How does the Breathing Filter Valve prevent the formation of negative pressure in the pipeline?

One of the main functions of the Breathing Filter Valve is to prevent the formation of negative pressure in the pipeline due to sudden pressure drop during transient flow. When water hammer, pump stop or valve sudden closure occur in the pipeline system, the internal pressure may drop rapidly, even below atmospheric pressure, resulting in liquid column separation or damage to the pipeline structure. The air valve dynamically adjusts the pipeline pressure through the mechanism of automatic air intake and timely exhaust to ensure stable operation of the system.

When the pressure in the pipeline is lower than atmospheric pressure due to water flow interruption or pressure fluctuation, the air intake device of the Breathing Filter Valve will respond immediately. The device is usually controlled by a float, spring or diaphragm mechanism, which can automatically open the valve when negative pressure is detected, allowing external air to quickly enter the pipeline. The key role of this process is to supplement the vacuum area in the pipeline to avoid the collapse of the pipe wall due to external atmospheric pressure, especially in thin-walled or flexible pipes. At the same time, the inhaled air can fill the cavity formed by the separation of the liquid column, reduce the water hammer effect caused by subsequent pressure recovery, and thus protect the pipeline system from impact damage.

When the pipeline pressure gradually recovers, such as when the water pump restarts or the water flow stabilizes, the air that entered before will be pushed to the valve by the flowing liquid. At this time, the exhaust function of the Breathing Filter Valve begins to work, slowly exhausting the air through small holes or slow-release structures to prevent gas accumulation from forming air blockage and affecting the water flow efficiency. When the liquid completely fills the pipeline, the float or mechanical seal inside the valve will rise under the action of buoyancy or pressure, and finally close the exhaust port to ensure that the valve is sealed and prevent liquid leakage. This process not only ensures the effective removal of gas in the pipeline, but also avoids waste or environmental pollution caused by liquid leakage.

The design of the Breathing Filter Valve fully considers automation and reliability. Its dual-function structure usually includes a large-caliber suction valve and a small-caliber exhaust valve to meet the needs of rapid air replenishment and slow exhaust, respectively. The valve realizes unpowered automatic opening and closing through mechanical structures such as floats, springs or diaphragms, without relying on external energy or control signals, and is suitable for stable operation in various complex environments. Some high-end models are also equipped with filtering components, such as filters or dustproof devices, to prevent impurities or insects from entering the pipeline and ensure the internal cleanliness of the system. These design features enable the Breathing Filter Valve to operate efficiently under different working conditions while extending its service life.

In actual engineering, Breathing Filter Valves are widely used in pipeline systems that need to prevent negative pressure and water hammer. For example, in a water supply system, when a water pump suddenly stops, the downstream pipeline may form a vacuum due to the inertial water flow. At this time, the air valve installed at the high point of the pipeline will quickly replenish air to prevent the pipeline from collapsing due to negative pressure. In long-distance water or oil pipelines, Breathing Filter Valves are often arranged at high points with undulating terrain to eliminate pressure fluctuations caused by liquid column separation. In addition, pressure pipelines, fire protection systems and drainage networks in industrial processes also rely on air valves to maintain pressure balance and ensure safe operation.