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DI water on Tin plated Copper coils

 

Recently we have installed Tin coated Copper humidification coils in our Air-Houses. The water is DI water from our Power-House. A suggestion has been made to put sacrificial anodes into the final feed tanks in each zone of the Air-House (55 anodes required). How do I size and install these anodes.

Steve Barmettler
- Shreveport, Louisiana USA

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I'm not fully sure you do need a sacrificial anode in this system because I would expect the tin coating to act as one. However, copper tubing can suffer from a variety of corrosion depending on the exact conditions of use. These problems are usually seen on potable supplies and depend on the water composition and temperature as well as the state of the internal bore of the tube. In the UK there is a propensity for low temperature corrosion caused by certain water mixes. To overcome it, the water industry normally puts a sacrificial aluminium rod in the water cylinder. It would typically be about 9-12 inches long and 1/4 inch in diameter. I would talk to the supplier of the equipment if I were you - they will have much better knowledge than anyone else.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK