Guidelines for the positioning of safeguards

The effectiveness of particular types of safeguards depends in part on the correct positioning of the relevant parts in relation to the danger zone.

• Type of devices to be used
• Response times of the safeguards used
• Time it takes to guarantee that the machine has reached a safe state after the safeguard has been operated, e.g. machine stopping time
• Bio-mechanical and anthropometric data of parts of the body
• Path taken by a body part when moving from the sensing or actuating element towards the danger zone
• The possible presence of a person between the device and the danger zone
• The possibility of undetected access to the danger zone

EN ISO 13855 primarily defines human approach speeds. These approach speeds need to be considered when designing safety measures and selecting the appropriate sensor technology. Different speeds and sizes are defined, depending on the direction and type of approach. Even an indirect approach is considered.

The problem regarding measurement of the overall stopping performance is considered alongside the measurement of safety distances. Clear specifications are provided as to how the stopping performance should and should not be measured.