Whenever I am doing a Chlorine project this always comes up, as I almost always try and get anyone who is using elemental chlorine to make the switch to “bleach”, or sodium hypochlorite (NaOCl). Too many facilities are not capable of safely storing and handling elemental chlorine – that is just a hard fact. These businesses who are using “short-filled” cylinders, a 1-ton cylinder filled only with 1,500 pounds, in order to avoid PSM application think that since PSM (or RMP) is not applicable that there are no OSHA standards that cover their use of the chlorine. Thus the environment and management system around the handling and storage of this Highly Hazardous Chemical (HHC)/Extremely Hazardous Substance (EHS) fall WAY SHORT of what is needed. So for these businesses we can use an INHERENTLY SAFER alternative that if they were doing all they needed to do to safely manage their Cl2, it would also be cheaper for them.
But wouldn’t we have to count the amount of Cl2 in the bleach and maintain those amounts less than 1,500 pounds of chlorine?
No, and here’s why…
The RMP regulations apply only to a process that contains more than a threshold quantity (TQ) of one of the SPECIFICALLY LISTED REGULATED SUBSTANCES in 40 CFR ยง68.130. Sodium hypochlorite (7681-52-9) is NOT a SPECIFICALLY LISTED REGULATED SUBSTANCES.
Elemental chlorine (7782-50-5) IS A REGULATED SUBSTANCE.
If elemental chlorine (or any other SPECIFICALLY LISTED REGULATED SUBSTANCES) is present in a process, the amount of that substance must be considered when determining whether the process is covered.
But, sodium hypochlorite (7681-52-9) does NOT contain elemental chlorine; rather it is a chemical compound comprised of a chlorine ion bonded to an oxygen atom.
Therefore, the amount of the chlorine ion present in sodium hypochlorite is NOT to be considered when determining whether a threshold amount of chlorine is present in a process.
Sodium Hypochlorite is prepared by reacting dilute caustic soda solution with liquid or gaseous chlorine, accompanied by cooling.
Reacting chlorine and sodium hydroxide will produce sodium hypochlorite: Cl2 + 2NaOH = NaOCl + NaCl + H2O
CLICK HERE for EPA’s Explanation
Another EPA Source: https://www.epa.gov/rmp/amounts-chlorine-present-sodium-hypochlorite