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.
Ex db eb classification is higher than Ex db, correct?
Composite explosion-proof marking indicates that a single explosion-proof type is not sufficient for this product and that two or more explosion-proof types must be adopted.
For example, explosion-proof equipment with antennas, where the antenna section is typically intrinsically safe. This device combines explosion-proof and intrinsic safety.
Additionally, the nozzle part of the oiler usually belongs to Zone 0, which can only be made as intrinsically safe ia. Other parts can be made into Zone 1, which can be intrinsically safe ib, or explosion-proof types.
Composite explosion-proof products do not imply that the product must meet all requirements of different explosion-proof types simultaneously, nor do they suggest that the explosion-proof level of composite explosion-proof types is necessarily higher than that of single explosion-proof types.
The main factor in determining the explosion-proof level of a product is the gas/dust combination, temperature class, and equipment protection level.
Gas Mix: II-C > II-B > II-A
Dust Combination: III-C > III-B > III-A
Temperature Grades: T6 > T5 > T4 > T3 > T2 > T1
Equipment Protection Combination: Ga > Gb > Gc, Da > Db > Dc
For more details, please contact Shenzhen ZhongNuo Testing Technology Co., Ltd. directly!

Domestic explosion-proof certification models are divided into three cases -- Shenzhen ZhongNuo Testing Technology Co., Ltd.
1. Explosion-proof certification system
Applicable Products: Electrical and non-electrical equipment used in places with explosive gases and dust, excluding those for mining purposes (except for products listed in the Explosion-proof 3C Catalogue).
Certification Model: Product Testing
Certification Certificate: Explosion-Proof Compliance Certificate
Certificate Validity: 5 years
Annual Audit Required: No
2. Explosion-proof 3C Certification System
Applicable Products: Electrical Equipment listed in the Explosion-Proof 3C Catalog
Certification Mode: Combination of Type Testing and Factory Audit
Certification Certificate: CCC Certificate
Certificate Validity: 5 years
Annual Audit Required: Yes, an annual audit is required.
3. Coal Safety/Mine Safety Certification System
Applicable Products: Various electrical and non-electrical equipment for use in both coal and non-coal mines.
Certification Model: Combination of Type Testing and Factory Audit
Certification Certificate: Mine Product Safety Mark Certificate
Certificate Validity: 5 years
Annual Audit Required: Yes, an annual audit is required

How to inquire about explosion-proof certification
Buyers and selectors of explosion-proof electrical equipment always choose manufacturers or distributors with a valid explosion-proof certificate.
So, how do consumers verify if the explosion-proof certification is genuine and valid?
Currently, there are over a dozen authorized certification bodies in China that issue explosion-proof qualifications.
There is no unified platform for checking explosion-proof certification issued by various organizations.
Explosion-proof certificates issued by various institutions can only be verified on their respective websites.
Of course, each issuing agency can verify the authenticity of certificates by phone.
If the inquiry certificate is genuine, the main parameters and validity period will be displayed below.
Of course, it wouldn't be found then.
It's worth noting that due to the manual upload of certification documents by various issuing authorities, there is a certain degree of lag.
That is to say, the newly acquired certificate may not yet be searchable on their website.
This would require a direct consultation with the shipping agency.

Non-metallic surface resistance limit requirements for explosion-proof equipment
In hazardous areas with explosive dust or gases/vapors, such as coal dust 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 hazard areas. When selecting electrical insulating materials, consider maintaining a low insulation resistance to prevent discharge when non-metallic components come into contact with charged components. 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 Class II explosive gas environments, when the surface area of a non-metallic shell of an electrical device exceeds a certain limit (as shown in Table 1), the surface resistance of the non-metallic material must be tested to ensure that: by selecting the material, the surface resistance meets at least one of the following requirements when measured 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 for verification. The assessment requirements are the same as those for the surface resistance test limit in Class II gas environments. For fixed-installed equipment that cannot meet the surface resistance limit, an "X" can be added after the "Explosion-proof" marking, a corresponding warning sign should be placed on the equipment, and the user should be informed in the user manual.
explosion-proof certification application consulting service - Shenzhen Zhongnuo Testing Technology Co., Ltd.