3.7 Calculation formula for the minimum safety distance of Multiple Light Beam Safety Devices for access guarding
If the risk assessment determines that a detection of the penetration of the entire body is sufficient, the following calculation formula must be applied. The additional 850 mm to be added on corresponds with the arm length:
S = (1600 x T) + 850 mm
Attention:
This type of arrangement of the protective device allows an operator to be between the sensor and the point of operation without being detected after crossing the protective device. A start/restart interlock function that prevents the machine from starting is provided in every case. The command device (reset button) must be positioned so that the entire danger zone can be seen and it cannot be operated from the danger zone.
With the risk assessment and selection of the appropriate protective device, a possible getting around, e.g. crawling under the lowest beam, reaching over the highest beam, reaching through or climbing through two beams must be taken into account. If the risk assessment allows the use of a single beam protective device, the minimum distance must be calculated according to the following formula:
S = (1600 x T) + 1200 mm
Number of beams and beam heights of Multiple Light Beam Safety Devices for access guarding in accordance with ISO 13855 (EN 999)
| Number of beams of the protective device |
Height of the beams above reference plane |
| 4 |
300, 600, 900, 1200 mm
|
| 3 |
300, 700, 1100 mm |
| 2 |
400, 900 mm |
Safety distance and beam heights of Multiple Light Beam Safety Devices for access guarding:
| a = |
Safety distance S and DS
|
| b = |
Height of the lowest beam above the reference level, see table above
|
| c = |
Height of the highest beam, see table above
|
| d = |
Measures to prevent access from the sides |
|
