Explosive Atmosphere

In a classified area, all electrical and non-electrical installations, telecommunications devices, and automation, in general, require special attention when applicable in this area and in compliance with the current regulations for installation in classified areas.

Examples of these installations include chemical plants, refineries and oil exploration platforms, the pharmaceutical industry, the food industry, and the sugar and alcohol industry.

Accidents are recurrent in these types of installations, both in Brazil and abroad, and verifying that in these accidents, only the certification of these “Ex” products is not enough to guarantee the safety of these installations.

Many of these accidents’ causes are associated with human and operational failures, failures in the execution of work procedures and specific activities related to classified areas, as well as lack of training and qualification of those involved in the execution and supervision.

At NCC, we take safety links in explosive atmospheres very seriously. Since 2004 we have been present in the Brazilian market with INMETRO accreditation in the sector, and, since 2011, we are in the international market with IECEx certification for Ex equipment and services companies – NCC has been the pioneer in IECEx certification in Brazil. The certification adds value to the product and increases the user’s or consumer’s confidence level. In Brazil, the Ex certification is mandatory, according to INMETRO Ordinance No. 179 of May 18, 2010, which specifies the certification criteria for Ex products in Brazil, which one of the links in this safety chain is classified areas.

Here are some of the Basic Concepts about Ex.:

Fire triangle 

    Area classification 

    Groups and subgroups of gases and dust

Classification system for electrical equipment referring to an explosive atmosphere for which they are intended to be used.

 

I: firedamp (coal mines)

IIA: propane representative gas

IIB: ethylene representative gas

IIC: hydrogen representative gas

IIIA: combustible fibers

IIIB: non-conductive dust

IIIC: conductive dust

Temperature class

Classification system for electrical equipment, based on the maximum surface temperature related to the specific explosive atmosphere for which the equipment is intended.

Equipment Protection Level (EPL)

Level assigned to equipment based on its likelihood of becoming an ignition source.

 

Ma: Very high protection level for installation in coal mine

Mb: High protection level for installation in coal mine

Ga: Very high protection level for installation in explosive gas atmosphere

Gb: High protection level for installation in an explosive gas atmosphere

Gc: Moderate level of protection for installation in an explosive gas atmosphere

Da: Very high level of protection for installation in an explosive dust atmosphere

Db: High level of protection for installation in an explosive dust atmosphere

Dc: Moderate level of protection for installation in an explosive dust atmosphere

Type of protection

Set of specific measures applied to electrical equipment to prevent the ignition of an explosive atmosphere around it (exclusion of one or more points of the fire triangle)

List of types of protection

“d”: Explosion-proof enclosure (equipment whose enclosure is designed to withstand the internal explosion pressure)

“e”: Increased safety (equipment constructed in such a way as to minimize the occurrence of sparks or electric arcs)

“i”: Intrinsic safety (equipment whose electrical circuits have limited energy and are incapable of igniting an explosive atmosphere)

“m”: Encapsulation (equipment whose parts capable of igniting an explosive atmosphere are encapsulated in a compound)

“nA”: Non-sparking (equipment constructed in such a way as to minimize the occurrence of sparks or electric arcs)

“nC”: Protected against sparking (equipment constructed in such a way as to prevent the occurrence of sparks or electric arcs)

“nR”: Restricted breathing (equipment designed to restrict the entry of gases)

“o”: Immersion in oil (equipment whose parts are capable of igniting an atmosphere explosive are immersed in a protective liquid)

“op”: Optical radiation protection (equipment whose optical values are limited and incapable of igniting an explosive atmosphere)

“p”: Pressurization (equipment that uses a shielding gas to maintain an internal pressure above the external explosive atmosphere)

“q”: Filling with sand (equipment whose parts capable of igniting an explosive atmosphere are immersed in a filling material)

“s”: Special (equipment designed in such a way as to demonstrate that it meets a certain level of protection, different from the standard types of protection)

“t”: Dust protection by enclosure (equipment whose enclosure is designed to prevent the ingress of dust)

 

NOTE: We portray the most common protection types at the moment, in which the standard is being extensively updated, such as, for example, the migration from “nA” to “ec,” which we will deal with these updates in the future in this blog.  

Example of marking 

 

  To access Ordinance No. 179 of May 18, 2010, in full, please visit http://www.inmetro.gov.br/legislacao/rtac/pdf/RTAC001559.pdf

Material subject to amendment(s) in case of change in the ordinance(s). Published: 02.03.21