BREEZE Haz Fire / Explosion

 Fire Models

• Confined Pool Fire was originally developed for the Gas Research Institute (GRI) and models a fire that occurs when liquid is ignited in a confined area such as a dike or a tank. The dike may be circular or rectangular. The model calculates the distance to various radiation levels specified by the user and also allows for the calculation of the dynamic temperature rise of a nearby target.
• Unconfined Pool Fire was originally developed for the GRI and models a fire that occurs when an unconfined spreading pool of liquefied fuel gas ignites. The model calculates the distance to various radiation levels specified by the user (e.g, the 5 kW/m2 level specified by the U.S. EPA in the 112(r) RMP regulations, or the radiant flux levels specified in the U.S. federal standard 49 CFR 193.2057 for LNG facilities) and calculates the radiation flux as a function of time at a given distance as the pool spreads.
• Jet Fire was originally developed for the GRI and models a fire that may result from the leak or rupture of a pipeline containing a compressed or liquefied gas under pressure. The model calculates the distance to various radiation levels specified by the user and can calculate the dimensions of a high velocity jet flame ensuing from a ruptured pipeline.
• BLEVE was originally developed for the GRI and models a fire that may result from the leak or rupture of a pipeline containing a compressed or liquefied gas under pressure. The model calculates the distance to various radiation levels specified by the user and can calculate the dimensions of a high velocity jet flame ensuing from a ruptured pipeline.

Explosion Models

If a quantity of flammable material is released, it will mix with the air and may result in a flammable vapor cloud. If this flammable vapor cloud finds an ignition source a vapor cloud explosion may result. Two main methodologies exist for modeling the explosion resulting from a vapor cloud explosion:

• TNT Equivalency methods
• Methods based on the fuel-air charge blast

The explosion models include the following widely accepted approaches:

• U.S. Army TNT Equivalency was based on the work of the U.S. Army. This model uses a proportional relationship between the flammable mass in the cloud and an equivalent weight of TNT and assumes that the entire flammable mass is involved in the explosion and that the explosion is centered at a single location. The model uses one of two blast curves, depending upon whether the explosion being modeled is a surface burst or a free-air burst.
• U.K. HSE TNT Equivalency was based on the work of the U.K. Health and Safety Executive (HSE). This model uses a proportional relationship between the flammable mass in the cloud and an equivalent weight of TNT. It assumes that the entire flammable mass is involved in the explosion and that the explosion is centered at a single location.
• TNO Multi-Energy treats the explosive potential of the vapor cloud as a corresponding number of equivalent fuel-air charges. The vapor cloud explosion is modeled as a series of sub-blasts with each sub-blast corresponding to a potential blast source within the cloud.
• Baker-Strehlow was based on the work of Baker and Strehlow and takes into account the variability of the blast strength by expressing the explosion as a number of fuel-air charges, each with individual characteristics.