Separation Distance
As a stand-alone safeguard, the sensor must be installed at a
separation distance (safety distance) such that the exterior edge
of the sensing surface is at or beyond the safety distance, unless
solely used to prevent start/restart or solely used for clearance
safeguarding (see ANSI B11.19).
The separation distance required for an application depends upon
several factors, including the speed of the hand (or individual),
the total system stopping time (which includes several response
time components), and the depth penetration factor. The user
must refer to the relevant standard to determine the appropriate
distance or means to ensure that individuals can not be exposed
to the hazard(s).
One formula used to calculate separation distance (Ds) is:
Ds = K × (Ts + Tr) + Dpf
where:
K = the OSHA-recommended hand speed constant of 1600 mm
(63 in) per second (see NOTE below);
Ts = the overall stop time of the machine, measured from the
application of the “stop” signal to the final ceasing of all motion
(including stop times of all relevant control elements, and
measured at maximum machine velocity).
Tr = the response time of the safety mat system: Module
response time plus the response time of the sensor(s), as stated
by the manufacturer.
Dpf = the added distance due to depth penetration factor: 1.2 m
(48 in)
Hazardous
Zone
or
Area
Safety Mat
Ds
K(Ts + Tr)
Dpf
Figure 2. Determining Separation Distance for the Safety Mat
NOTE: The OSHA-recommended hand-speed constant (K) has been determined by various studies, and
although these studies indicate speeds of 1600 mm (63 in) per second to more than 2540 mm (100 in)
per second, they are not conclusive determinations. The employer should consider all factors, including
the physical ability of the operator, when determining the value of K to be used.
If an individual can cross completely over the sensor and be no longer detected, supplemental safeguarding or other
means should be used to prevent unexpected startup and exposure to a hazard. At a minimum, the safety mat system (or
the machine control) must be manually reset and require re-initiation of the normal actuating means prior to the start or
re-start of the machine cycle.
Mechanical Installation
The Safety Module must be installed inside an enclosure.
It is not designed for exposed wiring. It is the user’s responsibility to house the Safety Module in an enclosure with NEMA 3
(IEC IP54) rating, or better. The Safety Module mounts directly to standard 35 mm DIN rail.
Heat Dissipation Considerations: For reliable operation, ensure that the operating specifications are not exceeded. The
enclosure must provide adequate heat dissipation, so that the air closely surrounding the Module does not exceed the
maximum operating temperature stated in the Specifications. Methods to reduce heat build-up include venting, forced
airflow (for example, exhaust fans), adequate enclosure exterior surface area, and spacing between modules and other
sources of heat.
MAX1524 and MAX2324 Safety Mat Monitoring Modules
P/N 122366 Rev. B
www.LARCO.com TEL: 800-523-6996
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