Is Animal Fat Flammable? (A Comprehensive Overview)

Is Animal Fat Flammable?

Animal fat is, generally, not considered flammable (a flammable substance or material is one with a flash point lower than 93 ºC at normal conditions), but they are all combustible (a material that can be ignited and consumed by means of a combustion reaction).

Although animal fat is not technically flammable it can catch on fire depending on conditions such as the temperature the fat is at and what type of fat it is. How promptly animal fat catches on fire depend on the specific characteristics of the given animal fat as well as the ambient temperature.

A distinct characteristic of animal fat is tt fires produced from burning animal fat and oil burns at very high temperatures.

If animal fat is subjected to temperatures above approximately 200 ºC for a certain amount of time, smoke will start to be produced, normally after this point is when animal fat can be ignited.

The temperature in which an oil or fat starts forming smoke can be called the smoke point temperature. After reaching the smoke point animal fat can be ignited either by heating or by nearby flames.

A large number of fire incidents in the past were related to fats and oils left unwatched under heating for prolonged periods. In some occasions burning animal fat can start a fire, in other occasions an already occurring fire can increase when it goes in contact with the fat.

Fires that involve cooking oil or fat are classified as class F fires in some countries. They differ from conventional fire due to extremely high temperatures being involved.

What is the Smoke Point of Animal Fats?

Also called burning point, the smoke point is a property that used to be used to evaluate oils and fats but it is no longer considered a reliable property given the potential misleading nature of its values.

The smoke point of a given fat or oil is very dependent on many variables such as the equipment used to measure it, the specific characteristics of the fat or oil.

Therefore a given smoke point for a given fat is not considered safe to determine the fire hazards of animal fat, but it can be considered as a general indicator of how readily the given animal fat can start to produce smoke.

Usually, when animal fat is heated it will produce smoke before starting to burn. The timeframe between the smoke production and the start of the fire varies according to the animal fat, temperature and other factors.

Some General Aspects of Animal Fats

Fats are lipids from animal origin which are solid at room temperature (oils are liquid at room temperature). Chemically, animal fat is composed of triglycerides, fatty acids, alcohols (cholesterol) among many other classes of substances.

What Are Fatty Acids?

A class of substances commonly present in most animal fats are fatty acids. These are organic acids (that is molecules containing the COOH functional group) with a carbon chain of typically 4 to 24 carbon atoms.

Carbon chains that only have single bonds are called saturated. If at least one double carbon-carbon bond (C=C) is present the acid is given the classification of unsaturated. 

Monounsaturated refers to fatty acids with only one double carbon-carbon bond, polyunsaturated refers to fatty acids containing two or more double carbon-carbon bonds.

Moreover, double carbon-carbon bonds have one of two possible geometric configurations. These configurations can be called cis  and trans. The cis configuration causes the carbon chain to be more cluttered, as a result cis fatty acid is more likely to be liquid than trans.

An example of an unsaturated fatty acid is linoleic acid, its molecule contains two carbon-carbon double bonds and both of them have a cis conficguration.

As molecules are composed mostly of carbon and hydrogen, fatty acids are all combustible substances. As they are capable of undergoing a combustion reaction in the presence of an oxidizer such as oxygen.

Usually, the heat required to promote the combustion of fatty acids is relatively high. As a result fatty acids are not so easily ignited as hydrocarbons or alcohols. But once ignited they release a relatively high amount of heat.

What Are Triglycerides

Another common class of substance that composes animal fats are triglycerides. The molecules of a triglycerides contain three esters groups adjacent to each other derived from a glycerol unit and three carbon chain units derived from three fatty acids.

Flash Point of Animal Fats

The flash point (flash point is the lowest temperature at which the vapors of a given material can be ignited in contact with an ignition source) of animal fats is higher than the smoke point.

Most animal fats don’t have a well established flash point given the highly varying nature of different types of animal fat as well as the variability in one same type of animal fat in regards to its method of production, additives, and conditions of storage.

Common Animal Fats and Some Related Fire Hazards

The potential a given oil or fat has to catch on fire by heating or by exposure to flames depends on factors such as:

  • The specific characteristics of the fat.
  • The storage time.
  • The ambient temperature.
  • If a pan is being used, it depends on its temperature, geometry and material.

Animal fat comes in very distinct forms, including butter, milk, lard, tallow, among others. Each one has its own properties and related fire hazards.

The following animal fats will be discussed in regards to their animal origin, general characteristics and some related fire hazards.

