The heat generated by the arc then vaporizes the mercury and sodium. The mechanism in mercury vapour lamp is more involved and sequential. Mercury vapor bulb facts 1 self ballasted mercury vapor sbmv bulbs bulbs have a filament inside that works as a ballast. The sodium is mixed with other impurities to create a more white light. Lamps operate at high voltages, if they are too close to any metal work or humidity is high, an earth fault can occur, as the arc jumps to ground. White light source xenon lamp has uniform excitation intensities across all the visible range. Among the light sources in use for general lighting, high pressure mercury vapour h. Sodium is the last material to vaporize as sodium vapor strikes an arc over 240 c. Principles of uv lamp disinfection uv disinfection is an increasingly popular residuefree method of killing or rendering harmless all microorganisms including bacteria, viruses, algae and protozoa in a range of environments such as water, air and on surfaces. The outer bulb may be clear or coated with a phosphor. Unlike normal glass which blocks ultraviolet radiation, pure quartz has a high. High and low pressure mercury vapor lamps disinfect the work is so special about them are very obvious differences. Therefore, most mercury vapor lamps have a phosphor coating that alters the color and improves color rendering to some extent. It needs to be vaporized and ionized before the tube will conduct electricity and the arc can start.
The determination of mercury by cold vapor atomic absorption. Such lamps generate an atmosphere of mercury vapour at high pressure. These additives enable the lamp to produce more visible light per watt with improved color rendition. So if the lamp is connected directly to a constantvoltage source like the power lines, the current through it will increase until it destroys itself. The low pressure mercury fluorescent lamps are commonly called as tube lights. He would create an arc through a metal, then observe what colors it produced when a prism. The gas in this case is sodium vapour, but several other gases may be such as mercury, ne. The mercury vapor lamp is a negative resistance device. After that the arc then heats up the mercury and the mercury vapor then lights, giving the lamp a bluish color. This lamp operates at 18 to 23 ma and is rated for 5000 hours of life. They generate light by sending an electrical charge through a gas to produce a plasma.
The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compact electronic ballast in the. Working principle of uv lamps uv lamps, ultroviolet, uvc. See the photos lower on this page for more details. It also needs to be underlined that mercury is not the only evil in the mercury filled lamps, but other chemicals present in the bulbs have the potential to cause sufficient damage to health. Working principle of sodium vapour lamp polytechnic hub. The mercury arc produces a bluish light that renders colors poorly. All credits and sources are located at the bottom of each lighting page. A sodium vapor lamp is a lamp that uses sodium to create light. Sodium vapour lamp, electric discharge lamp using ionized sodium, used for street lighting and other illumination. Low pressure mercury fluorescent lamps or tube lights. The cold vapor principle was first proposed by poluektov and coworkers in 1963 2. An electric current in the gas energizes mercury vapor which delivers ultraviolet radiation through discharge process and the ultraviolet radiation causes the phosphor coating of the lamp inner wall to radiate visible light. When current passes between the electrodes, it ionizes the neon and argon.
A fluorescent lamp is a low weight mercury vapour lamp that uses fluorescence to deliver visible light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb. During the last 15 years the luminous efficacy and the colour appearance of these mercury vapour lamps have been much improved by the application of europiumactivated phosphors. Mercury vapour lamps dealing with breakages some items of laboratory equipment contain mercury vapour lamps to generate uv light. Electrical articles 11 may 18 scientists have long been familiar with fact high luminous efficiency could be obtained by the use of sodium resistant glass, the sodium vapour lamp has now reached the practical stage.
The lamp produces a clarity of light that creates vivid color from objects illuminated by it. Mercury vapor lamps are the oldest highintensity discharge lamps in existence, although they are rapidly becoming outmoded by highpressure sodium, metal halide and fluorescent lamps. Blended mercury vapour lamps are an interesting technological development to see. Here also, the excited electrons of mercury atoms relax by emitting characteristic but ultraviolet 254nm, invisible light. As pressure increases the chance of multiple collisions gets increased. Electrical articles 8 may 18 the extensive use of the mercury vapor lamp depends entirely upon the versatility of the mercury vapor as regards pressure, temperature, voltage and other characteristics, each change resulting in a lamp of different spectral quality and. Like aquafine lp lamps, aquafine lp amalgam lamps are also considered to be monochromatic with a significant 254nm output peak. The body of the lamp is made from a high quality transparent vitreous quartz tube. It gives greenish blue colour light, which causes colour distortion. A compact fluorescent lamp cfl, also called compact fluorescent light, energysaving light and compact fluorescent tube, is a fluorescent lamp designed to replace an incandescent light bulb. Mercury vapor lighting is the oldest hid technology. Roughly 35% of the electrical energy imparted into the lamp becomes uvc energy of the. Working principle of mercury vapor lamp polytechnic hub.
