Bomb blast effects

The term
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The "ton of TNT" is a unit of energy defined by that convention to be 4.184 gigajoules, which is the approximate energy released in the detonation of a metric ton (1,000 kilograms or one megagram) of TNT. The convention intends to compare the destructiveness of an event with that of conventional explosives, of which TNT is a typical example (although other conventional explosives such as dynamite contain more energy).

The "kiloton (of TNT)" is a unit of energy equal to 4.184 terajoules.

The "megaton (of TNT)" is a unit of energy equal to 4.184 petajoules.

The kiloton and megaton of TNT have traditionally been used to describe the energy output, and hence the destructive power, of a nuclear weapon. The TNT equivalent appears in various nuclear weapon control treaties, and has been used to characterize the energy released in such other highly destructive events as an asteroid impact.

The explosive yield of a nuclear weapon is the amount of energy released when that particular nuclear weapon is detonated, usually expressed as a TNT equivalent (the standardized equivalent mass of trinitrotoluene which, if detonated, would produce the same energy discharge), either in kilotons (kt—thousands of tons of TNT), in megatons (Mt—millions of tons of TNT), or sometimes in terajoules (TJ). An explosive yield of one terajoule is 0.239 kt of TNT. Because the accuracy of any measurement of the energy released by TNT has always been problematic, the conventional definition accepted since the dawn of the Atomic Age is that one kiloton of TNT is simply to be 1012 calories equivalent, which is only approximately equal to the energy yield of 1,000 tons of TNT.

The yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. The practical maximum yield-to-weight ratio for fusion weapons (thermonuclear weapons) has been estimated to six megatons of TNT per metric ton of bomb mass (25 TJ/kg). Yields of 5.2 megatons/ton and higher have been reported for large weapons constructed for single-warhead use in the early 1960s. Since this time, the smaller warheads needed to achieve the increased net damage efficiency (bomb damage/bomb weight) of multiple warhead systems, has resulted in decreases in the yield/weight ratio for single modern warheads.

The relative effectiveness factor, or R.E. factor, relates an explosive's demolition power to that of TNT, in units of the TNT equivalent/kg (TNTe/kg). The R.E. factor is the relative mass of TNT to which an explosive is equivalent; the greater the R.E., the more powerful the explosive.

This enables engineers to determine the proper masses of different explosives when applying blasting formulas developed specifically for TNT. For example, if a timber-cutting formula calls for a charge of 1 kg of TNT, then based on octanitrocubane's R.E. factor of 2.38, it would take only 1.0/2.38 (or 0.42) kg of it to do the same job. Using PETN, engineers would need 1.0/1.66 (or 0.60) kg to obtain the same effects as 1 kg of TNT. With ANFO or ammonium nitrate, they would require 1.0/0.74 (or 1.35) kg or 1.0/0.42 (or 2.38) kg, respectively.

Pre-Napoleonic
Gunpowder, also known as black powder, is the earliest known chemical explosive. It is a mixture of sulfur, charcoal, and potassium nitrate (saltpeter). The sulfur and charcoal act as fuels, and the saltpeter is an oxidizer. Because of its burning properties and the amount of heat and gas volume that it generates, gunpowder has been widely used as a propellant in firearms and as a pyrotechnic composition in fireworks. Formulations used in blasting rock (such as in quarrying) are called blasting powder. Gunpowder is mainly used in older guns now because the propellants used today are too powerful and could break the already fragile barrels.

Gunpowder was invented in the 9th century in China, and the earliest record of a written formula for gunpowder appears in the 11th century Song dynasty text, Wujing Zongyao. This discovery led to the invention of fireworks and the earliest gunpowder weapons in China. In the centuries following the Chinese discovery, gunpowder weapons began appearing in the Muslim world, Europe, and India. The technology spread from China through the Middle East or Central Asia, and then into Europe. The earliest Western accounts of gunpowder appear in texts written by English philosopher Roger Bacon in the 13th century. he hypothesis that gunpowder was used by ancient Hindus was first mentioned in the eighteenth century by some Sanskrit scholars. The most ardent protagonists were Nathaniel Halhad, Johann Backmann, Quintin Craufurd and Gustav Oppert. However due to lack of sufficient proof, these theories have not been widely accepted.

