Class 1 / Division 2 and ATEX Zone 2 Explained

Certain industries, particularly oil and gas, are subject to hazardous environments. These environments are designated by National and International administrations and codes which implement legal standards and measures to protect workers and the environment itself. Hazardous Locations (HAZLOC) are standardised by the following.

The Occupational Safety and Health Administration (OSHA) defines a hazardous location as follows:

‘Hazardous locations are areas where flammable liquids, gases or vapors or combustible dusts exist in sufficient quantities to produce an explosion or fire. In hazardous locations, specially designed equipment and special installation techniques must be used to protect against the explosive and flammable potential of these substances.’

The National Electrical Code (NEC) and the Canadian Electrical Code (CEC) defines hazardous areas as the following:

‘An area where a potential hazard (e.g., a fire, an explosion, etc.) may exist under normal or abnormal conditions because of the presence of flammable gases or vapors, combustible dusts or ignitable fibers or flyings.’

In the US, NEC (National Electric Code) is followed, which puts HAZLOC (Hazardous Locations) into classes, divisions (and groups for the type of materials present) and for Europe, IEC (International Electrotechnical Commission) classifies HAZLOC by zones. Products such as a panel PC will then be certified to be safe in these areas before they can be applied.

In North America products are listed by UL (Underwriters Laboratories, a global safety consulting and certification company based in the US and 45 other countries) under what level of Class and Division the product is suitable for, whilst ATEX uses certified bodies to classify products for use in the EU. 

Outside of the European Union, regulations apply under the IEC Ex (International Electrotechnical Commission - System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres). IEC Ex is a voluntary system which provides an internationally accepted means of proving compliance with IEC standards. IEC standards are used in many national approval schemes and as such, IEC Ex certification can be used to support national compliance, negating the need in most cases for additional testing. 

UL Classes and Divisions

Class I — Flammable gas, vapors, and liquids

Class II — Combustible dusts

Class III — Ignitable fibers and flyings

Divisions go further in classifying how often the flammable/explosive substances are likely to be present under normal operating conditions.

Division 1 — Flammable substances are continually present or are likely to exist under normal operating conditions

Division 2 — Flammable substances are not likely to exist under normal operating conditions

European ATEX Equivalents

The abbreviation ATEX is derived from the French words, ATmosphères EXplosibles and represents 2 European directives stipulated for controlling explosive atmospheres:

1) Directive 99/92/EC (also known as 'ATEX 137' or the 'ATEX Workplace Directive') on minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres. 

2) Directive 94/9/EC (also known as 'ATEX 95' or 'the ATEX Equipment Directive') on the approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres. 

ATEX classifications are in zones, derived from the US ‘HAZLOC’ standard. They combine the ‘Class’ area classification and the ‘Division’ likelihood of explosive substance presence. It subdivides powders and dust from gases and vapors.

Hazard - Gas / vapor / mist

Zone 0 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is present continuously or for long periods or frequently

Zone 1 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is likely to occur in normal operation occasionally.

Zone 2 - A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Hazard - Powder / dust

Zone 20 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

Zone 21 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22 - A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

As with Class 1 (Vapors and gases) being a higher rating than Class 2 (Combustible dusts), gases being more permeable, Zone 2 is a higher rating than Zone 22 for the same reason.

Where embedded electrical products are concerned, the requirement for harsh environment industries such as oil and gas will usually be certification to Class 1 / Division 2 and/or ATEX Zone 2. As you can see from the comparison chart below, these 2 constructs are not dissimilar.  

 

Assured Systems offer a comprehensive range of Class 1 / Division 2 and/or ATEX Zone 2 qualified products including panel PCs, embedded computers, data modules and screens. View our ranges below - If there is something you need which is not listed, please contact us and our sales technicians will help to find you a solution.

View Our Class 1 / Division 2 and ATEX Zone 2 Approved Products

We can make your (Class 1/Division 2, ATEX Zone 2) project idea into a turnkey solution reality!

We offer a comprehensive solution service which includes extrusion design, manufacture, software programming and project management support. We have experience in large turnkey solutions for Class 1 / Division 2 and ATEX Zone 2 environment projects, be sure to give us a call +44 (0) 1785 879 050 UK  or +1 864 421 6991 US to discuss yours.

About Assured Systems

Assured Systems is a leading technology company offering high quality and innovative applied computing solutions to the embedded, industrial, and digital-out-of-home markets across the world. Headquartered in Stone, England and with offices in North America, our reach is truly global. Our impressive product portfolio includes a full range of Fanless Embedded Computer Systems, Digital Signage & Multimedia Computer Systems, Touchscreen Panel PCs, Human Machine Interfaces, Vehicle Mount Computers, Rackmount Computer Systems, Single Board Computers, Rugged Laptops & Tablets.

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