Breathing valve

A breathing valve (also known as a pressure/vacuum relief valve) is a specialized safety valve installed on the top of storage tanks. Its core function is to automatically regulate the internal pressure of the tank, preventing damage caused by overpressure or vacuum, while significantly reducing medium evaporation losses. It requires no external energy source and operates solely on the pressure differential between the inside and outside of the tank.Internally, the breathing valve consists of two mechanisms: a pressure relief valve (exhalation) and a vacuum relief valve (inhalation). When the pressure inside the tank rises above the set point of the pressure relief valve, the pressure valve opens to discharge excess gas into the atmosphere. When the pressure inside the tank drops below the set point of the vacuum relief valve, the vacuum valve opens to allow external air into the tank for pressure compensation. Under normal conditions, both valves remain closed, effectively preventing medium evaporation and escape.Breathing valves are categorized into:All-weather type (with flame arrester to prevent lightning-induced fires)Pressure-only / vacuum-only type (provides either positive pressure or negative pressure protection)Type with connection pipe (directs exhaled gas to a recovery system)The breathing valves produced by Kaivex are widely used on various fixed-roof storage tanks in industries such as petroleum, chemical, and food. Selection must be based on the tank design pressure, medium characteristics (toxicity, corrosiveness), breathing capacity (gas flow rate caused by filling/emptying and thermal effects), and set pressure (typically 80% of the vessel design pressure).