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INTRODUCTION TO EXPLOSIVES

INTRODUCTION TO EXPLOSIVES. Types of Energetic Materials. Pyrotechnics Propellants Unconfined, referred to as Propellants Confined, referred to as Low Explosives Explosives Primary Secondary Cap Sensitive Blasting Agent. WHAT IS AN EXPLOSIVE?. Types of Explosions. 1. Mechanical

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INTRODUCTION TO EXPLOSIVES

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  1. INTRODUCTION TO EXPLOSIVES

  2. Types of Energetic Materials • Pyrotechnics • Propellants • Unconfined, referred to as Propellants • Confined, referred to as Low Explosives • Explosives • Primary • Secondary • Cap Sensitive • Blasting Agent

  3. WHAT IS AN EXPLOSIVE?

  4. Types of Explosions • 1. Mechanical • 2. Chemical • 3. Nuclear

  5. Types of Explosions • HIGH ORDER vs. LOW ORDER • Applies to High Explosives • Functions as designed vs. fails to fully detonate • CAUSES OF LOW ORDER DETONATIONS • Deterioration of Explosives • Lack of Continuity in Explosives • Inadequate Initiation

  6. Explosive Propagation • Deflagration • Thermal Radiation perpetuates the reaction • Subsonic Reaction • Detonation • Chemical Decomposition characterized by the presence of a shock wave • Supersonic Speed of Reaction

  7. Explosive Effects • HEAT / FIRE • Fireball generated by reaction • Heat accompanying fireball • FRAGMENTATION • Fragmentation of container for explosives and other nearby objects • PRESSURE • Gas generated by conversion of solid energetic material to gaseous state

  8. Explosive PropertiesPressure • Positive Pressure • Short Duration • High Pressure Peaks • Out from Seat of Blast • Negative Pressure • Long Duration • Low Pressure Difference • In Towards Seat of Blast

  9. Positive And Negative Pressure

  10. Explosives Characteristics • Density • Weight per unit volume • Brisance • Shattering Power • Velocity of Detonation • Speed of reaction • Sensitivity • Ease of initiation from Impact, Friction or Blasting Cap

  11. Velocities of Detonation * Velocity depends upon confinement, density, booster and charge diameter

  12. Explosives Initiation A THREE STAGE EXPLOSIVE TRAIN Typically uses small amounts of highly sensitive explosives to initiate larger amounts of less sensitive explosives.

  13. Initiation Systems

  14. Initiation SystemsNon-Electrical: Burning • Safety Fuse or Time Fuse • Construction • Black Powder Core • Layers of Interwoven Cotton and/or Jute fibers • Tar • Wax or Plastic

  15. Initiation SystemsNon-Electrical: Burning • Safety Fuse • Appearance • Typically is monochromatic • May have plastic coat or wax coat over textiles

  16. Initiation SystemsNon-Electrical: Burning • Fuse Detonators • Shell • Aluminum Alloy • Primary Charge: • Lead Styphnate/Lead Azide Mixture (typical) • Base Charge: • PETN or RDX

  17. Initiation SystemsElectric Detonators • TYPES OF INITIATORS • Match • Bridgewire • Exploding Bridgewire • TYPES OF DELAY • Pyrotechnic • Electronic

  18. Initiation SystemsElectric Detonators • INSTANTANEOUS • SEISMIC • High precision instantaneous detonator • SHORT PERIOD DELAY • Typically delay periods of 25-100 ms per interval • LONG PERIOD DELAY • Typically delay periods of 250 - 1000 ms per interval

  19. DetonatorsElectric Match • Utilize a thin wire dipped into pyrotechnic mixture and coated with lacquer • Predominant type of electric detonator currently in production

  20. Detonators Bridgewire • Use thin wire in loose pack of pyrotechnic material • Higher precision than match, but more difficult to manufacture

  21. Detonator ConstructionShell • ALUMIMUM • Most Common • BRONZE • Used for Permissible Applications • COPPER • Used for Permissible Applications • PAPER

  22. Detonator ConstructionLeg Wires • Insulation • Protect leg wires against short circuits • Conductors • Copper • Tinned Copper • Iron • Tinned Iron

  23. Detonator ConstructionPlug and Shell Markings • PLUGS • Plastic or Rubber • Premolded or injected • MARKINGS • Warning Statements • Delay Markings • Stamped on base

  24. Detonator ConstructionOther Components • DELAY TUBES • Steel or Lead • Contain Pyrotechnic Delay Compound • Primary Explosives • Lead Azide • Lead Styphnate • Diazodinitrophenol (DDNP or Diazo) • Secondary Explosives • PETN • RDX

  25. Detonator ConstructionIdentification Points Crimp Style Leg Wire Colors Closure Plug Material & Construction Explosive Materials Used Shell Material Physical Dimensions

  26. Initiation SystemsNon-Electric Shock Tube Detonators

  27. Initiation SystemsNon-Electric Shock Tube Detonators • Shock Tube • External Layers • Polyethylene • Internal Layer • Surylyn (tm) • Explosive Composition • HMX • Aluminium • 1 lb/6,500 ft.

