Mercury-vapor lamp
A mercury-vapor lamp is a
Mercury vapor lamps are more energy
Mercury vapor lights operate at an internal pressure of around one atmosphere and require special fixtures, as well as an
Origins
Charles Wheatstone observed the spectrum of an electric discharge in mercury vapor in 1835, and noted the ultraviolet lines in that spectrum. In 1860, John Thomas Way used arc lamps operated in a mixture of air and mercury vapor at atmospheric pressure for lighting.[4] The German physicist Leo Arons (1860–1919) studied mercury discharges in 1892 and developed a lamp based on a mercury arc.[5] In February 1896 Herbert John Dowsing and H. S. Keating of England patented a mercury vapor lamp, considered by some to be the first true mercury vapor lamp.[6]
The first mercury vapor lamp to achieve widespread success was invented in 1901 by American engineer
Principle of operation
This section needs additional citations for verification. (April 2013) |
The mercury in the tube is a liquid at normal temperatures. It needs to be vaporized and ionized before the lamp can produce its full light output.[1] 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. In addition to the mercury, the tube is filled with argon gas at low pressure. When power is applied, if there is sufficient voltage to ionize the argon, the ionized argon gas will strike a small arc between the starting electrode and the adjacent main electrode. As the ionized argon conducts, the heat from its arc vaporizes the liquid mercury; next, the voltage between the two main electrodes will ionize the mercury gas. An arc initiates between the two main electrodes and the lamp will then radiate[9] mainly in the ultraviolet, violet and blue emission lines. Continued vaporization of the liquid mercury increases the arc tube pressure to between 2 and 18 bar, depending on lamp size. The increase in pressure results in further brightening of the lamp.[10][11] The entire warm-up process takes roughly 4 to 7 minutes. Some bulbs include a thermal switch which shorts the starting electrode to the adjacent main electrode, extinguishing the starting arc once the main arc strikes.
The mercury vapor lamp is a
Metal halide
A very closely related lamp design called the
Self-ballasted lamps
Self-ballasted (SB) lamps are mercury vapor lamps with a
Operation
When a mercury vapor lamp is first turned on, it will produce a dark
Color considerations
To correct the bluish tinge, many mercury vapor lamps are coated on the inside of the outer bulb with a
Emission line spectrum
The strongest peaks of the emission line spectrum are[13][14]
Wavelength (nm) | Name (see photoresist) | Color |
---|---|---|
184.45 | ultraviolet (UVC) | |
253.7 | ultraviolet (UVC) | |
365.4 | I-line | ultraviolet (UVA) |
404.7 | H-line | violet |
435.8 | G-line | blue |
546.1 | green | |
578.2 | yellow-orange |
In low-pressure mercury-vapor lamps only the lines at 184 nm and 254 nm are present. Fused silica is used in the manufacturing to keep the 184 nm light from being absorbed. In medium-pressure mercury-vapor lamps, the lines from 200 to 600 nm are present. The lamps can be constructed to emit primarily in the UV-A (around 400 nm) or UV-C (around 250 nm). High-pressure mercury-vapor lamps are commonly used for general lighting purposes. They emit primarily in the blue and green.
Ultraviolet cleaning
Low-pressure mercury-vapor lamps
Light pollution considerations
For placements where
Bans
In the EU the use of low efficiency mercury vapor lamps for lighting purposes was banned in 2015. It does not affect the use of mercury in compact fluorescent lamp, nor the use of mercury lamps for purposes other than lighting.[17]
In the US, ballasts for mercury vapor lamps for general illumination, excluding specialty application mercury vapor lamp ballasts, were banned after January 1, 2008.[18] Because of this, several manufacturers have begun selling replacement compact fluorescent (CFL) and light emitting diode (LED) bulbs for mercury vapor fixtures, which do not require modifications to the existing fixture. The US Department of Energy determined in 2015 that regulations proposed in 2010 for the mercury vapor type of HID lamps would not be implemented, because they would not yield substantial savings.[19]
Ultraviolet hazards
The arctube of mercury lamps produces large amount of short wave
Typical mercury vapor lamps with an outer envelope made of soda lime or borosilicate glass still allow a relatively large amount of 365 nm UV radiation to escape the lamp. This can cause the accelerated aging of some plastics used in the construction of luminaires, leaving them significantly discolored after only a few years' service. Polycarbonate suffers particularly from this problem and it is not uncommon to see fairly new polycarbonate surfaces positioned near the lamp to have turned a dull, yellow color after only a short time.
