Shenzhen Zhongnuo Testing Technology Co., Ltd. is based in South China and specializes in explosion-proof certification and coal mine safety certification application consulting services, offering a one-stop explosion-proof technology consulting service.
【Explosion Proof Knowledge】Ex Certification Classifications
Regarding the classification of explosion-proof certification levels, Shenzhen Zhongnuo Testing Technology Co., Ltd. can provide you with a detailed explanation as follows:
Explosion-proof electrical equipment is classified into different categories based on the application site, such as Class I explosion-proof certification, Class II explosion-proof certification, and Class III explosion-proof certification, etc.
Type I explosion-proof certificate: Primarily used in environments containing flammable and explosive mixtures, such as underground coal mines, and is typically used in conjunction with the coal safety certificate of the equipment.
Class II explosion-proof certificate: Applicable to flammable and explosive gas environments other than coal mines, such as the common flammable gases and steam environments in oil and chemical, gas, and other industries.
Type III explosion-proof certificate: Used in environments with combustible dust, such as flour mills, woodworking factories, and other locations where combustible dust is present.
Additionally, the explosion-proof marking is a crucial basis for determining the applicability range and safety grade of explosion-proof equipment. The explosion-proof marking typically consists of multiple components, including the explosion-proof type, equipment category, gas group, and temperature group.
Explosion-proof Types: Common types include隔爆型 represented by "d",增安型 represented by "e", and intrinsic safety type represented by "i", etc. Different explosion-proof types indicate the use of various explosion-proof techniques to achieve the explosion-proof performance.
Equipment Categories: Divided into Class I, Class II, and Class III, corresponding to the explosion-proof certification classification mentioned above.
Gas Groups: For II class equipment, further categorized based on the properties of flammable and explosive gases, such as IIA, IIB, IIC, and so on. Gases in different groups have variations in ignition energy and ignition limits.
Temperature Ranges: Represented by letters, indicate the allowable high surface temperature range of the equipment, such as T1 to T6. The higher the temperature range, the lower the allowable surface temperature, and the higher the relative safety in hazardous environments.
We hope this information helps you understand the classification of Ex explosion-proof certifications and the meaning of explosion-proof symbols. If you have any other questions or need further assistance, feel free to contact us anytime!

【Explosion Proof Knowledge】The relationship between Intrinsically Safe Certification and Explosion Proof Certification
Intrinsically safe certification is actually a type of explosion-proof certification. Specifically:
Intrinsic Safety Certification: This certification indicates that the equipment employs an intrinsic safety type of explosion-proof protection. Intrinsic safety explosion-proofing primarily involves limiting the energy of the equipment, such as by restricting working voltage, current, capacitance, inductance, etc., to ensure that even if sparks are generated internally, they are not sufficient to ignite the surrounding explosive environment. This certification is applicable to low-power products and handheld devices.
‌Explosion-proof Certification: This is a broader category, encompassing various explosion-proof protection types, such as intrinsic safety, increased safety, positive pressure, and encased types. These types are designed to ensure that equipment operates safely in explosive environments, preventing explosions or causing larger ones.
If you need more information about ATEX certification or explosion-proof certification, or if you need to apply for related certifications, please feel free to consult Shenzhen ZhongNuo Testing Technology Co., Ltd.

