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Embed code for: Explosives
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Meaning, Purpose & Scope:
Explosives are substances, which under suitable conditions of Initiation undergo a sudden chemical change releasing large amount of heat and pressure in the form of gases, which rapidly expand producing violent physical disruption of the surrounding environment. The heat energy released by the explosion serves to expand the gases causing them to push on the walls in surrounding areas with great force. Finally, the walls, vehicles or any other objects would fragment and fly outwards in all directions. It is this flying debris or sharpnels that produce devastating effect causing danger to life and limb in the immediate vicinity of such explosions. The speed at which explosives decompose varies greatly from one another and provide basis for their classification as high and low explosives. In the low explosive, this speed is called the speed of deflagration (burning). This is characterized by very rapid oxidation producing heat, light, and high-pressure wave. In high explosives, it is called speed of detonation. Detonation refers to the creation of an extremely high shock wave within the explosive charge.
It may be seen from the above that this definition does not include nuclear explosions or explosions due to sudden release of pressure like the bursting of a boiler or a gas cylinder. These type of explosions are known as physical explosions. The law enforcement agencies are concerned with explosions involving chemical substances. Gun powder (which constitutes a mixture of Sodium nitrate, charcoal and sulphur), Trinitrotoluene (TNT), Nitroglycerine, and Mercury fulminate are examples of chemical explosions.
Use of explosives for malicious purpose of causing harm to life and destruction of property is known since its invention. Ingenious ways of devising bombs and booby traps by making use of explosive mixtures locally available or by pilfering explosives meant for industrial or defence use are not uncommon in our country. Use of high explosives, smuggled from across the border, by criminals and terrorist elements has become a common phenomenon. The terrorists, militants, and extremist elements engaged in sabotage activities, make attempts on the life of innocent citizens, VIPs, security forces etc. The incidents of bomb blasts taking place in different parts of the country, causing destruction to life and property are clear indications of the magnitude of the problem confronting the law enforcement agency. The use of high explosives for fabricating Improvised Explosives Devices (IEDs) has been the most favourite weapon of terrorists and militants. Knowledge of explosives, explosive devices, sophistication of explosive materials used is essential, for the law enforcement agency to take adequate measures to safeguard the life and property of citizens, public property, protect VIPs etc., and to prosecute the offenders.
Types of explosives :
Low explosives: Low explosives decompose relatively slowly at rates that vary up to 1000 meters per second. Because of their slow burning rates, they produce a propelling or throwing action that make them suitable as propellants for ammunition or skyrockets. However they can result in violent explosions, if they are confined to a relatively small container and detonated. As most of these chemicals are otherwise useful in the manufacturing of household articles such as matchsticks, fireworks, fertilizers, etc., those with malicious intentions can have access to these substances. This is the main reason for several instances of explosions caused by these materials. Examples are Gunpowder, Smokeless Gun Powder and Potassium or Sodium chlorate mixtures.
High Explosives: The sensitivity of these explosives is the basis of classifying high explosives into 2 groups called initiating or primary high explosives and non-initiating or secondary high explosives.
Initiating or primary high explosives are ultra-sensitive to heat, shock or friction, and under normal conditions will detonate violently instead of burning. For this reason they are used to detonate other explosives, which causes chain reaction and are referred to as primers. They form ingredients of the blasting cap. Examples are Lead azide, Lead styphnate, and Mercury fulminate.
Non-initiating explosives are relatively insensitive to heat, shock or friction. They will normally burn rather than detonate if ignited in small quantities. This group comprises the majority of high explosives used for commercial and military blasting. Examples are TNT (trinitrotoluene) called Dynamite, PETN (penta erythritol tetranitrate), RDX (cyclotrimethylenetri nitramine), tetryl (2, 4, 6 – trinitrophenyl methyl nitramine).
The use of explosives in faction fights and terrorist and extremist violence is common. Whenever a bomb explodes it leaves its remnants in the form of pieces of glass, metal stones, paper; threads of jute, cotton or coconut fibre; coloured powders, soil, etc. By examining these remnants it is possible to know the nature of their contents and perhaps the source of manufacture and the origin of the individual constituents of the explosive devices.
Types of cases: In practice, police are required to deal with two types of situations where explosives are found. In the first type, the Investigating Officers come across explosives in the form of raw chemical substances and other components like shells, wires, detonators, batteries etc., or in ready to use IEDs recovered or seized. In the second type the Investigating Officers come across scenes of explosions where the effect of explosives is found in the form of damages to the persons and property.
Since these explosive substances are useful for civil, commercial and military purposes they are available for the genuine users having valid license or authorization. On the other hand use of these substances by any unauthorized person for the purposes other than the purposes for which license is granted is punishable by law. The Explosives Act, the Explosives Substances Act and the Rules made there under contain the law and procedure dealing with explosives.
Whenever explosives are used with criminal intent the police have to prove the motive, opportunity and means of such illegal use by the persons involved therein. The Investigating Officers and the police authorities should therefore follow systematic procedure for identification, handling, diffusion, sampling and disposal of explosives and their remnants.
Whenever live bombs / explosives or components of bombs / explosives are seized by the Investigating Officers and also as and when explosions take place, it is necessary to follow certain systematic procedures and practices in accordance with the rules and regulations contained in Explosives Act 1884, Explosive Substances Act 1908 and Explosives Rules 1983.
Common Types of Bombs and IEDs:
Country made throw down type bombs in different shapes and sizes.
