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4. Characteristics of the released hazardous chemicals

For proper and effective response mechanisms it is essential to know the characteristics of the released hazardous chemicals. The characteristics of the chemicals can be determined either knowing toxicity or inflammability. The following paragraphs help in understanding the nature of chemicals (MS and IHC rules 1989).

(A) Toxic Chemicals:

Chemicals having the following values of acute toxicity and which owing to their physical and chemical properties, are capable of producing major accident hazards:

 

Toxicity

Oral toxicity
LD 50 (mg/kg)

Dermal toxicity
LD 50 (mg/kg)

Inhalation toxicity
LC 50 (mg/l)

1

Extremely toxic

<5

<40

<0.5

2

Highly toxic

>5-50

>40-200

>0.5-2.0

3

Toxic

>50-200

>200-1000

>2-10

(B) Flammable Chemicals:

(i) flammable gases:

Gases which at 20o C and at standard pressure of 101.3KPa are:

  • ignitable when in a mixture of 13 percent or less by volume with air, or;
  •  
  • have a flammable range with air of at least 12 percentage points regardless of the lower flammable limits.

The flammability shall be determined by tests or by calculation in accordance with methods adopted by International Standards Organisation ISO Number 10156 of 1990 or by Bureau of Indian Standard BIS Number 1446 of 1985.

 

(ii) extremely flammable liquids:

  • chemicals which have flash point lower than or equal to 23o C and a boiling point less than 35o C.

(iii) very highly flammable liquids:

  • chemicals which have a flash point lower than or equal to 23o C and initial boiling point higher than 35o C.

(iv) highly flammable liquids:

  • chemicals which have a flash point lower than or equal to 60o C but higher than 23o C.

(vi) flammable liquids:

chemicals which have a flash point higher than 60o C but lower than 90o C.

(C) Explosives: explosives mean a solid or liquid or pyrotechnic substance (or a mixture of substances) or an article:

  • which is in itself capable by chemical reaction of producing gas at such a temperature and pressure and at such a speed as to cause damage to the surroundings ;
  • which is designed to produce an effect by heat, light, sound, gas or smoke or a combination of these as the result of non-detonative self sustaining exothermic chemical reaction.

Pollution Control Board and Chief Inspectorate of Factories or Controller of Explosives will confirm the properties of the released chemicals based on the above properties.

 

 
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