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Hazardous Areas Explained: Part 1 – Defining Hazardous Areas

Hazardous Areas can sometimes appear to be an area of ambiguity and mystery for some. 

Author: Brad Guy 

This article is aimed at removing the mystery and explaining the basics of hazardous areas by giving some examples of where hazardous areas may be found along with the basic individual requirements. 

Hazardous Areas are centred around electrical installations that may be surrounded by a flammable or combustible atmospheres where precautions need to be taken to prevent that electrical equipment becoming an ignition source and causing an explosion. 

RELEVANT STANDARDS 

Requirements for hazardous areas are found in the AS/NZS 60079 suite of standards. 

The main standards used for classification, design, installation and inspection are: 

  • AS/NZS 60079.10.1:2009 Explosive Atmospheres Classification of Areas – Explosive Gas Atmospheres 
  • AS/NZS 60079.14:2017 Explosive Atmospheres Design Selection, Erection and Initial Inspection 
  • AS/NZS 60079.17:2017 Explosive Atmospheres Electrical Installations Inspection and Maintenance 

WHAT IS A HAZARDOUS AREA? 

According to AS/NZS 60079.14:2017, a Hazardous Area is defined as an: 

Area in which an explosive atmosphere is present, or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment. 

An explosive atmosphere can be considered as a space that may at some stage through any means, contain a flammable mixture of gas and air or a combustible mixture of dust and air. 

This does not consider what is called “catastrophic failure” in the standards, in this contextan example would be the rupture of a process vessel or pipeline and events that are not predictable. It would also apply to failures that cause a release of flammable or combustible material due to lack of, or incorrect maintenance. 

EXAMPLES OF HAZARDOUS AREAS 

Such hazardous areas can be found in many places throughout industry in both large and small quantities, some examples are shown below. 

Food manufacturing, where, in this case it is the powdered milk that is combustible and when mixed with air if disturbed will ignite if an ignition source is available. 

Coal handling prep plants are also considered as hazardous areas due to the concentrations of combustible coal dust clouds that can develop from spillage. 

Gas wells, gas processing plants and gas fired generators are common areas that contain hazardous areas due to the natural gas that is released in different sections of the plant in concentrations that can be considered as a flammable mixture. 

 

Coal mines use MIBC which is flammable in certain concentrations requiring the surrounding area to be classified as a hazardous area. 

Coal fired power stations have hazardous areas where the coal dust can build up and form a combustible dust cloud. 

The process of making paper utilises dust ingredients that can form a combustible mixture. 

Ship fuel loading and unloading facilities have hazardous areas where fumes from the fuel can gather in flammable mixtures. 

LPG bullets and fittings may have hazardous areas around possible sources of release. 

On and offshore drilling rigs have many hazardous areas throughout the process area and extending further where the possibility of a flammable atmosphere may exist. 

 

Food processing where organic dusts such as flour and other organic dusts are utilised in the food making process to produce pastries, breads, cakes and biscuits etc.  

In some cases, copper mining utilises chemicals that can be extremely flammable. 

Hydrogen is another extremely volatile gas that can be used in power generation. 

Fuel farms are an obvious source of flammable liquids and vapours. 

Pet food manufactures can use flammable gasses throughout the process. 

3D printing is a relatively new industry that during the process may create a combustible dust atmosphere. 

Gas compressors will create a hazardous area where the gas can congregate in flammable mixtures. 

 

Mining and processing copper, lead, silver and gold uses processes that have flammable gases and vapours including tanker loading and unloading. 

Fume cupboards in laboratories will be considered as a hazardous area when flammable gasses and vapours are involved. 

Biogas is a by-product of sewage and landfill that is treated as a hazardous area. 

Methanol is a flammable liquid that gives off a flammable vapour and is used in some the processes at sewage treatment plants. 

 

All the examples shown above are only a small cross section of industry that may have areas that can create a flammable atmosphere and where electrical equipment may need to be installed such as lighting, motors for pumps, solenoid coils, limit switches, instrumentation etc. 

 In our next article, we’ll look at the requirements for managing Hazardous Areas. 



 

 

 

 


 

 

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