WARNING:
• Maintain the proper safety distance
• Failure to establish and maintain the minimum safety distance could result in serious bodily injury
or death.
• Locate the Safety Zone far enough from the nearest hazard such that an individual cannot reach
the hazard before cessation of hazardous motion or situation.
3.5 Minimum Safety (Separation) Distance Formula
When all factors that influence the Safety Distance are considered, the formula is:
For US Applications
For European Applications
DS = [K × (TS + TR)] + Dpf + ZSM + Zamb where
DS = the safety distance, in mm (inches)
K = 1600 mm per second (63 inches per second) (see note 1 below)
TS = maximum stopping time (sec) of the machine (see note 2 below)
TR = maximum response time (sec) of the Scanner (see note 3 below)
Dpf = Depth penetration factor: The additional distance required by
U.S. standards, such as ANSI B11.19, to prevent a person from
encroaching towards the hazard without being detected.
ZSM = the additional distance needed to account for distance
measurement error.
Zamb = the additional distance needed to account for error due to
reflections from retroreflective surfaces.
S = (K × T) + C + ZSM + Zamb where
S = the minimum distance between the hazard and the Safety Zone. S
is never less than 100 mm (4 in)
K = approach speed (see note 1 below)
2000 mm/s (79 in/s) for S < 500 mm (20 in)
1600 mm/s (63 in/s) for S > 500 mm (20 in)
T = overall system stopping performance in seconds (see note 2
below)
C = an additional distance in millimeters (inches), based on intrusion
towards the hazard prior to actuation of the Scanner. This value is
never less than zero.
ZSM = the additional distance needed to account for distance
measurement error.
Zamb = the additional distance needed to account for error due to
reflections from retroreflective surfaces.
Notes:
1. The OSHA-recommended hand speed constant K has been
determined by various studies, and although these studies
indicate speeds of 1600 mm/s (63 in/s) to more than 2540 mm/s
(100 in/s), they are not conclusive determinations. Consider all
factors, including the physical ability of the operator, when
determining the value of K to be used.
2. TS is usually measured by a stop-time measuring device. If the
machine manufacturer’s specified stop time is used, add at least
20% to allow for possible clutch/brake system deterioration. This
measurement must take into account the slower of the two MPCE
channels, and the response time of all devices or controls that
react to stop the machine (e.g., UM-FA-9A safety module). See
Notice Regarding MPCEs. If all devices are not included, the
calculated safety distance (Ds) will be too short and serious injury
could result.
Notes: The above formula is derived from ISO 13855 (2002).
1. If S is greater than 500 mm, then K = 1600 mm/s can be used
instead of the 2000 mm/s speed, however, if the 1600 mm/s
value is used, then S can never be less than 500 mm.
2. T is the time from the actuation of the sensing function to the
machine's assuming a safe condition, comprising a minimum of
two phases: T = t1 + t2 where
t1 is the maximum time between the actuation of the sensing function and
the output signal switching devices (OSSDs) being in the OFF state. This is
the response time of the SX5.
t2 is the maximum response time of the machine, i.e. the time required to
stop the machine or remove the risks after receiving the output signal from
the protective equipment. t2 is influenced by temperature, switching time of
valves, ageing of components, and other factors. t2 is usually measured by
a stop-time measuring device. If the machine manufacturer’s specified stop
time is used, add at least 20% to allow for possible clutch/brake system
deterioration. This measurement must take into account the slower of the
two MPCE channels, and the response time of all devices or controls that
react to stop the machine (e.g., UM-FA-9A safety module). If all devices are
not included, the calculated safety distance (Ds) will be too short and
serious injury could result.
Dpf Considerations
Horizontal Safety Zone Applications (parallel approach)
Dpf = 1200 mm (48 in)
Scanner-Specific Additional Distance Factors — Two Scanner-specific
factors must be considered when calculating the Minimum Safety distance:
ZSM and Zamb
ZSM Measurement Tolerance Factor — ZSM is the additional distance
needed to account for distance measurement error. The value for ZSM is
150 mm (5.9 in). For Vertical Safety Zones (normal approach), Zsm = 0
Distance Adjustment C, Based on the Possible Field Intrusion
Horizontal Safety Zone Applications (Parallel Approach)
C = 1200 mm – (0.4 × H) or C = 48 in – (0.4 × H)
where H is the distance of the Safety Zone above the floor or walking
surface (1000 mm maximum). C can never be less that 850 mm (34 in).
Additional Scanner-Specific Distance Factors
Two Scanner-specific factors must be considered when calculating the
Minimum Safety distance: ZSM and Zamb
ZSM Measurement Tolerance Factor—ZSM is the additional distance
needed to account for distance measurement error. The value for ZSM is
150 mm (5.9 in). For Vertical Safety Zones (normal approach), Zsm = 0
Z
amb
(Ambient Interference Factor) is the additional distance needed to account for measurement errors due to light
interference and/or reflections from highly reflective or shiny surfaces that are present in the scanning plan.
No ambient interference Z
amb
= 0
SX5 Safety Laser Scanner
30
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