Abstract: An airflow rate regulating device which is installed in a vacuum unit that collects contaminants from a processing station in a controlled space. This device enables a vacuum unit to maintain a continuous suction of contaminant particles from a processing station when there are pressure variations in the controlled space. The airflow rate regulating device is mounted in a suitable cabinet 88 and connected to a vacuum source. The airflow rate regulating device has a casing divided into two chambers separated by a wall having an passageway through which air flows from one chamber to the next. Each chamber features an airflow rate regulation valve comprising a movable member extending across the flow of air passing through the casing, that can be adjusted using counterweights.