The movement of hazardous substances by any mode of transport, presents in general, a greater risk of accidental release. It is due to the absence of the availability of appropriate information in transport accidents. The need for essential information to be clearly displayed in transport emergencies has always been accepted by both industry and emergency services. The basis of many emergency information systems adopted in various parts of the world has been a combination of hazard classification and United Nations substance identification.
U.N. classification for hazard and substance identification
The classification of chemical hazards as recommended by the UN Committee of Experts on the Transport of Dangerous Goods has been widely adopted for the transport of hazardous chemicals for all modes of transport. Hazard types are segregated into nine basic classes represented numerically. Many of these classes are further separated into divisions and subdivisions according to appropriate criteria. The international classification system is given in the table below (table-1). In India to manage accidents in the transportation of hazardous chemicals "Central Motor Vehicles Rules 1989" have been framed.
CLASS 1 EXPLOSIVES | Division 1.1 | Explosives with a mass explosion hazard |
|---|---|---|
Division 1.2 | Explosives with a projection hazard | |
Division 1.3 | Explosives with predominantly a fire hazard | |
Division 1.4 | Explosives with no significant blast hazard | |
Division 1.5 | Very insensitive explosives | |
Division 1.6 | Extremely insensitive explosive articles | |
CLASS 2 GASES | Division 2.1 | Flammable Gases |
Division 2.2 | Non Flammable Gases | |
Division 2.3 | Poison Gases | |
CLASS 3 FLAMMABLE LIQUIDS | Division 3.1 | Flashpoint below - 18°C (0°F) |
Division 3.2 | Flashpoint - 18°C and above but less than 23°C (73°F) | |
Division 3.3 | Flashpoint of 23°C and up to 61°C (141°F) | |
CLASS 4 FLAMMABLE SOLIDS, SPONTANEOUSLY COMBUSTIBLE MATERIALS, AND MATERIALS THAT ARE DANGEROUS WHEN WET | Division 4.1 | Flammable Solids |
Division 4.2 | Spontaneously combustible materials | |
Division 4.3 | Materials that are dangerous when wet | |
CLASS 5 OXIDIZERS AND ORGANIC PEROXIDES | Division 5.1 | Oxidizers |
Division 5.2 | Organic Peroxides | |
CLASS 6 POISONOUS AND ETIOLOGIC (INFECTIOUS) MATERIALS | Division 6.1 | Poisonous Materials |
Division 6.2 | Etiologic (Infectious) Materials | |
CLASS 7 RADIOACTIVE MATERIALS | ||
CLASS 8 CORROSIVES | ||
CLASS 9 MISCELLANEOUS HAZARDOUS MATERIALS |
The pictogram, hazard-warning diamonds may also bear an approved inscription quoting the hazard and /or the United Nations hazard class number. The basic principle, however, is that the shape, color, and pictogram convey a clear message of danger, thus overcoming language difficulties. With international acceptance, the value of such labeling system when displayed on vehicles and packages is clear because:
- It provides a warning to the general public to keep away.
- In an accidental situation, the emergency services are provided with an indication of the primary hazard likely to be encountered.
The class label for various types of hazardous chemicals, as per rule 137, provides information in detail according to table 2.
Table-2
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