Shenzhen Zhongnuo Testing Technology Co., Ltd. is based in South China and specializes in explosion-proof certification and coal safety certification application consulting services, offering one-stop explosion-proof technology consulting services.
The meaning of explosion-proof ratings is crucial for understanding and selecting the appropriate explosion-proof equipment. Below is a detailed explanation by Shenzhen Zhongnuo Testing Technology Co., Ltd. on the significance of explosion-proof rating letters:
I. Basic Composition of Explosion-Proof Marking
The explosion-proof marking is typically composed of several letters and numbers, mainly including the following parts:
"Explosion-Proof Marking: 'Ex' marking indicates that the equipment has passed explosion-proof certification and complies with explosion-proof standards."
Explosion-proof Type: Typically a letter indicating the type of explosion-proof protection the equipment employs
Gas Groups: Specify the gas group applicable to the equipment, such as I, IIA, IIB, IIC, etc., which represent different explosive gas environments.
Temperature Group: Represented by the letter "T" followed by a number, with the number indicating the high surface temperature of the equipment during operation. Commonly used are T1 to T6.
Equipment Protection Level: Indicates the Equipment Protection Level (EPL), commonly used to further classify the safety performance of equipment in explosive environments.
Section 2: Specific Meanings of Explosion-Proof Grade Letters
Explosion-proof protection type:
"ia" and "ib" denote the explosion-proof protection types of equipment. Equipment with an "ia" rating cannot ignite an explosive gas mixture under normal operation and two fault conditions, whereas equipment with an "ib" rating cannot ignite such a mixture under normal operation and one fault condition.
Gas Group Letters:
I: Used in coal mine gas environment.
IIA: Suitable for gases of lower hazard.
IIB: For ethylene and other moderately hazardous gases.
IIC: Suitable for gases of the same or higher hazard class.
The hazard levels progressively increase, i.e., IIA < IIB < IIC.
Temperature Group Letters and Numbers:
T1: The equipment's surface temperature does not exceed 450°C.
T2: Equipment surface temperature not to exceed 300°C.
T3: Equipment surface temperature does not exceed 200°C.
T4: Equipment surface temperature does not exceed 135°C.
T5: The surface temperature of the equipment does not exceed 100℃.
T6: Equipment surface temperature not to exceed 85°C.
Equipment Protection Level Letter:
Explosive gas environment equipment with a "protected" level, not a source of ignition under normal operation, anticipated failure, or rare fault.
GB: Equipment for explosive gas environments with "high" protection level, not a source of ignition under normal operation or anticipated fault conditions.
Gc: Equipment for explosive gas atmospheres with a "normal" protection level, not a source of ignition during normal operation.
Protection levels increase sequentially: Gc < Gb < Ga. Ga can be used in Zones 0, 1, and 2; Gb can be used in Zones 1 and 2; Gc can be used in Zone 2 only.
III. Example
For example, with the explosion-proof marking "Ex ia IIC T6 Ga":
"Ex": Indicates that the equipment is explosion-proof.
"ia": Indicates that the equipment's explosion-proof grade is a high level within the intrinsic safety category.
"IIC": Indicates that the equipment is suitable for IIC classification of explosive gas environments.
"T6": Indicates that the equipment's high surface temperature does not exceed 85°C.
"Ga": Represents the protection level of the equipment, applicable to Zones 0, 1, and 2.
In summary, understanding the meanings of explosion-proof ratings is crucial for correctly selecting and using explosion-proof equipment. Shenzhen ZhongNuo Testing Technology Co., Ltd., as a design and testing service provider for explosion-proof products, can offer you comprehensive testing and certification services for explosion-proof products, ensuring your equipment meets relevant standards and requirements. Should you have any questions or needs, please feel free to contact us at any time.

Limitation requirements for surface resistivity of non-metallic外壳on explosion-proof equipment
In hazardous areas with explosive dust or gases/vapors, such as coal powder and flour, static electricity can cause fires or explosions, posing significant danger. Therefore, it is advisable to minimize the use of insulating materials in explosive hazardous areas. When selecting electrical insulating materials, consider maintaining low insulation resistance to prevent discharge when non-metallic components come into contact with charged parts. For non-metallic insulating materials, the antistatic capability of the equipment can be assessed by measuring the surface resistance of the equipment's housing.
Surface Resistance, measured in ohms (Ω), refers to the resistance between two electrical contacts on the measuring surface.
In accordance with the requirements of the IEC 60079 series standards:
1. In II Division explosive gas environments, when the surface area of the non-metallic housing of electrical equipment exceeds a certain limit value (as shown in Table 1), a surface resistance test must be conducted on the non-metallic material to ensure that: by selecting the material, the surface resistance meets at least one of the following requirements during measurement according to IEC 60079-0 26.13:
At ≤1 GΩ, (505)% relative humidity;
At ≤100 GΩ, (305)% relative humidity.
2. In environments with Class III explosive dust, if the surface area of the non-metallic housing of electrical equipment does not exceed 500 mm², the risk of static electricity can be disregarded; if it exceeds this limit, a surface resistance test must be conducted. The requirements for determination are the same as those for the surface resistance test limit for Class II gas environments. For fixed installation equipment that cannot meet the surface resistance limit, an "X" can be added after the "Ex" marking, a corresponding warning sign should be placed on the equipment, and the user should be informed in the user manual.

Explosion-proof Certification Categories -- Shenzhen ZhongNuo Testing Technology Co., Ltd.
The防爆certification process is the work of determining if equipment meets the requirements of explosion-proof standards, type testing, and routine tests, and issuing the relevant compliance certificates.
Certificates are available for Ex equipment or Ex components.
Different regions have varying certification standards and systems for explosion-proof electrical products.
Currently, explosion-proof certifications worldwide can be categorized into domestic explosion-proof certifications, ATEX certifications, IECEx certifications, and North American explosion-proof certifications.

In the field of explosion-proofing, there is a clear distinction between intrinsic safety certification and explosion-proof certification, while intrinsic safety certification is also a specific form of explosion-proof certification.
Intrinsic Safety Certification: This certification indicates that the equipment employs an intrinsic safety type of explosion-proof protection. Intrinsic safety explosion-proofing primarily achieves this by limiting the energy of the equipment, such as by restricting working voltage, current, capacitance, inductance, etc., ensuring that even if sparks are generated internally within the equipment, they are not sufficient to ignite the surrounding explosive environment. Therefore, this certification is particularly suitable for low-power products and handheld devices.
‌Explosion Proof Certification: This is a broader category that encompasses various explosion protection types, such as flameproof, increased safety, positive pressure, and encased types. These types are designed to ensure that equipment operates safely in explosive environments, preventing explosions or triggering larger ones.
In simple terms, ATEX certification is a type of explosion-proof certification that focuses on intrinsic safety explosion-proof designs, while explosion-proof certification covers a broader range of explosion-proof designs.
If you need more information about ATEX certification or explosion-proof certification, or if you require related certification applications, Shenzhen ZhongNuo Testing Technology Co., Ltd. can provide you with the services and support you need.
Explosion-proof Certification Application Consulting Services - Shenzhen ZhongNuo Testing Technology Co., Ltd.