Description/ Specification of Breather Valve

A breather valve or pressure-vacuum relief valve is a safety valve that is most often found on storage tanks, process vessels, and low-pressure systems. The main function of the breather valve is to control pressure fluctuations due to filling and emptying or to temperature changes to prevent damage to the structure of the vessel and to reduce loss of product stored. The primary operation of a breather valve is to keep the internal pressure of the tank within a safe working range. If pressure inside a tank increases above the specified limit, the valve vents vapors into the air or a recovery system. Under a vacuum condition upon emptying or cooling, the valve permits air to be drawn into the tank to prevent collapsing. Types Breather valves are typically categorized into two primary types: Pressure relief valves, which open to vent excess vapors when internal pressure increases above the set point. Vacuum relief valves, which permit the admission of air to the tank when internal pressure falls below the set vacuum level. Most designs incorporate both functions in one pressure-vacuum relief valve. Flame arrestor-valves are also provided for flammable product tanks. Working Principle The valve works on a weighted pallet or a spring-loaded device. When tank pressure is above the set limit, the pallet rises, and vapor escapes. Likewise, during vacuum conditions, the pallet opens inward to take in air. When the pressure returns to normal, the valve automatically reseats, minimizing loss of product and outside contaminants entering. Main Components A standard breather valve will contain the valve housing, pressure and vacuum pallets, sealing means, and seat. Some will also contain flame arrestors, filters, or weather hoods. The pallets are typically slid along the body to permit free movement and are often made from corrosion-resistant material suitable for chemical or petroleum service. Features Important characteristics of breather valves are their simplicity of design, reliable function, minimal leakage, and versatility to suit a wide range of tank applications. Most valves are easy to install on tank nozzles and can be set to different set pressures. Due to their small size and light weight, they are convenient for use in above-ground storage systems. Maintenance Aspects Regular maintenance is required to provide smooth performance. Breather valves must be checked regularly for pallet wear, corrosion, or buildup that can interfere with sealing. Cleaning the valve seats and gasket or seal replacement when needed ensures tightness. Regular testing of set pressures is also necessary to verify accuracy. Valves are usually exposed to extreme weather conditions, so weather hoods and protective coatings are usually applied. Following manufacturer guidelines for servicing extends the valve’s operational life and reliability. Benefits Breather valves have various advantages. They are used to protect tanks against rupture or implosion caused by pressure changes, saving equipment that would otherwise be wasted. They minimize emissions of vapor and thereby help with environmental compliance and product conservation. They prevent entry of moisture, dust, or foreign materials, thereby maintaining product quality. Breather valves also increase overall operational safety in that they decrease explosion threats in a flammable storage situation. Finally, breather valves are critical to safe and effective operation of tanks. Their construction provides protection against pressure extremes, while their low maintenance and environmental benefits render them critical elements in industries dealing with liquids and gases. #breathervalve