Explosives - Sensitivity, Testing and Performance Flashcards
1
Q
How is the friction sensitivity of an explosive tested using the torpedo method?
A
- A “torpedo” is launched at the expolosive at an angle of 60 degrees.
- This impacts the explosive placed on the anvil leading to a mixture of friction and impact.
- The drop height is changed until 10 consecutive drops do not lead to detonation.
2
Q
What is the Rotary Friction Test?
A
- Negates any impact effects
- Explosive sample is initiated by a rough discus spun against it.
- Value for the Figure of Friction can be calculated through comparison with a standard value of RDX.
- The lower the value of the Figure of Friction, the more sensitive the explosive is.
3
Q
How is the impact sensitivity of an explosive standardised?
A
The impact sensitivity is standardised through the figure of insensitiveness.
Fi is the figure of insensitiveness = Drop height of explosive / Drop height of RDX standard
This value changes with the formulation of the explosive.
4
Q
How is static sensitivity of an explosive measured?
A
- 4J of energy is induced into the explosive.
- If an event occurs, reduce the amount of energy until no event occurs.
- If no event in 10 repetitions, then the explosive is not static sensitive.
- The human static on finger is about 0.02 J, and therefore if it is not sensitive to 2x this amount then the explosive is safe.
5
Q
How is heat sensitivity of an explosive measured?
A
- Heat the explosive gradually until an ‘explosive event’ occurs.
- Record the temperature for ignition to occur.
- Repeat 10 times.
T of I < 150 oC means the explosive has a short shelf life and is generally not used.
6
Q
How is the explosive performance of an explosive determined?
A
- The explosive performance of an explosive is determined using a ballistic mortar.
- The explosive detonates and the swing of the ballistic mortar is measured.
- This is then compared with a standard explosive.
