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detonating cord union
A shockwave driven reaction at a velocity great than the speed of sound in the medium.
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common.
Detonator (or cap) Sensitive
A term applied to any explosive which can be reliably initiated in the unconfined state by a number 8 detonator.
A blast hole which has had water removed using an in-hole pump or other mechanical means.
Typical dewatering truck fitted with submersible pump.
Direction of Movement
The preferred direction in which the blasted rock mass moves under influence of the blast – at right angles to the ‘angle of initiation’.
A form of misfire in which some explosive is left undetonated as a result of an adjacent explosion, eg. separation of charge by ground movement or severance of the initiating line.
One of the six divisions into which explosives are subdivided as follows:
Division 1.1 Explosives - Substances and articles which have a mass explosion hazard (a mass explosion is one which affects almost the entire load virtually instantaneously).
Division 1.2 Substances and articles which have a projection hazard but not a mass explosion hazard.
Division 1.3 Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard, or both, but not a mass explosion hazard.
Division 1.4 Substances and articles which present no significant hazard.
Division 1.5 Explosives - Very insensitive substances which have a mass explosion hazard. This division comprises substances which have a mass explosion hazard but are so insensitive that there is very little probability of initiation or transition from burning to detonation under normal conditions of transport.
Division 1.6 Articles containing extremely insensitive explosives.
NOTE: For a complete evaluation of these divisions see AS 1216.
Division 5.1 Oxidisers - Substances which, while not combustible, may by readily liberating oxygen, cause or contribute to the combustion of other material, and have been classified as Class 5.1 by the appropriate regulatory authority. These substances would be expected to fail the UN test for determining whether a material is a Class 1 explosive.
Hazard Division and Compatibility Group are the key descriptors used for storage and transport classification.
The following are typical for commercial explosives
In terms of explosives and blasting:
The 'donor' is the first part of the Donor-Receptor relationship that delivers energy to the receptor.
The key factor of the donor is the amount of energy provided. This may be measured in terms of equivalent mass of TNT.
The 'receptor' is the second part of the Donor-Receptor' relationship that accepts energy from the donor and, if sensitive enough, will then detonate.
On detonation the receptor becomes the donor to the next part of the explosives chain.
The Donor-Receptor relationship may be summarised as:
For reliable propagation the output of the donor must exceed the sensitivity of the receptor.
The Donor-Receptor relationship is key to understanding propagation and failures.