HANDLING INCOMPATIBILITY IN CHEMICAL LABORATORIES

 

HANDLING INCOMPATIBILITY IN CHEMICAL LABORATORIES

The innumerable chemicals which are used as reagents and solvent in chemical laboratories fall under different hazard categories based on their nature, the most common hazards classes are

§ Flammable/combustible

§  Corrosives (acids and bases)

§  Toxics/poisonous

§  Oxidizers

§  Compressed gases

§  Cryogens

§  Pyrophoric

§  Water-reactive

§  Explosive

These significant safety risk in terms of fire and health issues if not properly handled in chemical laboratories or process areas where local quality checking laboratories are operated.

HAZARDS DUE TO CHEMICALS CAN STEM FROM TWO FACTORS

·       Inherent hazards in nature and handling

·       Hazards due to the inadequacy of proper facilities for handling chemicals

The hazards during handling remains an important risk factor due to the presence of their inherent hazard individually and also due to the hazards that get multiplied due incompatibility of a certain set of chemicals resulting in exothermic reactions. Having a clear understanding of incompatibility reduces the risk proportion significantly.

 HANDLING OF INCOMPATIBLE MATERIAL

The single most important rule of chemical storage is to segregate incompatible chemicals to prevent accidental mixing which could cause the incompatible chemicals to react with each other exothermically (release of heat energy) which can act as an ignition source to other sensitive chemicals that can result in violent and explosive reaction or/and can result in the generation of toxic gaseous substances.

 

INCOMPATIBILITY HAZARDS CAN EXIST AT TWO POINTS

A.  During handling and storing

B.  At the point of disposal of used chemical bottles/cans/chemical contaminants.

 

A) DURING HANDLING AND STORING: While handling and storing chemicals it is important to know the incompatibles – those that react exothermally with one another. For example

 

 

1.  Acids with bases: Free acids like HCl, H₂SO₄, CH₃COOH or chemicals like potassium bisulphate should not be stored with bases like ammonia, lime, soda, metal oxides, etc.

 

2.  Oxidizers and solvents: Oxidizers when mixed with flammable solvents can cause fire, acids mixed with metal dust can produce flammable hydrogen gas

 

3.  Ammonium salts with basic oxides: These will react which can result in fire or explosion, hence should not be stored together.

 

4.  Bleaching powder vs turpentine: Bleaching powder liberates chlorine, which reacts exothermally with ammonia, ammonium carbonate or unsaturated organic substances like turpentine or linseed oil. This may be a source of the fire. Hence adequate care should be taken while storing such chemicals.

 

B) AT THE POINT OF DISPOSAL: Disposal of chemicals should be based on the thorough understanding of chemical hazards and their incompatibility, Planning of safe disposal should follow a rigorous process and procedure shall be approved by the competent authority and adhered to the system to reduce any untoward incidents. Some of the general guidelines to be followed at Disposal are

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Article by PJ Mohan

Sr.Faculty, NIFS