Does a weak salt-water solution corrode copper tube 1

[tinsnano]

Dear all,

I have refrigeration system where the evaporator is copper tube in a bath. Now I need to use salt-water solution to refrigerate another storage place a bit below 0 degree Celsius may be -1 degree Celsius. I am planning to immerse the copper evaporator in salt water and circulate this fluid to the target but I afraid if the salt solution may corrode the copper evaporator.

So please let me know if weak salt solution may corrode copper tube and if so what else can i use as fluid

 

[EdStainless]

Look at non-chloride salts, over the years many have been used. Or even a bit of alcohol or glycol will do it.
While Cu has fairly good corrosion resistance there is a high likelihood that you would get attack at any water/air interface.

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P.E. Metallurgy, Plymouth Tube

 

[tinsnano]

I am sorry to see the fast response lately due to internet connection problem.
Anyways thank you EdStainless, alcohol is a good choice for me it is available. but if you mention some non chloride salt for me that would be nice and one last question could sugar serve the purpose of salt?

 

[EdStainless]

I don't like using things that can crystallize out of solution unless you are in a sealed and fully wet system.
Corrosion under deposits is far worse than just in wet locations.

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P.E. Metallurgy, Plymouth Tube

 

[tinsnano]

Thank you EdStainless. I will try alcohol(ethanol solution)

 

[Compositepro]

Why not used automotive antifreeze? It contains corrosion inhibitors and is optimized for the purpose. The dye confirms that it is present in about the right amount. Ethanol is flammable and evaporates faster than water.

 

[tinsnano]

Yes Compositepro that is another alternative but I need the chiller to be a little below water freezing whereas automobile freezing point is far below 0 degree centigrade. 10% ethanol solution has freezing point of -4 degree centigrade ( i think i can control the freezing point by varying the concentration of ethanol). I don't know but if i can change the freezing point of automobile anti freez by diluting with water then I may switch to it. By the way is 10-20% ethanol flammable?

 

[EdStainless]

Then add just a little anti-freeze, say 15%.
There corrosion inhibitors in it are designed for mixed metallurgy systems.

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P.E. Metallurgy, Plymouth Tube

 

[tinsnano]

Thank you EdStainless currently I have done with alcohol as you said and seems fine. In case the volatility of the ethanol become problem then I may switch to antifree