A Dangerous Goods Officer (DGO) is appointed by the competent authority to administer and enforce the Dangerous Goods Legislation.

dBL or decibel linear peak is the maximum reading in decibels (dB) obtained using the "P" time – weighting characteristic as specified in AS 1259.1 – 1990 with all frequency weighted networks inoperative.

dBL is the scale used for measuring blasting overpressure.

dBA is weighted for human response (high frequencies and low frequencies beyond the range of hearing are not used) and is not used in the recording of blasting noise and overpressure. dBA is used to measure noise levels that affect hearing.

A dead blow hammer is a specialized mallet helpful in minimizing damage to the struck surface and in controlling striking force with minimal rebound from the striking surface. The head of these hammers are commonly hollow and filled with sand or lead shot, which both absorbs the impact of a strike and concentrates all of the energy of the blow in a focused point.

The operation of a pump when there is no flow due to the outlet or discharge line being closed or blocked.

Charges placed above a base charge at preselected intervals and which are completely separated from the base charge and each other.

Decomposition

The separation of a substance into simpler substances or basic elements. Decomposition can be brought about by exposure to heat, light, or chemical or biological activity.

The chemical decomposition of an explosive may take years, days, hours, or a fraction of a second. The slower processes of decomposition take place in storage and are of interest only from a stability standpoint. Of more interest are the two rapid forms of decomposition, deflagration and detonation.

A decoupled explosive is one that does not fill the blast hole. Decoupling is achieved by loading packages or tubes of explosives of a smaller diameter than the drill hole.

Decoupling is used to reduce the energy delivered by a blast hole. Both the reduced amount of explosives and the air-gap around the product are effective in reducing blast hole pressures.

Decoupled charges are commonly used when presplitting with drill holes up to 115mm in diameter.

Typical continuous packaged explosives loaded as a decoupled charge into a presplit.

Deflagration is a term describing subsonic combustion propagating through heat transfer; hot burning material heats the next layer of cold material and ignites it. Most "fire" found in daily life, from flames to explosions, is deflagration. Deflagration is different from detonation, which is supersonic and propagates through shock.

 Deflagration is a rapid high energy release combustion event that propagates through a gas or an explosive material at subsonic speeds, driven by the transfer of heat.

A detonator which contains a delay device designed to fire at a fixed interval after ignition.

A pyrotechnic substance contained within a metal jacket which causes a delay between the instant application of energy
and the time of detonation of the base charge of the detonator.