Gunpowder is assigned the UN number UN0027 and has a hazard class of 1.1D. It has a flash point of approximately 427–464 °C (801–867 °F). The specific flash point may vary based on the specific composition of the gunpowder. Gunpowder's specific gravity is 1.70–1.82 (mercury method) or 1.92–2.08 (pycnometer), and it has a pH of 6.0–8.0.

Gunpowder is classified as a low explosive because of its relatively slow decomposition rate and consequently low brisance. Low explosives deflagrate (i.e., burn) at subsonic speeds, whereas high explosives detonate, producing a supersonic wave. Ignition of the powder packed behind a bullet must generate enough pressure to force it from the muzzle at high speed, but not enough to rupture the gun barrel. Gunpowder thus makes a good propellant, but is less suitable for shattering rock or fortifications. Gunpowder was widely used to fill artillery shells and in mining and civil engineering to blast rock until the second half of the 19th century, when the first high explosives were put into use. Gunpowder is no longer used in modern explosive military warheads, nor is it used as main explosive in mining operations due to its cost relative to that of newer alternatives such as ammonium nitrate/fuel oil (ANFO). Black powder is still used as a delay element in various munitions where its slow-burning properties are valuable.

Gun powder\black powder was measured in various ways such as ounces, barrels, pounds and apothecary grains.

Napoleonic war
Weights and turms became more standarised and the kilogram joined the list of mesures.

American Civil War
Nitroglycerin (NG), also known as nitroglycerine, trinitroglycerin (TNG), trinitroglycerine, nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a heavy, colorless, oily, explosive liquid most commonly produced by nitrating glycerol with white fuming nitric acid under conditions appropriate to the formation of the nitric acid ester. Chemically, the substance is an organic nitrate compound rather than a nitro compound, yet the traditional name is often retained. Invented in 1847, nitroglycerin has been used as an active ingredient in the manufacture of explosives, mostly dynamite, and as such it is employed in the construction, demolition, and mining industries. Since the 1880s, it has been used by the military as an active ingredient, and a gelatinizer for nitrocellulose, in some solid propellants, such as cordite and ballistite.

Nitroglycerin is also a major component in double-based smokeless gunpowders used by reloaders. Combined with nitrocellulose, there are hundreds of powder combinations used by rifle, pistol, and shotgun reloaders.

For over 130 years, nitroglycerin has been used medically as a potent vasodilator (dilation of the vascular system) to treat heart conditions, such as angina pectoris and chronic heart failure. Though it was previously known that these beneficial effects are due to nitroglycerin being converted to nitric oxide, a potent venodilator, it was not until 2002 that the enzyme for this conversion was discovered to be mitochondrial aldehyde dehydrogenase. Nitroglycerin is available in sublingual tablets, sprays, and patches. Other potential suggested uses include adjunct therapy in prostate cancer.

TNT was first prepared in 1863 by German chemist Julius Wilbrand and originally used as a yellow dye. Its potential as an explosive was not appreciated for several years, mainly because it was so difficult to detonate and because it was less powerful than alternatives. Its explosive properties were first discovered by another German chemist, Carl Haeussermann, in 1891. TNT can be safely poured when liquid into shell cases, and is so insensitive that in 1910, it was exempted from the UK's Explosives Act 1875 and was not considered an explosive for the purposes of manufacture and storage.

The German armed forces adopted it as a filling for artillery shells in 1902. TNT-filled armour-piercing shells would explode after they had penetrated the armour of British capital ships, whereas the British lyddite-filled shells tended to explode upon striking armour, thus expending much of their energy outside the ship. The British started replacing lyddite with TNT in 1907.

Dynamite, nitroglycerin and TNT came up as the latest explosives and made more blast than the gunpowder. Dynamite was a more stable form of nitroglycerin and was cut in to standardised stick lengths in each producing country, thus measurement by sticks and stick lengths and whiths, or if cut by the end users, centimeters and inches of dynamite. Many sticks were made to wieght 1lb or 1kg in wieght or to exsplode with the force of 1lb or kg of compacted (powder rammed hard into a conatiner) gun powder.

