During the operation of the bag filter, the dust in the air contains more water and oil, and the moisture absorption and easy deliquescence dust. It may produce water film on the surface of the dust and increase the adhesion, which helps to capture the dust, but it will make the dust clear, especially when the high temperature gas is in the high temperature state. The cooling effect of external gas produces condensation, which not only causes the dust on the surface of the filter bag to clog, but also increases the running resistance of the dust removal equipment, which directly affects the normal operation of the dust removal equipment. Water repellent and oil resistant needle felt can effectively prevent water and all kinds of oil contamination to be attached and permeated. Compared with ordinary filter material, it not only has the characteristics of waterproof and oil proof, but also has anti - cleaning and easy stripping to dust.