Is hypochlorous acid corrosive?

Is hypochlorous acid corrosive?

One of the concerns around using chlorine as a disinfectant is its corrosivity. It is important to note that all chlorine solutions will contain salt, which is the primary corroder in chlorine. About one half to one third of the salt used to create hypochlorite (bleach) or hypochlorous acid is actually converted into chlorine. Both have the potential to corrode, but because a much higher PPM is required in bleach to achieve the same disinfecting power as hypochlorous, bleach users may experience significantly higher corrosion. This is because bleach would require more chlorine concentration (with the accompanying salt content) to do the same job as hypochlorous.

Corrosion from hypochlorous acid may occur from two sources – the salt content in the solution and the acidic nature of the solution. It is thought that the great majority of corrosion comes from the salt, especially since our solution is a very mild acid at 6 pH or higher.

The Hypo uses about 3.7 grams of salt per liter. The Eco One uses about 2 grams per liter. Both are extremely light saline solutions – about 1/10 of sea water. But it is not so much the concentration of the salt, as its presence, which makes the difference. In other words, a concentration of 4 grams per liter will not necessarily create any more corrosion than 2 grams per liter.

So how can you protect against corrosion? Corrosion is most likely to occur on unprotected metals where salts are allowed to accumulate. In other words, if a piece of unprotected metal is sprayed with hypochlorous every day and not cleaned, the accumulated salts and the daily wet/dry cycle will tend to accelerate corrosion.

The solution to this is simple: if you are spraying hypochlorous on unprotected metal on a regular basis, follow it with a water rinse.

Photo by Zsolt Palatinus on Unsplash


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