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.

The lapse of time between the application of a firing signal and the detonation of the base charge of a delay detonator.

Combination of delay elements within a detonator.

Where hole B requires hole A to have fired to provide the necessary relief then hole B is dependent on Hole A.

A flexible cord with a solid core of high explosives, commonly PETN.

A joiner to connect detonating cord.

Contains about 2 grams of HMX explosive

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.

 The commercial use of explosives uses non-electric or electric detonators. Many detonators' primary explosive is a material called Lead Azide pressed into place above the base charge, usually PETN.

 Delay detonators have a pyrotechnic delay train above the primary charge. This provides a time delay between the firing of the downline and the detonation of the base charge.

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.

Direct supervision is a term that is used to refer to situations in which a supervisor is present at all times. The supervisor oversees activities as they occur and provides constant direction, feedback, and assistance. For some types of workplaces, direct supervision is required for safety and health reasons.

A test for direct supervision is that the supervisor is constantly aware of what the supervised person is doing and is able to immediately communicate direction (such as Stop That Now!!)

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.

Doped Emulsion is a bulk explosive consisting of a blend of Emulsion with up to 50% AN prill added.

The addition of prill increases the heave componenet of the blend.

A blast hole containing two priming units, usually placed one near the top and one near the bottom of the blast hole.

Where, on a vertical drill pattern, a half spaced angled row is drilled to provide energy into the toe area of the front row.

A length of detonating cord or signal tube by which a Primer is lowered into a blast hole and which is the means of conducting the initiating signal down the blast hole.

A hole prepared for the insertion of an explosive charge.

A plan showing the layout of holes to be drilled for blasting.

A blast hole which contains no detectable water.

The operation of a pump when there is no flow due to its inlet being closed, blocked or empty, or any other physical condition where the material being pumped is prevented from flowing into the pump.

Airborne particulate matter ranging in diameter from 10 to 50 microns.

Water that is in motion (i.e. flowing water).

A blast hole may be considered to contain dynamic water where the recharge rate is more than 1 m per hour.
Holes containing dynamic water cannot be dewatered and should be loaded with a pumped, water resistant product.