| 摘要 |
A closure for a cylindrical opening having improved venting means including a plug body for removably positioning within and sealing a cylindrical opening, the body having an axial opening therethrough and having means when the plug is within the cylindrical opening to seal against pressure, a tubular valve element slidably received in the plug body opening, the element having at least one radial opening adjacent to and spaced from its closed inner end, a spring normally biasing the tubular element towards the plug outer end so that the radial opening is sealed by the wall of the plug member axial opening and a push rod for displacing the tubular element inwardly to expose the radial opening to the interior of the plug body to vent fluid pressure.
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