Aqueous film-forming foam fire extinguishing agent is an advanced derivative of high-efficiency water-based fire suppressants. It consists of hydrocarbon surfactants, fluorocarbon surfactants, additives, stabilizers and antifreezes. When fighting fires, it swiftly forms a water film on the surface of hydrocarbon fuels to restrain fuel evaporation. The foam spreads rapidly and covers the fuel surface, delivering dual fire suppression effects of foam and water film. It is effective against both oil fires and polar solvent fires.

The domestically developed SD-AFFF aqueous film-forming foam agent features extremely low surface tension below 18 mN/m at 20℃. It boasts rapid fire containment and extinguishment, high efficiency, favorable fluidity, strong self-sealing and anti-reignition capacity. It can put out hydrocarbon fires involving crude oil, gasoline, kerosene and diesel oil, as well as Class A fires of wood, fabric, paper, plastic and rubber. It greatly improves the fire-fighting efficiency of water and expands its application scope.

Foam agents extinguish fires by cooling burning substances and isolating air via surface coverage, so as to halt fuel evaporation and combustion. Theoretically, they can be applied to both Class A and Class B fires. Nevertheless, they have two obvious drawbacks when tackling Class A fires. Insufficient impulse limits the effective firing range of foam monitors, making it hard for foam to penetrate deep into fire zones, and foam may even be blown away by fire plumes, resulting in massive agent waste. Besides, uneven air distribution weakens foam stability, leading to low fire suppression efficiency, excessive agent consumption and poor cost-effectiveness. Hence foam agents are mainly used for Class B fire rescue.

To solve the above problems, modified foam fire suppression technologies including Class A foam agents and compressed air foam systems were first developed in the United States. Modified foam agents are essentially special water-based suppressants. Composed of thickeners, penetrants, flame retardants and foaming agents blended with water, Class A foam agents have a mixing ratio ranging from 0.1% to 1.0%. They are low-cost, capable of fast fire control, improving water utilization efficiency and cutting water consumption with reliable anti-reignition performance. Their fire extinguishing efficiency is far higher than plain water, and the dosage is only one tenth of conventional Class B foam agents. They cause no pollution and leave easy-to-clean residues.

Class A foam agents are applicable to factories, mines, oil fields, warehouses, hotels, restaurants, offices and residences. Mixed into solutions at 3% or 6% concentration via proportioning mixers, they can serve fixed fire suppression systems in oil depots, high-rise buildings, shopping malls and subways prone to Class A and Class B fires.

Foam blended with compressed air carries strong impulse and can penetrate deep into fire areas for enhanced suppression effect. Vehicle-mounted compressed air foam systems abroad achieve a firing range of 40 to 60 meters.