Butter

Butter is an emulsion (a mixture of two liquids that are not soluble in each other). Usually, it is composed of fat from cows, buffalo, goats or sheep. The two liquids that make up butter are the animal oils and water.

Butter is obtained from an inversion of churned cream. Milk proteins act as emulsifiers (agents that increase the solubility of two liquids that are otherwise insoluble in each other).

Butter usually becomes a thin liquid at temperatures around 32 ºC, below that temperature butter is more firm the cooler the temperature it is.

Butter can catch on fire if it is subjected to naked flames, the higher its temperature the more likely butter is to be ignitable. If used in a frying pan, for example, butter will be at risk of catching on fire once it starts to produce visible smoke.

The smoke point of butter is around 177 ºC. Note that this is the temperature butter itself must reach, not necessarily the surface temperature where the butter is placed at, which is normally higher than the smoke point.

Once butter is heated above its smoke point, butter is more easily ignited and it poses a higher risk to start a fire.

Dripping

Dripping is obtained from fatty parts of cows or pig carcasses. Dripping is similar to lard and tallow. Other names for dripping include beef dripping and pork dripping.

The smoke point of dripping is around 250 ºC and the flash point is around 290 ºC.

Lard

Lard is produced by rendering pig fatty tissues. It is white in appearance and semi-solid in consistency.

The smoke point is around 188 ºC and the flash point is above that temperature.

Lard is composed pretty much of fatty acids. The common chemical composition of lard is represented in the table below:

Acid nameCompositionMolecular formula
Palmitic acid 25% – 28%CH3(CH2)14CO2H
Stearic acid12% – 14%CH3(CH2)16CO2H
Myristic acid>1%CH3(CH2)12CO2H
Oleic acid44% – 47%CH3(CH2)7CH=CH(CH2)7CO2H
Palmitoleic acid>3%CH3(CH2)5CH=CH(CH2)7CO2H
Linoleic acid6% – 10%CH3(CH2)4CH=CHCH2CH=CH(CH2)7CO2

Milk

Milk is an emulsion of butterfat globules and water and a series of carbohydrates and proteins and minerals

Water is the main component of milk (around 87%) and so milk is non-flammable. If somehow milk were to be heated until all of its water evaporated, the remaining fat and proteins could eventually produce smoke.

Schmaltz

Schmaltz is obtained from rendering the fat from chicken or goose.

The smoke point of Schmaltz is around 190 ºC

Tallow

Tallow obtained by rendering cattle or sheep fat. It is composed primarily of triglycerides.

The smoke point of tallow is around 205 ºC.

Whale Oil

Whale oil can be obtained from the blubber of whales. It is composed mainly of triglycerides.

Whale oil was used in the 18th and 19th century as the fuel for candles.

The flash point of whale oil is around 230 ºC.

Conclusion

Some facts regarding animal fat and some representative examples along with some thermal and fire related properties were presented.

Frequently Asked Questions (FAQ): Is Animal Fat Flammable?

Can you burn animal fat?

Yes, many types of animal fat can be burned. Some types may only be carbonized and don’t produce flames. Overall it will depend on the specific fat and on the temperature.

Can fat cause fire?

Yes, it is possible for fat to cause a fire. Usually, extended heating or pressure would need to be applied to the fat prior to it becoming capable of catching on fire if subjected to a naked flame or a spark.

What is the flash point of animal fat?

It is overall difficult to determine the exact flash point of animal fats because their composition varies significantly. Overall, the flash point of animal fats is above 200 ºC.

How do you dissolve animal fat?

Solubility depends mainly on the polarity of the materials to be solubilized and the solvent. Water is a very polar substance while animal fat is made of substances with low polarity. Hydrocarbon based solvents are composed of low polarity substances. Hence hydrocarbon solvents can solubilise animal fat. Sometimes, animal fat contains molecules with high polarity in small amounts. Increase in temperatures usually increases the solubility of animal fat.

How do you render animal fat?

The basic process to render fat starts with melting it and then heating it at a low temperature until all water and volatile substances evaporate completely. Then, the remaining mixture is filtered to remove any remaining solids.

References

https://www.target-fire.co.uk/resource-centre/extinguish-class-f-fire-cooking-oils-gas/
https://drum.lib.umd.edu/handle/1903/11333

National Research Council, 1976, Fat Content and Composition of Animal Products, Printing and Publishing Office, National Academy of Science, Washington, D.C., ISBN 0-309-02440-4; p. 203, online edition.

https://nap.nationalacademies.org/read/22/chapter/14?chapselect=yo&Jump_to_Specified_Page_x=0&Jump_to_Specified_Page_y=0#203

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