ISO 24473:2008

Overview

ISO 24473:2008 - Fire tests - Open calorimetry specifies standardized test methods for measuring the rate of production of heat and combustion products for well‑ventilated fires up to 40 MW. The method simulates real‑scale fires on single objects or groups of objects to evaluate their contribution to fire growth using a specified ignition source. Tests produce time‑resolved data for all stages of a fire, including heat release rate (HRR) (based on oxygen‑consumption calorimetry) and smoke/optical density.

Key topics and technical requirements

• Scope & principle
  • Well‑ventilated, open‑calorimetry tests to assess object contribution to fire growth.
  • HRR calculated primarily from oxygen consumption (CO2‑based methods noted but not covered).
• Hood and exhaust system
  • Hood/duct must collect all combustion products without disturbing the fire‑induced flow.
  • Minimum clearances: open sides ≥ 2 m from walls for fires ≤1 MW; greater distances up to 10 m for 20 MW tests.
  • Annex A provides hood/exhaust design guidance.
• Exhaust duct instrumentation
  • Volume flow rate measured to ±5% accuracy; differential‑pressure instrument response ≤ 1 s (10→90%).
  • Gas temperature measured with 1.0–1.6 mm OD sheathed thermocouples near the bi‑directional probe.
  • Gas sampling across duct diameter; use inert tubing (e.g., PTFE), particulate filters, cooler, drying agent and oil‑free pump.
  • Oxygen analyser: paramagnetic or equivalent, 0–21% range, accuracy ±0.02% by volume, noise/drift ≤ 100 ppm over 30 min, resolution 0.01%.
• Additional instrumentation & procedures
  • Mass loss (weigh platform), heat‑flux meters, optical density/light measurement, data acquisition, ignition burner calibration.
  • System performance checks, HRR confirmation, response time and precision (see Annexes B–F).
• Safety
  • Tests involve high temperatures and potentially toxic combustion products; protective clothing, breathing equipment and extinguishing means are required.

Practical applications and users

ISO 24473:2008 is used by:

• Fire test laboratories conducting open calorimetry and full‑scale fire experiments.
• Product and materials manufacturers (furniture, façade systems, sandwich panels) assessing fire growth, HRR and smoke production.
• Regulators, certification bodies and fire safety engineers for performance verification and comparative testing.
• Researchers modeling fire dynamics or assessing toxic effluent under well‑ventilated conditions.

Typical applications include evaluating the contribution of a product to fire development, validating fire safety designs, and providing input data for fire‑modeling and risk assessments.

Related standards

Relevant referenced documents include:

• ISO 5660‑1 (cone calorimeter HRR)
• ISO 13943 (fire safety vocabulary)
• ISO 9705 (full‑scale room test)
• ISO 13784 / 13785 series (panel and façade tests)
• ISO/TS 14934 series (heat‑flux meter calibration)
• ISO 19702 (FTIR gas analysis guidance)
• EN 13823 (SBI test)

ISO 24473:2008 is the authoritative reference for open‑calorimetry measurement of heat release and combustion products for fires up to 40 MW and is essential for consistent, comparable large‑scale fire testing.