The working principle of the large chamber flame retardant breathing valve is to use a spring limit valve plate, which is determined by positive and negative pressure to exhale or inhale. The breathing valve should have both positive and negative pressure relief functions: when the container is under positive pressure, the breathing valve opens to exhale gas and release positive pressure; When the container is subjected to negative pressure, the fire breathing valve opens to inhale gas and release negative pressure. Therefore, ensure that the pressure is within a certain range and ensure the safety of the container. One is to exhale or inhale when reaching a certain pressure, and the other is designed to simply exhale without inhaling. It can be understood as using two check valves with appropriate pressure instead. The fire breathing valve can not only maintain the pressure balance of the storage tank, ensure that the tank is damaged in case of overpressure or vacuum, but also reduce the medium and loss inside the tank. This type of valve should generally be installed horizontally in pipelines.