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Operating Instructions
Chapter
5
C4000 Select
8012247/RI61/2007-11-30
© SICK AG • Industrial Safety Systems • Germany • All rights reserved
31
Installation and mounting
5.1.3
Minimum safety distance according to ANSI/CSA standards and OSHA
regulations
The following table summarizes typical calculations of the minimum safety distance.
Approach
Minimum safety distance calculation based on 30 mm object
detection (resolution)
Perpendicular
P
= 90º (± 5º)
D
s
= H
s
× (T
s
+ T
c
+ T
r
+ T
bm
) + D
pf
Where D
pf
is 3.08 inches (78.2 mm)
Horizontal
P
= 0º (± 5º)
D
s
= H
s
× (T
s
+ T
c
+ T
r
+ T
bm
) + D
pf
Where D
pf
is 48 inches (1.21 m)
Angular
5º
P
85º
For
P
30º, use the perpendicular approach.
For
P
30º, use the horizontal approach.
The minimum safety distance requirement is based on the beam
that is located the closest to the hazard.
This table presents summary information only and additional requirements may apply for
your application. Consult the relevant standards and regulations for additional require-
ments related to the minimum safety distance calculation.
The following example shows the calculation of the minimum safety distance based on
ANSI B11.19, CAN/CSA Z434 and OSHA 29 CFR 1910.217 for a perpendicular (e.g. verti-
cal) installation of a safety light curtain. Depending on the application and the ambient
conditions, a different calculation may be necessary.
First, calculate D
s
using the following formula:
D
s
= H
s
× (T
s
+ T
c
+ T
r
+ T
bm
) + D
pf
Where …
D
s
= The minimum safety distance in inches (or mm) from the hazardous point to the
protective device
H
s
= A parameter in inches/second or mm/second, derived from data on approach
speeds of the body or parts of the body.
Often 63 inches/second is used for H
S
.
T
s
= Stopping/run down time of the machine tool measured at the final control
element
T
c
= Stopping/run-down time of the control system
T
r
= Response time of the entire protective device after light path interruption
T
bm
= Additional response time allowed for brake monitor to compensate for wear
D
pf
= Depth of penetration factor. An additional distance added to the overall safety
distance required. The value is based on the intrusion toward the hazardous
point prior to detection by the safety light curtain. The D
pf
for a perpendicular
(vertical) safety light curtain with 30 mm (1.18 in) object sensitivitiy (resolution)
can be approximated based on the following formula from ANSI/RIA R15.06:
D
pf
(inches) = 3.4 × (object sensitivity – 0.276), but not less than 0.
= 3.4 × (1.18 – 0.276) = 3.08 in
Any additional response times that apply to your application must be accounted for in this
calculation.
Tab. 15: Minimum safety
distance formula summary
per ANSI/CSA standards
Note