Blog

What is Hypobromus Acid

1. Hypobromous acid is a fast-acting oxidizing biocide used in open cooling tower systems to kill:

1. 1. Bacteria (including Legionella)
   2. Algae
   3. Fungi
   4. Biofilms

1. It’s chemically similar to hypochlorous acid (HOCl) but:

1. 1. More effective at higher pH (7.5–9.0)
   2. Less likely to form chlorinated organics
   3. Less corrosive to metals than free chlorine

2. How HOBr Works

1. 1. Penetrates microbial cells (uncharged form)
   2. Oxidizes vital cell components: enzymes, DNA, membranes
   3. Destroys cells quickly, especially in biofilms

1. It’s particularly effective in hot, systems where pH > 8 pH,where chlorine loses activity.

3. How It’s Used in Cooling Towers

1. 1. As a primary oxidizing biocide, either continuously or in daily slug doses
   2. In larger systems

1. NaBr + bleach activation system (cheaper, safer than bromine tablets)

1. 1. In smaller systems

1. As a stabilized product sold at 7% or 10% activity

4. How It’s Made: NaBr + Bleach Reaction
   1. When 42% sodium bromide (NaBr) is mixed with 12% sodium hypochlorite (NaOCl) (bleach), a simple reaction occurs:

1. 1. Sodium bromide supplies Br⁻
   2. Bleach oxidizes Br⁻ → HOBr (active biocide)

1. Chemical Reaction:
2. NaBr+NaOCl+H2O→ HOBr + NaCl + NaOHNaBr + NaOCl + H2O
3. HOBr + NaCl + NaOHNaBr + NaOC l+ H2​O→ HOBr + NaCl + NaOH

1. 1. Occurs instantly in water at tower pH (~7–9)

5. Recommended Dose (General Guidelines)

6. Advantages:

1. 1. Works well in alkaline systems (up to pH 9)
   2. Effective against biofilms and Legionella
   3. Compatible with many scale/corrosion inhibitors
   4. Lower tendency to form chlorinated byproducts