When it comes to the transport of explosive substances, articles, and pyrotechnics – in short, the transport of materials of dangerous goods class 1 – the parties involved facing a huge amount of regulations, guidelines, and laws (Explosives Act, ADR, IMDG, weapons law, Hazardous Goods Transport Act, etc.).
An important indicator for materials of dangerous goods class 1 is the net explosive mass (NEM) also known as net explosive quantity (NEQ). This figure provides information about the proportion of the pure explosive substances that the article, objects, or substance contain.
Based on the net explosive quantity, various storage and transport requirements are defined such as the corresponding UN dangerous goods packaging, the equipment of the vehicle, the training requirements for the driver, or the relevant dangerous goods documentation. However, the net explosive mass can also have an impact on the transport route itself if, for example, transport is only allowed in a cargo aircraft or the port authorities of certain ports prohibit the handling or transit of defined NEQ quantities.
It is simply explained using the example of ammunition
The completely packed ammunition (left picture) including the outer packaging, inner packaging, and of course the ammunition itself, is indicated with the gross weight. The pure product (middle picture), namely the ammunition as it is fired (case, projectile, propellant charge, percussion cap), is indicated with the net weight. The propellant powder with which the projectile is driven out of the case (right picture) is given as the net explosive mass.
It is interesting that the net weight of certain goods can also be the same as the net explosive mass. This is the case when, for example, the pure propellant powder is shipped for the manufacture of ammunition.