| 摘要 |
Disclosed is a valve especially adapted for the control of gases in large cross sectional ducts, flues, chimneys and the like. The valve comprises a plurality of elongated, vane-like closures which, when in closed position not only substantially stop the flow of gas in the duct, etc., with which it is associated, but also form a closed chamber extending across the duct. Outside gas such as atmospheric air under pressure greater than the pressure of the gas being controlled is introduced into the closed chamber formed by the closures, thereby precluding leakage of the controlled gas past the valve. Further, when open, and due to their construction, the controlled gas flows through portions of the closures, thus reducing flow losses in the duct.
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