Lowpressure mercury vapor lamps cannot be directly operated on a 115 ac power line. It gives greenish blue colour light, which causes colour distortion. Unlike normal glass which blocks ultraviolet radiation, pure quartz has a high. The outer bulb may be clear or coated with a phosphor. Mercury vapour lamps dealing with breakages some items of laboratory equipment contain mercury vapour lamps to generate uv light. A fluorescent lamp is a low weight mercury vapour lamp that uses fluorescence to deliver visible light. The average life of tube lights is about 5000 hours and also. 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. 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. 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.
These additives enable the lamp to produce more visible light per watt with improved color rendition. The mercury in the tube is a liquid at normal temperatures. As pressure increases the chance of multiple collisions gets increased. Other materials and gases are used to help start the lamp or control its color. Here also, the excited electrons of mercury atoms relax by emitting characteristic but ultraviolet 254nm, invisible light. The mercury arc produces a bluish light that renders colors poorly. While the bulbs are being used, the mercury within them poses. The cold vapor principle was first proposed by poluektov and coworkers in 1963 2. A mercury vapor lamp is a gas discharge lamp that uses an electric arc through vaporized mercury to produce light. Why does greg gutfeld wear a ring on the middle finger on his left hand. 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.
Lamps of this type are used for general industrial lighting. 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. It can come in a high pressure or low pressure format. What are the advantages and disadvantages of the mercury. In europe it has fallen out of fashion due to its relative inefficiency and rapid lumen depreciation by contrast with other light sources. All credits and sources are located at the bottom of each lighting page. 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. A mercury vapor lamp consists of six major components. 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. 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 gas in this case is sodium vapour, but several other gases may be such as mercury, ne.
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. Sodium vapour lamp, electric discharge lamp using ionized sodium, used for street lighting and other illumination. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger borosilicate glass bulb. This lamp operates at 18 to 23 ma and is rated for 5000 hours of life. What is the working principle of mercury vapour lamp answers. He would create an arc through a metal, then observe what colors it produced when a prism. 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 electric current excites the mercury vapor in the tube, generating radiant. Uv curing troubleshooting alphacure uv lamp manufacturer. It requires a twominute warmup for the mercury vapor to dominate the discharge, then 30 minutes for complete stabilization. White light source xenon lamp has uniform excitation intensities across all the visible range. Low pressure mercury fluorescent lamps or tube lights. The mercury vapour lamp in construction is similar to sodium vapour lamp.
Blended mercury vapour lamps are an interesting technological development to see. The xenon gas which is easily ionized, facilitates striking the arc when voltage is applied across the electrodes. After that the arc then heats up the mercury and the mercury vapor then lights, giving the lamp a bluish color. It,s intensity decays over time, but the bulbs have a longer lifetime. 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. Among the light sources in use for general lighting, high pressure mercury vapour h. Working principle of sodium vapour lamp polytechnic hub. The construction and applications of sodium vapour lamps. Mercury vapor lamps with clear outer bulbs have cri values from 15 to 25, whereas phosphorcoated lamps have cri values from 40 to 55. Illustration of the components of a fluorescent lamp and how they work photo source. They are available in lengths from the very small of 150 mm to up to 2400mm.
Mercury vapor lamps produce light with a cct from 3000 to 7000 k. 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. Mercury vapor lamps are primarily used in industrial applications and outdoor lighting e. Despite their drop in popularity, however, these lamps are one of the most dependable. 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. Working principle of mercury vapor lamp polytechnic hub. The mercury vapor lamp is similar in construction to the sodium vapor lamp. 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.
Mercury vapour lamps have a number of advantages, especially compared to the high wattage incandescent lamps they were intended to replace at their launch. When current passes between the electrodes, it ionizes the neon and argon. Working principle of uv lamps uv lamps, ultroviolet, uvc. The lamp works by creating an electric arc through vaporized sodium metal. Mercury is present in the lamp in both the phosphor powder and in the vapor.
These lamps ma type are manufactured in 250 and 400 w ratings for use on 200250 v ac supply. Like aquafine lp lamps, aquafine lp amalgam lamps are also considered to be monochromatic with a significant 254nm output peak. 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. 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 sodium is mixed with other impurities to create a more white light. A sodium vapor lamp is a lamp that uses sodium to create light. The low pressure mercury fluorescent lamps are commonly called as tube lights. They generate light by sending an electrical charge through a gas to produce a plasma. 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. It needs to be vaporized and ionized before the tube will conduct electricity and the arc can start. The mercury vapor lamp is a negative resistance device. They have an efficiency of up to 190 lumens per watt compared to an incandescent street lamp which has between 15 and 19. Wattages range from 32 to 2,000, offering a wide range of indoor and outdoor applications.
See the photos lower on this page for more details. 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. Such lamps generate an atmosphere of mercury vapour at high pressure. This article discusses the construction and working principle of low pressure mercury fluorescent lamps also known as tube lights. It consists of a discharge envelope enclosed in an outer bulb of. The body of the lamp is made from a high quality transparent vitreous quartz tube. The lamp produces a clarity of light that creates vivid color from objects illuminated by it. 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. Therefore it requires a ballast to limit the current through it. 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. Fluorescent lamp and working principle of fluorescent lamp. Since the light emitted by a mercury vapor light has a blue tone, this needs to be accounted for, or color.
High pressure lamps have more components than low pressure and contain other substances such as mercury. Therefore, most mercury vapor lamps have a phosphor coating that alters the color and improves color rendering to some extent. The mechanism in mercury vapour lamp is more involved and sequential. 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 lamps generally contain between 10 and 100 mg of mercury. Sodium vapor lamps are some of the most efficient lamps in the world. The determination of mercury by cold vapor atomic absorption. Sodium vapour lights are a type of gasdischarge lamp. Again transition of the electrons requires least amount of input energy from a colliding electron. Mercury vapor lighting is the oldest hid technology. High and low pressure mercury vapor lamps disinfect the work is so special about them are very obvious differences.
To ascertain if the uv lamp is not producing full intensity uv light, perform a simple test with uv test strips. It is a gasdischarge lamp that uses sodium in an excited state to produce light. The heat generated by the arc then vaporizes the mercury and sodium. The move to metal halide bulbs, and then to the ultrahigh pressure mercury lamps used today, has both reduced the cost of the bulbs, and improved their lifetimes. 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. 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. 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.
Difference between sodium vapor lamp and mercury lamp. The average intensity is remarkably constant and reproducible after the thermal conditions stabilize. Sodium is the last material to vaporize as sodium vapor strikes an arc over 240 c. Mercury vapor bulb facts 1 self ballasted mercury vapor sbmv bulbs bulbs have a filament inside that works as a ballast. The sputtered electrons from the filaments, after having been accelerated by high voltage, hit the mercury atoms.
563 237 854 161 1576 1073 167 328 651 783 1158 1029 806 959 137 873 553 136 1081 25 256 1182 523 163 288 177 1160 762 1121 1466