| 摘要 |
A gas safety control hatch attached to the top of a crude oil storage or stock tank. The hatch has a lid which can be opened to enable the contents of the stock tank to be gauged. A liquid lock apparatus is provided between the interior of the hatch and the interior of the stock tank. The liquid lock comprises a downwardly extending conduit having one end opened into the hatch and the other end opened in proximity of the bottom of the stock tank so that liquid always covers the lower, marginal end of the conduit whenever any appreciable amount of crude is stored in the stock tank. Accordingly, when the lid of the hatch is opened, no obnoxious fumes from the vapor space within the tank can flow into the hatch; and accordingly, the tank can be safely gauged by running a sampling apparatus down through the conduit and into communication with the liquid phase of the tank contents.
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