Valve

Claim 1

A valve assembly for automatically relieving the partial vacuum in an unvented tank or container caused by withdrawing the fluid contents therefrom, said valve assembly comprising: means defining a channel, the outer end of said channel in open communication with the atmosphere and the inner end in open communication with the tank interior, a valve seat disposed within the channel, a valve member cooperative with said valve seat to seal the channel, and biasing means to bias said valve member into engagement with the valve seat, comprising a pivoted member on a pivotal support, one end of which pivoted member engages the valve member and the other end of which engages means for imparting a turning moment to the pivoted member greater than the turning moment imparted to the pivoted member by the valve member alone, said ends of the pivoted member being on opposite sides of the point of pivotal support of said pivoted member, the valve member being in a normally closed position in all orientations of the valve assembly, said valve member being biased to a normally closed position by the biasing means when the outer end of the channel is higher than the inner end and by gravity when the inner end of the channel is higher than the outer end, and the valve member being urged out of engagement with the valve seat by atmospheric pressure to permit air to enter the tank when the pressure differential between the atmosphere and the interior of the tank is sufficient to overcome the biasing effect on the valve member and the valve member being returned to its normally closed position when the partial vacuum in the tank has been relieved.