Zone Classification Studies

Short answer: Zone classification is the mapping of areas based on the frequency and duration of explosive atmosphere occurrence. Zones are defined as Zone 0/1/2 for gas and Zone 20/21/22 for dust, and this is the first step in determining what equipment can be placed in these areas.

The foundation of explosive atmosphere safety is accurate zone classification. Before deciding which equipment should be placed where, it is necessary to know how frequently an explosive atmosphere may be present at each location.

Incorrect classification is dangerous in two ways: considering an area harmless leads to a deadly explosion, while considering it unnecessarily dangerous results in unnecessary costs. An accurate map ensures both safety and economic efficiency.

What is involved in regional classification?

Identification of sources of leakage (continuous/primary/secondary)
Evaluation of ventilation level and availability.
Consideration of gas/powder properties (density, LEL)
Determination of the size and type of hazardous area for each leak.
Preparation of regional map and documentation.

Zone and Equipment Protection Level (EPL) Matching

Zone classification directly determines which equipment can be placed where. In gaseous environments, Zone 0 requires equipment with the highest level of protection (Ga), Zone 1 requires at least Gb, and Zone 2 requires at least Gc; in dusty environments, Zones 20/21/22 require Da/Db/Dc respectively. Without this match, selected equipment, even if certified, can be an ignition source if used in the wrong zone. IEC 60079-10-1 (gas) and 60079-10-2 (dust) standards define how the classification should be done. Zone classification forms the basis of both equipment selection and the Explosion Protection Document.

Legal Framework and Assessment

The area classification is carried out within the framework of the IEC 60079-10 series and explosive atmosphere regulations; it must be updated when the process or ventilation changes.

Frequently Asked Questions

What is the difference between Zone 0 and Zone 2?

In Zone 0, the explosive atmosphere is continuous/long-lasting, while in Zone 2 it is normally absent, or if it occurs, it is short-lived.

Are there different regions for dust?

Yes; dusty environments are classified as Zone 20/21/22.

When is the classification updated?

When the process, equipment, or ventilation changes, and during periodic reviews.