Look up ton in Wiktionary, the free dictionary.

The term ton or tonne generally refers to a unit of mass. However, there exists more than one measure of mass that are named "ton", so one has to be specific when using the term. While they do vary, a ton is generally one of the heaviest units of mass referred to in colloquial speech. The term ton is less frequently used to refer to a unit of force—usually weight at 1 g of earth gravity—or volume.

Contents 1 Units of mass 1.1 Common abbreviations 2 Units of force 3 Units of volume 4 Units of energy and power 4.1 Ton of TNT 4.2 Ton of coal equivalent 4.3 Refrigeration 5 Truck classes 6 Informal tons 7 See also 8 References

[edit] Units of mass

There are several similar units of mass or volume called the ton:

full name	common name	quantity		notes
		pounds	kilograms
long ton	"ton" (UK)	2,240.0	1,016.0	Used in countries such as United Kingdom which use the imperial system, except Canada. Conveniently, the mass is less than 2% different from the metric ton.
short ton	"ton" (US)	2,000.0	907.2	Used in the United States and Canada[1]
tonne, metric ton	"metric ton" (US, UK), else "ton"	2,204.6	1000.0	The tonne is also known just as a ton in areas which use the metric measurement system.
ton shortweight		2,240.0	1,016.0	Used in the iron industry in the 17th century and 18th centuries
ton longweight		2,400.0	1,088.6	Used in the iron industry in the 17th and 18th centuries. The hundredweight was 120 lb.[2]

Others

• The long ton is sometimes used for petroleum products such as aviation fuel.
• Increasingly, tonnes are being used rather than long tons in measuring the displacement of ships. See tonnage.
• Harbour ton used in South Africa in the 20th century, 2,000 pounds or one short ton.^{[citation needed]}

Both the long ton and the short ton are composed of 20 hundredweight, being 112 and 100 pounds respectively. Prior to the 15th century in England, the ton was composed of 20 hundredweight, each of 108 lb, giving a ton of 2,160 pounds.^{[citation needed]}

Assay ton (abbreviation 'AT') is not a unit of measurement, but a standard quantity used in assaying ores of precious metals; it is 29+¹⁄₆ grams (short assay ton) or 32+²⁄₃ grams (long assay ton), the amount which bears the same ratio to a milligram as a short or long ton bears to a troy ounce. In other words, the number of milligrams of a particular metal found in a sample of this size gives the number of troy ounces contained in a short or long ton of ore.^{[citation needed]}

In documents that predate 1960, the word ton is sometimes spelled tonne, but in more recent documents tonne refers exclusively to the metric ton.^{[citation needed]}

In nuclear power plants tHM and MTHM mean tonnes of heavy metals, and MTU means tonnes of uranium. In the steel industry, the abbreviation THM means 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced, particularly in the context of blast furnace production or specific consumption.

A dry ton or dry tonne has the same mass value, but the material (sludge, slurries, compost, and similar mixtures in which solid material is soaked with or suspended in water) has been dried to a relatively low, consistent moisture level (dry weight). If the material is in its natural, wet state, it is called a wet ton or wet tonne.

[edit] Common abbreviations

In the U.S. mining industry, 'T' is used to distinguish the traditional ton from the tonne, but 'T' is also the SI symbol for the tesla. The symbol 't', traditionally used for the long or short ton, is now reserved for the tonne.

[edit] Units of force

There are units of force based on each of these three mass units, but none are acceptable for use with SI. The tonne force, like the kilogram force, is no exception. Only the tonne as a unit of mass is acceptable for use with SI.

• 1 short ton force = 2000 pounds-force (lbf) = 8.896443230521 kilonewtons (kN)
• 1 long ton force = 2240 lbf = 9.96401641818352 kN
• 1 tonne force = 1000 kgf = 9.80665 kN

[edit] Units of volume

Also see tonnage.

The displacement ton is a unit of volume used for describing the displacement of a ship. It represents the volume of water displaced by the hull. It is usually abbreviated as DT.

One measurement ton is equal to 40 cubic feet. It is sometimes abbreviated as 'MTON'.^[3][4][5][6]

The freight ton represents the volume of a truck, train or other freight carrier. In the past it has been used for a cargo ship but the register ton is now preferred. It is equal to 40 cubic feet of space (1.132 cubic metres), but historically it has had several informal definitions. It is correctly abbreviated as 'FT' but some users are now using freight ton to represent a weight of 1 tonne, thus the more common abbreviations are now M/T, MT, or MTON (for measurement ton), which still cause it to be confused with the tonne, or even the megaton.

