Hypochlorous Acid (HOCl) and Hypochlorous Acid Generators

Posted by Sam Petegorsky on

HOCL vs Hypochlorite

There is a lot of confusion out there regarding Hypochlorous Acid Generators. The available information, in many cases is ambiguous and often contradictory. Now that we have Hypochlorous Acid Generators in stock and for sale on our website, I figured it would be a good time to post a blog to clarify some of that confusion.

(for general information regarding the efficacy and benefits of HOCl, please view my previous blog post.).

One of the areas that are that are often confused is the distinction between Hypochlorous Acid (HOCL), and Hypochlorite (the active ingredient in household bleach).

HOCl is up to 60 times as effective as a Hypochlorite. Not only that, but whereas Hypochlorite is highly corrosive, Hypochlorite is far more mild and is considered non-corrosive. So it has the benefit of being far more effective than Hypochlorite, while at the same time, being safer to use and will not corrode furniture and fixtures.

HOCl generators can produce either HOCl or Hypochlorite. For purposes of disinfecting, it would obviously be preferable to produce HOCl as opposed to Hypochlorite. While a Chlorine test can tell you the concentration of the solution you produce, it does not differentiate between HOCl and Hypochlorite. There is commercial equipment available that can distinguish between the two, but it is extremely expensive, and beyond the budget of the typical consumer.

So how can one insure that the product they are producing with HOCl generators is actually HOCl and not Hypochlorite?

There is a simple, and inexpensive solution to this problem, and that is a PH Test Strip. When making HOCl in a Generator, one should test the PH of the water first. At a PH of 5.5 or lower the solution will be 100% HOCl. At a PH of 6, the solution will be 90% HOCl and 10% Hypochlorite.

The PH of tap water can vary in different parts of the country. Additionally, the process that HOCl generators use, can cause the PH to rise. If you are concerned that your PH is higher than the targeted 5.5, you can add vinegar or citric acid (lemon juice), to lower the PH of the water, prior to running the HOCl generator.

Run Time vs. Salt

On another note, there are varying instructions for the amount of salt that should be used with an HOCl generator. The fact is, that there are 2 ways to increase the concentration of HOCl in the solution, you can either add more salt, or you can run the generator for a longer period of time. the result of either of these methods, is an increase in concentration. If someone disinfects frequently, and they are concerned about salt buildup, they have the option of using less salt, and running the generator for a longer period of time (the concentration can be measured by using a chlorine test strip. Either method is equally effective, it is a matter of personal preference.

Effective Concentration (PPM)

There is also some confusion regarding the effective concentration of HOCl. HOCl is a much stronger oxidizing agent than Hypochlorite and is effective at a lower concentration. According to the NIH, HOCl at a concetration of 200ppm is effective with a dwell time of just 1 minute, and even at a concentration of 50ppm is effective with a dwell time of just 3 minutes (far less than most disinfectants that require a dwell time of 10 minutes).

Source for effective HOCL concentration:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315945/

Source for Relationship Between HOCl and Hypochlorite at various PH values :  http://www.hydroinstruments.com/files/Basic%20Chemistry%20of%20Chlorination.pdf

Share this post

← Older Post Newer Post →

  • Just wanted to let you know that there was a typo in the fourth paragraph. I believe: “HOCl is up to 60 times as effective as a Hypochlorite. Not only that, but whereas Hypochlorite is highly corrosive, Hypochlorite is far more mild and is considered non-corrosive” should read “…Hypochlorite is highly corrosive, HOCl is far more mild and is considered non-corrosive.”

    Will on

Leave a comment

Please note, comments must be approved before they are published.