Descaling copper boilers--something NOT to do!!! - Page 2

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#11: Post by chang00 »

Likewise, I don't have a degree in chemistry, but rather in molecular biology and doctorate in medicine. Professor Pavlis/rpavlis is correct. Bad idea to use hydrochloric acid.


#12: Post by gor »

I've seen it used for years by the commercial boys (coffee roasters and coffee equipment service depts) when cleaning out copper and brass components.

I also use this method with no adverse effects to the boilers and brass components i.e steam valve bodies etc.
Currently I have a boiler soaking in dilute HCl, which started off with 1 inch deposits in the HX and boiler inner.
It is almost completely done and it has only taken a week. I don't use heat or concentrated solutions af acid.



#13: Post by chang00 »

On different note regarding hydrochloric acid, from a physiologic point of view.

It is the main acid in the stomach, produced by the parietal cells. The acid sterilizes the food we eat, and pepsinogen is cleaved in acidic environment provided by HCl to become the active digestive enzyme pepsin. The pH in the stomach can reach as low as 1. The production of HCl is via a series of ion pumps (hydrogen potassium ATPase); the common anti acid medication omeprazole/Prilosec acts as an inhibitor of this proton pump to reduce the acid production.

Additionally, if one is to google hydrochloric acid MSDS, there are tons of information regarding the industrial risks of this acid in high concentrations and metal/copper.

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#14: Post by hankbates »

I worked for quite a few years in the application of corrosion resistant machinery as used in the chemical, food, and other process industries. Most of the applications used 316 stainless steel, but other more corrosion resistant materials were also used.
When corrosion caused the failure of this very expensive equipment, in most cases it was due to the presence of even small amounts of chloride ions in acidic (even slightly acidic) environments. I do not recall any cleaning regimen which called for the use of hydrochloric acid.
We found that when chloride attack occurred on most metal surfaces, it was anything but uniform, which would be predictable. Perversely, random pitting occurred, as the presence of higher concentrations of dissolved metal ions and chloride ions accelerated the reaction. This is is in line with Robert Pavlis' excellent explanations above.
In the words of one experienced supervisor: "I hate chloride attack, because the surfaces look so good while they are going to hell."
There are too many other cleaning agents (sulfamic, for one) commercially available to take a chance on using hydrochloric for cleaning anything other than throwaway items. In my opinion, to use this acid to clean an espresso machine or any other expensive equipment is being penny wise and pound foolish.

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#15: Post by erics »

I just saw advice on cleaning copper that if anyone followed it with a copper boiler they would destroy the boiler!! The advice said to use "muriatic acid" to clean copper.
Could you please provide a link to that "advice"? Have you tried doing a search on this forum using the term "muriatic acid"? Because . . . evidently, muriatic acid has been used (with no ill consequences) for some years to clean heavy scale deposits from espresso machine boilers by some well respected forum members. I have no idea what concentration levels were used nor do I know what concentration level you are referring to. I seem to remember from my masonry cleaning adventures that muriatic acid (as sold in the stores) was a 10% solution and certainly that product was even further diluted before use.

Eric S.
E-mail: erics at rcn dot com