A hexamine fuel tablet (or heat tablet, Esbit) is a form of

solid fuel Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fu ...

in tablet form. The tablets burn smokelessly, have a high

energy density In physics, energy density is the quotient between the amount of energy stored in a given system or contained in a given region of space and the volume of the system or region considered. Often only the ''useful'' or extractable energy is measure ...

, do not liquefy while burning and leave no ashes. Invented in 1936 in Murrhardt,

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, the main component is

hexamine Hexamethylenetetramine (HMTA), also known as 1,3,5,7-tetraazaadamantane, is a heterocyclic organic compound with diverse applications. It has the chemical formula (CH2)6N4 and is a white crystalline compound that is highly soluble in water and p ...

, which was discovered by

Aleksandr Butlerov Alexander Mikhaylovich Butlerov (; 15 September 1828 – 17 August 1886) was a Russian chemist, one of the principal creators of the theory of chemical structure (1857–1861), the first to incorporate double bonds into structural for ...

in 1859. Some fuel tablets use 1,3,5-trioxane as another ingredient. ''Esbit'' is a

genericized trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or ...

that people often use to refer to similar products made by other companies. In most countries from the former Soviet bloc, fuel tablets are called ''dry fuel''.

Uses

The tablets are used for cooking by campers, militaries, and relief organizations. They are often used with disposable metal stoves that are included with

field ration A field ration is a type of prepackaged military ration designed to be easily and quickly prepared and consumed in the field, in combat, at the front line, or where eating facilities are otherwise unavailable. Field rations are primarily used ...

packs. Another common use is to provide a heat source for model

steam engine A steam engine is a heat engine that performs Work (physics), mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a Cylinder (locomotive), cyl ...

s, such as those manufactured by Wilesco and

Mamod Mamod was a toy manufacturer that was based in Britain that specialized in producing live steam Models until closure in 2024. The company was founded in Birmingham in 1937 by Geoffrey Malins. The name "Mamod" is a Portmanteau, combination of " ...

, and other external combustion engines such as

Stirling engine A Stirling engine is a heat engine that is operated by the cyclic expansion and contraction of air or other gas (the ''working fluid'') by exposing it to different temperatures, resulting in a net conversion of heat energy to mechanical Work (ph ...

s and pop pop boats.

Advantages and disadvantages

Hexamine is prepared by the reaction of

formaldehyde Formaldehyde ( , ) (systematic name methanal) is an organic compound with the chemical formula and structure , more precisely . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde. It is stored as ...

and

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

. In an acidic environment hexamine is converted to toxic formaldehyde, where the main hazard for

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

is by

ingestion Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms, inge ...

. As with trioxane, hexamine has an almost unlimited shelf life if stored properly, in a sealed dry container. However, the heat given off cannot be easily adjusted, so water can be boiled, but cooking requiring

simmering Simmering is a food preparation technique by which foods are cooked in hot liquids kept just below the boiling point of water (lower than ) and above poaching temperature (higher than ). To create a steady simmer, a liquid is brought to a boil, ...

is more difficult. Tablets are a powerful stove fuel (30.0 MJ/kg), but are sensitive to wind and dampness. Esbit's Safety Data Sheet states combustion can create formaldehyde, ammonia,

nitrogen oxide Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide * Nitrogen dioxide (), nitrogen(IV) oxide * Nitrogen trioxide (), o ...

hydrogen cyanide Hydrogen cyanide (formerly known as prussic acid) is a chemical compound with the chemical formula, formula HCN and structural formula . It is a highly toxic and flammable liquid that boiling, boils slightly above room temperature, at . HCN is ...

and ingestion may cause

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat. Over 30 d ...

vomiting Vomiting (also known as emesis, puking and throwing up) is the forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteritis, pre ...

, gastrointestinal disturbances, and kidney damage. When burned, the chemical oxidation of the fuel yields noxious fumes, which requires cooking foods in a container, such as a pot or pan, with a tight fitting lid. Burned tablets leave a sticky dark residue on the bottom of pots. If tablets are stored or used under damp conditions they can break up while burning and shed burning fragments, though this claim is hard to verify or reproduce. As hexamine is a precursor for the simplest synthesis of the chemical explosive

RDX RDX (Research Department Explosive or Royal Demolition Explosive) or hexogen, among other names, is an organic compound with the formula (CH2N2O2)3. It is white, odorless, and tasteless, widely used as an explosive. Chemically, it is classified ...

, its possession is tightly regulated in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

References

External links

Esbit Compagnie GmbH website
{{DEFAULTSORT:Hexamine Fuel Tablet Fuels Camping equipment Solid fuels

Uses

Advantages and disadvantages

See also

References

External links