Overview
ISO 14520-8:2019 specifies physical properties, performance requirements and system-design rules for gaseous fire‑extinguishing systems using HFC‑125 (pentafluoroethane). The standard covers storage, filling, superpressurization (nominal systems at 25 bar and 42 bar), extinguishing concentrations for total‑flooding applications, basic toxicological and environmental data, and minimum safety considerations for personnel and system integrity.
Key topics and technical requirements
- Extinguishant specification: minimum purity 99.6% by mass; water ≤ 10 ppm; acidity ≤ 3 ppm; non‑volatile residue ≤ 0.01%.
- Physical properties: molecular mass 120.02, boiling point −48.09 °C, freezing point −101 °C, critical temperature 66.02 °C, critical pressure 36.18 bar abs.
- Storage & fill density: maximum fill density 929 kg/m3 (for both 25 and 42 bar systems). Exceeding fill limits can cause “liquid full” containers and unsafe pressure rises.
- Superpressurization: containers superpressurized with nitrogen (moisture ≤ 60 ppm) to equilibrium pressures of 25 bar or 42 bar at 20 °C. Manufacturer data required for alternative fill/superpressurization levels (pressure vs temperature curves, max fill density, etc.).
- Design & extinguishing concentrations: extinguishment and minimum design concentrations are given for representative fuels (e.g., heptane extinguishment 9.3% by volume, minimum design 12.1%; wood crib extinguishment 6.7%, minimum design 11.2%). Tables provide agent mass per unit volume across temperatures for target concentrations (total flooding).
- Safety and toxicology: NOAEL 7.5% by volume, LOAEL 10%; approximate lethal concentration (ALC) for a 4‑hour rat exposure >70% by volume. Designers must consider hazards from the agent, combustion and breakdown products.
- Environmental data: GWP (100 yr) = 3,500; ODP = 0.
Applications
- Design and specification of total‑flooding gaseous fire‑extinguishing systems using HFC‑125 in enclosures (electrical rooms, data centers, machinery spaces, storage areas) where a gaseous agent is required.
- Determining agent quantities, container selection, and pressure/temperature safety limits for storage and transport.
- Risk assessments addressing personnel safety, toxicology limits, and emergency planning for system discharge.
Who should use this standard
- Fire‑protection engineers and system designers
- Fire‑extinguishing system manufacturers and suppliers
- Authorities having jurisdiction (AHJs), facility safety managers, testing laboratories and consultants involved in specifying, approving or installing HFC‑125 systems
Related standards
- ISO 14520‑1:2015 - Gaseous fire‑extinguishing systems - Part 1: General requirements
- Other parts of the ISO 14520 series (see ISO catalogue) for additional agent‑specific or application rules
Keywords: ISO 14520-8, HFC‑125, gaseous fire‑extinguishing systems, total flooding, fill density, superpressurization, design concentration, GWP 3500, nitrogen pressurization, fire protection design.
Open preview (PDF)Gaseous fire-extinguishing systems — Physical properties and system design — Part 8: HFC 125 extinguishant