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Control measure

Prevent heat transfer to flammable liquid

Control measure knowledge

A boil-over usually occurs when there is:

  • A full surface tank fire
  • The tank contains petroleum mixtures with a wide range of boiling points
  • There has been a long pre-burn time
  • There is a heat wave

A boil-over can occur in two different ways:

  • Water being introduced to the container
  • The heat wave meeting water already present at the bottom of the container

Where a heat wave is suspected to be travelling down through a flammable liquid, operational tactics should be implemented to prevent the heat wave reaching any water at the base of the container. Extinguishing the fire will prevent further heat transference, slowing and finally stopping the heat wave. Typically, foam is the most effective method for tackling a flammable liquid surface fire.

Thermal imaging may be able to identify the level between hot and cooler liquid within the container. While applying uniform cooling to the tank may slow or stop the progress of the heat wave, if the cooling is not uniform, this may risk the integrity of the tank. There is a risk that the side of the tank may split, resulting in a large spill of burning flammable liquid.

Further thermal imaging equipment monitoring will enable the incident commander to determine the success of this control measure.

Tactical actions

Incident commanders should:
  • Consider applying foam to a flammable liquid surface fire to limit heat transfer

  • Consider boundary cooling containers of a flammable liquid to limit heat transfer

  • Monitor tank contents using thermal imaging equipment