GB/Z 20423-2006 provides guidance on the cleanliness inspection of hydraulic system assemblies. Applicable to all types of hydraulic system assemblies. The standard details the process of cleanliness inspection, covering the preparation of the system before inspection, such as determining the location and method of sampling. Clarify the means of collecting contaminants, such as using appropriate filtrating devices. Specify the method of analyzing contaminants, including particle counting, composition identification, etc. Also formulate cleanliness grade determination criteria and data reporting requirements. Inspection according to this standard can accurately evaluate the cleanliness of hydraulic system assemblies, ensure the stable operation of the system, prevent failures caused by pollution, and improve equipment Reliability and service life.