Abstract: A vent valve for venting fuel and other such tanks includes a float having a valve closure poppet for opening and closing the valve at a predetermined liquid level in the tank. The valve also has a bellows actuator which relieves excessive internal tank pressures by holding the closure poppet open in opposition to buoyant forces on the float when the excessive pressures are encountered. The bellows actuator and the valve poppet are self-compensating since higher internal tank pressures cause the actuator to increase the valve opening for greater pressure relief.