A Boilover type of fire

Fire

Fire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....

 refers to an extremely hazardous situation where an attempt is made to extinguish semi-enclosed oil

Oil

An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....

 or petrochemical

Petrochemical

Petrochemicals are chemical products derived from petroleum. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sources such as corn or sugar cane....

 fueled fire with water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

. The hazard results due to the difference in density

Density

The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...

 between oil and water. Boilover is also common in the home as a chip pan fire when cooking.

As water is being pumped onto the surface of the fuel (where the flames are evident) it will quickly sink below the fuel due to the water's higher density. The water collects at the bottom of the container and has little effect on extinguishing the flames of the lighter petrochemical fuel. As the temperature of the fire builds, the collected layer of water is heated. The water will eventually vaporise into steam, as its boiling point of 100 °C (212 °F) at standard pressure, is reached. The water will then expand to more than 1700 times in volume

Volume

Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....

, as compared to its liquid state. The rapidly expanding steam (possibly superheated) expels the oil or fuel above upward and out of the container, resulting in the discharging of burning oil onto a large and uncontrolled area outside of the container.

See also

• Expansion ratio
  Expansion ratio
  The expansion ratio of a liquefied and cryogenic substance is the volume of a given amount of that substance in liquid form compared to the volume of the same amount of substance in gaseous form, at a given temperature and pressure....
  
  
• Fire Extinguisher Foams
• Phreatic eruption
  Phreatic eruption
  A phreatic eruption, also called a phreatic explosion or ultravulcanian eruption, occurs when rising magma makes contact with ground or surface water. The extreme temperature of the magma causes near-instantaneous evaporation to steam, resulting in an explosion of steam, water, ash, rock, and...
  
   - a similar concept in volcanic eruption
• Chip pan fire

External links

• Boilover Explosion Video With Commentary
• Calculations for two moving boundary sub-problems.