Gas explosions can be defined as the combustion of a premixed gas cloud containing fuel and an oxidizer that can result in a rapid rise in pressure.
Source: API RP 2FB, Recommended Practice for the Design of Offshore Facilities Against Fire and Blast Loading, First Edition, April 2006. Global Standards
Combustion of a flammable gas or mist which generates blast waves due to confinement of the combustion induced flow or the acceleration of the flame front by obstacles in the flame path
Source: ISO 13702:2015, Petroleum and natural gas industries — Control and mitigation of fires and explosions on offshore production installations — Requirements and guidelines, Second Edition, August 2015. Global Standards