The tank top breathing valve is an important accessory to protect the safety of oil tanks. It is installed on the tank top and is used to automatically control the opening and closing of gas channels inside and outside the tank, maintain pressure balance of the tank, protect against overpressure or vacuum in the tank, and reduce the evaporation loss of oil products within a certain range.

The breathing valve uses the weight of the valve disc (sometimes a weight block on the valve disc) to control the exhalation pressure and suction vacuum inside the tank. When the pressure of the gas in the tank exceeds the allowable pressure value of the oil tank, the pressure valve is pushed open, and the mixed oil and gas escapes (exhales) from the tank, causing the pressure in the tank to no longer increase. When the vacuum degree of the gas in the tank exceeds the allowable vacuum degree of the oil tank, the vacuum valve is opened and air is sucked in (inhaled) to maintain the pressure balance of the oil tank. The pressure is within a certain range, and the oil tank does not breathe, so the breathing valve reduces the evaporation loss of the oil to a certain extent. The pressure and vacuum values controlled by the breathing valve should be determined based on the allowable values of the oil tank structure itself. When selecting the breathing valve model, it should be determined based on the * large displacement during oil delivery and receiving operations. When the diameter of the breathing valve is greater than 250mm, two breathing valves not exceeding 250mm can be selected.

When the oil and gas pressure inside the tank is greater than the allowable pressure of the oil tank, the oil vapor escapes through the pressure valve, and the vacuum valve is closed at this time; When the oil and gas pressure inside the tank is less than the allowable vacuum degree of the oil tank, fresh air enters the tank through the vacuum valve. At this time, the pressure valve is closed, and the allowable pressure (or vacuum pressure) is controlled by adjusting the weight of the disc.