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JenAct Limited
of Whitchurch, Hants (U.K.) is delighted to report that they are working with Southampton University to further the development of their new UV sterilization technology. Ultraviolet light at a particular frequency kills bacteria and is widely used to sterilize products such as water and food products.
Conventionally, UV light is generated with germicidal bulbs very similar to strip lights in appearance or with higher power bulbs using electrodes. The fluorescent
tube approach is quite efficient in the germicidal UV (about 30%) but can only operate at low power, typically 50 to 70 watts max. Arc lamps operate at high powers, (1000 watts plus.) but also at
higher internal pressures -- resulting in much heat and a drop in germicidal UV to about 5 - 7%. These bulbs have to allow clear passage between their electrodes and virtually always have to be
cylindrical in shape. Consideration has to be made of the effect of the internal plasma materials on the internal electrodes. Electrodes break down over the life of a bulb and cause UV output to
fall gradually.
JenAct
has developed a system in which microwaves are used to energize an UV-emitting electrodeless bulb. There are no restrictions placed on the bulb design by electrodes and these bulbs can operate as low, medium or high-pressure bulbs. As there are no electrodes, bulb life is extended almost indefinitely. (JenAct has never had a bulb fail).
By controlling power and volume, JenAct
has been able to produce similar UV outputs to low pressure lamps (high in germicidal UV) from microwave powered lamps running at powers up to 800 watts. This is new technology, offering low pressure wavelengths at about 10 times the power of conventional systems -- with the additional advantages of long bulb life and the ability to make bulbs virtually any shape.
JenAct
has financed a project at the University of Southampton to investigate bulb fill possibilities and output characteristics with a wide variety of fill elements. Many possibilities suited to many different applications are emerging. One possibility is the production of an On Line Bottle Sterilization system, for which JenAct received a DTI 'SMART' award. By a new process, bulbs can be energized by microwaves outside a conventional microwave oven, thus enabling on-line application. The Hg plasma emission spectrum is high in germicidal UV (254 nm). In tests, 6-log bacterial reduction of levels of common “bugs” has been achieved in three seconds.
In addition, JenAct has conducted extensive research and development of microwave power supplies, with the aims of increasing efficiency; controlling power
(and thus UV output and temperature) and reducing power supply size. Improvements have been made in each of these three areas.
A true variable power microwave power supply has been constructed able to feed continuous power from 50 to 800 watts. This has enabled data to be obtained on the
relationships between fill criteria and output UV and temperature.
A 200watt power supply is in the design stage, which will not need a standard transformer and thus will be much smaller and lighter. This will have application in the
'portable' and lab fields where it will still offer four times the power of the most powerful low-pressure lamps.
In addition, JenAct
and its parent company R.A. Jenton have patent applications on various parts of the above technology.
Strategic alliances are sought with companies who would like to introduce and exploit JenAct technologies in their chosen fields.
Applications Include: – Sterilization of water, food surfaces, air conditioning ducts, medical devices, implants, hospital rooms, and food
factory air, curing of thin coatings for lenses, silicones, printed articles, visible lighting.
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