Larco Safety Mat Systems - Manual (Page 11)

11
Installation, Use and
Maintenance Guide
a. Recommended Testing Intervals
Larco recommends that its safety mats be tested at the beginning of each shift and more often under severe conditions.
Examples of severe conditions would include frequent or constant submersion in fluid and continuous forklift traffic.
b. Mat Design Characteristics
Electrically, the safety mat itself is a relatively simple device that, for testing purposes, can be compared to a Single Pole Single
Throw (SPST) normally open switch. When no pressure is applied to the mat, the switch should be open. When pressure is
applied to the mat, the switch should be closed. The typical Larco safety mat has two white wires internally attached to one of
the contacts, and two black wires attached to the other contact.
With this arrangement there should always be continuity between like-colored wires. In its open state (no pressure applied),
there should be no continuity between either black and either white wire and conversely, there should be continuity between
black and white wires when the mat is in a closed (pressure applied) state.
Before testing, ensure the safety of the individual performing the test by neutralizing the hazard. The safety mat control device,
such as the Larco Zone Monitor will provide a visual indication of the mat status (open or closed) while performing the test.
Refer to the specific instructions included with your control device for appropriate control reactions to mat activation and
de-activation. If a Larco Zone Monitor is not being used, an open circuit is defined in resistive terms as one million ohms or
more and a closed circuit as ten ohms or less.
Typical Larco mat installations include an aluminum extrusion around the perimeter of the mat or group of mats, which serves
as a ramp up to the mat surface and also as a method for securing the mat(s) to the mounting surface. This extrusion is not
considered part of the active area of the mat. If the installation consists of multiple mats, there may be extrusion at the area
where two mats meet. This extrusion is considered part of the active area, and, when pressure is applied, should activate one
or both of the mats that it joins.
b. Testing Activation and De-Activation
Test for mat activation by stepping on the mat surfaces and verifying that activation (contact closure) takes place whenever
pressure is applied. Don’t limit the test to only one area of the mat(s). Extend the test to the edges corners and all across the
mat surface.
The instructions included with the control system will also include methods for testing reactions to a disconnected mat or
broken mat wire. Be certain of proper operation before putting the equipment into use. Contact your supplier immediately if
there is any suspicion of improper operation.