Comprehensive Analysis and Selection Points of Brass Check Valve

I. Basic Concept

A brass check valve is a type of valve that automatically controls opening and closing via the flow pressure of the medium. Its core function is to prevent backflow in pipelines, protect equipment safety, and maintain normal system operation. The valve body is made of brass, and the internal disc or core opens when the medium flows forward and automatically closes when the medium flows backward. It belongs to the category of automatic valves and does not require external power.

II. Structure and Working Principle

(1) Typical Structural Components

1. Valve Body: Cast or forged from brass, with threaded, socket, or flanged interfaces at both ends.

2. Disc/Core: Types include swing, lift, and butterfly, which achieve sealing through gravity or spring force.

3. Sealing Surface: The contact surface between the disc and the seat is precisely ground to ensure no leakage during reverse flow.

(2) Working Principle

· Forward Flow: The medium pressure pushes the disc to rise or open, with low flow resistance.

· Reverse Cut-off: When the medium flows backward, the disc automatically fits the seat under gravity or spring force, blocking the flow.

III. Classification by Structural Form

1. Swing Brass Check Valve

· The disc rotates around the shaft with low flow resistance, making it suitable for large diameters.

· Applications include main water supply and drainage pipelines, as well as water hammer prevention at the outlets of water pumps.

2. Lift Brass Check Valve

· Features: The core moves up and down vertically, with high sealing precision, suitable for small diameters.

· Applications: Backflow prevention for water meters and water heater inlet pipes.

3. Butterfly Brass Check Valve

· Features: The disc swings around the central axis in a disc shape, with a small volume, suitable for low-pressure pipelines.

· Applications: Air conditioning condensate pipes, pipelines behind household gas meters.

IV. Application Fields

· Building Water Supply and Drainage: Backflow prevention at the outlet of water pumps, such as secondary water supply systems, and one-way protection for water heaters.

· HVAC: Brass check valve to prevent hot water backflow in heating pipes, protection of air conditioning compressor inlets and outlets.

· Gas Systems: Safety backflow prevention for household gas stoves and gas water heaters.

· Industrial Equipment: Unidirectional control of pipelines for small chemical equipment and food machinery.

V. Installation and Maintenance Key Points

(1) Key Installation Steps

1. Flow Direction Confirmation: The arrow mark on the valve body must be consistent with the medium flow direction.

2. Installation Direction:

· Swing type: When installed horizontally, the disc shaft needs to be horizontal; when installed vertically, the medium needs to flow from bottom to top.

· Lift type: The core axis needs to be perpendicular to the pipeline.

3. Vibration Avoidance: Large-diameter check valves need to be equipped with supports to prevent vibration noise caused by frequent opening and closing of the disc.

(2) Maintenance Notes

· Regular Inspection: Disassemble the valve body every six months to clean the scale and impurities on the surface of the disc and seat.

· Troubleshooting:

· Leakage: This may be due to wear on the sealing surface, requiring grinding of the disc or replacement of the sealing ring.

· Abnormal noise: The disc hits the valve body, possibly due to too high a medium flow rate, requiring reducing the flow or replacing it with a silent check valve.

VI. Material Advantages and Limitations

Advantages:

· Corrosion Resistance: Resistant to water, gas, and general neutral media, suitable for household and light industry scenarios.

· Good Sealing Performance: The precisely manufactured disc and seat are closely matched, resulting in a low leakage rate.

· Convenient Installation: Primarily featuring a threaded connection, this valve can be installed without the need for professional tools.

Limitations:

· Low Maximum Pressure Resistance: Typically, the working pressure is ≤ 1.6 MPa. For high-pressure systems, steel check valves are recommended.

· Poor High-Temperature Performance: The strength of the brass check valve diminishes when temperatures exceed 200°C, making it unsuitable for high-temperature media, such as superheated steam.

· Limitations in Large Flow Scenarios: The swing disc may experience water hammer at high flow rates, necessitating the use of a buffer device.