ATEX guides

ATEX Certificate for Ex d

ATEX guides

Explosion resistance is established in explosion-proof devices and equipment with Type "d" protection, through the physical protection of the enclosure, only in gas atmosphere with explosion risk. There are several ways to create explosion-proof characteristics for Ex d protection, all of which correspond to the technical specifications set out in the EN 60079-1. Ex d explosion-proof protection consists of three explosion-proof levels under the db, da and dc subsidiaries. The marking included in the ATEX certificates for Ex d have two different structures, for equipment and components. Here there are important examples of Explosion Proof products having Ex d protection.

ATEX Certificate for Ex d equipment

Scope of application

Issuance ATEX certificate for electrical equipment, explosion-proof enclosures and components with physical protection of the body which is used in explosive gas atmospheres.

What is Ex d protection?

Physical protection of the body during an explosion

Standards for the issuance of ATEX certificate for Ex d devices

  • EN 60079-0

  • EN 60079-1

The method of creating explosion-proof properties for equipment Ex d protection

Through the design and manufacture of a "body" or "enclosure" with technical specifications in accordance with EN 60079-1, including:

  • The ability to withstand gas explosions inside the enclosure and without compromising the integrity of the body

  • The body should be designed therefor that the flame does not leak out in the event of an explosion, and the flame cools if the flame passes through the enclosure gaps

  • All other explosion-proof fittings and parts used on the enclosure of Ex d equipment must be installed as thread type with a depth of at least 8 mm and a number of threads of at least 5 and the appropriate quality according to EN 60079-1.

  • Strength of joints during use or operation

  • Choosing and using the appropriate distance between the electrical components and the body

  • High quality body insulation materials and / or O-rings, including resistant to heat, humidity and direct sunlight

  • Having resistance to impact

  • Having the appropriate degree of protection against dust and humidity

  • Machining properties complying with the EN 60079-1

Explosion proof protection levels for Ex d

The Exd protection includes three levels of db, da and dc protections with below details:

Ex da (EPL “Ma” or “Ga”)

It is used only for catalytic sensors or portable gas detectors and must have the following conditions:

  • The maximum internal space of the enclosure of Exd equipment with da protection, shall not exceed 5 cubic centimeters.

  • The electrical conductor inside the sensor must be connected to the inside of the enclosure joints through sealed joints.

  • Electrical circuits used in Ex d equipment with da protection type, shall be considered for Group I mining, with maximum power consumption of 3.3 Watts, and for Group II surface complexes, with a maximum power consumption of 1.3 Watts.

  • The “non-transmission of internal ignition” test shall be carried out by the numbers of repetition according to the table 1 of the EN 60079-1.

Ex db (EPL “Mb” or “Gb”)

It is used for all explosion-proof equipment or components that can meet the general conditions which are required for an enclosure.

Ex dc (EPL “Gc”)

It is used for electrical equipment or components with an explosion-proof switch and contactor.

Ex dc devices must have the following conditions:

  • The maximum internal space of the Ex dc equipment enclosure, shall not exceed 20 cubic centimeters.

  • If equipment with a Ex dc protection level is used on the surface, all requirements of EN 60079-0 or IEC 60079-0 are applicable for sealing of such equipment.

  • Permanent working temperature range (COT): for parts used in Ex dc equipment and for the minimum permanent working temperature of the relevant non-metallic part, it must be applied equal to the minimum service temperature of the equipment and for the maximum permanent working temperature of that non-metallic part, it must be applied 10 degrees Kelvin above the maximum service temperature of the equipment.

  • For electrical equipment designed for Ex dc protection type, the maximum effective voltage in their AC or DC currents shall be equal to and less than 690 volts and 16 amps.

Marking of explosion Proof products with Type d or Ex d protection

1- explosion proof products that are equipped for normal use or under certain conditions

  • For zones 0, 1 and 2: II 1G Ex da T... Ga 

  • For zones 1 and 2: II 2G Ex db t... Gb

  • Only for zone 2: II 3G Ex dc T... Gc

2- explosion proof products that are in components or parts

  • For zones 0,1 and 2: II 1G Ex da Ga

  • For zones 1 and 2: II 2G Ex db Gb

  • Only for zone 2: II 3G EX dc Gc

Explosion proof products designed and manufactured based on d or Ex d protection

  • enclosures or explosion proof boxes

  • electric machines

  • lighting fixtures and hand lights

  • Transformers

  • heaters

  • lamp holders

  • control units and signaling devices (push bottoms, signal lights, switches, micro switches, limiting switches)

  • electronic boards

  • cable glands

  • adapters (thread conversions and inlet sizes)

  • sockets and plugs

  • ballasts of lightings

  • conduit, caps and fittings (nipples, nuts and spools)

Tests required for Ex d equipment

  • impact test

  • degree of protection against dust and water (IP) test

  • durability tests including resistance to heat and humidity and cold cycles

  • temperature measurement test

  • reference pressure test

  • over pressure test

  • non-transmission of internal ignition test

 

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