Parts of Blasting Systems

Blasting Caps are small, sensitive explosive devices that are generally used to transmit the detonation signal into a blasthole and detonate cap sensitive explosives. Blasting Caps can initiate instantaneously or can contain delay element so that the cap fires at a predetermined delay time in milliseconds.

No. 8 Blasting Cap is an industry standard blasting cap used as a detonator (Figure 1-5). It contains two grams of a mixture of 80% mercury fulminate (a secondary explosive) and 20% potassium chlorate (a primary explosive), or a blasting cap of equivalent strength. An equivalent strength cap comprises 0.014-.016 oz of pentaerythritol tetranitrate (PETN) base charge pressed in an aluminum shell with bottom thickness not to exceed 0.03 in., to a specific gravity of not less than 0.81 oz/in3, and primed with standard weights of primer depending on the manufacturer. It is the most common type of blasting cap in use as of 2016.

A Booster is a sensitive, high energy, charge that can be used to set off a less sensitive explosive. Blasting agents such as ANFO require a booster to achieve detonation. A booster can be a more energetic charge placed in a specific location in a blasthole to have more energy in a harder rock layer.

A Delay is the time interval between successive detonations. These are used by the blaster to provide a progressive relief for rock to displace into as the shot evolves.

Detonating Cord is a round, high detonation velocity, flexible cord containing a center core of high explosive, usually PETN, within a reinforced waterproofing covering.

A Detonator is a device, either electric or non-electric, that is inserted into an explosive and used to cause the detonation.

The Initiation System is the entire system used to initiate the blast. This includes the detonator (electric or non-electric), delay devices, and all their connecting parts.