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SICK MSL
8 007 653/09-04-01 Technical Description • MSL © SICK AG • Safety Systems • Germany • All rights reserved
5 Mechanical installation
5.1 General
The MSL can be fitted in any
required position. The devices are
to be mounted such that the danger
zone can only be reached by
interrupting at least one light beam.
The choice of the MSL type,
number of beams and beam gaps
are determined by the requirements
of the respective machine and
specifications of the relevant
regulation body.
When assessing the risk situation,
consideration must be made to the
possibility of bypassing the
protection field by:
‡
Crawling underneath
‡
Reaching over the top
‡
Reaching through two light
beams
‡
Climbing through two light
beams
Fig. 7: Safety distance and height of the point of danger for multi-beam vertical access
protection
5.2 Safety distance to
point of danger,
determination of
safety distance
A safety distance must be main-
tained between the protection field
and the point of danger. This safety
distance should guarantee that the
point of danger can only be
reached by the time the hazardous
motion of the machine has come to
rest (
fig. 7). The safety distance
(according to EN 775, 999 and 294)
is dependent on:
‡
The stop time of the machine
‡
The response time of the
protection installation
‡
The person's speed of approach.
The stop time is a specification of
the machine itself.
5.2.1 General formula for the
safety distance in
accordance with
EN 999
The saftey distance S is calculated
from the formula
S = (K T) + C
S
Safety distance in mm
T
Stop time of machine plus
response time
C
Constant for calculated distance
in mm
K
Speed of approach
5.2.2 Safety distance for multi-
beam access control in
accordance with
EN 999
Several individual beams are used to
prevent invasion of the whole body
or parts of the body which are
larger than the minimum resolution
(beam gap + 23 mm beam
diameter). The approach speed is
taken as 1600 mm/s and C is
850 mm.
The minimum distance to the point
of danger is thus:
S = (1600 mm/s T) + 850 mm
The position of the beams is also to
be observed (
table 3).
5 Mechanical installation
Table 3: Number of light beams, height above relevant level and beam gap
Number of
Height above reference level
Beam gap
beams
(e. g. floor, in mm)
in mm
2
400, 900
500
3
300, 700, 1100
400
4
300, 600, 900, 1200
300
Point of danger
Mechanical
safeguarding
Entry/exit
guarding with
MSL
Direction of entry into
hazardous area