WW1
Pure EGDN was first produced by the Belgian chemist Louis Henry (1834–1913) in 1870 by dropping a small amount of ethylene glycol into a mixture of nitric and sulfuric acids cooled to 0 °C. The previous year, August Kekulé had produced EGDN by the nitration of ethylene, but this was actually contaminated with beta-nitroethyl nitrate.

Other investigators preparing NGc before publication in 1926 of Rinkenbach's work included: Champion (1871), Neff (1899) & Wieland & Sakellarios (1920), Dautriche, Hough & Oehme.

The American chemist William Henry Rinkenbach (1894–1965) prepared EGDN by nitrating purified glycol obtained by fractioning the commercial product under pressure of 40mm Hg, and at a temperature of 120°. For this 20g of middle fraction of purified glycol was gradually added to mixture of 70g nitric acid and 130g sulfuric acid, maintaining the temperature at 23°. The resulting 49g of crude product was washed with 300ml of water to obtain 39.6g of purified product. The low yield so obtained could be improved by maintaining a lower temperature and using a different nitrating acid mixture.

1) Direct Nitration of Glycol is carried out in exactly the same manner, with the same apparatus, and with the same mixed acids as nitration of glycerine. In the test nitration of anhydrous glycol (100g) with 625g of mixed acid HNO 3 40% & H 2SO 4 60% at 10-12°, the yield was 222g and it dropped to 218g when the temp was raised to 29-30°. When 500g of mixed acid HNO 3 50% & H 2SO 4 50% was used at 10-12°, the yield increased to 229g. In commercial nitration, the yields obtained from 100 kg anhydrous glycol and 625 kg of mixed acid containing HNO 3 41%, H 2SO 4 58% & water 1% were 222.2 kg of NGc at nitrating temp of 10-12° and only 218.3 kg at 29-30°. This means 90.6% of theory, as compared to 93.6% with NG.

C2H4(OH)2 + 2 HNO3 → C2H4(ONO2)2 + 2 H2O or through the reaction of ethylene oxide and dinitrogen pentoxide:

C2H4O + N2O5 → C2H4(ONO2)2 2) Direct Production of NGc from Gaseous Ethylene. 3) Preparation of NGc from Ethylene Oxide. 4) Preparation of NGc by method of Messing from ethylene through chlorohydrin & ethylene oxide. 5) Preparation of NGc by duPont method.

Amatol is a highly explosive material made from a mixture of TNT and ammonium nitrate. The British name originates from the words ammonium and toluene (a raw material of TNT). Similar mixtures (1 part dinitronaphthalene and 7 parts ammonium nitrate) were known as Schneiderite in France. Amatol was used extensively during World War I and World War II, typically as an explosive in military weapons such as aircraft bombs, shells, depth charges, and naval mines.It was eventually replaced with alternative explosives such as composition B, torpex, and tritonal. An Amatol explosion is 1.10% stronger than TNT.

Explosives were to be measured by the ton. The official pound, kilogram and ton were devised. The TNT equivalent was first though. Explosives like Ethylene glycol dinitrate, Hexanite and Amatol came along by WW1.


 * Example: Amitol is 0.10 more powerful than TNT, so 1 lb of TNT causes a 1 lb blast, but 1 lb of Amatol causes a 1.10 lb bast.

WW2
Torpex is a secondary explosive, 50% more powerful than TNT by mass. Torpex comprises 42% RDX, 40% TNT and 18% powdered aluminium. It was used in the Second World War from late 1942. The name is short for "Torpedo Explosive", having been originally developed for use in torpedoes. Torpex proved to be particularly useful in underwater munitions because the aluminium component had the effect of making the explosive pulse last longer, which increased the destructive power. Torpex was used only in critical applications, e.g. torpedoes and the Upkeep, Tallboy, and Grand Slam bombs. It was also used in the Operation Aphrodite drones. Torpex has long been superseded by H6 and PBX compositions. It is therefore regarded as obsolete, so Torpex is unlikely to be encountered except in old munitions or unexploded ordnance.

