Glowing (Smouldering) Combustion
Definition
Surface-phase oxidation of solid char without a gas-phase flame, typically at 400-700°C. Produces large amounts of CO and can persist at lower oxygen concentrations than flaming combustion.
- Temperature range
- Approximately 400 to 700C
- Combustion type
- Surface oxidation of solid char, no flame
- Key product
- Large quantities of carbon monoxide
- Oxygen requirement
- Lower than flaming combustion
Common questions
Why is smouldering combustion particularly dangerous in fire deaths?+
It produces large amounts of carbon monoxide while generating little visible flame or heat signature, so CO levels in an enclosed space can rise for a long period before detection, increasing the risk of poisoning before a fire is even noticed.
How can smouldering combustion transition into flaming combustion?+
If enough heat accumulates and pyrolysis gases build up, or the smouldering material is disturbed and exposed to more oxygen, the process can transition to flaming combustion, sometimes called the smoulder-to-flame transition.
How does an investigator recognise smouldering versus flaming fire damage at a scene?+
Smouldering damage tends to show deep, slow charring localised around ignition sources like a cigarette or overheated material, whereas flaming fires show faster, more extensive char and characteristic V-shaped burn patterns.
Related terms
- Arrhenius Equation
- Mathematical expression relating reaction rate to temperature: k = A × exp(-Ea/RT). The exponential dependence explains the self-accelerating nature of combustion as...
- Auto-Ignition Temperature
- The minimum temperature at which a material ignites spontaneously without a pilot flame or spark. Relevant to the assessment of ignition scenarios...
- Carboxyhaemoglobin (COHb)
- The compound formed when carbon monoxide binds to haemoglobin at the oxygen-binding site, with an affinity 200-250 times greater than oxygen. Produces...
- Conductive Heat Transfer
- Transfer of thermal energy through a solid material by molecular vibration. Rate depends on thermal conductivity, temperature gradient, cross-sectional area, and path...
- Convective Heat Transfer
- Transfer of heat by bulk movement of a fluid (gas or liquid). In compartment fires, the buoyant hot gas plume carries most...
- Fire Tetrahedron
- The model of sustained combustion requiring four concurrent elements: fuel, oxidiser, heat, and an uninhibited radical chain reaction. Replacing the older fire...
- Flaming Combustion
- Gas-phase oxidation of volatile pyrolysis products above the fuel surface, producing a visible flame at 800-1200°C. Produces less CO than smouldering under...
- Flash Point
- Lowest temperature at which a liquid gives off enough vapour to form an ignitable mixture in air, but the vapour does not...
- Radiative Heat Transfer
- Transfer of heat by electromagnetic waves (infrared). Scales as the fourth power of absolute temperature; at near-flashover temperatures it can simultaneously ignite...