Uses and working principle of breather valves

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　　I. Purpose and Working Principle of Breather Valves 　　1. Types and Functions of Flame Arresters 　　There are many types of breather valves, but the main ones include explosion-proof flame-arresting breather valves and all-weather flame-resistant breather valves. These are used as ventilation devices on fixed storage tanks containing crude oil, gas oil, kerosene, light diesel, and aromatics. Their function is to reduce the evaporation and loss of oil products, prevent external flames from spreading, and protect the storage tanks from damage in cases of overpressure or vacuum. It is often used in conjunction with a hydraulic safety valve; once the breathing valve fails and ceases to function, or if excessive pressure or vacuum occurs inside the tank for other reasons, the hydraulic safety valve takes over to regulate the pressure. 　　It is widely used in pipelines for heating fuel gas, natural gas, and liquefied petroleum gas, as well as in systems for oil and gas recovery, coal mine gas emission control, and gas analysis; it helps to ensure the safe operation of gas pipelines and the points where gas is used. A flame arrester is a safety device that prevents the spread of flames from flammable gases or liquids and stops backflow that could lead to explosions; it is typically installed in tanks and pipelines used for transporting or discharging such flammable and explosive gases. 　　II. Uses and working principle of flame arresters The key to ensuring the safe, stable, and long-term operation of oil tanks in oil storage and transportation systems lies in the proper use and maintenance of mechanical breathing valves. Mechanical breather valves help maintain a constant pressure inside the oil tank, preventing the oil from oxidizing and deteriorating due to exposure to air. They also reduce evaporation losses, thereby ensuring the safety of the oil tank. A mechanical breathing valve can be integral, capable of performing both exhalation and inhalation functions. It can also be separate, performing inhalation or exhalation tasks independently. 　　1. Types and functions of breather valves 　　1. The casing is made of cast steel and aluminum alloy, offering good corrosion resistance ； 　　Based on their application, flame arresters can be classified into tank flame arresters, gas station flame arresters, heating furnace flame arresters, flare stack flame arresters, vent pipe flame arresters, gas transmission pipeline flame arresters, and so on. 　　In accordance with the provisions of the **Standard Code for Fire Protection Design of Petrochemical Enterprises (GB50160-90)**. “Fixed-roof tanks for Class A and Class B liquids shall be equipped with flame arresters and breather valves.” It is evident that breather valves and flame arresters are essential safety devices for storage tanks. It not only maintains pressure balance in the storage tank, preventing it from being damaged under conditions of overpressure or vacuum, but also reduces the evaporation and loss of the medium inside the tank. A breathing valve is a safe and energy-saving device that helps maintain pressure balance in storage tanks and reduces the evaporation of the medium; it is often used in conjunction with a flame arrester. Today, we will explain in detail the respective uses and working principles of flame arrestors and vent valves, so that users can better understand the differences between them. 　　A flame arrester (also known as a fire arrester or flame inhibitor) is a safety device used to prevent the spread of flames from flammable gases and vapors of flammable liquids. 　　Class B positive pressure: 980 Pa (100 mmH2O); negative pressure: 295 Pa (30 mmH2O). 2. Working principle of the breathing valve: A spring-type breathing valve uses a spring to hold the valve plate in place, with inhalation or exhalation determined by the positive or negative pressure. There are also gravity-operated breathing valves, which are regulated by gravity; they open to release pressure when the air pressure inside the container exceeds the force of gravity. Specific description: When the pressure inside the storage tank is in balance with atmospheric pressure, the exhaust valve disc of the breather valve fits tightly with the exhaust valve seat, and the intake valve disc fits tightly with the intake valve seat. When the pressure inside the tank exceeds atmospheric pressure (that is, an excessive positive pressure is generated), this high pressure acts directly on the valve disc of the breather valve, overcoming the weight of the valve disc as well as the external air pressure acting on it, thereby opening the valve disc. Conclusion: A flame arrester can prevent backflow, while a breather valve can regulate the pressure in pressure vessels; the flame arrester and the breather valve can be used together. 2. The flame-retardant layer is made of stainless steel, offering excellent flame-retardant properties as well as good corrosion resistance ； 　　Class A positive pressure: 355 Pa (36 mmHg); negative pressure: 295 Pa (30 mmHg). Class C positive pressure: 1765 Pa (180 mmHg); negative pressure: 295 Pa (30 mmHg). Channel A is used to release excess pressure from the tank, thereby maintaining equilibrium between the pressure inside the tank and atmospheric pressure. When the pressure inside the tank is lower than atmospheric pressure (i.e., an excessive negative pressure is created), atmospheric pressure enters through the suction channel B and acts directly beneath the suction valve flap. It overcomes the weight of the valve flap as well as the pressure inside the tank acting on that flap, thereby opening the suction valve flap and supplying pressure to the tank so as to maintain equilibrium between the tank pressure and atmospheric pressure. 　　Reduce the control pressure of the breather valve, thereby increasing the evaporation losses of the oil