AEC OFC Series - Manual (Page 17)

OFC Series Extrusion Control Units Page 17
Every effort has been made to incorporate these standards into the
design of the OFC blender; however, it is the responsibility of the
personnel operating and maintaining the equipment to familiarize
themselves with the safety procedures and the proper use of any
safety devices.
2-8-3 Fail Safe Operation
If a safety device or circuit should fail, the design must be such
that the failure causes a “Safe” condition. As an example, a safety
switch must be a normally open switch. The switch must be held
closed with the device it is to protect. If the switch fails, it will go
to the open condition, tripping out the safety circuit.
At no time should the safety device fail and allow the operation
to continue. For example, if a safety switch is guarding a motor,
and the safety switch fails, the motor should not be able to run.
2-8-4 Safety Device Lock-Outs
Some safety devices disconnect electrical energy from a circuit.
The safety devices that are utilized on OFC models are primarily
concerned with the pneumatics and electrical power disconnection,
and the disabling of moving parts that may need to be accessed
during the normal operation of the machine.
Some of the safety devices utilize a manual activator. This is the
method of initiating the safety lock out. This may be in the form of
a plug, disconnect plug, lever or a handle. Within this lockable
handle, there may be a location for a padlock. Personnel servicing
the equipment should place a padlock in the lockout handle.
WARNING!
Always disconnect and lockout all electrical power and pneumatic
(i.e. compressed air) sources prior to servicing or cleaning any
Blender, including all OFC units. Failure to do so may result in
serious injury.
At no time must anyone remove the lockout or reconnect the twist
plug, other than the person who installed the lockout or who
unplugged the twist plug.
2-8-5 Lock-Outs, Plugs, and Other Safety Devices
The OFC Blender utilizes several types of safety devices.
The Line Cord Plug