General Concentration Requirements for Aqueous Film-Forming Foam Fire Extinguishing Agent
When prepared with seawater, the concentration of aqueous film-forming foam solution shall stay consistent with that mixed with fresh water. The agent and its solution cause no environmental pollution and pose no obvious toxicity to organisms during production and application.

High-performance aqueous film-forming foam agent can be blended with fresh water at the volume ratios of 3:97 or 6:94, compatible with most proportioning mixers and foam spraying equipment. Water separated from the foam layer forms a protective film on fuel surfaces to isolate air. Featuring outstanding fluidity, it achieves rapid fire suppression, long-lasting sealing performance and excellent flashback resistance. Containing fluorosurfactants, the solution has reduced surface tension and can float steadily on fuel surfaces. Its film-forming effect works better on fuels with high surface tension such as diesel and aviation gasoline than low-tension fuels like alkanes and regular gasoline.

This agent consists of fluorocarbon surfactants, hydrocarbon surfactants, additives including foam stabilizers, antifreezes, cosolvents, thickeners and water.

Fluorocarbon surfactant serves as the core component, accounting for 1% to 5% of total content, which can be single or blended surfactants. Its hydrophilic group is mainly anionic, and cationic and nonionic types are also applicable. Polyethylene content ranging from 0.1% to 0.5% is added to enhance anti-reignition and self-sealing capacity.

Non-fluorinated surfactant content is controlled between 0.01% and 0.5%. It boosts foam expansion ratio and stability, cuts interfacial tension between foam solution and oil, improves oil affinity, and facilitates the formation and spreading of durable water film.

Solvents such as butyl glycol ether and butyl diglycol take up 5% to 40%. They dissolve various ingredients, optimize foam performance, lower freezing point and promote foam generation. The agent plays an irreplaceable role in liquid fire fighting, especially in petrochemical fire protection.

Also known as light water foam, it has favorable critical shear stress and fluidity, spreading quickly over fuel surfaces to form tight isolation film. It suppresses fuel volatilization and extinguishes fires fast via dual effects of foam covering and water film isolation.

Common mixing concentrations are 1%, 3% and 6%, fitting most foam proportioning and generating devices. It is used to put out Class A and Class B fires involving petroleum, gasoline and other hydrocarbon combustibles.

Its drawbacks lie in high production cost and short drainage time, only half that of protein and fluoroprotein foam agents, resulting in weak foam stability and easy dissipation.