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24-Pump, 128-Station Controller Chapter 2: Functional Description 11
• Identify and locate specific safety devices.
• Understand the proper use of the safety devices provided.
• Describe the function of the safety device.
Safety Circuit Standards
Safety circuits used in industrial systems protect the operator and maintenance personnel
from dangerous energy. They also provide a means of locking out or isolating the energy for
servicing equipment.
Various agencies have contributed to the establishment of safety standards that apply to the
design and manufacture of automated equipment. The Occupational Safety and Health
Administration (OSHA) and the Joint Industrial council (JIC) are just a few of the
organizations that have joined with the plastics industry to develop safety standards.
Every effort has been made to incorporate these standards into the design of the controller;
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.
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.
Safety Device Lock-Outs
Some safety devices disconnect electrical energy from a circuit. The safety devices that are
used in this Controller are primarily concerned with electrical power disconnection.
WARNING! Always disconnect and lockout all electrical power and pneumatic (i.e. compressed air)
sources prior to servicing the 24-Pump, 128-Station Controller. Failure to do so may
result in serious injury. No one but the person who installed the lockout may remove
it.