8-1 European Safety Distance Formulas
8 Safe Mounting Distance
14
8 Safe Mounting Distance
A F3SL system must be mounted far enough from the machine danger zone so the machine will stop before a
hand or other body part reaches the hazardous area. This distance is called the safety distance. It is a calculated
number based on a formula. See Figure 8-1 for an illustration of the safety distance.
Figure 8-1 Safe Mounting Distance
Regardless of the calculated distance, a F3SL system should never be mounted closer than 5.5 inches
(140 mm) from the point of operation hazard. This is required by Table 0-10 in OSHA 1910.217.
8-1 European Safety Distance Formulas
The following discussion is based on standard EN999:1998 and applies to light curtains used in industrial
environments.
8-1-1 Safety Distance Formula for Systems with a Minimum Object Resolution
of 40 mm or Less
When the minimum object resolution of the system is 40 mm or less, use the following formula:
S = (K x T) + C
where:
S = the minimum distance in millimeters, from the danger zone to the detection point, line, plane or zone.
K = 2000 mm/s
T = the overall system stopping performance in seconds.
T = t
m
+ t
s
t
m
= maximum stopping time of the machine is seconds.
t
s
= response time of the safety light curtain in seconds.
This response time is given in 2-2 Technical Specifications.
C = 8(d-14 mm), but not less than zero.
d = the minimum object detection of the F3SL system in millimeters.
i.e.:
S = (2000 mm/s x T) + 8(d – 14 mm)
WARNING
Never install a F3SL system without regard to the safety distance. If the F3SL system is mounted too close
to the point of operation hazard, the machine may not stop in time to prevent an operator injury.
Light Curtain
D
s
Ds is the minimum safe distance
between the light curtain sensing
field and the point of operation
hazard (pinch point).
Summary of Contents for F3SL
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