Detonator
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A detonator, also known as blasting cap, is used to trigger bombs, shaped charges and other forms of *explosive material and explosive devices. Detonators can be found in either electrical or non-electrical form. There are three categories of electrical detonators namely; instantaneous electrical detonators (IED), short period delay detonators (SPD) and long period delay detonators (LPD). SPD's are measured in milliseconds and LPD's are measured in seconds. Detonators can be chemical, mechanical, or electrical with the most common being mechanical and electrical. Explosive Ordnance Devices or EOD (hand grenades, limpet mines etc) mostly make use of mechanical detonators whilst the commercial use of explosives uses electrical detonators. Another form of detonator used in the commercial sector is that of the capped fuse which is a length of safety fuse to which an ordinary detonator has been crimped. Many detonators' primary (sensitive to heat, shock and friction) explosive is a material called ASA compound. This compound is formed from Lead Azide, Lead Styphnate and Aluminium and is pressed into place above the base charge usually TNT or tetryl in military detonators and PETN in commercial detonators. Other materials such as DDNP diazo di-nitro phenol are also used as the primary charge to reduce the amount of lead emitted into the atmosphere by mining and quarrying operations. Old detonators used mercury fulminate as the primary, and it was often mixed with potassium chlorate to yield better performance. Detonators vary in size and strength. The only detonators used for military applications are #6 blasting caps and #8. There are so many different types of blasting caps with different primaries and different sizes though that it is nearly impossible to put a number to a detonator any more.
In a nuclear weapon a nuclear fission bomb is used as detonator to start nuclear fusion reactions.