When the pressure of the medium in the tank is within the controlled operating pressure range of the breathing valve, the breathing valve does not work and keeps the tank tightly sealed;
When the medium is replenished to the tank to increase the pressure of the upper gas space in the tank and reach the positive operating pressure of the breathing valve, the pressure valve is opened and the gas escapes from the outlet of the breathing valve so that the pressure in the tank does not increase continuously.
The atmosphere outside the tank opens the negative pressure valve disc of the breathing valve.
