Overview
ISO 6944-2:2009 - Fire containment: Elements of building construction - Part 2: Kitchen extract ducts specifies standardized test methods to evaluate the fire resistance of commercial kitchen extract (exhaust) ducts. The standard is intended to demonstrate the ability of a duct or duct assembly to limit fire spread when a fire originates either inside the duct (typical grease/duct fire) or outside the duct (room/furnace exposure), and to assess the structural integrity of the duct under these fire conditions.
Key topics and requirements
- Two attack scenarios
- Fire inside the duct: simulated using a gas-fired premix burner attached to an insulated L-shaped combustion chamber that feeds flue gases into the test specimen. The method models grease build-up and the severe temperatures possible in kitchen extract systems.
- Fire outside the duct: exposure uses furnace conditions defined in ISO 834-1 to assess penetration seals and structural restraint when the duct is within a fire-resisting barrier.
- Test specimen scope: vertical and horizontal ducts, with or without branches, including joints, exhaust openings, suspension devices and penetrations.
- Test equipment details (selected, as given in the standard):
- Minimum L-shaped combustion chamber total length: L1 + L2 ≥ 700 mm.
- Combustion chamber internal duct dimensions: minimum 700 mm × 700 mm.
- Ceramic fibre insulation thickness: minimum 50 mm; density ≈ 120 kg/m3 ± 30 kg/m3.
- Duct orifice flow control permitted for large orifice areas (>0.75 m2) with exhaust remaining ≥75% open.
- Instrumentation & conditioning
- Flue gas temperature measured by a thermocouple grid (Type K or Type S Inconel-sheathed thermocouples; tips projecting 25 ± 1.5 mm).
- Unexposed surface temperatures recorded with a minimum of 14 thermocouples on the horizontal section and additional thermocouples at joints and access covers.
- Laboratory ventilation and conditioning requirements (e.g., CO kept
Open preview (PDF)Fire containment — Elements of building construction — Part 2: Kitchen extract ducts
