it can be solved by installing a fan-type four-blade or six-blade exhaust fan at the exhaust port or replacing a large-capacity fan. Because the newly installed smoke exhaust pipe can't do water pressure test and leak detection, the sealant can't be completely bonded when oil leakage occurs in the later period, and the accumulated oil and water in the pipe are not cleaned and maintained regularly. 1. Check which problem is the most serious, and check whether the hood and flue are leaking air, which can alleviate some problems. If not, the general fan has the biggest problem and may need to be replaced. If the cost is reduced, the fume hood can be kept. 2. Pipes are generally made of galvanized sheet and stainless steel. Thin sheets for small pipes cannot be completely sealed and butted like natural gas pipelines and heat-sealed pipes. 3. Because the newly installed smoke exhaust pipe can't be used for pressure test and leak detection, the sealant can't be completely bonded when it leaks oil in the later period. 4. Oil and water accumulated in the pipeline are not cleaned and maintained regularly. Because the newly installed smoke exhaust pipe can't do water pressure test and leak detection, the sealant can't be completely bonded when oil leakage occurs in the later period, and the accumulated oil and water in the pipe are not cleaned and maintained regularly. 5. The oxidation chemical reaction of oil dirt and oil-water mixture inside the pipeline corrodes the pipeline, resulting in slow leakage. 6, long-term corrosion by kitchen grease and oil-water mixture oxidation sealant. 7. In the modification process based on the original system, because the original whole system was covered with oil pollution, the sealant was applied after modification, resulting in non-adhesion and oil leakage.