1. Basic definition
A pneumatic gate valve is a valve that is opened and closed by a compressed air-driven actuator. Its core function is to control the flow of fluid in the pipeline by vertically lifting the gate. Compared with manual gate valves, it has automatic control capabilities and is suitable for industrial scenarios that require rapid response or remote operation.
2. Core structure
Main components
Valve body and valve cover: constitute the flow channel and chamber, usually made of stainless steel, cast steel or carbon steel, suitable for different media (water, steam, oil, etc.).
Gate: divided into rigid gate (integral structure) and elastic gate (can be slightly deformed to compensate for the deviation of the sealing surface), and the sealing surface is often designed as a wedge or parallel plane.
Actuator: pneumatic cylinder or piston mechanism, which converts the kinetic energy of compressed air into mechanical force to drive the valve stem.
Auxiliary design
Equalizing hole: Some models are equipped with equalizing holes on the gate to balance the pressure of the middle cavity inside the valve body and the inlet cavity to prevent high pressure accumulation from causing safety hazards.
Manual backup mechanism: When the pneumatic system fails, manual operation can be switched to ensure emergency control.
3. Working principle
Action process
The compressed air enters the actuator to push the piston, and drives the valve stem and gate to move vertically through the transmission rod.
When opened, the gate is completely separated from the valve seat flow channel to form a full-diameter flow; when closed, the gate presses the valve seat to block the medium.
Sealing mechanism
Forced sealing: Relying on pneumatic thrust to make the gate fit tightly with the valve seat, suitable for low-pressure or clean media.
Self-sealing: Under high-pressure conditions, the medium pressure assists in enhancing the sealing pressure ratio and improving reliability.
4. Types and adaptation scenarios
Ordinary pneumatic gate valve
Applicable media: conventional fluids such as water, steam, and oil products, with a nominal pressure of up to 6.4MPa and a temperature range of -20℃ to 550℃.
Typical applications: pipeline cut-off control in petrochemical and power systems.
Pneumatic Knife Gate Valve
Structural features: The gate is knife-shaped, specially designed for medium containing particles, viscous or slurry, and can cut off fiber impurities.
Applicable scenarios: Slurry conveying pipelines in sewage treatment, papermaking and metallurgical industries.
5. Performance advantages
Automatic control: Can be integrated into the PLC system to achieve remote operation and process automation.
Fast response: The opening and closing speed of pneumatic drive is significantly faster than manual operation, and it is suitable for high-frequency working conditions.
High reliability: Resistant to high temperature, high pressure and corrosive media, special design (such as elastic gate) reduces the risk of blocking.
