Radiant energy – Invisible radiant energy responsive electric signalling – Ultraviolet light responsive means
Reexamination Certificate
1999-03-04
2001-11-06
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Ultraviolet light responsive means
C250S372000
Reexamination Certificate
active
06313468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a device for the continuous determination of a UV-transmission into flowing or running media, such as drinking water or purified waste water.
2. The Prior Art
The prior art has shown ways to disinfect microbiologically contaminated media by UV-irradiation. The disinfecting effect depends upon the condition or state of the medium. Contaminants in the form of dissolved or undissolved ingredients reduce the effective penetration depth in the UV-radiation. Therefore, it may be necessary to test media parallel with the UV-irradiation for their UV-transmission and thus for their suitability for disinfection by UV-irradiation.
Therefore, the invention is an improvement over the prior art because it provides a device for the determination of the effective UV-transmission depth into flowing media that provides a reliable evaluation.
SUMMARY OF THE INVENTION
This device overcomes measurement errors that could be caused by aging, temperature and flow variations, and other influences that could impair the radiation power of the UV-radiation source. These problems are avoided by employing the same UV-radiation source both for measuring the irradiation intensity in a flowing medium and in a reference space. The reference space is designed as a hollow space or cavity and may be filled with a medium that may be a solid, a liquid or a gas that is permeable to UV-radiation. It is possible also to use the same basic medium that is contained in the medium to be disinfected. Thus the reference medium can be filled with pure water so that it compares to waste water in the medium to be disinfected. It is also important to know the degree of UV-irradiation intensity damping in the medium in the reference space. Errors in measurement can be compensated by comparing the Pleasuring signals of the two UV-sensors.
The UV-sensors may be spaced apart from the emitting surface of the UV-radiation source at an equal distance or at a different distance. When spaced at an equal distance, the signals can be more simply processed so that the measuring signals of the two UV-sensors can be equally weighed. With different spacings, the measuring signals are weighed with reversed dependence on the spacing from the UV radiation emitting surface. This measurement takes into account that the intensity of irradiation decreases as the spacing from the emitting surface of the UV-radiation source increases.
The UV-sensors detect the radiation of the UV-radiation source preferably the center. Since the homogeneity of the radiation is particularly high in the center, particularly accurate measured values arc obtained.
If the reference space is not sealed against the measured medium, the sensors are spaced so that one UV-sensor is always arranged in the reference space and the other UV-sensor always in the flowing medium. These sensors are placed within the variation tolerance between the medium and the reference space. With this design, the sensors are positioned with the beast amount of spacing. Furthermore, this assures that the sensors detect about the same irradiation intensity range of the UV-radiation source and thus achieve high measuring accuracy.
Since the emitting surface of the UV-radiation has a specified minimum length of 13 cm, this source assures that there is a range or zone where the radiation intensity is homogeneous. This range is present in the center of the UV-radiation source. In addition a tail 5 cm in length extends the UV-radiation source, into the flowing medium and into the reference space. This design assures that ranges are available for each measurement where there is a constant radiation intensity.
The UV-radiation source is designed in the form of a cylindrical gas discharge lamp that is arranged in a protective tube. This tube projects partially into the flowing medium and partially into the reference space. The UV-radiation source can be employed in a drain normally used for disinfection to carry out the measurement there in any desired location. The cylindrical shape of the gas discharge lamp assures that an emitting surface can abut or adjoin both the medium and the reference space. Therefore, the same irradiation intensity of the UV-radiation source is available in both zones.
A cleaning device is associated with the UV-radiation source and the UV-sensor arranged in the flowing medium. Such a cleaning device prevents the formation of coatings on the UV-sensor and on the UV-radiation source. These coatings come from ingredients in the water, in the form of suspended substances. These coatings would grow over time and thereby increase the damping between the UV-radiation source and the UV-sensor, and falsify the measuring result. Cleaning the sensor assures that the measuring result exclusively relates to the UV-transmission of the medium itself.
In a preferred embodiment, the cleaning device comprises a first stripper for the UV-radiation source or its protective tube, and a second stripper for the UV-sensor. The two strippers are actuated at intervals by a common linear drive. By designing the cleaning device in the form of a stripper the flow of the radiation between the UV-radiation source and the UV-sensor is interrupted only for a short time. Therefore, the measurement, has to be interrupted only briefly as well. Due to such intermittent actuation, sufficiently long measuring periods are available, and the source is cleaned regularly. Therefore, the measurement can be viewed as being unimpaired by contaminations.
According to one embodiment, the first stripper forms a ring that encloses the UV-radiation source or its protective tube. In addition this ring can enclose this source or its tube partly in the form of ring segments. Furthermore, the second stripper is mounted on the ring or ring segment. The first and the second strippers are directly coupled to each other and are additionally guided on the UV-radiation source or its protective tube. Furthermore, this design assures that the first stripper from the UV-radiation source or its protective tube and the spacing of the second stripper from the UV-sensor are always optimally spaced.
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Collard & Roe P.C.
Gagliardi Albert
Hannaher Constantine
Wedeco AG Water Technology
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