Low Pressure Mercury Lamp Pdf

They produce light when an electric current passes between two electrodes also called cathodes in a tube filled with low pressure mercury vapor and inert gases.

Low pressure mercury lamp pdf.

Nyc subways were still using original mercury arc rectifiers to convert ac to dc power up until the end of the 20th century. New high power amalgam lamps are significantly more powerful than low pressure lamps. High pressure mercury lamps kolorlux standard 50w 80w 125w 250w and 400w kolorlux deluxe 50w 80w 125w 250w and 400w data sheet product information kolorlux mercury vapor lamps are often used due to their relative efficiency. It needs to be vaporized and ionized before the lamp can produce its full light output.

The inner surface of the lamp is coated with a fluorescent and often slightly phosphorescent coating made of varying blends of metallic and rare earth. In addition to the mercury the tube is filled with argon gas at low pressure. Low pressure mercury vapor discharge lamp having a closed elongated lamp envelope and comprising at least two electrodes disposed near a first end of the lamp envelope at least one electrode is situated at the end of at least one inner tube situated within and sealed in a gas tight manner to the lamp envelope this inner tube having at least one opening to the inside of the lamp envelope the. To facilitate starting of the lamp a third electrode is mounted near one of the main electrodes and connected through a resistor to the other main electrode.

A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon xenon neon or krypton. Amalgam lamps use a mercury amalgam mix to control mercury vapor pressure. Two varieties of such lamps exist. Phosphor coated bulbs offer a better color rendering index than either high or low pressure sodium lamps.

The electric current excites the mercury vapor in the tube generating radiant energy primarily in the ultraviolet uv range. These early low pressure lamps used a lot of mercury today s lamps use a tiny amount of mercury. Some key differences between lamps. The mercury in the tube is a liquid at normal temperatures.

A sodium vapor lamp is a gas discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589 nm. Rather than a cold spot the lamp s amalgam spot on pellet regulates mercury vapor pressure during operation and yields up to three times the uvc output of a standard low pressure mercury lamp of the same length. Low pressure and high pressure low pressure sodium lamps are highly efficient electrical light sources but their yellow light restricts applications to outdoor lighting such as street lamps where they are widely used. Medium pressure lamps produce the greatest uv output per unit length of lamp of the 3 lamp types.

Right around 1900 the mercury arc rectifier was developed this luminous device was very important for power conversion. Conventional low pressure and amalgam lamps are significantly more energy efficient than medium pressure lamps. The pressure inside the lamp is around 0 3 of atmospheric pressure.