| 摘要 |
A valving assembly for a liquid-containing tank comprises a housing which includes vent and valve passageways extending axially therethrough. A roll-over valve is supported in the vent passageway by a spring which is calibrated normally to open the vent passageway to normalize the pressure inside the tank. Movement of the roll-over valve is assisted by the spring to close the vent passageway and prevent movement of the liquid from the tank when the tank is tilted. An excessive pressure valve is disposed in the valve passageway and urged by a spring normally to close the valve passageway. The spring is calibrated to provide movement of the excessive pressure valve member to open the valve passageway when the vent passageway is closed and superatmospheric pressure within the tank exceeds a predetermined level.
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