Fine filter main filter, flow meters, control valves and other protective filter. In refining factory finished library, and transit Depot, and airport storage depot, particles pollution more serious of occasions, installation in storage filter separation device (a, level) of front (series using) as pre filter used, can effective to extended poly knot filter of life; Dang installation in flowmeter, and control valve Qian using Shi, can effective to intercept size larger of particles impurities, prevent its occurred mechanical damaged.