Uvc washington dc1/26/2024 Screens of many electronic devices can be affected by UV degradation due to the grade of plastic used and the very thin film generally used. Rubbers in general such as motor belts and conduits used in the HVAC industry have proven to stand germicidal UV very well over the last 20 years of cumulated field experience. For critical components such as exposed electrical wire direct insulation coating, it is recommended to cover the wires with aluminum tape or run the wires inside protective metallic rigid or flex conduits according to good practice and general electrical codes prescriptions. Associated with this there would be some limiting distance, a film thickness or penetration depth, to which UV would penetrate.īased on several decades of use, experience has shown that within a few exceptions, the UV induced damages tend to remain superficial and do not generally affect the structural or mechanical integrity of thick plastic components. It describes the susceptibility of a material to degrade under UV exposure. The photochemical degradation of materials is a dose-dependent function that depends only on the quantum yield and the molar absorption coefficient at the irradiation wavelength (Bolton and Stefan 2002). This would enable them to develop resistance to further UV exposure (Owen 1976). Materials that would darken to UV after exposure create a thin UV-proof film on the surfaces of polymers like PVC. Experimental data indicates the response of most of these properties to extended ultraviolet exposure results in data that can be effectively modeled with exponential decay curves of one or more orders. There are as many as thirteen different properties of plastics which can be used as indicators of photodegradation, including coloration, tensile strength, elongation, hardness, degree of polymerization, infrared absorbance, etc. Plastic properties and protection against degradation As the concentration of pigments increases, the depth of discoloration or fading also decreases. The depth of discoloration is reduced by the presence of color pigments. The fading of pigments and dyes can be evaluated in terms of the loss in concentration over time (Feller 1994). Surface yellowing tends to block UV and protects the inner plastic. Yellowing of polymers from ultraviolet exposure tends to be concentrated on the immediate surface. High quality pure plastics are relatively resistant to UV but impurities and residual solvents in low-grade plastics are mainly responsible for their quick photodegradation. Quantum yields as low as 0.0001 (10,000 photons per molecule) have been reported for most plastics. For the bleaching of certain dyes the quantum yield has been reported to be about 0.002, meaning a thousand photons must be absorbed before two molecules are bleached. In the photodeterioration of paints, varnishes, and textiles, the quantum yield is several order of magnitudes less than unity (Feller 1994). For most common polymers the depth of UV penetration is typically about 0.025 mm to 0.050 mm i.e. Since UV transmissivity tends to be very low for most materials, even at millimeter thicknesses, most of the photodegradation will occur on the immediate surface of a material, to a depth of typically less than 0.01 to 0.1 millimeter. The depth to which ultraviolet light penetrates the polymer creates a region of absorption where photochemical reaction may take place, and where photodegradation may occur. 100–400 nm wavelength, the photons energy exceeds the bond energy of the carbon bonds in the polymer or else exceeds the activation energy of chemical reaction (Moreau and Viswanathan 1976). For higher square footage applications, installing two air health units, one over the A/C coil in the supply and one in the return, is ideal for its’ cumulative effect.When polymers are exposed to ultraviolet light, i.e. If there is no A/C system or the location is not accessible, the optional location is in the return air duct, preferably downstream of the filter. The moisture on the coil and in the drain pan is a prime breeding ground for bacteria, spores, viruses and other contaminants. This will treat the indoor air while simultaneously keeping the coil clean. The best location for Air-Care UVC Silent Light is over the A/C coil. The use of the ultraviolet light for air purification has been proven effective in hospitals, schools, daycare centers, restaurants, and hotels. Our UVC Air Purifier uses powerful ultraviolet light to help reduce and kill mold, bacteria, viruses, and other airborne invaders. The UVC home air sanitizer helps fight indoor air pollution and purify the air in your entire home 24/7.
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