The Science and Applications of Ultra Violet Fluorescent Tubes and Lamps
1. Introduction to Ultraviolet Light and Fluorescence
Ultraviolet (UV) light is light in the range from 100 nanometers (nm) to 400 nm. It is just outside the range that human eyes can see, so it appears invisible to our natural senses. UV is shorter in wavelength than violet light, the highest frequency of visible light, and is typically divided into three ranges: UVA (400 nm-315 nm), UVB (315 nm-280 nm), and UVC (280 nm-100 nm). UVB is the kind of UV that gives you a sunburn, while UVC is the kind you get in a germicidal lamp. These three subtypes have particular differences in effects on materials, as well as impact on health and environmental safety regulation. It is important that this topic delves into the effects of UV so that individuals understand why it is an important criterion. There is a tendency to think that UV is basically a "hardened light," typically used to cure materials, but UV fluorescent tubes have a wide range of technology applications that can be discussed. Fluorescence occurs when a material absorbs UV light and re-emits visible light.
This is a reversible process and, once returned to the dark, the material will eventually revert back to its original state because the trapped energy is lost. This stored energy may also be lost during collisions between molecules. When it abandons the excited state and falls back down to its ground state, it emits light, with the position of the peak emission determined by the molecular structure. The higher the absorptive energy, the closer the molecule is to the UV. It is this process of moving back down from this initial bond being made when it is hit by UV radiation that generates the latter form of radiation, albeit only visible light. It is fundamentally important to us that UV has a higher energy than visible light. It is for this reason that excessive amounts of UV can be hazardous to our health, causing skin cancer, eye cataracts, and immune system suppression. Despite this, it is interesting to note that low-intensity doses of UV have therapeutic effects such as the biosynthesis of vitamin D, treatment of skin diseases, treatment of jaundice, and improvement of mood disorders and sleep patterns. Given these properties, it may be utilized for applications such as sterilization and security inks, and is used for commercial purposes in the following ways.
2. Principles of Operation for UV Fluorescent Tubes
UV fluorescent tubes operate to emit UV light. Typically, they are long tubes with a small diameter. The tube is filled with a low-pressure gas. There is a pair of electrodes across the diameter at each end of the tube extending inside the tube. Small amounts of mercury vapor are added to the gas to aid starting and give the tube slightly more light output. The interior of the tube has a phosphor coating that converts the UV light to visible light. The glass of the tube varies from transparent to semi-transparent for UV, and opaque with a small number of holes at one end to emit visible light. The design of the tube is to create a UV source with as much of the UV light as possible in a range that makes the phosphor as efficient as possible. The basic process of producing UV light is performed with a discharge of electrical energy. That is, a current passing in a sealed tube full of gas with a suitable voltage. It can be demonstrated by a normal fluorescent tube that emits visible light. The visible light will excite the phosphor or simply turn the UV light into visible light. To understand the principles of the light source and its applications, some knowledge of atomic and subatomic structure and processes is needed. This understanding provides insight into the principles and precautions to apply for the operation and use of these light sources.
3. Types and Varieties of UV Fluorescent Lamps
One kind of UV curved fluorescent tube is a low-pressure mercury-vapor arc lamp. These lamps have high efficiency, little discharge temperature, and a long lifetime of 8,000 to 20,000 hours. They have an emission line from 254 nm to 185 nm; their energy is mainly concentrated at 254 nm, with a small amount at 185 nm and 365 nm, from weak to medium intensity. The power of these light sources ranges from 4 W to 200 W, but the power of a single curved airflow lamp is only 9 W. The most common tubes connected in series are indicative of those that have the benefits of being made on a large scale since the early 20th century. These tubes are small in size, have a diameter of about 8 mm to 38 mm, good optical properties, good air-tightness, a small change in optical properties, and are easy to trigger. They are typically applied for reading lights, sterilization, and air purification. Here, the typical power rate of the tube is 3 W to 30 W.
