Cabinet exhaust hoods are commonly known as fume hoods are similar to containment hoods. Small parts painting cabinet, chemical laboratory fume hood is the typical structure of the cabinet-type exhaust hood. Large chamber-type fume hoods, one side is completely open the operator works inside the cabinet, are mainly used for large parts painting, bagging of powders, so on. The working mouth of the fume cupboard has a great influence on the airflow distribution inside the cupboard, the airflow distribution directly affects the working effect of the cabinet-type exhaust hood.