Gas fireball

What is a Gas Fireball

A Gas Fireball is a fire that burns rapidly, causing the burning mass to ascend into the air in the form of a cloud or ball. Gas Fireballs are characterised by their very short duration.

How does a Gas Fireball arise?

A Gas Fireball is generated when a highly pressurised flammable gas is suddenly released and immediately ignited. Initially, the fireball takes on a hemispheric shape. As a result of entrained air and combustion gases, the released gas expands, causing the fire to increase in volume. Buoyancy effects cause the fire to rise, transforming it into a spherical-shaped fireball. The formation of a Gas Fireball is not dependent on meteorological conditions due to the high burst pressure involved. If the pressurised gas is released from transportation equipment like pipelines, the ignition may result in a fireball carried by a Jet Fire, which can then transition into a Jet Fire.

Characteristics of a Gas Fireball

The fireball radiates an intense thermal flux. The calculation and the heat radiation at certain distances involve applying mathematical models. As mentioned in the combustion characteristics chapter the SEP, view factor, and atmospheric transmissivity are part of the heat radiation calculation (Bosch, 2005).

In cases where pressurised gases are released from transportation pipelines, the ignition of the released gas may initially resemble a fireball phenomenon. However, as the event progresses, it can transition into a Jet Fire (Boot, 2015).

References

Bosch, C. v. (2005). Methods for the calculation of physical effects 'Yellow book' CPR 14E. The Hague: Ministerie van Verkeer en Waterstaat.

Boot, H. (2015). Identification of existing tools for the modelling of hazardous phenomena. Utrecht: TNO.