Ex i or Ex d? Why is it important to pay attention?

One of the issues that may arise when working with control and instrumentation equipment is the explosion-proof nature of these devices, depending on their installation location. This information is usually indicated on the equipment nameplate, referred to as "Ex Marking." The occurrence of sparks due to switching, lightning, voltage fluctuations, or earth fault errors in electrical equipment during operation is both possible and inevitable. Therefore, in environments containing combustible or flammable materials, the installation and use of such equipment must comply with explosion-proof standards such as IECEx or ATEX. Explosion-proof equipment under these standards is generally classified into two categories: Ex d (Flameproof / Explosion Proof) and Ex i (Intrinsically Safe).

In Ex d standard equipment, the occurrence of sparks and energy release is possible, but the equipment housing is designed to be isolated from the environment, ensuring that no energy escapes during an arc. In Ex i standard equipment, however, the generation of sparks and energy release is not possible. This is achieved by reducing the voltage, current, and overall power of the device in its design, which is why such equipment is referred to as intrinsically safe. In some cases, due to specific sensitivities, both methods may be used simultaneously, known as a combination approach.

An important consideration is that environments with explosion hazards (Hazardous Areas) are assessed and classified based on the type of flammable material and its persistence in the environment. These areas are generally divided into three categories.

Zone 0 (Flammable material is present continuously or for long periods)

Zone 1 (Flammable material is present occasionally)

Zone 2 (Flammable material is absent or present only rarely and accidentally)

So, in response to the question: Ex i or Ex d? Why does it matter?

In Zones 1 and 2, both Ex d and Ex i equipment can be used; however, in Zone 0, only equipment meeting the Ex i explosion-proof standard can be installed and operated.

Based on its experience in various industries, Isatis Farayand Abzar Company supplies explosion-proof instrumentation equipment for immediate delivery from stock or via special orders.