Abstract: A vacuum breaker valve assembly is provided including a housing mountable to a transport tank. The housing has a wall defining a passageway through the housing and there is a valve member movable within the housing. Structure is provided for permitting the valve member to move in response to variations in tank pressure between (1) and open state when atmospheric air external of the tank is allowed to travel through the passageway and into the tank once a predetermined vacuum pressure condition is reached, and (2) a closed state wherein the passageway is sealed to prevent atmospheric air travel into the tank when the predetermined vacuum pressure condition in the tank has not been reached. A housing lid is mounted to the housing and includes a vent hole for allowing atmospheric air to enter the housing passageway. A bottom wall integral with the housing wall includes a vent hole therethrough communicating with the interior of the tank.