Hazards presence-sensing devices

Recent developments in machine controls and changes in U.S. standards now permit the initiation of some machine cycles without an overt action on the part of the machine operator. These systems, known as presence-sensing device initiation (PSDI), automatically cycle the machine upon the sensing-device determination that the operator is clear of hazard areas. Similar systems have been utilized outside the United States, but normally the design and function of the machines have been approved by government or professional third parties. Many safety professionals recommend that PSDI be utilized only if the machine control has been designed and periodically tested by the original machine manufacturer. Under no conditions should any part of the body other than hands be placed inside dies or other points-of-operation while machine power is active. 

Specific standards have not been adopted for the installation, adjustment, and maintenance of RF presence-sensing devices. Employers nsing snch devices should have had safety hazard analyses performed to determine potential failnres or limitations of the devices in their applications. Employers should be aware that the performance of a CPS device may be affected as environmental and physical conditions are changed. 

The hazard tree also helps identify protection devices to include in equipment design that may minimize the possibility that a source will develop into a condition. Examples would be flame arrestors and stack arrestors on fire tubes to prevent flash back and exhaust sparks, gas detectors to sense the presence of a fuel in a confined space, and fire... 

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