1. Key components and materials refer to the components, parts, and raw materials that play a crucial role in ensuring that certified products meet certification and standard requirements. For components and materials within the scope of mandatory product certification purchased domestically, the manufacturing enterprise shall provide a mandatory product certification certificate;
2. The changes to key components and materials are divided into Class A changes and Class B changes, with the following principles:

(1) Class A changes should be approved by the certification body. When making changes, whether the entire machine meets safety requirements must be determined by the laboratory according to the relevant tests specified in the machine and component standards, and approved by the certification body after passing the evaluation.

(2) B-type changes may not require approval from certification bodies. When making changes, whether the entire machine meets safety requirements can be confirmed/technically judged by the certification technical responsible person of the production enterprise. When the evaluation of the change situation meets the conditions and requirements of Class B change, approval from the certification body is not required and can be directly reported to the certification body.

(3) After Class B changes, the technical parameters and performance should not be lower than the technical parameters and performance confirmed in the type test report, otherwise it will be considered as Class A changes. After the change, it should be reported, otherwise it will be considered as no change, and corresponding punishment will be imposed depending on the severity of the situation.

(4) For components and materials within the scope of non mandatory product certification, production enterprises should provide corresponding voluntary certification certificates, valid testing reports issued by CNAS accredited laboratories, or complete machine testing. The certification basis for the voluntary certification certificate and the testing basis for the testing report should comply with the corresponding clauses in the standard requirements for whole machine certification.

(5) The list of key components and materials, the standards for testing basis, and the quantity of samples sent along with the whole machine test shall be reviewed by the contracted laboratory and confirmed by the issuing authority.

(6) The controlled classification of key components and materials for various explosion-proof types is as follows:

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