Safety In The Use of Radiofrequency Dielectric Heaters And Sealers
İÇİNDEKİLERContentsPreface Introduction Sources Radiofrequency radiation 3.1. Electromagnetic radiation 3.2. Quantities and units of exposure Exposure and energy absorption Radiofrequency biological effects 5.1. Whole-body response 5.2. Localized responses 5.2.1. Reproductive system 5.2.2. Teratogenic effects 5.2.3. Effects on the eye 5.2.4. RF burns and operator hand numbness 5.2.5. Carcinogenesis 5.3. Conclusion Occupational exposure standards and guidelines 6.1. ICNIRP guidelines Exposure assessment 7.1. Measurement of RF fields 7.2. Measurement of induced currents Control technology and radiation protection programme 8.1. General obligations and duties 8.1.1 Role of competent authorities 8.1.2. Responsibility of the employer 8.1.3. Duties of the worker (user) 8.1.4. Responsibility of manufacturers 8.2. Work practice controls 8.2.1. Maintenance procedures 8.2.2. Operator procedures 8.2.3. Identification of RF hazard areas 8.3. Design and installation considerations 8.3.1. Shielding 8.3.2. Installation details 8.3.2.1. Installations near pipes 8.3.2.2. Grounding 8.4. Medical surveillance 8.4.1 Normal conditions 8.4.2 Abnormal conditions Appendix A. Shield theory, design and construction 1. Basic principles Current paths Resistance 2. Shielding design and construction Characteristics and selection of shielding materials Joints Ports or slot openings in shielding Doors and removable panels Vestibules (shielding tunnels) High-frequency power connections 3. Summary of control technology Appendix B. Radiofrequency characteristics of capacitors and inductors and implications for shielding Capacitors Inductors Appendix C. Resonant conductors and waveguides: Applications to shielding Resonant conductors Waveguides Appendix D. Effects of ground planes and reflectors on operator exposures References List of figures 1. Schematic diagram of a radiofrequency sealer 2. The electromagnetic spectrum 3. Whole-body averaged energy absorption rate 4. Unshielded and shielded RF heater used in the study 5. RF energy coupling to pipes 6. Method to prevent the coupling of RF radiation to pipes 7. Clamp installed around pipe and connected to the cabinet to inhibit currents 8. Square copper duct 9. RF energy leak A-1 General principle of shielding A-2 Cross-section of the shielding cabinet A-3 Effects on current distribution of different orientation of openings A-4 Slot openings parallel to current paths improve shielding compared to non-parallel slots A-5 Perforated metal plate across wide opening as part of shielding A-6 Current paths across a perforated metal sheet A-7 Contact strips between removable panel and fixed part of the cabinet A-8 Contact strips for frequently used sliding door A-9 Current flow in a shield opening with a vestibule A-10 Current flow in a shield opening without a vestibule A-1 1 Principle of a "short vestibule" D-1 Workplace exposure situations when using RF heaters D-2 RF absorption for grounded and ungrounded operators List of tables 1. ICNIRP occupational exposure limits to radiofrequency fields 2. Conductivity, skin depth and resistance per unit surface area of materials NOTLARA Practical Guide |