RDX is the organic compound with the formula (O2NNCH2)3. It is a white solid widely used as an explosive. Chemically, it is classified as nitramide. A more powerful explosive than TNT, it was used widely in World War II. RDX is also known as Research Department Formula X.

It is often used in mixtures with other explosives and plasticizers or phlegmatizers (desensitizers). RDX is stable in storage and is considered one of the most powerful and brisant of the military high explosives.

RDX is also known, but less commonly, as cyclonite, hexogen (particularly in Russian, German and German-influenced languages), T4 and chemically as cyclotrimethylenetrinitramine. In the 1930s, the Royal Arsenal, Woolwich, started investigating cyclonite to use against German U-boats that were being built with thicker hulls. The goal was an explosive more powerful than TNT. For security reasons, Britain termed cyclonite as "Research Department Explosive" (R.D.X.). The term RDX appeared in the United States in 1946. The first public reference in the United Kingdom to the name RDX, or R.D.X. to use the official title, appeared in 1948; its authors were the Managing Chemist, ROF Bridgwater, the Chemical Research and Development Department, Woolwich, and the Director of Royal Ordnance Factories, Explosives; again, it was referred to as simply RDX.

Torpex, Composition B, Composition H6, RDX and Minol were both common and noticeably more powerful explosives. Torpex had 50% more blast as TNT had, so making a standard table and blast measure necessary when planning a detonation. Every one was already used to TNT, so the bomb's charge would be measured by the Tn, lb or kg in dead weight, but the blast would be measured in the equivalent to the Tn, lb or kg of TNT expected to from such a blast.


 * Example: Torpex is 0.50 more powerful than TNT, so 1 lb of TNT causes a 1lb blast, but 1 lb of Torpex causes a 1.50lb bast.

The TNT equivalent was first codified and scientifically defined.

Conventional blasts
Tovex (also known as Trenchrite, Seismogel, and Seismopac) is a water-gel explosive composed of ammonium nitrate and methylammonium nitrate that has several advantages over traditional dynamite, including lower toxicity and safer manufacture, transport, and storage. It has thus almost entirely replaced dynamite. There are numerous versions ranging from shearing charges to aluminized common blasting agents. Tovex is used by 80% of international oil companies for seismic exploration. Torvex is 0.80% as effective as TNT.

C-4 or Composition C-4 is a common variety of the plastic explosive family known as Composition C. The British version of the explosive is known as PE-4 (Plastic Explosive). C-4 is composed of explosives, plastic binder, plasticizer to make it malleable, and usually a marker or odorizing taggant chemical.

C-4 has a texture similar to modeling clay and can be molded into any desired shape. C-4 is stable and an explosion can only be initiated by the combination of extreme heat and shock wave from a detonator. C-4 is 1.34 times as effective as TNT.

Semtex is a general-purpose plastic explosive containing RDX and PETN. It is used in commercial blasting, demolition, and in certain military applications. Semtex became notoriously popular with terrorists because it was, until recently, extremely difficult to detect, as in the case of Pan Am Flight 103. Semtex is 1.35 times as effective as TNT.

For its original military use it was manufactured under the name B 1. It has been manufactured in Czechoslovakia under its current name since 1964, labeled as SEMTEX 1A, since 1967 as SEMTEX H and since 1987 as SEMTEX 10.

The composition of the two most common variants differ according to their use. The 1A (or 10) variant is used for blasting, and is based mostly on crystalline PETN. The version 1AP and 2P are formed as hexagonal booster charges; a special assembly of PETN and wax inside the charge assures high reliability for detonating cord or detonator. The H (or SE) variant is intended for explosion hardening.

Cyclotol is an explosive consisting of castable mixtures of RDX and TNT. It is related to the more common Composition B, which is roughly 60% RDX and 40% TNT; various compositions of Cyclotol contain from 65% to 80% RDX.

Typical ranges are from 60/40 to 80/20 RDX/TNT, with the most common being 70/30, while the military mostly uses 77/23 optimized in warheads.

