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Working principle of breathing valve

by:Sino Valves     2021-11-18

Breathing Valve is a safe and energy-saving product used to balance the air pressure of the storage tank and reduce the volatilization of the medium. Its principle is to use the weight of the positive and negative pressure valve disc to control the positive and negative exhaust pressure of the storage tank; Ensure that the pressure in the tank does not continue to drop or rise, and balance the air pressure inside and outside the tank, which is a safety device to protect the storage tank.

Working principle of the breathing valve (picture)

1. When the pressure of the medium in the tank is under the control operating pressure of the breathing valve When it is within the range, the breathing valve does not work to maintain the airtightness of the oil tank;

2. When the pressure in the storage tank is too high (when the operator delivers gasoline to the storage tank, the tank starts to pressurize) When the set pressure is reached, the breathing valve starts to work, the positive pressure valve disc of the breathing valve is opened, and the air pressure generated in the storage tank starts to be discharged. When the pressure in the tank is lower than the set pressure, the breathing valve sealing plate is closed. Keep it closed to prevent volatilization of the medium in the tank.

3. When negative pressure is generated in the storage tank (when the operator delivers gasoline outside the storage tank, negative pressure is generated in the tank) reaches the set negative pressure, the breathing valve starts to work, and the breathing valve When the negative pressure valve disc is opened, air will be sucked into the storage tank. When the pressure in the tank returns to the normal set pressure, the breathing valve sealing plate is closed and kept closed to prevent the medium in the tank from volatilizing.

The principle of breathing valve structure

The breathing valve means not only to ensure that the tank space is isolated from the atmosphere within a certain pressure range, but also to communicate with the atmosphere when it exceeds or falls below this pressure range. (Breathing) a kind of valve. Its function is to prevent the storage tank from being damaged due to overpressure or vacuum, and to reduce the evaporation loss of the storage liquid. It is mainly composed of valve seat, valve cover, protective cover and two sets of opening and closing devices controlled by vacuum and pressure. The opening and closing device includes valve clack, guide rod, spring, spring seat and sealing ring, etc. When the pressure in the tank reaches the rated positive exhalation pressure, the pressure valve flap opens and the vapor in the tank is discharged; when the vacuum in the tank reaches the rated suction negative pressure, the vacuum valve flap opens and air enters.

1. The breathing valve is mainly composed of a valve body, a positive pressure valve disc, and a negative pressure valve disc.

2. The tight breathing valve is usually used in low-pressure straight-through pipelines. The sealing performance depends entirely on the goodness of the fit between the plug and the plug body. The tightness of the sealing surface depends on tightening the lower nut. Achieved. Generally used for PN≤0.6Mpa.

3. Packing type breathing valve realizes the sealing of the plug and the plug body by compressing the packing. Due to the packing, the sealing performance is better. Usually this kind of breathing valve has a packing gland, and the plug does not need to extend out of the valve body, thus reducing a leakage path of the working medium. This kind of breathing valve is widely used for pressure of PN≤1Mpa.

4. The self-sealing breathing valve realizes the compression and sealing between the plug and the plug body through the pressure of the medium itself. The small head of the stopper extends upwards out of the body, and the medium enters the big head of the stopper through the small hole at the entrance, and presses the stopper upwards. This structure is generally used for air medium.

5. Now the application range of oil-sealed breathing valves continues to expand, and oil-sealed breathing valves with forced lubrication have appeared. Due to forced lubrication, an oil film is formed between the plug and the sealing surface of the plug body. In this way, the sealing performance is better, the opening and closing is labor-saving, and the sealing surface is prevented from being damaged.


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