Uses
Area and street lighting
Although other types of
UV curing
Mercury vapor lamps are used in the printing industry to cure inks. These are typically high powered to rapidly cure and set the inks used. They are enclosed and have protections to prevent human exposure as well as specialised exhaust systems to remove the ozone generated.
Molecular spectroscopy
High-pressure mercury vapor (and some specially-designed metal-halide) lamps find application in molecular spectroscopy due to providing useful broadband continuum ("noise") energy at millimeter and terahertz wavelengths, owing to the high electron temperature of the arc plasma; the main UV emission line of ionized mercury (254 nm) correlates to a blackbody of T= 11,500 K. This property makes them among the very few simple, inexpensive sources available for generating such frequencies. For example, a standard 250-watt general-lighting mercury lamp produces significant output from 120 GHz to 6 THz. In addition, shorter wavelengths in the mid-infrared are emitted from the hot quartz arc-tube envelope. As with the ultraviolet output, the glass outer bulb is largely opaque at these frequencies and thus for this purpose needs to be removed (or omitted in purpose-made lamps).[citation needed]
Projection
Special ultra high-pressure mercury vapor lamps called Ultra-high-performance lamps or UHP lamps, are commonly used in digital video projectors, including DLP, 3LCD and LCoS projectors.
See also
- History of street lighting in the United States
- List of light sources
- Ultra High Performance lamp
References
- ^ a b c d e f "What color is mercury discharge tube? – handlebar-online.com".
- ^ ISBN 978-0-471-19210-7.
- ^ Gendre, Maxime F. (2011). "Two Centuries of Electric Light Source Innovations" (PDF). Eindhoven Institute for Lighting Technology, Eindhoven Univ. of Technology, Eindhoven, Netherlands. Retrieved April 3, 2012.
{{cite journal}}
: Cite journal requires|journal=
(help) - ^ Gendre, Maxime F. Two Centuries of Electric Light Sources Innovations. p. 4. (PDF) . Retrieved on 2012-01-02.
- ISBN 0-9726596-1-7, p. 88
- – via pubs.rsc.org.
- ^ doi:10.1038/108188b0.
- ^ Hewitt, Peter Cooper (1900). "Method of Manufacturing Electric Lamps". US Patent US682692A.
- ^ Schiff, Eric (4 December 2001). "How do neon lights work?". Scientific American. Retrieved 16 April 2019.
- ^ Whelan, M. "Mercury Vapor Lamps". Edison Tech Center. Retrieved 24 November 2017.
- ^ "The Mercury Vapor Lamp". Lamptech. Retrieved 24 November 2017.
- ^ Hull, Janet Starr. "Mercury Vapor Lights". Archived from the original on 30 May 2015.
- ^ Persistent Lines of Neutral Mercury (Hg I). Physics.nist.gov. Retrieved on 2012-01-02.
- ^ Nave, Carl R. (2010). "Atomic Spectra". HyperPhysics website. Dept. of Physics and Astronomy, Georgia State Univ. USA. Retrieved 2011-11-15.
- ^ "Crystec Technology Trading GmbH, Low pressure mercury-vapor lamps".
- ^ "Surface cleaning by UV-light". Crystec Technology Trading GmbH.
- ^ Phasing out of mercury vapor lamps. www.osram.co.uk. Retrieved on 2015-03-18.
- ^ Department of Energy §431.286 Energy conservation standards and their effective dates. Retrieved on 2020-06-30.
- ^ HID Lamp Final Determination DOE 2015-12-02 Retrieved 2017-10-14
- ^ "Duro-Test Safe-T-Vapor". www.lamptech.co.uk. Retrieved 2022-11-06.
- PMID 7181332.
Further reading
- Waymouth, John (1971). Electric Discharge Lamps. Cambridge, MA: The M.I.T. Press. ISBN 978-0-262-23048-3.
- Museum of Electric Lamp Technology
External links
- Media related to Mercury-vapor lamp at Wikimedia Commons