The register ton is a unit of volume used for the cargo capacity of a ship, defined as 100 cubic feet (roughly 2.83 cubic metres). It is often abbreviated RT or GRT for gross registered ton (The former providing confusion with the refrigeration ton). It is known as a tonneau de mer in Belgium, but, in France, a tonneau de mer is 1.44 cubic metres or about 1.88 cubic yards.

The Panama Canal/Universal Measurement System (PC/UMS) is based on net tonnage, modified for Panama Canal billing purposes. PC/UMS is based on a mathematical formula to calculate a vessel's total volume; a PC/UMS net ton is equivalent to 100 cubic feet of capacity.^[7]

The water ton was formerly used in Great Britain and is equal to 224 imperial gallons, the volume occupied by a mass of one long ton under the conditions that define the imperial gallon.

See 1 E-1 m³ and orders of magnitude (volume) for a comparison with other volumes.

(Note that volume tons are units of convenience used in shipping and are not useful in science except that they are exactly defined.)

[edit] Units of energy and power

[edit] Ton of TNT

• A ton of TNT or tonne of TNT is a unit of energy equal to 10⁹ (thermochemical) calories, also known as a gigacalorie (Gcal), equal to 4.184 gigajoules (GJ).
• A kiloton of TNT or kilotonne of TNT is a unit of energy equal to 10¹² calories, also known as a teracalorie (Tcal), equal to 4.184 terajoules (TJ).
• A megaton of TNT (1,000,000 metric tonnes) or megatonne of TNT is a unit of energy equal to 10¹⁵ calories, also known (infrequently) as a petacalorie (Pcal), equal to 4.184 petajoules (PJ).

Note that these are small calories (cal). The dietary Calorie (Cal) is distinct and equal to one kilocalorie.

Early values for the explosive energy released by trinitrotoluene (TNT) ranged from 900 to 1100 calories per gram. In order to standardise the use of the term TNT as a unit of energy, an arbitrary value was assigned based on 1000 calories (1 kcal, 4.184 kilojoules) per gram. Thus there is no longer a direct connection to the chemical TNT itself. It is now merely a unit of energy that happens to be expressed using words normally associated with mass (e.g., kilogram, tonne, pound).^[8][9] The definition applies for both spellings: ton of TNT and tonne of TNT.

Measurements in tons of TNT have been used primarily to express nuclear weapon yields, though they have also been used since in seismology as well.

[edit] Ton of coal equivalent

• A ton of coal equivalent or tonne of coal equivalent (TCE), a conventional value of 7 Gcal (IT) = 29.3076 GJ.

A Quintal is more commonly used as a measuring unit in India for Agri Purposes*

[edit] Refrigeration

The unit ton is used in refrigeration and air conditioning to measure heat absorption. Prior to the introduction of mechanical refrigeration, cooling was accomplished by delivering ice. Installing one ton of refrigeration replaced the daily delivery of one ton of ice.

• In North America, a standard ton of refrigeration is 12,000 BTU/h (3517 W). This is approximately the power required to melt one short ton (2000 lb) of ice at 0 °C in 24 hours, thus representing the delivery of 1 ton of ice per day.
• A less common usage is the power required to cool 1 long ton of water by 1 °F every 10 minutes = 13,440 BTU/h ≈ 3939 W.^[10][11][12]

The refrigeration ton is commonly abbreviated as TR.

[edit] Truck classes

When light-duty trucks were first produced, they were rated by their payload capacity in tons (e.g., ¹⁄₂-, ³⁄₄- and 1-ton). The Ford F-150, Chevy/GMC 1500, and Dodge 1500 are a ¹⁄₂-ton. The Ford F-250, Chevy/GMC 2500, and Dodge 2500 are a ³⁄₄-ton. The Ford F-350, Chevy/GMC 3500, and Dodge 3500 are a 1-ton. But throughout the years, the payload capacities have increased while the ton title has stayed the same. The current ton rating scheme is just a generic truck name.

[edit] Informal tons

• Ton is also used informally, often as slang, to mean a large amount of something (material or not), for example, "Man, I just ate a ton of french fries back there". It can also be used as a highly derogatory meaning for very overweight persons, e.g., "look at that ten-ton Tess".
• In Britain, a ton is colloquially used to refer to 100 of a given unit. Ton can thus refer to a speed of 100 miles per hour e.g. "Lee was doing a ton down the motorway"; to money e.g. "How much did you pay for that?" "A ton" (£100); to 100 points in a game e.g. "Eric just threw a ton in our darts game"; or to a hundred of pretty much anything else.
• A ton is 100 runs in the game of cricket (more commonly known as a century).

[edit] See also

• Conversion of units
• Medieval weights and measures
• Ancient weights and measures
• English unit
• Imperial unit
• U.S. customary unit

[edit] References