Flammable Gas-Cloud Dispersion → Vapour-Cloud Explosion

A release of volatile liquid or gas forms a heavier-than-air cloud that spreads low between equipment until it finds an ignition source. Congestion and confinement accelerate the flame, turning ignition into an explosion rather than a fire.

Buncefield and Flixborough are the defining cases: a drifting cloud plus one spark produced two of the largest industrial explosions in European history. The trainable skill — interpreting the gas-detection map and isolating before the clock runs out — is exactly what was missing in both.

1. Read the spreading gas-detection pattern across fixed detectors.
2. Isolate the source feeding the cloud (ESD/block-in).
3. De-energise and clear ignition sources within the cloud footprint.
4. Initiate area muster/evacuation away from the cloud path.
5. Beat the pre-set ignition countdown; escalate to emergency response.

VCEs are the dominant catastrophic-loss mechanism: Marsh's "100 Largest Losses in the Hydrocarbon Industry" finds vapour cloud explosions account for the greatest frequency of losses in the energy sector since 1974 (Marsh 100 Largest Losses reports,…

Buncefield 2005: ~250–300 tonnes of petrol overfilled → ~360 m cloud → one of Europe's largest peacetime explosions, ~43 injured (Buncefield MIIB report). Flixborough 1974: ~40 tonnes cyclohexane → VCE killed 28 and destroyed the plant (HSE case study).