Features of Vacuum Shut-off Valves and What to Note During Use

A vacuum shut-off valve is a type of valve used to reduce the gas pressure within a system to a certain level, commonly utilized in vacuum systems. It boasts excellent sealing performance and corrosion resistance, often serving as a connecting component for pressure-reducing devices or as a medium cutoff.

The working principle of a vacuum shut-off valve involves the reciprocating motion of the actuating part, which creates a resistance moment and additional force as the fluid passes through a certain gap, thereby preventing the fluid from continuing to flow and achieving the purpose of stopping the airflow.

Upon closing the passage, the liquid-sealed face automatically seals the pathway with friction against the tube wall, achieving a check valve effect.

Vacuum cutoff valves are primarily used in the oil refining industry for controlling high-temperature, high-pressure sulfur-containing gas flows in oil heating furnaces, for flow regulation in the chemical production process, and for throttle treatment in gas transmission lines.

Its structural features include a double-seated enclosed design, full-bore design, suitable for a wide range of nominal sizes, and offers various material options such as WCB stainless steel plate, titanium, Monel, etc.

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The main features of the vacuum cutoff valve include:

1. Simple structure, compact size, and lightweight: The vacuum cutoff valve boasts a straightforward design, making it easy to install and maintain.

2. Tight and Reliable: Double-sealed design ensures zero leakage, suitable for high-pressure and vacuum environments.

3. Easy Operation: Quick on/off with just a 90-degree rotation for switch control, ideal for long-distance operation.

4. Wide Application Range: Suitable for a variety of working conditions, from small to large diameters, and from high vacuum to high pressure.

5. High Corrosion Resistance: The valve stem has been specially treated for excellent corrosion resistance, abrasion resistance, and wear resistance.

6. Easy Maintenance: The sealing rings are removable for easy replacement and maintenance, and repairs can be conducted without shutting down the equipment.

‌Key Points to Consider When Using Vacuum Shut-off Valves:‌

1. Operate smoothly to avoid impact force: When opening or closing a stop valve, the force should be applied smoothly and not with an impact. The high-pressure stop valves with impact opening and closing have considered this impact force, but general stop valves cannot withstand it.

2. Maintain handwheel rotation position: Leave space for the valve handle to rotate; it should not be used for throttling. Clockwise rotation of the handwheel closes the valve, while counterclockwise rotation opens it.

3. Regular Inspections and Maintenance: High-pressure shut-off valves require regular maintenance after installation to check for seal wear and ensure the valve stem is intact. Any issues encountered should prompt maintenance and replacement as needed.

‌Specific precautions to be taken during the operation process are detailed below‌

1. Apply even force during operation: When turning off the cut-off valve, do so steadily and evenly; avoid using impact force to switch the valve.

2. Prevent residual impurities from damaging the sealing surface: When the pipeline is initially used, there is a significant amount of internal debris. You can slightly open the regulating valve to flush it away with the high-speed flow of the medium, then gently close it and resume normal operation.

Avoid facing the valve rod directly: The operator's body must not face the valve rod during operation.

4. Storage precautions: When storing vacuum shut-off valves, they should be protected from rain, water, and moisture, and the flange cover should be tightly sealed.

‌Note Special Precautions in Special Cases‌

   1‌. Special Medium Handling: Certain media cool and contract after the cutoff valve is closed, so operators should close it once more at an appropriate time to ensure no fine gaps remain on the sealing surface.

2. Regular Testing: Valves stored for over 12 months should be retested during use to ensure their stable performance.