Tr
the maximum response time, in seconds, of the EZ-SCREEN LS Basic emitter/receiver pair (depending on model)
Dpf
the added distance due to the depth penetration factor as prescribed in OSHA 29CFR1910.217, and ANSI B11.19
for U.S. applications. See Depth Penetration Factor (Dpf) table below or calculate using the formula (in mm): Dpf =
3.4 × (S - 7) where S is the resolution of the light curtain (for S ≤ 63 mm).
Table 3: Depth Penetration Factor (Dpf)
23 mm System
54 mm (2.14 in)
US Application example: Model SLLVP23-630
K = 63 in per second
Ts = 0.32
(0.250 seconds is specified by the machine manufacturer; plus 20% safety factor; plus 20 ms interface module
IM-T-9A response)
Tr = 0.0125 second
(the specified SLLVP23-630 response time)
Dpf = 2.14 in
(for 23 mm resolution)
Ds = 63 × (0.32 + 0.0125) + 2.14 = 23.1 in
Mount the EZ-SCREEN LS Basic emitter and receiver so that no part of the defined area is closer than 23.1 inches to the
closest reachable hazard point on the guarded machine.
Calculations for European Applications
The Minimum Distance formula for European applications:
S = (K × T) + C
S
the Minimum Distance, in mm, from danger zone to light screen center line
K
hand-speed constant (see Note 2 below);
2000 mm/s
(for Minimum Distances < 500 mm)
1600 mm/s
(for Minimum
Distances > 500 mm)
T
the overall machine stopping response time (in seconds), from the physical initiation of the safety device and the
machine coming to a stop (or the hazard removed). This can be broken down into two parts:
Ts
and
Tr
where
T
=
Ts
+
Tr
C
the additional distance, in mm, based on intrusion of a hand or object towards the danger zone prior to actuation of a
safety device. Calculate using the formula (in mm):
C = 8 × (d - 14)
where
d
is the resolution of the light curtain (for
d
≤ 40 mm).
Table 4: Intrusion Factor (C)
23 mm System
72 mm (2.8 in)
European Application example: Model SLLVP23-630
K = 1600 mm per second
T = 0.3325
(0.250 seconds is specified by the machine manufacturer; plus 20% safety factor; plus 20 ms interface module
IM-T-9A response), plus 0.0125 seconds (the specified SLLVP23-630 response time)
C = 8 × (23 - 14) = 72 mm
(for 23 mm resolution)
EZ-SCREEN
®
LS Basic Safety Light Curtain
www.bannerengineering.com - Tel: + 1 888 373 6767
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