Start with the fuel. Hydrocarbons such as gasoline (petrol) and oil can be covered with AFFF or fluoroprotein foam. Polar solvents, which mix with water, need an alcohol resistant grade: the AR-AFFF and AR-SFFF concentrates contain polysaccharides that form a polymer film on the solvent, which HD compares to a raft holding the foam blanket up.
Then match the mixing ratio to your proportioning equipment. The number in the name is the percentage of concentrate in the foam solution: AFFF 1-C6 is used at 1%, AFFF 3-C6 at 3% and AFFF 6-C6 at 6%. For alcohol resistant grades the first figure applies to hydrocarbon fires and the second to polar solvents, so AR-AFFF 3X6-C6 runs at 3% on hydrocarbons and 6% on polar solvents, and 1X3-C6 at 1% and 3%. Most HD concentrates can be mixed with fresh, sea or hard water.
Choose the chemistry. AFFF is a synthetic foam that forms a thin film over the fuel to seal in vapour. Fluoroprotein (FP) and film forming fluoroprotein (FFFP) are protein based, with good sealing and burn back resistance, and HD lists its FP grades for sub-surface injection and long pre-burn tank farm fires. HD's fluorinated foams use C6 surfactants, which HD describes as environmentally safer, and AR-SFFF F3 3X3 is completely free of fluorinated chemicals (PFAS free).
Finally, check approvals and temperature. AFFF 1-C6, AFFF 3-C6, AFFF 3F-C6, AR-AFFF 3X3-C6 and AR-SFFF F3 are UL Listed, and AFFF 3F-C6 and HD AR-AFFF 3X3-C6 are also FM Approved. AFFF 3FZ-C6 is made for use down to -18°C (0°F). Prices on request: call or WhatsApp +91 92440 89060.