Sterling AF-XXX Manuel D’Utilisation

Additive Feeders 

Chapter 2: Functional Description 

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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 additive 
feeder; 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. 

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. 

Some safety devices disconnect electrical energy from a circuit. The safety devices that are 
used on these additive feeders are primarily concerned with 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, 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. 

In addition to the safety devices listed above, these additive feeders are equipped with a line 
cord plug.  This allows the operator or maintenance personnel to unplug the additive feeder 
from its power source and tag it out.  The plug can then be tagged with any number of 
approved electrical lockout tags available at most electrical supply stores.