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drilling rig worker in hazardous area CorDEXHow to Classify a Hazardous Area

Posted on: 29th, May 2015

In this blog we have taken another section from our recent white paper on the ‘Regulations Governing the Use of Non-Certified Instruments‘ to deliver you some quick pointers about classifying a hazardous area. So first, let’s look at what a hazardous environment may look like…

Hazardous environments can be predominantly found in chemical manufacturing, oil & gas platforms, refineries, underground mining, petrol station forecourts, paint manufacturing, and cosmetic manufacturing etc.

The hazardous areas that are present within these particular facilities can be classified using specific criteria and should be carried out in accordance with the following standard:

  • IEC 60079-10-2 [1]

Two main criteria to be considered when classifying a potentially hazardous vapour environment are:

  1. The area where the probability of the hazardous vapour or gas being present, referred to as “zones”.
  2. An understanding of the particular type of vapours & gases present; these are then categorised into “gas groups”.

1.1. Zones

The majority of these facilities process substantial quantities of potentially explosive liquids and gases and the concentration of vapours will vary in different areas of the facility. Some areas will have these vapours present for long periods or even at all times, others areas will only experience the presence of ignitable vapours at certain times. Due to the varying levels of vapours present on these facilities they are categorised into sections known as zones. The method of determining the type of zone depends on the amount of time a potentially explosive vapour is present. (See Table 1).

Table 1. Zone Characteristics 

zone characteristics in hazardous areas CorDEX

1.2. Gas Groups

Every explosive vapour or gas comprises of different chemical properties that will determine the probability and severity of an explosion. Each gas falls into one of three gas sub-groups IIA, IIB & IIC, the sub-group that a gas falls into is determined by how volatile/destructive they would be if ignited, where gases in sub-group IIC are more volatile/destructive than those in IIA. (See Table 2).

Table 2. Example gas & vapours and their corresponding gas group.

gas group table CorDEX

These gas groups also indicate the level of energy required to ignite the gas, where group IIA requiring greater energy whilst group IIC requires lower energy to ignite.

Want to know more about hazardous areas, how you can classify them and what regulations are set in place to ensure safety in these type of environments? All you need to do is download our white paper on the ‘Regulations Governing the Use of Non-Certified Instruments Within the Oil, Gas and Petrochemical Industries’.

Regulations governing the use of non-certified instruments

Want to read about the use of non-certified hand-held instruments within potentially hazardous (explosive) working environments? If you work in the oil, gas or petrochemical fields then this one if for you.

Download Now

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Posted In: Intrinsic Safety

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