Sensitiveness is the characteristic of an explosive which defines its ability to propagate through the entire length of the column charge and controls the minimum diameter for practical use.
Sensitiveness is measured by determining the explosive’s critical diameter. The term critical diameter is commonly used in the industry to define the minimum diameter in which a particular explosive compound will detonate reliably. All explosive compounds have a critical diameter. For some explosive compounds, the critical diameter may be as little as a thousandth of an inch.
On the other hand, other compounds may have critical diameters measured in inches. The diameter of the proposed borehole on a particular job will determine the maximum diameter of explosive column. This explosive diameter must be greater than the critical diameter of the explosive to be used in that borehole. Therefore, by preselecting certain borehole sizes, one may eliminate certain explosive products from use on that particular job.
Sensitiveness is also a measure of the explosive’s ability to propagate from cartridge-to-cartridge, assuming the diameter is above critical. It can be expressed as the maximum separation distance (in inches) between a primed donor cartridge and an unprimed receptor cartridge, where detonation transfer will occur.
