In the industrial plant where flammable liquids, gases and vapours, combustible dust or fibres and flyings are handled, processed, or otherwise generated, there can be a risk of fire or explosion. In order to have a fire or an explosion, fire triangle or explosion pentagon must be met. There must be fuel present, the fuel must be mixed with an oxidant (typically the oxygen in the air) in the appropriate ratio, and an ignition source of enough intensity must be present.

Hazardous area classification (HAC) identifies the areas in a plant where an explosive or flammable atmosphere may be present under foreseeable circumstances.

The procedure is used to identify the extent and duration that flammable atmospheres can be present in normal and conceivable abnormal conditions. The aim is to identify whether flammable atmospheres can form in a process equipment and process operation when the plant is in use and to identify whether the flammable atmosphere can be present:

1. a) Continously
2. b) During normal operation of the process, or
3. c) Only during abnormal or mal-operation conditions and then only for a short time.

This assessment must cover the release of flammable materials, the nature of the material, ventilation, and frequency of release and the potential duration of such an event.

Originally HAC was used to enable process companies to make the correct choice of electrical equipment to prevent electrical ignition of flammable atmospheres. Now HAC is being applied in wider risk assessment work and to counter a range of ignition sources, such as electrostatic sparks, and flammable substances, such as solvent vapours, gases or mists and dust clouds. For this reason, HAC is needed not only in chemical plants but in a variety of other industries including food, power, wood, etc.

At Sigma-HSE (India), our hazardous area classification consulting services are designed as per the customer needs to follow IEC, IS/IEC, NFPA and other standards. Our team members are knowledgeable about classification, electrical equipment and wiring, applicable standards and codes, chemicals used, plant safety, ventilation assessment, and more. When you work with us, we ensure safe and consistent classification via the application of sound engineering judgment and the careful evaluation of all data in accordance with established techniques.

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