RF Safeguarding Devices

RF safeguarding devices are used to control machine operations by detecting changes in the RF field. RF safety products include personal monitors, survey instruments, area monitors, and protective garments. RF personal monitors are devices worn on the body that sound an alarm when radio frequency (RF) rises above a preset threshold. RF survey instruments can detect all frequencies with equal sensitivity (a flat frequency response), or vary sensitivity as a function of frequency in accordance with a particular standard (a shaped frequency response). RF area monitors sound an alarm or send an electronic signal when RF levels exceed a preset threshold in an area such as a shop floor. RF protective garments provide significant protection (10 dB or more); however, they must be worn properly. RF machine safeguards include presence-sensing devices, which can sound a warning, change machine function, or stop the machine. RF safeguarding devices also include safety mats, safety gates, safety relays, and safety interlock switches.

RF safeguarding devices protect against several kinds of equipment, including transmitter type (fixed, mobile, portable), field characteristics (far-field exposure, near-to-far field transition regions, and near-field exposure), exposure limits such as maximum permissible exposure (MPE), and specific absorption rate (SAR). Limits for RF safeguards differ for controlled populations (occupational workers) and uncontrolled populations (general population). RF safeguarding devices are used in broadcast facilities for radio, TV and telecommunications, radar installations, industrial facilities that use processes such as induction heating and microwave applications, and in medical facilities that use processes such as electrosurgery and magnetic resonance imaging (MRI).

The United Stated Federal Communications Commission (FCC) sets RF exposure limits based on the American National Standards Institute (ANSI) / Institute of Electrical and Electronic Engineers (IEEE) standard ANSI/IEEE C95.1 and the National Council on Radiation Protection and Measurements (NCRP) Report No. 86. Some RF safeguarding devices meet requirements from the U.S. Occupational Safety and Health Administration (OSHA). Others comply with the B11 series of safety standards from the American National Standard Institute (ANSI). RF safeguarding devices are covered by the European Telecommunications Standards Institute (ETSI), the International Council on Non-Ionizing Radiation Protection (ICNIRP), and other organizations.

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