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A germicidal lamp (also known as disinfection lamp or sterilizer lamp) is an electric light that produces ultraviolet C (UVC) light. This short-wave ultraviolet light disrupts DNA base pairing , causing formation of pyrimidine dimers , and leads to the inactivation of bacteria , viruses , and protozoans .
Unlike conventional germicidal UV-C lamps, which are limited to upper-room (above people's heads [8]) pathogen inactivation or use in unoccupied spaces due to their negative effects on human skin and eyes, far-UVC is considered promising for whole-room pathogen inactivation due to its enhanced safety. This allows for the installation of far-UVC ...
Lamp age or fouling or outages (reduction in UV intensity) Bulbs require periodic cleaning and replacement to ensure effectiveness. The lifetime of germicidal UV bulbs varies depending on design. Also, the material that the bulb is made of can absorb some of the germicidal rays. Lamp cooling under airflow can also lower UV output.
Germicidal lamps are simple low-pressure mercury vapor discharges in a fused quartz envelope. Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these gases.
Normally, the quartz envelope of standard low-pressure germicidal "G-series" fluorescent lamps is intentionally doped with materials to absorb mercury emissions below 254nm. This is to prevent ozone production in situations where ozone is not desired (in an EPROM eraser or mineral-hunting lamp, for example). The common G4T5 lamp is one of these.
The lamp's electrodes are typically made of coiled tungsten and are coated with a mixture of barium, strontium and calcium oxides to improve thermionic emission. A germicidal lamp uses a low-pressure mercury-vapor glow discharge identical to that in a fluorescent lamp, but the uncoated fused quartz envelope allows ultraviolet radiation to transmit.
Unfiltered light from a high-pressure lamp is rich in UVC used in germicidal lamps, for water purification, but it damages human skin. The contents of a high-pressure lamp are inert gas (such as argon) and mercury. [2] There are no phosphors used, and the mercury is clearly visible if it is not in a gaseous state.
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