Overview
EN 15004-9:2017 (CEN) provides specific requirements for gas extinguishing systems using the IG-55 extinguishant (ISO 14520-14:2015, modified). This part of the EN 15004 series focuses on physical properties, system design, storage pressures and safety for IG-55 total‑flooding systems. IG-55 is an inert blend of nominally 50% argon and 50% nitrogen and is electrically non‑conductive with the same approximate density as air.
Key Topics
- Extinguishant composition and purity: IG-55 is nominally 50% argon / 50% nitrogen (±5%). Typical purity requirements include >99.9% component purity and strict moisture limits.
- Physical properties and quantities: The standard provides tabulated agent volumes per protected volume (V/V) across temperatures and design concentrations. It also gives an approximate relation for the specific reference volume SR (SR = k1 + k2 · TR with k1 = 0.6598 and k2 = 0.002416) used to calculate agent requirements.
- Design concentrations: Representative extinguishment and minimum design concentrations for tested fuels are included. For example, heptane extinguishment is ~36.5% by volume with a minimum design concentration of 47.6% (accounting for safety factors). Surface Class A fuels (wood crib, PMMA, PP, ABS) and Higher‑Hazard Class A guidance are provided.
- Storage and fill pressures: EN 15004-9:2017 covers systems operating at nominal fill pressures of 150 bar, 200 bar and 300 bar at 15 °C and provides container working pressures (e.g., 150 bar fill → max working pressure 178 bar at 50 °C; 200 bar → 240 bar; 300 bar → 366 bar).
- Personnel safety: The standard highlights hazards from oxygen reduction and combustion products. Physiological guidance lists a NOAEL equivalent at 43% by volume and a LOAEL at 52% by volume (hypoxic atmosphere equivalents).
- Environmental profile: IG-55 is an inert gas mixture with zero GWP and zero ODP, an important consideration for environmentally sensitive installations.
Applications
EN 15004-9:2017 is aimed at designers, installers, safety engineers and authorities having jurisdiction for facilities requiring clean total‑flooding protection where electrically non‑conductive and environmentally benign agents are required. Typical application benefits:
- Reliable total‑flooding protection for electronic, electrical and high‑value assets
- Clear guidance on agent quantity calculations and container selection
- Integrated safety measures addressing personnel exposure and fire combustion products
Related Standards
- EN 15004-1:2017 - Design, installation and maintenance for gas extinguishing systems (normative reference)
- Other EN 15004 parts (e.g., Parts 2–10) addressing physical properties and system design for alternative agents
For project implementation use the tables and calculation methods in EN 15004-9:2017 along with EN 15004-1:2017 design rules. Consult local regulations and competent authorities for application- and jurisdiction-specific requirements.
