Banner EZ-SCREEN­ Safety Light Curtain Systems - Manual (Page 19)

page 19
Banner Engineering Corp. • Minneapolis, MN U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
Installation and Alignment
EZ-SCREEN Grid
Instruction Manual
Calculation of separation distance takes into account several factors, including a
calculated human speed, the total system stopping time (which itself has several
components), and the depth penetration factor. The formula used to calculate
separation distance is:
Ds = K x (Ts + Tr) + Dpf
where:
Ds = the separation distance, in inches;
K = 63" per second (or 1600 mm per second), the OSHA-recommended (or
EN 999-recommended) hand-speed constant 1 ;
Ts = the overall stop time of the machine (in seconds) from the initial “stop”
signal to the final ceasing of all motion (including stop times of all
relevant control elements, and measured at maximum machine
velocity)
2 . See the Warnings on page 20, and the Notice Regarding
MPCEs (at left).
This measurement must take into account the slower of the two MPCE
channels, and the response time of all devices or controls (such as
interface modules) that react to stop the machine. If all devices are not
included, the calculated separation distance (Ds) will be too short and
serious injury could result.
Tr = 0.024 seconds, the maximum response time of the EZ-SCREEN Grid
System; and
Dpf = 36" or 48", the added distance due to depth penetration factor (for U.S.
applications, prescribed in ANSI/RIA R15.06 and ANSI B11). Because the
beam spacing of the EZ-SCREEN Grid is larger than 2.5" but less than
24", Dpf is either 36" or 48":
• Dpf is 36" if the top beam is 48" or higher and the bottom beam is
12" or less from the floor (a reach-through hazard).
• Dpf is 48" if the top beam is 36" to 48" above the floor and the
bottom beam is 12" or less from the floor (a reach-over hazard).
In European applications, Dpf is 850 mm, prescribed in EN 999.
NOTES:
1)
The OSHA-recommended hand speed constant K has been determined by
various studies, and although these studies indicate speeds of 63"/second to
more than 100"/second, they are not conclusive determinations. The user
should 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, at least 20% should be added to
allow for possible clutch/brake system deterioration.
Figure 3-2. Determining Dpf (reach-
through versus reach-over
hazards per ANSI/RIA
R15.06)
Notice Regarding
MPCEs
Each of the two Machine Primary
Control Elements (MPCE 1 and
MPCE2) must be capable of
immediately stopping the dangerous
machine motion, irrespective of the
state of the other. These two channels
of machine control need not be
identical, but the stop time
performance of the machine (Ts, used
to calculate the separation distance)
must take into account the slower of
the two channels.
Reaching Over
Beam 1
Beam 2
Reaching Through
Beam 1
Beam 2
Beam 3
Beam 4