What is a Zone 1 hazardous area?

What is a Zone 1 hazardous area?

Where goods that have the potential to create explosive atmospheres are stored, processed and/or transported, the facility operator is required to have a hazardous area classification to AS/NZS 60079.10.1 (explosive gas) and/or AS/NZS 60079.10.2 (combustible dust).

Hazardous areas are classified into Zones 0, 1,2, for gases, combustible dust atmospheres are denoted by a leading “2”, e.g. Zone 21.

Classification of hazardous areas are based on the following factors:

  • Likelihood of the explosive atmosphere forming
  • The grade of release
  • Dispersion of the formed gas/vapour/dust

The lower the Zone number the higher the risk associated with the Zone i.e. the greater the likelihood of an explosive atmosphere being present. In this blog we a focusing on Zone 1 hazardous areas, so what does that mean for facility operators?

According to AS/NZS 60079.10.1 a Zone 1 hazardous area is formed due to primary source of release. Primary releases are from equipment such as pump seals, relief valves, sample points, etc. which are a source of release of a flammable gas, occasionally (not continuously) in normal operation. The size of the classified Zone 1 is related to a range of process and environmental factors such as the expected volume and pressure of release, ventilation in the area and the dispersion rate of the gas.

Classified Zones are related to equipment protection levels detailed within AS/NZS 60079.14. The lower the denoted Zone, the higher associated risk with the Zone, which in turn requires higher integrity equipment and installation techniques. In operational terms, higher risk zones equate to higher installation and operational costs. But don’t give up hope there are ways and means to reduce operational costs associated with hazardous areas

Hazardous areas can be a scary, but at QGE it’s our passion to ensure facilities operating without a bang! We’d love to help, so please get in touch.

Figure 1: Hazardous area classification drawing extract example