Figure 4. 254nm spectrum of a UV amalgam lamp and an effective spectrum for killing bacteria (E. coli as in DIN 1031 Part 10). |
To further increase this effect, the Chlorominator also features up to 12 Heraeus Noblelight low pressure amalgam lamps (see image at top of p. 1) and the UV medium pressure lamps. These are located in the outlet of the irradiation chamber. With their quasi- monochromatic spectrum of 254nm and high efficiency of around 35%, they're well suited to disinfection of the water in swimming baths (see Figure 4).
Compared with conventional mercury low pressure lamps of the same geometry, amalgam lamps offer significantly greater power. While mercury low pressure lamps typically have a specific electrical power of 0.3-0.5 W/cm of illuminated length, amalgam lamps approach 6 W/cm because of a different pressure/temperature ratio. Mercury low pressure lamps achieve optimal mercury vapour pressure of 0.8 Pa, and hence their maximum UVC output, at around 40ºC. Increasing or reducing temperature by increasing or reducing electrical input power only leads to a reduced UVC output.
The amalgam lamp also reaches its optimum vapour pressure at 0.8 Pa, but this is at a corresponding temperature of 90-130ºC (depending on the model). This higher level temperature is responsible for the higher specific electrical power of the amalgam lamp and thus for its higher UVC output per centimetre of illuminated length. As such, amalgam lamps are much more compact than mercury lamps of the same output. Consequently, system builders can scale down equipment, as they need fewer lamps and casings and hence less space. A smaller number of power supply units is also another potential saving.
A Case in Point
The Chlorominator, with its advanced UV technology, is already in use in a large number of swimming bath installations. Recently, the newly built spa centre at Bad Liebenstein, Germany, received two of the UV generators. Bad Liebenstein is the oldest spa town in the central German state of Thuringia. This new spa was to be opened in Spring 2009. Amongst other things, it offers a swimming pool, speciality showers, a sauna suite with ice tubs and immersion pools, and relaxation baths using the local spa water. Here, the oldest spa and curative bath in Thuringia, (the healing and curative effect of the water from the Casimir spring has been acknowledged since 1601) is now using modern water treatment with UV technology as well. Medium pressure and amalgam low pressure lamps cut the chloramines in the water and help water disinfection, so facility users can safely and peacefully relax, from top to toe, and look forward to their next visit.
Author's Note: Thomas Lödel is marketing manager for Heraeus Noblelight GmbH of Hanau, Germany. With subsidiaries in the USA, UK, France, China, Australia and Puerto Rico, the Heraeus Group member makes infrared and UV emitters for various applications in industrial manufacture, environmental protection, medicine and cosmetics, research, development and analytical laboratories. Contact: +49 6181 35-9379, [email protected] and www.heraeus-noblelight.com
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