- The requirements are based on anthropometric and biomechanical data; they apply to persons aged 14 and over and to children older than 3 years when reaching through openings.
- The standard distinguishes between low and high risk; selecting protective measures requires a machine risk assessment.
- For upward reach: 2,500 mm (low risk) and 2,700 mm (high risk) as the minimum safety distances
- For openings: 20 mm requires 120 mm from the hazard, and 80 mm requires 850 mm; used, among other things, in robot enclosures and guards
EN ISO 13857 defines detailed requirements for minimum safety distances that must be maintained to prevent access to potentially hazardous areas of a machine. Protection against reaching into danger zones is a key element of machine safety. In this article, we discuss the main design principles and practical guidance on how to implement these requirements in an industrial environment.
Understanding Minimum Safety Distances
Minimum safety distances are defined on the basis of anthropometric and biomechanical data that account for differences in human body dimensions. It is important for the design office to understand these values and apply them correctly in its designs. The document refers to persons aged 14 and over, while also considering children over 3 years of age in the context of reaching through openings.
Risk Categories
The standard distinguishes between two main risk levels: low and high. When designing protective measures, a thorough machine risk assessment should be carried out to determine which category applies:
- Low risk: Applies to situations where the hazard is limited to minor injuries, such as scratches.
- High risk: Applies to situations where there is a potential for serious injury, such as fractures or amputations.
Minimum Safety Distances for Reaching Upwards
One of the key aspects is the correct design of the height of the hazardous area in the context of reaching upwards:
- Low risk: The minimum safety distance should be 2 500 mm.
- High risk: The minimum safety distance should be 2 700 mm.
Reaching Over a Protective Structure and Minimum Safety Distances
The standard specifies requirements for minimum safety distances when reaching over a protective structure. To determine the appropriate distances, use the tables included in EN ISO 13857, which define these values precisely according to the height of the protective structure and the potential risk.
Reaching Around a Protective Structure
The standard defines requirements for minimum safety distances when reaching around protective structures. These distances must be designed appropriately to prevent access to hazardous areas. Here as well, the relevant tables in the standard should be used.
Reaching Through Openings and Minimum Safety Distances
The standard defines the maximum dimensions of openings in protective structures in the form of slots, squares, and circles that must be maintained to prevent limbs from reaching hazardous areas. These dimensions are specified for different body parts, such as the fingertip, finger, hand, or the entire upper limb, which determines the minimum safety distance from the hazardous area.
Practical Examples
This standard is most commonly used when installing fencing to separate hazardous areas protected against access, for example by interlocking safety devices (so-called interlocked guards). EN 14120 covers the types of guards. Implementation of the safety function itself depends on the machine risk assessment, but also on how frequently a given area must be accessed. A good example of where fencing with an appropriate mesh size compliant with EN ISO 13857 is used is fencing around the working area of an industrial robot. The mesh opening has a specific size precisely to prevent access to the hazardous area and minimize the footprint of the fencing (up to 120 mm from the hazard). Of course, such fencing can be installed around any production line that includes hazardous areas.
Another example is machine guards of all kinds. According to EN ISO 13857, if an opening is 20 mm wide, the safety distance from the hazardous area must be 120 mm to prevent a finger from being inserted under the guard.
- 20 mm wide slot: The minimum safety distance is 120 mm.
- 80 mm wide opening: The minimum safety distance is 850 mm
Protective Structures and Minimum Safety Distances
Protective structures are physical barriers that prevent access to hazardous areas. These may include machine guards, barriers, grilles, or other elements that restrict access. The choice of the right type of protective structure depends on the specific machine and the risk being assessed.
Additional Protective Structures
In some cases, additional protective structures may be required to restrict the free movement of limbs and thereby improve safety. Examples include double barriers or mesh guards. For existing equipment, this may also involve adapting machines to minimum safety requirements.
Special Requirements for Children and Minimum Safety Distances
The standard also takes into account specific requirements for protecting children, who may reach through openings in protective structures. For children over 3 years of age, special minimum safety distances must be applied, which differ from those for adults.
Monitoring and Maintenance of Protective Structures
Protective structures must be regularly monitored and maintained to ensure their effectiveness. Attention should be paid to any damage, deformation, or wear that may reduce the level of protection. In practice, these checks are often part of a broader machinery and production line safety audit.
Safety Costs and Minimum Safety Distances
Safety costs are significant because they include machine design, installation, and maintenance of appropriate protective measures. Companies often cut corners on safety, which is harmful for several reasons. First, it can lead to serious accidents and injuries that are costly from both medical and legal perspectives. Second, poorly conceived guarding systems can interfere with work if they are badly designed and selected, reducing operational efficiency and increasing the risk that employees will not follow safety procedures.
Another example is machine guards and all related guarding components. According to EN ISO 13857, if an opening is 20 mm wide, the safety distance from the hazardous area must be 120 mm to prevent a finger from being inserted under the guard.
Summary Providing appropriate minimum safety distances and using protective structures in accordance with EN ISO 13857 is essential to protect workers from access to hazardous areas. With proper design and maintenance of these protective measures, accidents can be effectively prevented and workers’ health protected. Safety costs are significant, and companies often try to save money in this area. In addition, machine guards often make work more difficult, but in most cases this simply means the designers did not fully think the solution through. Proper implementation also supports machine compliance and CE certification.
Industrial Automation and Minimum Safety Distances
Industrial automation plays a key role in improving efficiency and safety in manufacturing plants. The use of advanced control and monitoring systems makes it possible to automate production processes while minimizing the risks associated with access to hazardous areas. The use of sensors, light curtains, and emergency stop devices can significantly improve operational safety while ensuring compliance with standards such as EN ISO 13857.
Industrial Machine Construction and Minimum Safety Distances
Design and construction of industrial machines must take strict safety standards into account to protect operators and other workers from potential mechanical hazards. Industrial machine design and construction includes a range of activities, including risk assessment, the design of protective structures, and the implementation of safety systems. Compliance with EN ISO 13857 is critical because minimum safety distances must be strictly observed. Proper industrial machine design requires:
- Risk assessment: Identifying potential hazards and assessing the risks associated with different machine operations.
- Design of protective systems: Taking minimum safety distances into account when designing guards, barriers, and other protective structures.
- Integration of industrial automation: Using advanced control systems that automatically monitor and manage machine safety.
- Regular maintenance and inspection: Ensuring that all protective systems are fully functional and effective.
EN ISO 13857 is harmonized with the Machinery Directive 2006/42/EC, so it works alongside most standards applied in the design and construction of special-purpose machines and industrial machinery. For example, EN 14120 discusses various types of guards that can be used together with the guidance on safety distances set out in EN ISO 13857:2020-03. The regulatory context is also evolving, as outlined in the Machinery Regulation 2023/1230/EU.
Minimum Safety Distances in Machine Design
The standard defines the minimum safety distances intended to prevent access to the machine’s hazardous zones. It covers, among other things, reaching upward, over and around protective structures, and through openings.
They are determined on the basis of anthropometric and biomechanical data and the results of the risk assessment. The standard applies to persons aged 14 and over and, in the context of reaching through openings, also takes into account children over 3 years of age.
The standard distinguishes between low risk (e.g., minor injuries) and high risk (e.g., fractures or amputations). The requirements for protective measures should be selected on the basis of the machine risk assessment.
For low risk, the minimum distance is 2,500 mm; for high risk, it is 2,700 mm. The height of the danger zone must be designed with this risk category in mind.
If the gap width is 20 mm, the minimum distance from the hazardous zone must be 120 mm. For an opening 80 mm wide, the minimum safety distance is 850 mm.