Hazard types are defined in regulation 2 of the Manufacture and Storage of Explosives Regulations 2005 (MSER):
| Hazard type | Definition(regulation 2 MSER) | Explanation |
|---|---|---|
| Hazard Type 1 | An explosive which, as a result of, or as a result of any effect of, the conditions of its storage or process of manufacture has a mass explosion hazard | a mass explosion is one in which the entire body of explosives explodes as one |
| Hazard Type 2 | An explosive which, as a result of, or as a result of any effect of, the conditions of its storage or process of manufacture has a serious projectile hazard but does not have a mass explosion hazard | |
| Hazard Type 3 | An explosive which, as a result of, or as a result of any effect of, the conditions of its storage or process of manufacture has a fire hazard and either a minor blast hazard or a minor projection hazard, or both, but does not have a mass explosion hazard | ie those explosives which give rise to considerable radiant heat or which burn to produce a minor blast or projection hazard |
| Hazard Type 4 | an explosive which, as a result of, or as a result of any effect of, the conditions of its storage or process of manufacture has a fire or slight explosion hazard, or both, with only local effect | ie those explosives which present only a low hazard in the event of ignition or initiation, where no significant blast or projection of fragments of appreciable size or range is expected |
The ‘hazard type’ (HT) system applies to manufacture and storage and reflects the conditions found in these situations.
UN/ADR ‘hazard division’ (HD) classification is assigned to explosives as they are packaged for transport according to the UN recommendations.
In some cases the hazard type may differ from the UN/ADR ‘hazard division’ classification for transport – although generally the hazard type will correspond to the hazard division:
UN hazard division classification is assigned to explosives as they are packaged for transport. The nature of packaging (or lack of it) and the quantity and arrangement in storage can have a significant effect on the hazard presented in non-transport situations.
Therefore, the hazards presented by explosives must be assessed throughout the course of their manufacture, storage and handling to ensure that the correct hazard type is used under all conditions.
This assessment may require tests and trials to be carried out to determine how an explosive behaves in particular circumstances and the hazard type may vary as conditions change.
For example, propellants classified as UN Hazard Division 1.3 would under normal circumstances be regarded as Hazard Type 3. However, under specific circumstances these propellants can be Hazard Type 1. Such circumstances include confinement, during processing at elevated pressure and/or temperature, and the critical diameter and bed depth of the material. Examples of where these circumstances may occur are:
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