AboutDominick G. Kasmauskas Expertise Former NFPA Fire Service Section, Director, Executive Board. NJ Certified Firefighter, Fire Instructor, Fire Inspector, Haz Mat Instructor. Volunteer Firefighter since 1974, Capt. Lieut. and President. National Fire Academy Fire Officer II certified. Presently a Regional Manager for the Natl Fire Sprinkler Assn and a certified fire protection specialist and a certified code enforcement official in NY State.
Experience Various awards and citations.
My oddest "call" was at my company picnic, in a remote area, when someone at the picnic had heart failure. While trying to perform CPR I was also giving directions to ALS and BLS to get to the scene.
Every alarm is an accomplishment.
Question what should be the criteria for deciding the minimum quantity of AFFF foam to be stored at chemical site.
Answer My initial opinion is to consult the chemical or chemicals' MSD Sheets to make sure none are reactive to water or water-based fire protection methods. Also, make sure that AFFF is the foam you need. AFFF will not work on all chemical fires.
Next is to consult the appropriate NFPA standard for foam (NFPA 11, NFPA 16, NFPA 275, NFPA 412, or NFPA 1150).
Consulting with your local fire department is paramount as they need to know what you are storing in their jurisdiction and they may have a "foam bank" in their fire department.
I hope this helps and feel free to follow up with any further details.
I am not a Haz Mat "expert" nor a chemist. These answers are based on initial thoughts to your question.