| 摘要 |
An apparatus for preventing backflow and contamination, and detecting by-pass leaks in a flow control arrangement is disclosed. The apparatus includes a vent line connecting a sweep gas source and a vent. Constant process-inert gas flows from the source through the vent line into the vent. The vent line is connected with the flow control arrangement. Any leakage in the flow control arrangement is channeled to the vent line and swept into the vent along with the sweep gas. As a result, pressure in the flow control arrangement cannot build up and leakage backflow is prevented. A flow switch may be disposed on the vent line for detecting leakage. The sweep gas flow rate is controlled at a constant level that is inadequate to actuate the flow switch and keeps the flow switch ready to actuate by any superimposed leakage. The flow switch detects a leakage when it actuates.
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