Abstract: A ventilation control valve for a fuel tank is disposed in a ventilation passage which communicates an inside and an outside of a fuel tank. The ventilation control valve includes a float that floats on a liquid level of a fuel and moves up and down. The ventilation control valve includes a valve mechanism which switches a passage sectional area of the ventilation passage in conjunction with the float to an open state and a restricted state in which the passage sectional area is restricted from the opened state. The float has a volume chamber in which volume changes in accordance with a vertical movement of the float. A control gap as a flow rate adjusting mechanism is formed between the cylindrical wall of the float and the cylindrical wall of a case. Due to the control gap, the volume chamber functions as a damper.

Abstract: A ventilation control valve for a fuel tank is disposed in a ventilation passage which communicates an inside and an outside of a fuel tank. The ventilation control valve includes a float that floats on a liquid level of a fuel and moves up and down. The ventilation control valve includes a valve mechanism which switches a passage sectional area of the ventilation passage in conjunction with the float to an open state and a restricted state in which the passage sectional area is restricted from the opened state. The float has a volume chamber in which volume changes in accordance with a vertical movement of the float. A control gap as a flow rate adjusting mechanism is formed between the cylindrical wall of the float and the cylindrical wall of a case. Due to the control gap, the volume chamber functions as a damper.