Fire divisions

To facilitate fire fighting, explosives and ammunition are divided into four Fire Divisions according to their behavior when involved in a fire and the action to be taken in dealing with such fires. The Fire Divisions are synonymous with the UN Hazard Divisions 1.1 to 1.4 and the hazard decreases with the ascending Fire Division, as described below  

4) Fire Division 4 These explosives present no significant explosion hazard but have a moderate fire hazard. The effects of fire are usually confined within the package. An external fire would not cause mass explosion of a package of such items. There could be toxic substances in them which may evolve toxic fumes on burning. These explosives belong to UN Compatibility Group K. 

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Figure 6.3 Fire division symbols for use on explosive buildings and stacks. Reprinted from DRDO s Storage and Transport of Explosives Committee (STEC) Pamphlet No.6, 1995 (As Amended).

Each of the four fire divisions is indicated by a distinctive symbol (Figure 6.3) in order to be recognized by fire-fighhng personnel approaching a scene of fire. The color of all four symbols is orange in accordance witb tbe color code of UN for Class 1 (Explosives and Ammunition) and the numbers are painted in black so that these symbols can be idenhfied from a long range, the symbols differ in shape as follows. 

After loading the explosives, the appropriate Fire Division symbol should be displayed on the vehicle by the side of the red flag, for guidance to the firefighting personnel. If the vehicle is loaded with explosives of more than one Fire Division, the Fire Symbol to be displayed on the vehicle should be of the more hazardous Fire Division. 

A single particle of the fire dust is a mixture of liquid and solid substances and has cohesion. When a strong wind blows against the particle, it is divided into many smaller particles by the occurrence of a spray-like phenomenon. This is called fire division". 

Fine fire division produces quite beautiful fire dust, but its life is shortened. On the contrary, rough fire division decreases the beauty, but lengthen the life. In view of this, it is necessary to plan the composition or the manufacturing process of the composition to obtain proper fire division according to the intention. 

The fire division occurs most easily when the cohesion of the particle is weakest. With the fire dust of black pov/der-type compositions the point may be a content of about 7% sulphur. If the sulphur content is larger than that, the potassium sulfide, KiSx. content,in a particle increases to produce strong cohesion, which makes the fire division more difficult. If the content is less than that, unburned charcoal aggregates and in this case the fire division is also difficult. 

Moreover the fire division depends upon the wind velocity, i.e. for a flying star it depends on the velocity of the star. The most representative example is the "Chrysanthemum of Mystery (see 15 2). When we ignite this star on the ground no fire division occurs, but when we fire it through the air we see a lonely kind of fire dust which is caused by the movement of the star. Another good example is the star "silver wave"(see also 15.2). 

This star burns on the ground producing only a small number of poor sparks and remains as a melted cinder. However when it is shot, a good fire division occurs with a beautiful effect. 

It will be seen that the fire division can be tested only when the burning star is moving through the air. 

Storage should preferably be in separate fire divisions from highly combustible commodities or well segregated from not so highly combustible commodities such as sulfur, flour, sugar, compressed cotton, and charcoal. 

Division 1.4 Eire or projection hazard Division 1.5 May explode in fire Division 1.6 No hazard statement used... 

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