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Zone 1 vs. Zone 2 Hazardous Areas

Introduction

Explosive atmospheres can be caused by flammable gases, mists, vapors or by combustible dusts, in combination with oxygen. With a certain concentration level all that is needed to cause an explosion is a source of ignition. According to the IECEx, ATEX and CSA standard for use of electrical equipment in hazardous areas, hazardous areas are classified into zones and each zone has unique characteristics. Also, each scheme has its own method of marking equipment. Knowledge about the marking requirements and how equipment can be correctly identified is therefore important for both engineers, designers, safety officers, mobile workers and others. To clarify and simplify, we have made this introduction to the subject, where you can learn more about the different classes and zones.

 

 

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Definitions

The likelihood of there being an explosive hazardous gases present at each given moment is the determining factor when an area is classified. According to a recent Wikipedia article on the subject, the classes and zones are defined to as follows

Division 2 or Zone 2 area
This is a step up from the safe area. In this zone the gas, vapor or mist would only be present under abnormal conditions (most often leaks under abnormal conditions). As a general guide for Zone 2, unwanted substances should only be present under 10 hours/year or 0–0.1% of the time. 
Division 1 or Zone1 area
Gas, vapor or mist will be present or expected to be present for long periods of time under normal operating conditions. As a guide for Zone 1, this can be defined as 10–1000 hours/year or 0.1–10% of the time.

Error types and markings

Intrinsically Safe products for use in hazardous environments carry a wide range of markings. The markings cover both the area of safe use (the zone) and the level of intrinsic safety the product is designed for. By level of intrinsic safety, we mean the number errors or malfunctions the device or system can be exposed to and still be considered safe for use. According to the definitions, hazardous area equipment can be exposed to the following errors or malfunctions

  • Error of a safety component, like an exposed electrical circuit or short-circuiting
  • Error in a coupling, exposed electrical circuits
  • Error in isolation, short-circuiting

 

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The level of safety required to maintain sufficient protection from explosions and fires relate to the number of the above mentioned errors an intrinsically safe device is designed to be protected against. Therefore, intrinsically safe products are categorized into three:

  • ia – Safe with two individual errors, can be used in Zone 0
  • ib – Safe with one individual error, can be used in Zone 1
  • ic – Safe under normal operation, can be used in Zone 2

 

PS: You can find more info on this subject in our Equipment Protection Level (EPL) blog post here.

There are several different certification schemes and markings being used today, and it is not always easy to relate to all of them. Therefore, to make it easier in practice, we have made our own guidelines, a checklist if you will, where you can find out which product suits your needs.

Safety Guidelines

The different zones within a hazardous area in needs to be clearly marked. While working at a refinery, plant, ship, rig or platform, mobile workers need to know exactly what area they are working in at all times. However, in practice this is not always straight forward, since there are many ways of interpreting the guidelines. There are also some factors that should be taken into consideration. First of all, Zone 2 certified equipment is not allowed to be carried through a Zone 1 environment, not even when the Zone 2 equipment is powered off. Secondly, if there is an emergency, all zones are automatically upgraded to a Zone 1, immediately making all Zone 2 equipment in violation with the guidelines. Thirdly, mobile devices are often carried around by users that might be unaware of the risk they are exposing them to, or unaware of which Zone they are working in. All in all, this is complicated, and a reason why many companies are now standardizing on Zone 1 solutions for all their mobile devices.

Zone 1

Zone 1 certified mobile devices is recommended if one of the following guidelines is true for the area in question:

  • There are mobile workers that work in Zone 1 areas on the installation
  • The marking of the different areas and Zones on the installation is unclear
  • Mobile workers are working near the drilling floor or process facilities, where gas leaks most often occur
  • If there is a chance of an emergency gas leak, or if there has been gas leaks previously

Zone 2

Zone 2 certified mobile devices can in some instances be sufficient if all of the following guidelines are in place:

  • There are mobile workers that only work in safe area or Zone 2
  • The marking of the different areas and zones on the installation cannot be misinterpreted
  • There is no chance that mobile workers can enter Zone 1 or Zone 0 by mistake
  • There is no chance of an emergency, where the security policy is tightened
  • All personnel have been trained in hazardous area safety

Do not compromise on safety

Zone 1 products should be used in plants or installations where Zone 1 areas can be found. This is especially important when it comes to mobile devices, which is carried around the premises. These guidelines is just an introduction. Always consult an HSE or Safety specialist if in doubt. Do not take unnecessary risk.

 

 

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Zone 1 products can be sexy!

Ex Zone 1 equipment have for a long time been synonymous with bulky, heavy, slow, hard to use products. This goes for both mobile devices such as PDAs and cameras but also for other types of equipment. We wanted to change that! Therefore, we created the worlds first IECEx and ATEX certified product with a design award, the Impact X! The Impact X has won the Norwegian Design Councils Award for Design Excellence in April 2014. With the latest products from BARTEC PIXAVI, the decision is easy. Choose a Zone 1 solution that is powerful, flexible and easy to use. Read more about the Impact X Intrinsically Safe Smartphone and the Gravity X Intrinsically Safe Camera.