Hazard type (HT) is central to both the safety provisions and the licensing requirements.
Hazard type defines and describes the nature of the hazard arising from an explosive in manufacture and storage conditions.
|Hazard type||Definition(regulation 2 ER2014)||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|
Hazard type represents the potential behaviour of the explosives in the form in which they are
manufactured or stored. This means that explosives do not have inherent hazard types that can be automatically ascribed without consideration. Hazard type will be dependant on:
- the quantity of explosives
- the types of explosives
- the loading density
- packaging (if any) or containment
- the presence of barriers or other controls that will prevent rapid communication of an event between explosives;
- how an event involving the explosives might progress or degrade any controls
How explosives of different hazard type can affect their surroundings can also depend on the orientation
of any packaging, additional confinement or building that they are in.
Determination of hazard type
For those explosives being kept as packaged for carriage, and that have been classified, there will generally be a direct correlation between the UN hazard division (HD) assigned them on classification for transport and the hazard type (HT) they should be allocated for storage, ie:
- UN HD 1.1 = HT 1
- UN HD 1.2 = HT 2
- UN HD 1.3 = HT 3
- UN HD 1.4 = HT 4
Explosives that have been assigned, on classification, the UN HD 1.5 and 1.6 will need to be considered in detail and on a case-by-case basis before a hazard type can be allocated.
Detailed information on the determination of hazard type can be found in the overarching guidance – safety provisions L150 and relevant sub-sector guidance.