Overview
EN 15004-11:2024 - Fixed firefighting systems - Gas extinguishing systems - Part 11 - specifies the physical properties and systems design rules for gaseous fire-extinguishing systems using Halocarbon Blend 55 (ISO 14520-17:2022, modified). Published by CEN, this standard covers product specification, storage and container characteristics, extinguishing and design concentrations, safety of personnel, environmental considerations, and systems operating at nominal pressures of 25, 35, 42 and 50 bar, superpressurized with nitrogen.
Key topics and technical requirements
- Extinguishant composition and purity: Halocarbon Blend 55 is a ~50/50 mass blend of HFO‑1233zd(E) and FK‑5‑1‑12. Minimum purity is 99.5% by mass; limits for acidity, water content and non‑volatile residue are specified.
- Physical properties: Molecular mass (184.72), boiling point (20.7 °C), high vapour density (~6.38× air) and other critical properties are tabulated for design calculations.
- Design and extinguishing concentrations: Tables provide mass-per-volume requirements and reference extinguishing/design concentrations (examples: extinguishing concentrations for common fuels are typically in the mid 5%–6% range; higher hazard minimum design concentrations up to 7.8% by volume).
- Container fill density and pressure limits: Maximum fill density and maximum working pressures are given for each nominal system pressure (e.g., max fill density ≈ 1 308 kg/m³ for 25/35 bar containers). Exceeding fill density risks “liquid full” conditions and rapid pressure rise with temperature.
- System design parameters: Fill density, superpressurization method (nitrogen), required agent quantity per protected volume, temperature/pressure relationships and guidance on alternative fill/superpressurization levels.
- Safety and toxicology: Personnel safety considerations include hazards from the agent, combustion products and decomposition products. Toxicological limits (e.g., NOAEL ~8.7% by volume) and 4‑hour LC50 data are provided.
- Environmental properties: Environmental behavior and considerations are addressed to support compliant selection and use.
Practical applications and users
EN 15004-11:2024 is intended for professionals involved in design, installation, commissioning and regulation of fixed gas extinguishing systems using Halocarbon Blend 55. Typical users include:
- Fire protection engineers and system designers
- Manufacturers of extinguishing agents and storage containers
- Installers, commissioning and maintenance teams
- Facility managers and safety officers for enclosed hazards (e.g., data centers, telecom rooms, electrical/industrial control enclosures)
- Regulators and conformity assessment bodies
The standard enables safe, compliant deployment of total flooding gas extinguishing systems, defining the calculations and constraints needed to size agent storage, determine design concentrations and manage personnel and environmental safety.
Related standards
- EN 15004-1:2019 - Design, installation and maintenance (normative reference)
- ISO 14520-17:2022 - Source international standard (taken over and modified by CEN)
Keywords: EN 15004-11:2024, Halocarbon Blend 55, gas extinguishing systems, fixed firefighting systems, fill density, design concentration, superpressurized with nitrogen, CEN standard, extinguishant properties.
