Results when high-pressure flammable material is ignited as it is being released from containment. The effect zone of a jet fire is proportional to the size of the flame generated. As a high-pressure material is released from a hole, the material will exit with a velocity that is mainly a function of system pressure and hole size. As distance away from the hole increases, the amount of oxygen in the mixture increases as air is entrained in the jet. As the upper flammability limit threshold is crossed, the fuel and air react, releasing the energy of combustion. As the combustion continues, entrained air, unburned fuel and combustion products continue to move in the direction of the release due to the momentum generated by the release.