Improvised hand grenades similar in appearance to Military explosives made of hardware material like pipes.
Claymore mines. (usually placed in metallic pipes / cylinders).
Position bombs / Booby traps (e.g. effigy bombs, TV / letter / book bombs etc.)
Remote control bombs (Infrared, Microwave Control).
Time bombs. (Quartz clock, Time pencils, pre-determined timers (integrated Circuits), Timers used in household gadgets like washing machine timers etc.)
Incendiaries (Petrol bombs / Molotov cocktails, Acid bulbs)
IEDs, bombs / in any other shape, form, and design.
The basic raw materials, explosive in nature commonly used for making the IEDs and bombs include the following chemicals:
Gunpowder (sodium / potassium nitrate, carbon and sulphur in black / brown colour).
Potassium chlorate (dull white powder having shades of yellow / grey).
Arsenic sulphide (orange powder).
Sulphur (yellow powder)
Phosphorus (red powder).
Aluminium (grey metallic powder).
Potassium nitrate (white crystalline / pale yellow).
Ammonium nitrate (white crystalline)
Charcoal (black powder).
Gelatin Sticks consisting of Nitroglycerine, Nitro-cellulose (straw / red coloured).
ANFO Sticks (Ammonium Nitrate and Fuel Oil) (Grey in colour)
RDX (normally white but can be modified to black / yellow / orange and other colours)
TNT (pale yellow to brown).
SEMTEX (Consisting of RDX with PETN – in any additive colour).
PEK (Plastic Explosives) (yellow, plasticine like) or
Any other single or mixture of chemicals, which can cause explosions in combination or alone.
Components used in making Bombs / IEDs:
Grenade shell, metallic tins, pipes, sharpnels (pieces of glass, nuts, screws, nails, blades, stones, metal/glass balls and aluminum flakes etc.), thread rolls, safety fuses, detonators, batteries (wet / dry), exploder dynamo, detonating cord, wires, switches etc., and Oils like Petrol, Diesel, Grease, Petroleum Jelly, Acids, etc.
Civil explosives coming under schedule I of Explosive Rules, 1983 listed below will be exclusively dealt by the Chief Controller of Explosives for diffusion, assessment and disposal. Authorized explosives (Civil explosives) like Gunpowder (class – 1 explosives), Dynamites/Gelatin such as Superdyne, Formadyne, Dynex, Acquadyne, Safex, Kelvex, Indogel, Salvo Super, Idealboost, Hyprime (class –2 explosives), Ajax-G, Polar Viking, Polar Ajax, Special Gelatine, Noblegel, Telgex, Bharatgel etc. (class – 3 Nitro compound explosives), safety fuse (class – 6, division –3) Fireworks belonging to class – 7 division – 2, Slurry explosives such as ANFO (Ammonium Nitrate Fuel Oil Mixture) etc., belonging to class – 2.
Military Explosives – Role of Military Bomb Disposal Squad:
Military explosives such as grenades, shells, anti-personal and anti-tank land mines etc., are handled exclusively by the officers of Military Bomb Disposal. All Military Explosives can be easily identified by the markings such as year, type etc.
Unexploded bombs (UXB):
Unexploded country bombs (UXBs) made in soda-water bottles, jam tins, water cistern floats, coconut shells, bundles of jute, hemp or cloth, or bamboo tubes, book bombs and letter bombs may be designed to explode.
When moved in any way.
When turned over.
When placed in water.
When thrown down.
When a fuse is lighted.
By a clockwork arrangement, or
By Chemical reaction.
Before handling the bomb the Bomb Disposal Squad examines the UXB and takes appropriate steps to render the UXB safe.
In all cases of explosions the Investigating Officer collects the residual explosion materials from the scene of crime. The Bomb Disposal Team Officers should be called to the scene of crime if any live bombs are suspected to be present even after explosion. In sensational and important cases, scientific personnel of FSL and local scientific personnel of the Investigating Team should be requisitioned immediately for physical inspection and for assessment of the damage, risk potential and the nature of explosion. The experts, who inspect the scene of explosion, will be in a position to collect relevant material for chemical analysis as well as make an in-depth study of the damage and risk assessment.
In case the risk potential assessment is required in major explosions, the Investigating Officer should forward full details of the remnants of materials seized along with photographs of the scene of explosion. Any opinion regarding the cause of explosion, seat of explosion, quantity of explosive materials responsible for causing the explosion etc., can be offered by FSL only when a video tape, colour photographs and full description of the materials seized and the damages occurred are sent.
Methods of analysis:
Remnants from the exploded and defused bombs and explosives are analyzed in FSL by semi-micro analysis, flame photometric analysis methods etc., to detect various cations and anions, nitro-compounds in high explosives. The detection and identification techniques range from simple chemical tests to the sophisticated analytical techniques like ion chromatography, capillary electrophoresis, scanning electron microscopy-energy dispersive x-ray spectroscopy, gas chromatography with electron capture detection, gas chromatography-mass spectrometry, and high performance liquid chromatography.
Remnants from the exploded and defused bombs and explosives are analyzed in FSL by semi-micro analysis, flame photometric analysis methods etc., to detect various cations and anions, nitro-compounds in high explosives. The detection and identification techniques range from simple chemical tests to the sophisticated analytical techniques like ion chromatography, capillary electrophoresis, scanning electron microscopy-energy dispersive x-ray spectroscopy, gas chromatography with electron capture