Mercury lamps are used primarily for general street, parking and hibay industrial lighting applications where good efficiency and long life is desired and color rendering needs. The average life of tube lights is about 5000 hours and also. Mercury vapour lamps have a number of advantages, especially compared to the high wattage incandescent lamps they were intended to replace at their launch. What are the advantages and disadvantages of the mercury. Mercury vapor is the original and now the oldest hid technology and has been supplanted by other hid types that offer higher efficiencies and better color properties. Mercury vapor lamps are primarily used in industrial applications and outdoor lighting e. The xenon gas which is easily ionized, facilitates striking the arc when voltage is applied across the electrodes. The average intensity is remarkably constant and reproducible after the thermal conditions stabilize. The mercury vapor lamp is similar in construction to the sodium vapor lamp. Uv curing troubleshooting alphacure uv lamp manufacturer. Illustration of the components of a fluorescent lamp and how they work photo source.
It can come in a high pressure or low pressure format. The construction and applications of sodium vapour lamps. These lamps ma type are manufactured in 250 and 400 w ratings for use on 200250 v ac supply. Despite their drop in popularity, however, these lamps are one of the most dependable. A mercury vapor lamp consists of six major components. The mercury in the tube is a liquid at normal temperatures. They are available in lengths from the very small of 150 mm to up to 2400mm. Fluorescent lamp and working principle of fluorescent lamp. The sputtered electrons from the filaments, after having been accelerated by high voltage, hit the mercury atoms. Mercury vapor lamps with clear outer bulbs have cri values from 15 to 25, whereas phosphorcoated lamps have cri values from 40 to 55. The mercury lamp was the first kind of metal vapour light source that was mass produced for general lighting applications, and still today it remains one of the most popular discharge lamps produced globally.
While the bulbs are being used, the mercury within them poses. The so called blended mercury lamp is an example of a hybrid of two very different lighting technologies. High pressure lamps have more components than low pressure and contain other substances such as mercury. A mercury vapor lamp is a gas discharge lamp that uses an electric arc through vaporized mercury to produce light. Mercury vapor lamps generally contain between 10 and 100 mg of mercury. Lamp that produces light as a result of an electrical discharge, generated between two electrodes, in a highpressure mercury vapor that is contained in a transparent bulb. Sodium vapour lights are a type of gasdischarge lamp. Sodium vapor lamps are some of the most efficient lamps in the world. This article discusses the construction and working principle of low pressure mercury fluorescent lamps also known as tube lights. Low pressure mercury vapour uv lamps home study factors the pressure of several tons, low pressure mercury vapor discharge lamp, while the reaction of mercury mainly 184. Other materials and gases are used to help start the lamp or control its color. Without some means of limiting the lamp current, the lamp would quickly be destroyed.
The electric current excites the mercury vapor in the tube, generating radiant. Mercury is present in the lamp in both the phosphor powder and in the vapor. To ascertain if the uv lamp is not producing full intensity uv light, perform a simple test with uv test strips. Since the light emitted by a mercury vapor light has a blue tone, this needs to be accounted for, or color. Why does greg gutfeld wear a ring on the middle finger on his left hand. A lowpressure sodium vapour lps lamp contains an inner discharge tube made of borosilicate glass that is fitted with metal electrodes and filled with neon and argon gas and a little metallic sodium. Mercury vapor lamps are less efficacious than other hid lamp types, typically producing only 30 to 65 lpw, but they have longer lamp lives and. What is the working principle of mercury vapour lamp. In europe it has fallen out of fashion due to its relative inefficiency and rapid lumen depreciation by contrast with other light sources. Again transition of the electrons requires least amount of input energy from a colliding electron. The mercury vapor raises the gas pressure and operating voltage, and the sodium vapor produces light when the pressure within the arc tube is sufficient. The extensive use of the mercury vapor lamp depends entirely upon the versatility of the mercury vapor as regards pressure, temperature, voltage and other characteristics, each change resulting in a lamp of different spectral quality and efficiency.
It requires a twominute warmup for the mercury vapor to dominate the discharge, then 30 minutes for complete stabilization. It,s intensity decays over time, but the bulbs have a longer lifetime. Difference between sodium vapor lamp and mercury lamp. Therefore it requires a ballast to limit the current through it. Metal halide lamps are similar to mercury vapor lamps but use metal halide additives inside the arc tube along with the mercury and argon. The lamps have a socalled negative resistance, meaning that the lamp s electrical resistance falls with rising lamp current. What is the working principle of mercury vapour lamp answers. It consists of a discharge envelope enclosed in an outer bulb of.
The lamp works by creating an electric arc through vaporized sodium metal. The result is that projectors using bulb technology are more reliable today than they ever have been before, says felix pimentel, product manager for optoma technology inc. Wattages range from 32 to 2,000, offering a wide range of indoor and outdoor applications. Lamps of this type are used for general industrial lighting. In case of fluorescent lamp the mercury vapour pressure is maintained at lower level such that 60% of the total input energy gets converted into 253. They have an efficiency of up to 190 lumens per watt compared to an incandescent street lamp which has between 15 and 19. In some versions, fluorescent powder is applied that converts the ultraviolet part, which is emitted together with visible light, into visible light to improve the color. It is a gasdischarge lamp that uses sodium in an excited state to produce light. Lowpressure mercury vapor lamps cannot be directly operated on a 115 ac power line. The mercury vapour lamp in construction is similar to sodium vapour lamp.
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