Fig 1
 

HOW IS UV LIGHT GENERATED?

The UV Arc Tube, a quartz tube similar to a fluorescent strip light, is filled with and inert gas, which provides the initial discharge and the means of exciting the minute amount of mercury present. A Low Pressure glow discharge produces a line spectrum at 185.0 and 253.7 nm.

As the current is increased, the Arc Tube heats up rapidly, the pressure increases and produces the typical Medium Pressure spectrum shown in fig 1. It is a complex combination of spectral lines, continuum and absorption lines. Fig1 shows:

the position of UV-C in the electromagnetic spectrum
the UV absorption curve of DNA
the outputs of Low and Medium Pressure electrical

    discharge lamps and arc tubes

Fig 1 also compares the spectrum from the Medium Pressure Arc Tube with the germicidal effectiveness curve, and shows that the Arc Tube produces a powerful bactericidal dose of UV across the desired waveband. Hanovia offers both Low and Medium Pressure technology and will advise which is appropriate according to the application.

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