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.
Low pressure mercury lamp pdf.
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.
The pressure inside the lamp is around 0 3 of atmospheric pressure.
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.
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.
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.
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.
Medium pressure lamps produce the greatest uv output per unit length of lamp of the 3 lamp types.
It needs to be vaporized and ionized before the lamp can produce its full light output.
Conventional low pressure and amalgam lamps are significantly more energy efficient than medium pressure lamps.
These early low pressure lamps used a lot of mercury today s lamps use a tiny amount of mercury.
In addition to the mercury the tube is filled with argon gas at low pressure.
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.
Right around 1900 the mercury arc rectifier was developed this luminous device was very important for power conversion.
Amalgam lamps use a mercury amalgam mix to control mercury vapor pressure.
A fluorescent lamp tube is filled with a gas containing low pressure mercury vapor and argon xenon neon or krypton.
Nyc subways were still using original mercury arc rectifiers to convert ac to dc power up until the end of the 20th century.
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.
øgermicidal lamps operate at a very low gas pressure.
Some key differences between lamps.
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.
This coating covers more than 70 of the diameter of the lighted length of the lamp.
Two varieties of such lamps exist.
