ISO 7203-2:2019

Overview

ISO 7203-2:2019 - Fire extinguishing media - Foam concentrates - Part 2 specifies essential properties and performance requirements for medium‑ and high‑expansion foam concentrates intended for top application to water‑immiscible liquids (Class B fuels). The standard defines test methods, minimum performance on test fires, classification, labelling and compatibility considerations to ensure reliable control, extinction and inhibition of reignition of liquid fuel fires.

Key topics and technical requirements

• Scope & classification: Defines medium‑expansion (expansion ratio 21–200) and high‑expansion (>200) foam concentrates and the conditions for each class.
• Performance on test fires: Specifies minimum extinguishing performance and burn‑back resistance. Typical limits in the standard:
  • Medium‑expansion: extinction time ≤ 120 s; 1% burn‑back time ≥ 30 s.
  • High‑expansion: extinction time ≤ 150 s (burn‑back requirement not applicable).
• Expansion and drainage: Minimum expansion measured in specified annex test methods (Annex F for medium, Annex G for high); 25% drainage time concept defined for foam stability.
• Chemical and physical properties:
  • Sediment limits: ≤ 0.25% before ageing and ≤ 1.0% after ageing (Annex C).
  • Viscosity: Requires determination (ISO 3104 and Annex D). Highly viscous or pseudo‑plastic concentrates must be marked if they may need special proportioning equipment.
  • pH: Must be between 6.0 and 8.5 and show limited change after temperature conditioning.
  • Surface/interfacial properties: Surface tension of foam solution must be within ±10% of characteristic value; AFFF/FFFP agents have interfacial tension and spreading‑coefficient requirements relative to cyclohexane (tight tolerances after temperature conditioning).
• Temperature, freezing and ageing: Requirements and tests for freeze/thaw tolerance and temperature for use.
• Marking & packaging: Shipping containers must include designation, recommended concentration, storage/use temperatures, sea‑water suitability, batch number, supplier details and safety warnings.
• Compatibility: Annexes address compatibility with other concentrates and with powders.

Practical applications and users

ISO 7203-2:2019 is used by:

• Fire‑protection product manufacturers (foam concentrate formulation, QA/QC).
• Firefighting equipment suppliers (proportioners, monitors, high‑expansion systems).
• Industrial fire safety engineers for specifying foam for fuel storage, loading terminals, shipboard and offshore installations.
• Certification bodies and testing laboratories performing foam performance and stability tests. The standard helps ensure reliable firefighting foam performance for Class B fires involving water‑immiscible liquids and guides safe selection, labelling and use.

Related standards

• ISO 7203‑1 (low‑expansion for water‑immiscible liquids)
• ISO 7203‑3 (low‑expansion for water‑miscible liquids)
• ISO 7076 (foam systems) and other fire‑extinguishing media standards (e.g., ISO 6183, ISO 7201 series)

Keywords: ISO 7203-2:2019, foam concentrates, medium-expansion foam, high-expansion foam, firefighting foam, water-immiscible liquids, AFFF, FFFP, fire test performance.