This standard specifies six methods for determining the moisture content in plastic powders, granules, and products, providing critical guidelines for plastic processing and quality control. These methods differ in principle, accuracy, and scope of application. For instance, Method A (Anhydrous Methanol Extraction) is suitable for samples with a moisture content not less than 0.1%; Method B (Tube Furnace and Sample Bottle Evaporation) and Method C (Pressure Measurement Method) can measure moisture content as low as 0.01%; among them, Method E, based on calcium hydride, offers the highest accuracy, reaching 0.001%. In terms of detection instruments, depending on the specific method employed, the standard may involve Karl Fischer moisture analyzers (used in conjunction with evaporation methods), tube furnaces with carrier gas or specialized evaporators, and moisture analyzers based on calcium hydride reaction pressure measurement.