explosives
DESCRIPTION
Explosives. CHS Science Dept. Forensics. Definitions. Explosion - A chemical or mechanical action resulting in the rapid expansion of gasses. Deflagration - A very rapid oxidation reaction accompanied by a low intensity pressure wave with a disruptive effect. Definitions cont. - PowerPoint PPT PresentationTRANSCRIPT
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ExplosivesCHS Science Dept.
Forensics
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Definitions• Explosion- A chemical or
mechanical action resulting in the rapid expansion of gasses.
• Deflagration- A very rapid oxidation reaction accompanied by a low intensity pressure wave with a disruptive effect.
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Definitions cont• Detonation- an extremely
rapid oxidation reaction accompanied by a violent disruptive effect and an intense, supersonic shock wave.
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Types of explosives• High Explosive- Explosives
with a velocity of detonation greater than 1000m/s (meters per second).
• Low Explosive- Explosives with a velocity less than 1000m/s.
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Low Explosives• Most widely used low-
explosives group are black powder and smokeless powder.
• Gunpowder burns, it is only explosive when confined.
Sulfur, Potassium nitrate, Charcoal Nitrocellulose
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Low explosives• Natural gas mixed with air.• Can cause large
explosions
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High Explosives
• Primary Explosives- are ultra-sensitive to heat, shock, or friction and will normally detonate rather than burn.
• Due to this characteristic they are used to detonate other explosives and are often called
Primers
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High Explosives• Dynamite was discovered by
Alfred Nobel when he mixed diatomaceous earth with nitroglycerine making it less sensitive
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High Explosives• Commercial explosives
–ANFO Ammonium Nitrate Fuel Oil
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Jig saw activity• Military high explosives page 456
• TATP page 454• Nitrate Ammonium Explosives page 453
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Explosives Unit• The Explosives Unit (EU)
conducts examinations of evidence associated with bombing matters.
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• The unit conducts forensic examinations of:
• Improvised Explosive Devices (IEDs), Incendiary Devices, and their respective remains
• While providing expert witness testimony in court regarding the results of these examinations.
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• The EU also provides direct field support in: –Bombing matters –Bombing crime scene investigations
–Searches of bomb factories and safe houses in which bombs or bomb components may be encountered.
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• The EU also performs chemical analyses to determine the type of explosive used in an improvised explosive or incendiary device.
• This includes analyzing bulk substances and the residues left behind after an explosive detonates.
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False alarms• Some of the calls to the
bomb squad are false alarms or pranks
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Equipment• Bomb containment• Bomb Suit• Search Mirror• Disruptor- shoots high
pressure H2O to disarm bombs
• Detectors• Endoscopes
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Robots
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Refrences• http://www.fbi.gov/hq/lab/lab2006/
labannual2006.htm#22
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References• Saferstein, Richard. Criminalistics an introduction to forensic science. Upper Saddle
River, N.J: Prentice Hall, 2004. Print. •
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Pictures• Slide 2
– http:// www.hsvpolice.com/News%20Releases/bomb_squad_vehicle.jpg• Slide 3
– http://www.insidesocal.com/sgvcrime/MOLOTOV.jpg– http://www.globalsecurity.org/military/intro/images/ied-cutout01.jpg
• Slide 6– http://www.thebostonchannel.com/2007/0131/10891659_400X300.jpg
• Slide 8– http://miamiherald.typepad.com/crime_scene/2009/02/page/2/– http://www.made-in-china.com/image/2f0j00vMATmJaBSUgwM/EOD-
Bomb-Disposal-Suit-BD2010-.jpg– http://www.fieldforensics.com/blast-containment.htm– http://www.made-in-china.com/image/2f0j00MByaIJWhbRurM/Disruptor-
AL-LNDK-.jpg– http://www.bulletproofbodyarmorhq.com/catalog/images/eod20.jpg
• Slide 9– http://www.armedforces-int.com/images/companies/958/bomb-disposal-
robots-3b.jpg
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Pictures• Slide 2
– http://www.hnd.usace.army.mil/pao/CEAInfo/Explosion%20Photo.JPG
• Slide 5– http://upload.wikimedia.org/wikipedia/commons/d/df/
Pyrodex_powder_ffg.jpg– http://www.aiexplosives.com/Files/Image/Smokeless
%20powder.jpg• Slide 6
– http://www.treehugger.com/landfill-gas-flare.jpg– http://media.sacbee.com/smedia/2008/12/24/17/835-
explos10.standalone.prod_affiliate.4.jpg• Slide 7
– http://upload.wikimedia.org/wikipedia/commons/4/40/Nitroglycerin-2D-skeletal.png
• Slide 8– http://blogs.sfweekly.com/thesnitch/
Nobel_medal_dsc06171.jpg– http://www.urbanrivers.org/drawingdiatoms/diatom.jpg