Cyclotol is not commonly used, but was reportedly the main explosive used in at least some models of US Nuclear weapon. Sublette lists Cyclotol as the explosive in the US B28 nuclear bomb and possibly related weapons that used the common Python primary - W34, W28, W40, and W49.

It was also used in the B53 nuclear bomb and associated W53 warhead. In a modern military industry last 20 years Cyclotol can be used as filler and main charge most of cluster submunition, especially with a piezoelectric crystal igniter.

Nukes, Cyclotol, Tovex, C-4 and Semtex now came in to use. It was at this time that Kt and Mt came in to usage.

C-4 is 1.34 times as effective as TNT, Semtex is 1.35 times as effective as TNT and Torvex is 0.80% as effective as TNT.


 * Example: Torvex is 20% less powerful than TNT, so 1 lb of TNT causes a 1 lb blast, but 1 lb of Torvex causes 0.80 lb a bast.


 * Example: C-4 is 0.34% more powerful than TNT, so 1 lb of TNT causes a 1 lb blast, but 1 lb of C-4 causes a 1.34 lb bast.


 * Example: Semtex is 0.35% more powerful than TNT, so 1 lb of TNT causes a 1 lb blast, but 1 lb of Semtex causes a 1.35 lb bast.

Atomic blasts
Nukes were to be measured in the much greater megaton and kiloton range.

Today
The ton equivalent (now 'blast ton', 'explosive ton', 'TNT ton', 'ton of TNT', 'ton blast', 'ton explosion' just 'ton') is also used as a way of estimating the blast form IEDs, terrorist devices and accidental industrial explosions.

IMX-101 is now becoming more common place in the USA and in time the rest of NATO's nations.

The blast comparison list!
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 * Bang goes the tonnage!

The bomb blast list!
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 * Bombs away!

Blast shelters
A blast shelter is a place where people can go to protect themselves from bomb blasts. It differs from a fallout shelter, in that its main purpose is to protect from shock waves and overpressure, instead of from radioactive precipitation, as a fallout shelter does. It is also possible for a shelter to protect from both blasts and fallout.

Blast shelters are a vital form of protection from nuclear attack and are employed in civil defense. There are above-ground, below-ground, dedicated, dual-purpose, and potential blast shelters. Dedicated blast shelters are built specifically for the purpose of blast protection and thus vary in ways from air-aid shelters, radiation shelters, dugouts, foxholes, vaults, basements, privately improved bomb shelters, Safe rooms, mine bed\quarry bottom improvised smelters and bunkers. Dual-purpose blast shelters are existing structures with blast-protective properties that have been modified to accommodate people seeking protection from blasts. Potential blast shelters are existing structures or geological features exhibiting blast-protective properties that have potential to be used for protection from blasts.

Blast shelters deflect the blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker. While frame buildings collapse from as little as 3 psi (20 kPa) of overpressure, blast shelters are regularly constructed to survive several hundred psi. This substantially decreases the likelihood that a bomb can harm the structure.

The basic plan is to provide a structure that is very strong in compression. The actual strength specification must be done individually, based on the nature and probability of the threat. A typical specification for heavy civil defence shelter in Europe during the Cold war was an overhead explosion of a 500 kiloton weapon at the height of 500 meters. Such a weapon would be used to attack soft targets (factories, administrative centres, communications) in the area.

Only the most heavy bedrock-shelters would stand a chance of surviving. However, in the countryside or in a suburb, the likely distance to the explosion is much larger, as it is improbable that anyone would waste an expensive nuclear device on such targets. The most common purpose-built structure is a steel-reinforced concrete vault or arch buried or located in the basement of a house.

Blast resistant doors protect people and property from explosions and shrapnel. One type is four inches of concrete that resists structural fires, cutting torches, fires, withstand a 50 PSI (3 bar) blast load in a seated condition, 14.5 PSI (1 bar) rebound load in a unseated condition and multiple hits with a 7.62 NATO round with no penetration.

Also see

 * 1) Nukes
 * 2) Science
 * 3) Torpedoes
 * 4) Land and sea mines
 * 5) Popular types of explosives
 * 6) Ballistic missiles, missiles and military rockets