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, production enterprises should provide mandatory product certification certificates;
2. The changes of key components and materials are divided into Class A changes and Class B changes, and the principles are as follows:

(1) A-class 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 tests specified in the relevant items of the machine and component standards, and approved by the certification body after passing the evaluation.

(2) B-class changes do not require approval from the certification body. When making changes, whether the entire machine meets safety requirements can be confirmed/technically judged by the certification technical person in charge of the production enterprise. When the evaluation of the change situation meets the conditions and requirements of Class B changes, it is not necessary to obtain approval from the certification body and directly report to the certification body.

(3) After a Class B change, the technical parameters and performance should not be lower than those confirmed in the type test report, otherwise it will be considered a Class A change. After the change, it should be reported, otherwise it will be considered as no change, and corresponding penalties 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 of the voluntary certification certificate and the testing basis of the testing report should comply with the corresponding provisions of the whole machine certification standard requirements.

(5) The list of key components and materials, the standards for testing, and the quantity of samples sent 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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