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topic 5376

Tests and Controls for Quality of Ordinary Tap Water


I am improving a small anodising unit of aluminium nameplates. I would like to know how to control the quality of the water used in the sulfuric acid bathes. This water is ordinary tap water. Thank You, Merci beaucoup. Cedric ODY

Cedric ODY
Cuspal - Dublin, Ireland


Now, here's a touchy issue. First, you have to define what you need. Demineralized, deionized, distilled, softened, or whatever. A part of this decision will be how much you want to pay for improved water quality. An adjunct question is to determine the incoming water quality (here in the US we're facing the issue of having to treat effluent streams to a higher quality than the incoming tap water).

A common method to indicate water quality is to determine the conductivity or resistivity of the water. Rinse water additions are frequently controlled this way.

One important point. If you want to control the water quality, you will have to do some sort of treatment to the water (probably ion exchange for small volumes). In this case, there are small lamp indicators of water conductivity which go out when the conductivity becomes too high. At this point you change the columns and you are back in business.

James Toter
- Largo, Florida


We have a cyanide silver electroless plate for copper bars. Using a cartridge deionizer for city water to supply a small still works fine. When the indicator light changes at 10K resistivity, we change the cartridge and return it to the supplier for regeneration. Before the addition of the deionizer, we needed to acid etch the still weekly to remove salt buildup. Now it needs cleaning very infrequently. This system supplies about 4 liters/hour of 10 micromos/cm (or better) water. We use this to make up chemical solutions additions from powder.

W. Carl Erickson
- Rome, New York

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