TNT equivalent

Physical unit
Unit name	TNT equivalent
Physical quantity (s)	Energy , internal energy , chemical energy
Formula symbol	${\displaystyle W;\,E}$
dimension	${\displaystyle {\mathsf {ML^{2}T^{-2}}}}$
In SI units	${\displaystyle \mathrm {1\,kg_{TNT}=4{,}184\,MJ} }$
Derived from	Energy release of one kilogram of TNT

TNT equivalent is a non- SI conform but still used unit of measurement for the energy released in an explosion . The information relates to the total energy released, not just to the kinetic energy , which, for example, can be significantly less than the total energy in the case of nuclear weapons . Therefore, the explosive power is only partially comparable with that of a corresponding amount of the explosive TNT .

TNT equivalent is used to indicate the explosive power of military weapons, industrial explosives and other explosive devices, or in general for the sudden (explosive) release of energy, e.g. B. by meteorite impacts . To simplify matters, sometimes only the equivalent mass ("explosive force two kilotons") is mentioned.

TNT has a molar mass of 227.1 g / mol and releases an energy of approx. 1,047 kJ / mol (approx. 250 kcal / mol). This results in an energy density of around 4.6 MJ / kg (approx. 1000 kcal / kg). At the time of the definition, calculations were not made with joules  (J) but with thermochemical calories (cal). In order to have a "handy" unit, 1 cal was taken as the basis and the energy equivalent of a kiloton of TNT was defined as 1 · 10 ¹²  cal or 4.184 · 10 ¹²  J: 10 ⁶  cal / kg = 4.184 · 10 ⁶  J / kg = 4.184 MJ / kg. Or short:

1 kT (kiloton TNT) = 4.184 · 10 ¹²  J = 1.162  GWh

Units are kilotons (kT), megatons (MT) and gigatons (GT). To avoid confusion with the masses, the TNT equivalent units are often written with capital letters, so MT instead Mt . However, other spellings are also used; there is no binding standard.

TNT equivalent of explosive weapons

• Fireworks : The TNT equivalent of freely available fireworks is less than one gram.
• Improvised bombs : Explosives that were used in terrorist attacks mostly had an explosive force of a few kilograms of TNT (such as the attacks by the RAF ), and more rarely more than 1000 kg of TNT (such as the bombing of Oklahoma City ).
• Conventional weapons : The US Army's most powerful conventional explosive weapon , GBU-43 / B Massive Ordnance Air Blast , achieves 11 tons of TNT-equivalent explosive force with a dead weight of about 9.5 tons. Russia claims to have achieved 44 tons of explosive power with an aerosol bomb of about the same size and thus to have the most powerful conventional bomb in the world. The sum of all (conventional) bombs dropped on cities in World War II is an estimated 2 megatons.
• Nuclear weapons : The atomic bomb dropped on Hiroshima by the United States in 1945 had an explosive force of around 13 kilotons of TNT. The warheads ( B61 , W76 , W88 ), which made up the bulk of the US post-Cold War tactical nuclear arsenal, have a TNT equivalent of less than 20 to over 300 kilotons, depending on the model and setting. Strategic warheads for ICBMs and bombers in the still active US arsenal have a TNT equivalent of several hundred kilotons to 1.2 megatons ( B83 ). The Castle Bravo hydrogen bomb, detonated by the US in 1954 and the most powerful bomb ever detonated in a US nuclear test, exploded about 15 megatons of TNT. In 1961 the USSR detonated the largest ever tested hydrogen bomb with around 50 megatons of TNT equivalent ( Tsar bomb ).
• Antimatter : 1 kg of antimatter would have an explosive force of 43 MT if annihilated with 1 kg of matter.

Other explosives compared to TNT

Wood has four times the energy density of TNT. Nevertheless, its "explosive power" is low, since the power , ie the energy release per time , is very small compared to typical explosives. Correction factors take into account the explosiveness of different explosives. The values ​​are obtained by comparing the pressure waves or impulse waves that the explosives generate compared to TNT. For wood, a comparative value would be close to 0.

Explosives conversion factor

Gunpowder	0.25 ... 0.4		Torpex	1.3
Ammonium nitrate	0.5		C4	1.35
Dynamite / ballistite / cordite	0.8		RDX / cyclonite / hexogen	1.5
Amatol	0.85		Semtex	1.6
TNT	1.0		PETN / Nitropenta	1.7
HMX	1.1		HNIW / CL20	1.9
NGL	1.2		ONC	2.1
HMTD	1.25		Chlorate explosives	0.8 ... 1.0 note

^Note
The most explosive mixtures are with red phosphorus and are considered dynamite-like when mixed in the finest possible way.
The detonation speed in the explosion is only 3.35 km / s for Chloratite 3, but its explosive power is ≈1 TNT equivalents.

See also

• Lead block bulge
• Sand test

literature

• Zoltán Török, Alexandru Ozunu: Hazardous properties of ammonium nitrate and modeling of explosions using TNT equivalency , Environmental Engineering and Management Journal, Vol. 14, September 2015 ( Researchgate.net online access ).

Web links

• Nuclear Weapons FAQ , Section 1.3 - Definition of the unit kiloton TNT equivalent
• Guide for the Use of the International System of Units (SI) . - Conversion of different units (English)
• Ernest E. Ludwig: Applied process design for chemical and petrochemical plants , Volume 2

Individual evidence

1. ↑ GBU-43 / B / "Mother Of All Bombs" / Massive Ordnance Air Blast Bomb. Retrieved January 23, 2020 . 
2. ↑ The strategic warhead B53 with up to 9 megatons of explosive power is no longer in active service in the USA, but was present as part of the reserve or hedge until it was dismantled in October 2011 in the Pantex factory in Amarillo, Texas .
3. ↑ Thus, in a single explosion, about a tenth of the total explosive force of all nuclear weapons tests ever carried out was released.