Working principle of breathing valve and precautions for installation and maintenance

The breathing valve is a kind of safety valve. It is a ventilation device fixed on the top of the tank to ensure the normal state of the internal pressure of the tank and prevent the tank from being damaged due to overpressure or ultra-vacuum in the tank. For volatilization loss, breathing valves are usually used in conjunction with flame arresters.Today, will introduce the breathing valve technology to you. I hopeEveryoneIt is helpful to understand and recognize the breathing valve technology!

First, the characteristics of the breathing valve:

The valve body of the breathing valve can withstand 0.2Mpa’s water pressure, without penetration and deformation. When the relative air humidity of the breathing valve is greater than 70% and the lower temperature is -30°C, the opening pressure of the valve disc meets the working pressure requirements after 24 hours of freezing (allowable pressure difference is plus or minus 20pa).

2. Classification of breathing valve:

The first is to breathe or inhale when a certain pressure is reached; the other is designed to simply breathe without breathing, which can be understood as being replaced by two one-way valves with appropriate pressure. The second type of breathing valve is similar to a one-way check valve. It can only exhale outward, but cannot inhale inward. When the pressure in the system rises, the gas will be emptied through the breathing valve to ensure that the pressure of the system is constant. For storage tanks storing toxic substances, there is no breathing valve, or treatment devices such as activated carbon filters are added. Breathing valves are generally used on atmospheric or low-pressure storage tanks, that is, only atmospheric and low-pressure storage tanks have tank breathing discharge, and high-pressure storage tanks have no discharge, no breathing loss and work loss. The main emissions from fixed roof tanks are divided into breathing losses and work losses.

Third, the working principle of the breathing valve:

The breathing valve is a spring-limited valve plate, which is determined by positive and negative pressure to breathe or breathe. The breathing valve should have two functions of releasing positive pressure and negative pressure, specifically: when the container is under positive pressure, the breathing valve opens the exhaled gas to release the positive pressure; when the container is under negative pressure, the breathing valve opens the inhaled gas to release the negative pressure . This ensures that the pressure is within a certain range and the safety of the container is ensured.

Fourth, the selection method of breathing valve:

1. Requirements for the installation location and temperature range. For example, in cold areas, all-weather breathing valves should be selected, and pipeline breathing valves should be selected for installation in pipelines.

2. The control pressure of the mechanical breathing valve should be adapted to the relevant pressure bearing capacity.

3. The specifications of the mechanical breathing valve should meet the requirements of the larger flow of oil in and out of the oil tank.

Five, the installation and maintenance of the breathing valve should pay attention to the following matters:

variousBreathing valves should be installed vertically.There should be no resistance at the outlet of the breathing valve to avoid pressure.The breathing valve should be specially tested before installation, and its official tightness should be checked.Periodic inspections of breathing valves in use should be made.

6. Instructions for use of breathing valve:

callThe suction valve is installed on the top of the storage tank, which is to solve the positive and negative pressure of the gas in the tank, so that the liquid in the tank is not hindered.If the liquid in the tank is output to the outside, the tank must be sucked into the tank from the outside air (called negative pressure).If the breathing valve is automatically closed when it stops working, the liquid and gas in the tank will not leak out, so that the quality of the liquid in the tank is favorably guaranteed.The breathing valve is used on oil and liquid tanks to remove the positive and negative pressure gas in the tank, so that the liquid in the tank is convenient to enter and exit.If the tank body is not equipped with a breathing valve, the liquid in the tank will be blocked to some extent, and the tank body may be deformed and vibrated.

Seven, breathing valve operating pressure:

Class A positive pressure:

355Pa (36mm water column) negative pressure:

295Pa (30mm water column)

Class B positive pressure:

980Pa (100mm water column) negative pressure:

295Pa (30mm water column)

Class C positive pressure:

1765Pa (180mm water column) negative pressure:

295Pa (30mm water column)


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