In particular industries and academic sectors, medium-pressure and high-pressure mercury lamps can also be used for specialty applications. The medium-pressure mercury lamp has a higher ultraviolet radiation energy density than the low-pressure mercury lamp, and its radiation spectrum is wider. The potential for industrial applications is great in the field of printing plate printing. The excimer lamp is currently under intense research; it has excellent application potential. The xenon mercury lamp can emit mercury and xenon gas discharge fluorescent lamps that emit visible cold white light. With advances in technology, many new and innovative UV fluorescent lamp designs have emerged. In general, in the choice of UV lamp, individuals and industry professionals need to choose according to the efficiency, lifetime, UV spectrum, cost of the lamp, and their applications.
4. Applications of UV Fluorescent Tubes and Lamps in Various Industries
IV. Applications
Owing to its higher potency, shorter exposure period, cost efficiency, and decreased chemical waste, UV fluorescent lamps have long been used as UV sources in a wide spectrum of purposes or applications ranging from water and air purification to medical care, food preservation, and biosciences. For example, in the healthcare sector, fluorescent technology also plays a role in cancer photodynamic therapy for the treatment of dermatological and oncological lesions and acne. The technology enables the treatment period to be assessed by non-invasive examination of the tumor during progress while offering significant cosmetic advantages. Continuous research and growth in photobiology R&D also unlock fresh fields of applications for the use of UV-light systems in other sectors.
In the agricultural industries, UV light has lately been involved in innovative Integrated Pest Management procedures. Fitting and grow rooms are disinfected by UV with a range of equipment where air sterilization is achieved through an exhaust air dust level, while room sterilization is done using portable systems. In addition to treatment that wipes out pathogenic organisms like saprobic fungi, pest diseases, insects, germs, and yeasts, UV irradiation improves immunity and also the quality, taste, and appearance of crops. A developed hot water UV technique kills food organisms and decreases serum plants in fresh-cut goods such as baby spinach and fruits like strawberries. Therefore, an extreme high-power ultraviolet pulse light source design is important for quality management in the farming and production of elevated bacteria-count commodities, which are UV-sensitive. For the prevention of fresh-cut fruit from pathogenic organisms, UV bridging-resistant UV rays and evaluated new emerging antimicrobial treatments were introduced. Both plants had a high-energy UV light and the process architecture for plant traffic as well as practical production environments was predicted.
5. Safety Precautions and Maintenance Guidelines for UV Fluorescent Lamps
Safety Precautions
Users, service personnel, and bystanders should be made aware of potential health hazards while working around ultraviolet light. As the level and duration of UV exposure may exceed safe levels, precautions must be observed. When working around UV fluorescent lamps, the use of an ultraviolet eye filter is recommended. The intensity of visible light in excess of 1 foot candle is considered to be acceptable for brief viewing of UV lamps from distances less than 10 feet in the direction of radiation. Prolonged or intense exposure to this visible light may damage eyesight; for that reason, it is recommended that one wears a face shield or safety glasses with side shields. Safety equipment used with lamps should be of one-piece polycarbonate for resistance to UV exposure and have a UV protective coating or lens. It is also recommended that long-sleeved clothing be worn for protection against exposure of skin to UV light. Cover that hazardous energy source with UV lamp replenishment gloves to avoid exposure.
Preparations
It is important to use easy-to-install and easy-to-replace ultraviolet fluorescent lamps. Lamps shattering during installation or maintenance can be a hazard to personnel. For added safety, ensure that reflectors are fitted with protective screens if damage or shattering of the lamp is possible.
Maintenance
Regular inspections of the UV lamp reflector area should be conducted to minimize dirt build-up on the reflector surface and the lamp’s quartz surfaces. The quartz surface can be wiped clean with a soft, dry, clean cloth. If there is a build-up of dirt, the quartz can be cleaned with alcohol to remove grease, oils, and dust. UV lamps must be properly disposed of in accordance with environmental regulations. This may include professional handling and disposal. Check with local authorities for proper disposal. To avoid contamination, when the lamp is changed, replace gaskets and tighten glands around lamp terminals to recommended torque settings.
