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3.3.
How to calculate safety distance
IMPROPER SAFETY DISTANCE
To ensure the proper safety distance ( D
The safety distance between the sensing field and the danger zone must be large enough to ensure that if the sensing field
is entered, the danger zone cannot be reached before the hazardous movement is stopped.
The approach speed or velocity of movement into the danger zone ( V ) depends on the position of the safety light curtain.
The additional safety distance ( C ) depends on the minimum object detection (resolution) of the safety light curtain.
Failure to comply with these instructions could result in death or serious injury.
The safety distance (see Figure 3-2) is the minimum distance between the sensing field and the danger zone. This distance
ensures that the danger zone cannot be reached until the machine motion has been stopped.
Figure 3-2 Light curtain safety distance diagram
NOTICE
If mechanical or process constraints require closer proximity to the dangerous machine motion, the FF-LS14 safety light
curtain is better suited than the FF-LS30 safety light curtain for such applications (FF-LS14 Series has better minimum
object detection). The FF-LS30 safety light curtain requires greater safety distance (2.15 in more than FF-LS14 in the US
and 128 mm more in Europe) than the FF-LS14 safety light curtain if installed on the same machine.
3.3.1.
Normal approach point-of-operation guarding
Point-of-operation is defined as that area where a machine performs work (such as cutting, shaping, boring, or forming) on a
material.
3.3.1.1. European safety distance calculation
The safety distance D
(see Figure 3-3) between the danger zone and the optical axis shall be no less than the value
S
calculated using the following formula:
≥ 2000 mm(t
D
+ t
S
1
2
V is the velocity of movement (approach speed) into the danger zone; (2000 mm/s)
t
is the response time of the FF-LS light curtain (s)
1
t
is the stopping time of the equipment (s)
2
C is additional safety distance C = 8 (minimum object detection - 14) mm
This formula applies for all safety distances of D
500 mm using the formula above, reduce the distance above using the formula below. A minimum distance of 500 mm is
required.
≥ 1600 mm(t
D
+ t
) + C (mm) where, D
S
1
2
V is the velocity of movement (approach speed) into the danger zone; (1600 mm/s)
t
is the response time of the FF-LS light curtain (s)
1
t
is the stopping time of the equipment (s)
2
C is additional safety distance C = 8 (minimum object detection - 14) (mm)
D
shall be greater or equal to 500 mm. When access to the danger zone can be gained from over the top, around the
S
sides, or underneath the safety light curtain, provide additional safeguarding devices (or hardguarding) to prevent access.
107022-16 EN FR26 GLO 301 Printed in Germany
) use the formulas described in this section.
S
Danger Zone
Light Beam
Sensing Unit A
Optical Axis
) + C (mm) where, D
is the safety distance
S
greater than 100 mm up to and including 500 mm. If D
S
is the safety distance AND D
S
D
s
Sensing Unit B
> 500 mm
S
is greater than
S
16
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