Safety Requirements for ESPD Systems

 

When it comes to the safety of packaging machines, experienced designers appreciate the Type C series of standards DIN EN 415. The ten parts of this standard describe a large number of requirements for machines.

Currently these are:
The various machines are usually closed systems that operate fully automatically. In order to transport products and materials into and out of the safety area, non-contact protective devices are used, especially for larger openings, which are controlled by corresponding safety functions. It must be ensured that products and materials can be transported in and out without persons being able to enter the danger zone undetected through these openings. One way to protect such openings is to bypass or hide the ESPD system. This function is also called muting.

DIN EN 415-10:2014, Section 5.2.1.4 places corresponding requirements on the function of such systems, as the following abbreviated copy shows.

a) The bypass period shall be limited to a period which is only long enough to allow the product to pass through the detection zone.
b) the configuration of the bypass sensors shall be capable of distinguishing a person from the material;
c) all bypass functions must have the same performance level;
d) there must be no operational waiting position for a product within the bypass area.

 

 

For further details, DIN EN 415-10:2014 refers to DIN EN IEC 62046:2019.
Section 5.5.3 requires the bypass function to be automatically initiated and terminated. This can be done by using appropriately selected and arranged sensors or, in some cases, signals from the safety-related control system. No bypass condition shall be made possible by faulty signals, sequences or timing of the bypass sensors or signals.
The control circuit performing the bypass function must have a suitable safety-related performance level (SIL or PL, see DIN EN 62061:2016 or DIN EN 13849-1:2016).
In addition, the safety of the machine during muting must be ensured by other means, for example by maintaining the following lateral distances and by ensuring that the load is at least 900 mm high.
If the requirements described above do not guarantee safety, other solutions may be used, such as interlocking function.

 

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• Both sensors must be within the danger zone
• Both beams must be used within a certain period of time
• If the electrosensitive protecting device is free or 4 seconds passed after leaving the first sensor, muting must be deactivated
• If the termination only occurs after 4 seconds, an additional distance d8 must be met.

 

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• The intersection point must be within the danger zone
• The intersection point should be as close as possible to the ESPD ( ≤ 200 mm) ( ≤ 200 mm)
• The distance between the load and the guard should not exceed 200 mm
• A round test piece of 500 mm must not trigger muting.

• If there is a risk of body parts being crushed between the load and stationary parts, DIN EN 349:2008 recommends a minimum distance of 500 mm between the moving load and the stationary parts of the system to avoid the risk of crushing or shearing. Further details are given in EN 349.

 

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• The muting sensors should be as close as possible to the "ESPD" (distance < 200 mm)
• The distance between sensors S1 and S4 must be greater than 500 mm
• The distance between sensors S1 and S2 and between sensors S3 and S4 must be greater than 250 mm
• The distance between the load and the guard should not exceed 200 mm.

 

• If there is a risk of body parts being crushed between the load and stationary parts, DIN EN 349:2008 recommends a minimum distance of 500 mm between the moving load and the stationary parts of the system to avoid the risk of crushing or shearing. Further details are given in EN 349.