Ex certification markings usually consist of a combination of letters and numbers, with each part having a specific meaning.

STS will explain the meaning of each component of such markings one by one:

For example, the meaning of the common Ex certification marking Ex db ib IIC T4 Gb:

(1) Ex: Indicates that the device is an explosion-proof electrical equipment, suitable for explosive and flammable environments.

(2) db ib: Refers to the explosion-proof protection types adopted by the device, meaning flameproof (db) combined with intrinsically safe (ib). A flameproof device means that if an explosion occurs inside the device, the flame and explosion products will not spread to the outside through the device's mating surfaces; an intrinsically safe device means that the electrical sparks or thermal effects generated under normal operating conditions and specified fault conditions cannot ignite explosive and flammable mixtures.

(3) IIC: Indicates that the device is suitable for Group IIC explosive and flammable gas atmospheres, which include hydrogen, acetylene and other such gases.

(4) T4: Denotes the temperature class, meaning the maximum surface temperature of the device does not exceed 135°C, ensuring that the surrounding explosive and flammable mixtures cannot be ignited at this temperature.

(5) Gb: Refers to the equipment protection level, applicable to Zone 1 and Zone 2. Zone 1 means an area where explosive and flammable gas mixtures may occur under normal conditions; Zone 2 means an area where explosive and flammable gas mixtures are unlikely to occur under normal conditions and only appear occasionally for short periods under abnormal conditions.

Let us look at another example: Ex db eb II C T6 Gb:

(1) Ex: Also indicates an explosion-proof electrical equipment.

(2) db: The protection type is flameproof.

(3) eb: The protection type is increased safety. An increased safety device means that additional protective measures are applied to equipment that does not generate electric arcs, sparks or high temperatures under normal operating conditions to enhance its safety level.

(4) II C: Indicates that the device is suitable for Group IIC explosive and flammable gas atmospheres, with representative gases being hydrogen and acetylene.

(5) T6: The temperature class is T6, meaning the maximum surface temperature of the device does not exceed 85°C.

(6) Gb: The equipment protection level, applicable to Zone 1/Zone 2.

It should be noted that these are only common examples of Ex certification markings for explosion-proof equipment used in explosive and flammable gas atmospheres. For equipment used in underground coal mine environments or explosive and flammable dust atmospheres, their corresponding Ex certification markings will differ accordingly.

If you need to learn more about Ex certification and Ex marking-related information and questions, we recommend consulting STS, where we will provide more professional explanations.