UV & materials selection
Question: We use extruded aluminum with anodization for the UV chamber of our water purifier. The anodization depth is about 15 micron. We are debating the use of stainless steel for UV chamber material. Can you explain the relative advantages and disadvantages of this choice? Which is better from the point of UV radiation reflection, resistance to corrosion by potable water, durability and other related aspects of a drinking water purifier? I am the head of R&D department of Eureka Forbes Ltd., which is one of the largest manufacturers of UV-based domestic water purifiers in India. We are members of WQA. We look forward to your expert views.
Eureka Forbes Ltd.
Answer: Reflective properties of metals will vary considerably with slight changes in composition and surface finishing. The reflective properties of your specific anodized material could be directly compared against stainless steel (SST) or other surfaces by irradiating the surface of samples with a UV light and taking radiometer readings at a fixed distance and (preferably high) angle. Unfortunately, I don’t have information on the corrosivity of your particular material. You may find additional help by posing your question to the International UV Association: www. iuva.org/PublicArea/index.htm
A ‘Carefree’ response to Expert answer
In response to the “Ask the Expert” question: “Catalytic: ‘No-salt’ solution or gimmick?” as published in WC&P (May 2000, p. 18-19), several types of alternative water treatment devices were mentioned in the answer from the “Expert.” This response will speak for the “Care Free” in the question from Laurel Epstein.
The report authored by Leon Kim, as published in WC&P’s February 1987 issue, contained print errors in the pages with chemical notations about the process. As soon as we noticed the error, we had other thirdparty experts review it. Corrections were made to any copies we had that weren’t distributed and we notified others we knew had the old printed version. Our copies of the corrected report is identified with “Revised 6/87” on the front cover. Copies are available from our office upon request.
Our product is roughly categorized as a “catalytic” water conditioner and it does fall in the category of alternative water treatment [in comparison] to the established ion exchange treatments. We also claim our unit doesn’t require use of chemicals or additives to function properly. We describe our process as electromechanical with electrochemical results. By that we mean the three simultaneous mechanical functions that take place in our unit are initiated by the flow of water through the unit. By example, when the water reaches the end-use such as irrigation of lawns or field crops or greenhouse crops, the electrochemical results take place in the soil and roots and leaves of the plants or trees. Other benefits are found in residential and commercial applications. Users have told us of excellent results on grass, flowers and field crops even with salty water.
To simply state one of the functions, our active alloy core releases negative ions (electrons) into the flowing water stream by a controlled reduction/oxidation process. The release of electrons is done catalytically on the surface of the core. This makes the water more electron-rich than it was and added electrons do the work several chemical products would do. The result is the bond that holds calcium and magnesium (scale) together is broken and the minerals pass on through the water without combining to make mineral scale buildup. Another result of the process is that existing mineral scale buildup will be removed by contact with our conditioned water.
In 1998, we were in contact with NSF International to be part of the development of a protocol for testing these kind of water conditioners. We offered to provide units for testing and to help them develop the test protocols to ensure a fair test for all participants. The whole effort seemed to come to a halt when two of the key participants from NSF International changed work assignments. Our offer is still open.
Dave Mattson, Customer Relations
Carefree Water Technologies Inc.
Santa Ana, Calif.
From the Editor: As stated in the 1987 article this letter refers to, WC&P takes a neutral position on such technology and publication of these comments should not be construed in any way as an endorsement of the products mentioned. We also do not stand behind any article that has been modified from its original form as published in WC&P, as changes were not reviewed by our Technical Review Committee. Still, we also welcome efforts on behalf of NSF to verify the performance claims of such alternative equipment and note that the WQA Magnetics Task Force is reviewing technical literature on the subject. It was to present a summary at the Water Quality Association Convention last month in Orlando.
Correction: In the February issue of WC&P, a graph accompanying the story “New Anion Exchange—Poly-vinylpyridine,” on page 90 was incorrect. It should have shown a comparison of a chromatographic nitrate peaking for two different types of resins.