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Q & A: brass and aluminum

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Most recent answer: 12/27/2010
Q:
We have an aluminum fire boat. Can we mount a brass "deck gun" on the boat? A deck gun is an appliance used to move water at high pressures,(1500 psi)for fire fighting. I have been told there is an adverse effect when brass and aluminum are put together but am having difficulty finding out what the reaction is. Any help would be greatly appreciated.
- Sean Donovan (age 51)
Ocean City, MD, USA
A:
There is an anodic corrosion effect when brass and aluminum are in electrical contact and exposed to water. Aluminum ions (+) tend to go off into solution, accompanied by the formation of some (-) hydroxyl ions at the brass. Effects like that can be a big problem if you make some pipe or vessel with metal parts with very different anodic potentials, like brass and aluminum.

In the particular set-up you're describing, I really don't see how there would be a big problem. I'm assuming that the cannon wouldn't attach directly to any metal fitting on the boat, but would draw water through a rubber hose. Just as a precaution, you might want to make sure that the brass is not in electrical contact with any aluminum.

You could probably get much more expert opinion using the search term "anodic corrosion".

Mike W.

(published on 12/27/2010)

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