ISO 7203-3:2019

Overview

ISO 7203-3:2019 specifies essential properties and performance requirements for low-expansion foam concentrates intended for top application to fires of water‑miscible liquids. The standard defines what constitutes low-expansion foam (expansion ratio 1–20), sets minimum test‑fire performance, and describes laboratory tests, marking and documentation needed for foam concentrates used in firefighting and industrial fire protection.

Key technical topics and requirements

• Scope and application: Focused on low‑expansion foam concentrates for control, extinction and inhibition of re‑ignition on water‑miscible liquids. Foam concentrates that also comply with ISO 7203‑1 are acceptable for water‑immiscible liquids.
• Grades and classification: Extinguishing performance graded Class I or II; burn‑back resistance graded levels A, B or C.
• Physical and chemical properties: Requirements and tests for viscosity (Newtonian and pseudo‑plastic behavior), pH, sediment (maximum 0.25% by volume before ageing), and tolerance to freezing and thawing.
• Foam performance metrics: Definitions and test procedures for expansion, 25% drainage time, and drainage limits. Clause 9 requires averaging results from two expansion/drainage tests.
• Test fire performance: Minimum performance on specified test fires is required (detailed in Annex F), including acceptable testing temperature ranges and decision‑tree guidance.
• Marking and documentation: Requirements for marking, packaging and a specification sheet listing characteristic values and declared temperature ranges.
• Normative and informative annexes: Includes procedures for sampling and conditioning (Annex A), sediment and viscosity determination (Annexes C and D), expansion/drainage testing (Annex E), fire testing (Annex F), compatibility (Annex H), and small‑scale fire tests (Annex I).

Practical applications - who uses this standard

• Foam concentrate manufacturers - to design, test and certify products that meet international performance and storage requirements.
• Fire protection engineers and consultants - to specify appropriate foam concentrates for industrial, petrochemical, marine and transportation hazards involving water‑miscible liquids.
• Testing and certification laboratories - to perform standardized viscosity, sediment, expansion, drainage and fire tests.
• Procurement and safety managers - to evaluate product datasheets, marking and compatibility (including sea‑water use) when selecting foam concentrates for fire suppression systems.
• Fire brigades and emergency responders - to understand operational limits (temperature, application type) and expected burn‑back resistance.

Related standards

• ISO 7203‑1 (top application for water‑immiscible liquids)
• ISO 7203‑2 (medium/high‑expansion foam concentrates)
• ISO 7076 (foam systems)
• Referenced test standards: ISO 3104, ISO 3219, ISO 3310‑1

ISO 7203‑3:2019 is essential reading for anyone specifying or verifying firefighting foam concentrates, ensuring consistent performance, safety and compatibility for suppression of fires involving water‑miscible liquids.