References

Since July 2003 all Ex products in the European market must be certified to the ATEX directive. This involves the testing and assessment of such products to the latest ATEX standards.

Canadian Standards Authority provides certification for Canada. If a product is CSA listed, you know it has passed the stringent Canadian tests for electrical safety.

G = Gas, D = Dust, M = Mining.   *in presence of explosive atmosphere

Equipment Protection Level	Zone
Ga	0
Gb	1
Gc	2
Da	20
Db	21
Dc	22
Ma	Energised
Mb	De-energised*

Ex areas can be known by different names such as “Hazardous Locations”, “Hazardous Areas” “Explosive Atmospheres”, and the like and relate to areas where flammable liquids, vapours, gases or combustible dusts are likely to occur in quantities sufficient to cause a fire or explosion. The modern day automation of industry has meant an increased need to use equipment in Ex areas. Such equipment is termed “Ex equipment”

Exd (or EExd as it used to be known) explosion proof equipment uses a flameproof housing to withstand an internal explosion ensuring dangerous sparks or flames can not reach the potentially ignitable surroundings. Exd explosion proof and Exia intrinsically safe assemblies conform to either ATEX or IECEx standard or both.

Intrinsically safe Exia equipment is designed to not produce any arcs or sparks which could ignite an explosive mixture. Exia intrinsically safe and Exd explosion proof assemblies conform to either ATEX or IECEx standard or both.

Gases are classified according to the ignitability of gas-air mixture. Refer to EN 60079-20-1 for classification of common gases and vapours.

Gas Groups	Representative Test Gas
I	Methane (mining only)
IIA (least easy to ignite)	Propane
IIB	Ethylene
IIC (most easy to ignite)	Hydrogen + Acetylene

GOST-R certification refers to a set of technical standards valid in the territory of the Russian Federation. This system is aimed at ensuring the safety and high quality of products and services.

The IECEx scheme is the future route of global compliance. It aims to harmonise standards to allow free movement of goods by establishing a certification accepted worldwide.

The following countries have signed up to the IECEx Scheme

Australia	Germany	New Zealand	South Africa
Canada	Hungary	Norway	Sweden
China	India	Romania	Switzerland
Czech Republic	Italy	Russia	UK
Denmark	Japan	Serbia and Montenegro	USA
Finland	Korea	Singapore
France	Netherlands	Slovenia

The term IECEx comes from IEC - the International Electrotechnical Commission and Ex for Explosive equipment.

National Institute of Metrology, Standardisation and Industrial Quality (Inmetro) was created in 1973 overseeing all Brazilian certification. The Inmetro mark is mandatory for electrical equipment used in hazardous locations in Brazil.

The term “Intrinsically Safe” (I.S.) is frequently used to describe any product destined for an explosive area. In reality, I.S. is a protection concept based around limiting the available electrical energy to nonincendive levels so that sparks cannot occur from short circuit or failures which could cause an explosive atmosphere to ignite.

SIL stands for Safety Integrity Level. A SIL is a measure of safety system performance, or probability of failure on demand (PFD). The higher the SIL level, the lower the probability of failure on demand for the safety system and the better the system performance.

	Probability of Failure on Demand (PFD)	Safety Availability in %	Risk Reduction Factor
SIL 1	0.01 - 0.1	90 - 99	10 - 100
SIL 2	0.01 - 0.001	99 - 99.9	100 - 1000
SIL 3	0.001 - 0.0001	99.9 - 99.99	1000 - 10000

UL (Underwriters Laboratories Inc) provides certification for the United States of America. If a product is UL listed, you know it has passed ULs stringent tests for electrical safety.