Focusing on Fire Safety and HVAC Security: Challenges in the Application of Automatic Air Vents in High-Pressure Environments

In high-rise building water supply systems, fire sprinkler systems, and long-distance industrial pipeline networks, the accumulation of air in pipelines is not only an efficiency issue but also a serious safety hazard. When gas accumulates in high-pressure pipelines, it can form an “air lock,” reducing the flow cross-section, causing pressure fluctuations, and even triggering destructive water hammer.

In high-rise building water supply systems, fire sprinkler systems, and long-distance industrial piping networks, gas accumulation in pipelines is not only an efficiency issue but also a serious safety hazard. When gas accumulates in high-pressure pipelines, it can form an “air lock,” reducing the flow cross-section, causing pressure fluctuations, and even triggering destructive water hammer. The application of brass automatic air vents in these high-pressure environments presents far more demanding challenges than in residential heating systems.

I. The Challenge of Exhaust Venting in High-Pressure Environments

In fire protection systems, the piping network is normally kept filled with water and under constant pressure, typically maintained at 1.0 MPa to 1.6 MPa, or even higher.

High exhaust resistance: Under high-pressure conditions, the gas is compressed, increasing its density, and significant back pressure must be overcome during venting. If the flow passage diameter of the exhaust valve is improperly designed or the float’s buoyancy is insufficient, the valve may fail to open properly under high pressure, preventing gas from being discharged.

Water hammer risk: When a fire pump starts or a valve closes rapidly, the flow velocity in the pipeline changes abruptly. If air vents fail to promptly vent air pockets or allow air to cushion the pressure surge, the resulting pressure wave may instantly exceed the pipeline’s pressure rating, leading to pipe rupture.

II. Technical Responses: Structural Reinforcement and Material Upgrades

To address the challenges of high pressure, industrial-grade brass automatic air vents have undergone numerous technological upgrades in both design and manufacturing:

Applications of stainless steel components: Under high-pressure service conditions, conventional plastic levers may experience creep or fracture. Therefore, high-pressure vent valves typically employ fully stainless-steel float and lever mechanisms, such as those made from 304 or 316L stainless steel. The high strength of stainless steel ensures the stability of the actuating mechanism under high-pressure surges, preventing deformation and jamming.

Special steam–water separation design: To prevent high-velocity gas flow from entraining and ejecting water droplets, high-pressure exhaust valves are often equipped with a “steam–water separation plate” or a labyrinthine flow passage. As the gas flows at high speed, liquid droplets strike the baffle and fall back, ensuring that only dry gas is discharged and thereby preventing secondary hazards caused by high-pressure water spray.

High-pressure-resistant sealing materials: The sealing gasket shall be made of high-pressure- and aging-resistant EPDM rubber or PTFE, and shall be equipped with a metal reinforcing ring to prevent the seal from being extruded or torn under high-pressure impact.

III. Special Requirements for Application Scenarios

During fire safety acceptance inspections, the reliability of automatic air vents is a critical veto item. Particularly in high-rise buildings, air vents must be installed at the highest point of the system as well as at local high points, such as areas where pipes pass over beams and columns. For ultra-high-rise water supply systems with pressures exceeding 2.5 MPa, a pressure-reducing orifice plate or an isolation valve is typically installed upstream of the air vent to protect the valve body from transient high-pressure surges.

In summary, under high-pressure conditions, brass automatic air vents serve not only as air-venting devices but also as safety valves that prevent water hammer and safeguard the physical integrity of the piping network.