Automation Canada - Machine Safety - 4

2. SELECT THE APPROPRIATE EMERGENCY STOP DEVICES.
Since conveyors come in different lengths and layouts, it doesn't
always make sense to use a typical pushbutton emergency stop. This is
because workers might not always be close enough to reach the button
and stop the system when an emergency occurs.
A cost-effective approach would be to use a rope switch, which offers
a range of spans. Rope switch installation is simple and can be done all
along the conveyor's perimeter. This means that a person working at
any point of the conveyor will have easy access to the safety device and
will be able pull the cord to stop the system if necessary.
3. DESIGN A WORKING SAFETY CIRCUIT.
All safety input devices, including E-stop pushbuttons and rope
switches, must be connected to safety-rated logic devices (either safety
monitoring relays or a safety controller). Non-safety-rated devices are
insufficient for this purpose and should not be used.
Built-in self-monitoring capabilities and redundant circuits are
important for ensuring that the safety function prevails in the case of a
component failure like a short circuit. The system should also
automatically test the correct opening and closing of the safety devices
in each on-off cycle.
4. MAKE SURE YOUR OPERATORS ARE WELL TRAINED ON
SAFETY.
Once you've implemented a safety solution, and it's been validated
and verified, the next step is training. You'll need to train workers on the
important conveyor rules, including general operation and
maintenance. You should also consider training on functional safety to
make sure that everyone understands how safety devices work and how
they should be maintained.
Since many conveyor-related injuries occur when workers are
performing maintenance activities, putting clear lockout/tagout
policies in place and training them on the use of lockout devices to
isolate energy sources for machinery to prevent accidental activation is
key.
CANADIAN AUTOMATION
VOLUME 4, ISSUE 2
4
Automation Canada - Machine Safety

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