  28. Initiation SystemsNon-Electric Shock Tube Detonators • NONEL CAP CONSTRUCTION

  29. Propellants

  30. PropellantsBlack Powder • History • Oldest Explosive Known • Used as both propellant and explosive • Composition • Potassium Nitrate, Sulfur, Charcoal • Appearance • Granular Black Powder • Four Grain Sizes • Fg, FFg, FFFg, FFFFg

  31. PropellantsPyrodex • History • Subsitute for Black Powder • Equal on Volume Basis • Less Corrosive • Formulation • Perchlorate Based formulation • Use • Small arms • Equivalent sizes to Black Powder and in Pellet form

  32. PropellantsSmokeless Powders • History • Single Base developed in 1884 • Double Base (Ballistite) developed in 1886. • Double Base (Cordite) developed in 1888. • Developed to replace Black Powder • Used as propellant for ammunition from small arms to cannon

  33. PropellantsSmokeless Powder • Types • Single Base - Nitrocellulose (NC) base • Small Arms Ammunition • Double Base - Nitroglycerine (NG) and Nitrocellulose (NC) base • Small Arms and larger ordnance ammunition • Triple Base - Nitroglycerine, Nitrocellulose and Nitroguanadine base • Military rockets

  34. PropellantsSmokeless Powder • Physical Appearance • Extruded Propellants • Usually in the form of a cylinder, length greater than diameter • Flake or Disc Propellants • Extruded Propellants cut into thin wafers. Width greater than length • Ball Propellants • Spherical shape, sometimes flattened • Sheet-Cut Flake or Ribbon Cut Propellants • Material rolled flat and cut into diamond or square shape

  35. Propellants/Pyrotechnics Improvised Low Explosives • Potassium Chlorate Mixtures • KCl03 And Sugar • Burns inefficiently and less powerful than Black Powder • Flash Powders • Potassium Perchlorate Mixtures • Flash Powders • Typically used in fireworks compositions

  36. Explosives

  37. Organics Carbon/Hydrogen Bonds form basis of molecule Inorganics Do NOT have hydrocarbons forming structure of molecule. Usually ionic acids or bases, or salts Usually primary explosives Pure Explosive Compounds

  38. Aromatic Monosubstituted Trinitrobenzenes (TNBs) TNT TNB Tetryl Picric Acid Polysubstituted TNBs Trinitroresorcinol Lead Styphnate TATB Aliphatic Nitrate Esters Nitroglycerine Ethylene Glycol Dinitrate (EGDN) Pentaerythritol Tetranitrate (PETN) Methyl Nitrate Nitramines Cyclonite or RDX Octogen (HMX) Pure Explosives CompoundsOrganics

  39. Fulminates Mercury Fulminate Silver Fulminate Azides Lead Azide Silver Azide Ammonium Nitrate Pure Explosive CompoundsInorganics

  40. Explosives • Commercial Explosives • Manufactured products used in explosives industry • Military Explosives • Demolition charges and common ordnance in use by military forces of U.S. • Improvised Explosives • Compounds which can be manufactured by individual or group

  41. Commercial High Explosives • Over 5 billion pounds used per year in U.S. • Most of it is Ammonium Nitrate based bulk explosive • Used in less than 5% of all bombing incidents • Commercial high explosives are designed for safety in manufacturing, storage, and handling, consistency and predictability of performance, low cost, and shelf life as a secondary concern

  42. Commercial High Explosives • Dynamite • First commercially sucessful high explosive product • Invented by Alfred Nobel in 1866 • Most widely used explosive from 1860’s to 1940’s • Wide range of powers available across various types

  43. Commercial High Explosives • Dynamite • Straight Dynamite - Nitroglycerine added to Kiselguhr (inert earth) • Gelatin Dynamite - Nitrocellulose added to Nitroglycerine (also known as Blasting Gelatin) • Ammonia Dynamite - Ammonium Nitrate replaces Kiselguhr and adds energy, reduces cost, less water resistant

  44. Commercial High Explosives • Dynamite • Ammonia Gelatin - Adds nitrocellulose to Ammonia dynamite to form gelled product, more expensive, more water resistant. • Semi-Gelatin Dynamite - Less than ideal amount of Nitrocellulose added product. Less expensive than gelatin dynamite, almost as good water resistance. • Permissible Dynamite - Approved for underground blasting with reduced flame and fumes. Specialized products typically used in coal mines.

  45. Commercial High Explosives • Dynamite • Packaging • Convolute Paper Shell • Spiral Wound Paper Shell

  46. Commercial High Explosives BINARY • Composition: • Ammonium Nitrate & Nitromethane • Packaging • Plastic Tubes (see right) • Plastic Bags • Performance • VoD: approx. 18,000 fps • Uses: • Limited Construction, Farm Use

  47. Commercial High Explosives WATER GEL/SLURRIES • Developed as Non-Nitroglycerine alternative to dynamite • Used in bulk (non-cap sensitive) formulations starting in 1958 • Used in packaged (cap sensitive) formulations starting in 1970 • Consists of Oxidizer, Fuel, Water, Thickener, Gelling Agent and Sensitizer • Less sensitive, more economical, and more efficient than dynamites

  48. Commercial High Explosives WATER GEL/SLURRIES • Packaged in Plastic Film Cartridges (chubs) • Can be insensitive at low temperatures

  49. Commercial High Explosives EMULSIONS • Introduced as Blasting Agents in 1968 • Extremely fine Ammonium Nitrate particles suspended in fuel and water and stabilized against separating with emulsifying agent • More efficient, powerful, and stable than water gels • Equivalent to dynamites in many formulations • Less sensitive than dynamites to heat, shock, friction and more economical to manufacture

  50. Commercial High Explosives EMULSIONS • Packaged in either paper shells (as dynamites) or plastic film cartridges • Creamy appearance of material • May be colored white, gray or pink depending on manufacturer

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