What does intrinsically safe mean?

Intrinsically Safe is a required standard for devices used in highly hazardous areas that may contain flammable gases, powders or fuels.

The standard ensures that an "Intrinsically Safe appliance" is not capable of initiating combustion or igniting gases or fuels. You can use it in the vicinity of gases or fuels without risking static electricity or heat release from the device, which will ignite the surrounding volatile gases, powders and liquids.

 

The Hazardous Locations are organised in three classes:

• Class I: Flammable gases, vapours or liquids
• Class II: Flammable dust
• Class III: Flammable fibres and kites

Apart from these classes, there are also two divisions:

• Division 1: conditions expected in daily operations
• Division 2: Conditions not likely to occur during normal operations

 

Classification of an area

Hazardous areas are divided into Zones (European and IECEX method) or Classes and Divisions (North American method).

 

 

European & IECEX classification	Definition of zone or division	North American classification
Zone 0 (gases)	An area in which an explosive mixture is continuously present or present for long periods	Class I Division 1 (gases)
Zone 20 (dusts)		Class II Division 1 (dusts)
Zone 1 (gases)	An area in which an explosive mixture is likely to occur in normal operation	Class I Division 1 (gases)
Zone 21 (dusts)		Class II Division 1 (dusts)
Zone 2 (gases)	An area in which an explosive mixture is not likely to occur in normal operation and if it occurs it will exist only for a short time	Class I Division 2 (gases)
Zone 22 (dusts)		Class II Division 2 (dusts)

 

What is ATEX certification?

 

ATEX is an abbreviation of the French, ATmosphère EXplosible (or explosive atmospheres. ATEX designates hazardous materials, such as explosives. It sets requirements for companies that handle and transport these hazardous materials, and it requires those companies to protect their employees against the risk of explosion.

 

ATEX applies in atmospheres where explosions can occur due to dusts, vapours or gases that can ignite or explode. So it applies to most workplaces that use or store flammable or explosive materials - for example, factories that use flammable products or generate flammable dust clouds.

 

What is IECEx?

 

IECEx stands for certification by the International Electrotechnical Commission for Explosive Atmospheres. To be IECEx certified, all products must go through an audited process by the International Electrotechnical Commission to ensure they meet minimum safety requirements. This process will determine whether the products can be used in hazardous or potentially explosive locations.

 

Because they are IECEx certified, the products and equipment can be traded in different countries without having to be retested and re-certified for each country. As different countries have different safety standards, products from one country must be retested in another to meet the guidelines for use in hazardous areas. Therefore, IECEx acts as a common set of safety standards for certification of participating countries, helping to reduce testing and certification costs for manufacturers. Participating countries in the IECEx scheme include most countries in Europe, Canada, Australia, Russia, China, USA and South Africa.

 

 

Differences between ATEX & IECEX

 

The difference between ATEX and IECEx  is primarily that ATEX is only valid in the EU and IECEx aims at worldwide acceptance. ATEX is legally required for all electrical and non-electrical equipment in hazardous areas. IECEx is only for electrical equipment in hazardous environments.

 

The main difference between them is that ATEX  is law driven and IECEx  is standard driven. For ATEX, compliance with the standards is not mandatory, but under IECEx the standards are mandatory. For ATEX, the manufacturer is fully responsible for collecting the modules for examination and production control. For IECEx, a third party (certification) party is responsible for bringing together all aspects of design and manufacturing assessment to issue a public certificate. In practice, this means that IECEx  is perceived to be more stringent than ATEX  in terms of the processing of evidence during the certification process and the assurance of the quality system by the manufacturer.

 

ATEX and IECEx both use the same standards, so in terms of technical content there is basically no difference. The only visible difference is in many cases the marking on the equipment.

 

Some other very notable differences apply to use of ATEX equipment, for example Zone 2 equipment under ATEX is approved for use with a manufacturer’s declaration and this is NOT accepted here in Australia where third party testing is a mandatory part of compliance.

 

Types of Protection Techniques

 

These methods are the basis for the various explosion protection techniques.  While intrinsic safety is only one of the techniques it is the most common in terms of portable electronic equipment.  It is a misnomer to call all explosion protected equipment “intrinsically safe” or “IS” and may lead to confusion.

Each technique, see “Other Valid Techniques for Explosion Protection” Page 20, has a descriptor; “Ex i”, “Ex n” “Ex d”, etc.  This is important as the selection of equipment fit for the specific hazard relies on the selection of the correct technique for the type of hazard/s.

Not all techniques are suitable for all types of hazards. Some techniques are limited to Zone 2 or Zone 1 and 2 and would not be suitable in a Zone 0 environment.  Some techniques are suitable for dust (Group III) and not gas (Group II) and vice versa.

Multiple techniques may be used on an apparatus. This is common and acceptable only if the certificate of compliance identifies the technique suitable for the application and the marking describes it as such.