Overview
EN 15004-6:2020 - "Fixed firefighting systems - Gas extinguishing systems - Part 6" provides specific requirements for gas fire‑extinguishing systems that use HFC‑23 (trifluoromethane) as the extinguishant. Adopted by CEN from ISO 14520‑10:2019 (with modifications), the standard covers the physical properties, system design, fill densities, operational pressures (nominal 41 bar and 70 bar superpressurized with nitrogen), safety and usage guidance needed for total‑flooding HFC‑23 systems.
Key topics and requirements
- Physical properties of HFC‑23: molecular mass 70, boiling point –82 °C, critical temperature 25.9 °C, vapour pressure ~41.80 bar at 20 °C, and a liquid density and vapour density specified for design calculations. HFC‑23 is colourless, almost odourless and electrically non‑conductive; density ≈2.4× air.
- Extinguishing and design concentrations: Reference extinguishment values and minimum design concentrations for representative fuels (e.g., heptane and surface Class A materials). Design concentration guidance includes multiply factors (e.g., 1.3) and tables of agent mass per unit volume versus temperature.
- Storage and fill density: Containers must be filled and specified so pressures never exceed container limits at maximum design temperature. Avoid “liquid full” conditions which can cause rapid pressure rises.
- Nominal pressure levels: Applies to systems at 41 bar (no nitrogen superpressurization) and 70 bar (superpressurized with nitrogen); includes guidance for superpressurization and alternative fill levels.
- Safety and toxicology: Toxicological thresholds (NOAEL 30% vol; ALC >65% vol) and the need to assess risks from the extinguishant, combustion products, and breakdown products during discharge.
- Environmental considerations: Clause added addressing environmental properties (new in the 2020 revision).
Applications and who uses this standard
- Fire protection engineers and system designers specifying fixed gas fire suppression systems using HFC‑23.
- Facility managers, data center operators, industrial plant safety teams and building services professionals planning total‑flooding suppression for enclosed hazards.
- Installers, maintenance contractors and certifying bodies ensuring compliance with CEN requirements for storage pressure, fill density and safety.
- Regulators and procurement/specification writers referencing required concentrations, toxicology limits and compatibility with EN 15004‑1 design, installation and maintenance rules.
Related standards
- EN 15004‑1:2019 - Design, installation and maintenance for fixed gas extinguishing systems (normative reference).
- ISO 14520‑10:2019 - International source standard (adopted with CEN modifications).
- Other parts of EN 15004 cover FK‑5‑1‑12, HFC‑125, HFC‑227ea and various inert gas systems for broader system design alignment.
Keywords: EN 15004‑6:2020, HFC‑23, gas extinguishing systems, fixed firefighting systems, fill density, 41 bar, 70 bar, gas fire suppression, design concentrations, EN 15004‑1.
