| 摘要 |
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. When a pressure disturbance occurs in the controlled room from a door opening, or when a hose leading the contaminant source is disconnected, the airflow rate regulation valves react to maintain sufficient vacuum pressure at the contaminants source. Since the airflow rate regulating device is mechanical, its response time to pressure is nearly instantaneous.
|
