The use of high speed  ventilate valve (P / V valve) is used in liquid cargo ship loading, sailing, ballast, unloading time. The utility model can automatically control the pressure balance inside and outside the cabin without any manual mode, and can also provide fire protection and explosion-proof automatic protection on the deck. When the liquid cargo in the port, the vacuum valve is automatically opened in an inert gas system not timely supply situation, can prevent the vacuum cabin; normal navigation, as a result of temperature due to increased cabin pressure or pressure when loading the cabin. At this time, the valve will automatically open the exhaust gas, so that the pressure balance inside and outside the cabin. When the pressure inside and outside the cabin to achieve balance, the vacuum valve or valve can automatically reset. If a spark occurs outside the cabin, the spark will be extinguished in the vacuum valve.