DANGER
Hazard due to lack of effectiveness of the protective device
Persons and parts of the body to be protected may not be recognized in case of non-
observance.
b
Make sure that the following design requirements are met so that the single-beam
photoelectric safety switch can fulfill its protective function.
°
Sender and receiver must be arranged such that persons or parts of the body
are reliably detected when they enter the hazardous area.
°
Ensure that nobody can pass under the light beam or pass by the side of the
protective device.
°
If people can stay between the protective device and the hazardous point
without being detected, check if additional protective measures (e.g., restart
interlock) are required.
DANGER
Hazard due to lack of effectiveness of the protective device
Certain types of light radiation can influence the protective device, e.g., light radiation
from fluorescent lamps with electronic ballast installed in the path of the beam, or
beams from laser pointers directed at the receiver.
b
If this type of light radiation is present in the environment of the protective device,
take additional measures to ensure that the protective device does not become
dangerous.
4.3.1
Minimum distance from the hazardous point
Overview
A minimum distance must be maintained between the single-beam photoelectric safety
switch and the hazardous point. This distance is required to prevent a person or part of
their body from reaching the hazardous point before the end of the machine’s danger‐
ous state.
Calculating the minimum distance according to ISO 13855
The calculation of the minimum distance is based on international or national stan‐
dards and statutory requirements applicable at the place of installation of the machine.
If the minimum distance is calculated according to ISO 13855, it depends on the fol‐
lowing points:
•
Machine stopping time (time interval between triggering the sensor function and
the end of the machine’s dangerous state)
•
Response time of the protective device
•
Reach or approach speed of the person
•
Number of beams and beam separation of the single-beam photoelectric safety
switch
•
Type of approach: orthogonal (at right angles) or parallel
•
Parameters specified based on the application
For the USA (scope of OSHA and ANSI), different regulations may apply, e.g.:
a) Laws: Code of Federal Regulations, Title 29 (CFR 29), Part 1910.217
b) Standards: ANSI B11.19
Complementary information
Additional information is available in the ISO 13855 standard and in the Guide for Safe
Machinery.
PROJECT PLANNING
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Subject to change without notice