【Ex-proof Mark】Meaning of Letters in the Ex-proof Certification Mark
The meaning of the letters in the explosion-proof certification mark is crucial for understanding and selecting the appropriate explosion-proof equipment. Here are the meanings of some common explosion-proof grade letters:
This is the explosion-proof electrical equipment symbol, indicating that the equipment is explosion-proof. This symbol must be printed on all explosion-proof equipment.
ib, db, eb: These letters represent the explosion-proof protection types of equipment. For example, ib indicates intrinsic safety protection, db indicates flameproof protection, and eb indicates increased safety protection. Sometimes, equipment may utilize multiple protection types, such as db ib indicating both flameproof and intrinsic safety.
This letter specifically refers to the gas environment in coal mines. If explosion-proof equipment is suitable for coal mine environments, this letter will be included in its marking.
IIC: This symbol indicates that the equipment is suitable for explosive gas atmospheres of IIC category gases, including and the like.
The number following T (e.g., T4, T6): This indicates the temperature category, denoting the high surface temperature of the equipment. For instance, T6 signifies that the equipment's high surface temperature does not exceed 85°C, while T4 indicates it does not exceed 135°C. The temperature category is a crucial factor to consider when selecting explosion-proof equipment to ensure safe operation in specific environments.
Mb, Gb: These letters denote the protection level of the equipment. For instance, Mb indicates that the device can be used in the 1st area of mining environments, while Gb means the device is suitable for the 1st and 2nd areas of non-mining gas environments.
In summary, a composite explosion-proof marking such as Ex db ib IIC T4 Gb can be interpreted as follows: The equipment is an electrical device for non-mining explosive gas environments, utilizing both intrinsic safety and explosion-proof protection. It is suitable for IIC, IIB, and IIA gas classifications, with a maximum surface temperature of no more than 135°C, and is applicable in Zones 1 and 2.
We hope this information helps you understand the meanings of explosion-proof ratings. If you need more information about explosion-proof certification and markings, Shenzhen Zhongnuo Testing Technology Co., Ltd. is here to provide you with further clarification.

Basic Knowledge of Explosion-Proof Marks and Ratings
The explosion-proof marking and explosion-proof grade are important indicators for assessing the performance and application scope of explosion-proof equipment. Below, Shenzhen ZhongNuo Testing Technology Co., Ltd. will explain these two concepts in detail for you.
Explosion-Proof Marking
Explosion-proof markings are typically composed of a series of letters and numbers, indicating the explosion-proof type, equipment category, gas group, and temperature group of the explosion-proof equipment. Below is an example of a typical explosion-proof marking and its meaning:
Ex db ib IIC T4 Gb
Ex: Indicates that this equipment is for electrical devices used in flammable and explosive gas environments.
db: Explosion-proof type.
IB: Protection type is intrinsic safety ( intrinsic type ). Here, "DB IB" indicates that the device employs both explosion-proof and intrinsic safety as its explosion prevention methods.
IIC: Indicates that the equipment is suitable for environments with flammable and explosive gases, specifically IIC category gases (such as and the like). IIC category gases are generally hazardous, with a lower ignition energy and a wider ignition limit range.
T4: Temperature Category, indicating that the surface temperature of the equipment does not exceed 135°C. The higher the temperature category (the larger the number), the lower the allowed surface temperature, and the higher the safety in hazardous environments.
Gb: Equipment Protection Level, applicable to Zones 1 and 2.
Explosion-proof type
The explosion-proof type refers to the technical means used by explosion-proof equipment to prevent explosions from occurring. Common explosion-proof types include, but are not limited to:
Explosion-proof (d): By encapsulating components that may produce sparks or high temperatures within a robust housing, the housing can withstand the explosion pressure and prevent the flame from spreading outward in the event of an internal explosion.
Increased safety type (e): Reduces the likelihood of equipment producing sparks or high temperatures by enhancing safety features, such as improving insulation levels and employing non-sparking designs.
intrinsic safety (i): Limits the energy in the equipment circuit so that it produces sparks or high temperatures capable of igniting flammable explosive mixtures in both normal operation and fault conditions.
Intrinsically Safe Rating
Although the term "explosion-proof grade" may not be directly mentioned in standards, the various parts of the explosion-proof marking actually cover the equipment's explosion-proof performance grade. For example, the equipment category (I, II, III), gas group (IIA, IIB, IIC, etc.), and temperature group (T1 to T6) information collectively determine the equipment's explosion-proof grade and application range.
If you need more information about explosion-proof markings and ratings, or have questions regarding explosion-proof testing, certification, and construction, feel free to consult Shenzhen ZhongNuo Testing Technology Co., Ltd. at any time. We will provide you with the answers and services you need.
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