Analysis/detection of explosive materials Flashcards
What is high explosive?
High explosives detonate at a rate greater than the speed of sound.
What is low explosive?
Low explosives are mixtures of chemicals that burn very rapidly, but subsonically (as opposed to supersonically), meaning that they “deflagrate.”
What is the speed of propagation of an explosion is?
In the range of 1500 – 9000 m/s
If the density of the propagating medium is greater then..?
The faster the sound propagates.
The most common explosives are compounds with?
C, H, N, and O
What are the the principal products of the combustion?
CO2, H2O and N2
When are low explosives to detonate high explosive?
Low explosives are used to detonate a high explosive that is insensitive and stable.
Five types of secondary high explosives
Dynamite; RDX; TNT; PETN; tetryl, tetrile, Nitramine; TATP; ammonium nitrate-Fuel oil
Two Main Categories of High Explosive ?
Primary & Secondary
What are primary high explosives?
These are explosive that are ultrasensitive to heat, shock, or friction and provide the major ingredients found in blasting caps or primers used to detonate other explosives.
What are examples of primary high explosive?
Lead azide; lead styphnate; DDNP; mercury fulminate; silver fulminate
What are secondary high explosives?
Secondary high explosives are those chemicals that do not have to be contained to explode and are relatively stable and safe to handle. They require an electrical spark, fuse, intense heat, or sharp blow to initiate their explosion.
What is brisance?
This is the shattering capability of a high explosive, determined mainly by its detonation pressure.
The relative power of one
explosive to the other is measured by?
Power Index (PI)
Power Index formula?
PI = (Q vexp/Q vpicric acid ) x 100
What is an explosion?
An explosion is a chemical reaction, in which the explosive breaks apart into its constituent atoms which rapidly rearrange into a series of small stable molecules.
What can Springall Roberts rules tell?
Springall Roberts rules give an approximate estimate for the products of decomposition.
What are Springall Roberts Rules?
- C is converted to CO
- Any O remaining is incorporated in H2O.
- If any O remains after rule 2, the it is converted to CO2.
- N is converted to N2.
- One-third of the CO is oxidized to CO2.
- One-sixth of the original amount of CO is converted to C and water.
What are Kristiakowsky – Wilson Rules when the OB is greater than 40%?
- C-atoms are converted to carbon monoxide (CO)
- If O2 remains, hydrogen oxidised to water (H2O)
- If any O2 remains CO oxidised to carbon dioxide (CO2)
- N-atoms converted to nitrogen gas (N2)
What are Kristiakowsky – Wilson Rules when the OB is greater than -40%?
- H-atoms are converted to water (H2O)
- If any O remains, C is converted to CO
- If any O remains, CO is converted to CO2
- All N is converted to N2
How can Peroxide Based Explosives synthesised?
These can be synthesised from readily available materials
and are very sensitive (easy to explode).
Two common types of peroxide based explosive?
The two common ones are : triacetonetriperoxide (TATP
C9H18O6) and hexamethylenetriperoxide diamine (HMTD C6H12N2O6)
The heat of combustion is the energy released during….?
The heat of combustion is the energy released during complete oxidation to CO2 and H2O.
In the cases when oxygen balance is insufficient for complete combustion then?
The oxygen balance is insufficient for complete combustion, and the energy released is heat of explosion (Q).
What are the five types of low explosives ?
Gunpowder; methane or ethane gas; air mixtures; sugar-potassium chlorate mixtures
Oxygen Balance of Mixed Explosives
Ω = (Ω1 x Y1) + ( Ω2 x Y2)/100
Slide 33
The maximum heat is realised for an oxygen balance of zero, and mixtures should be designed to have a balance of zero whenever possible.
