Although the refrigeration system components in the factory after a rigorous cleaning and drying process, but according to the pipeline, especially when welding, the tube part of the welding slag and scale bonding around the interface. In addition the compressor will run after part of the metal end, the refrigerant itself also contains a certain amount of impurities, as the refrigerant circulating in the refrigeration system changes, they enter the expansion valve will plug the valve hole into the compressor will be hair and Scratch the cylinder. To this end, the refrigeration system should be equipped with equipment to remove these impurities, this equipment is the filter. Filter should be installed in the expansion valve (capillary), solenoid valves and other self-control valve and the compressor return pipe, the installation should pay attention to the flow direction of the filter logo, do not reverse. When the refrigerant flows out from the filter through the filter, impurities and contaminants are left in the filter. Filtration oil filter generally 80-100 mesh specifications, filter gas refrigerant generally 70-100 mesh, filter liquid refrigerant available 60 mesh, but the expansion valve and solenoid valve before the filter needs 120-200 mesh fine Filter. Filter material is stainless steel, phosphor bronze or brass. Drying filter: not only in the refrigeration system impurities dirt, but also there will be moisture. There are many sources of moisture, refrigerants, frozen oil in water, the system of pipes and equipment is not dry and there is moisture and moisture remains. Refrigerant (freon) and water can not be dissolved with each other. In order to prevent ice blocking, a dryer must be installed to adsorb moisture in the system. In small and medium-sized refrigeration equipment and refrigerators, air conditioners, refrigeration systems, widely used with desiccant - dirt filter, with drying and filtering. Refrigerators and air conditioners in the cooling system of the drying filter cartridge, with Ф16-18mm brass, shut down after desiccant molding, direct cooling system with pipe welding. Early use of anhydrous calcium chloride, silica gel, now mostly hygroscopic "molecular sieve." Desiccant performance specifications table