1. Core structure and composition
Pneumatic actuator
The upper part of the pneumatic knife gate valve is the pneumatic actuator, which drives the piston or cylinder to produce linear motion through compressed air, driving the valve stem to rise and fall. According to the control requirements, the actuator can be divided into two types: single-acting (spring reset) and double-acting (bidirectional air control).
Gate valve body
Gate plate: The core opening and closing part, usually a wedge-shaped blade structure, moves perpendicular to the flow direction of the medium. The gate plate is divided into a rigid gate plate (integral metal) and an elastic gate plate (which can be slightly deformed to compensate for sealing deviation).
Valve body: The built-in sealing surface cooperates with the gate plate, and a metal or elastic material (such as PTFE) composite seal is used to adapt to particles and high-viscosity media.
2. Working principle
Pneumatic drive process
Open the valve: Compressed air enters from the lower part of the cylinder, pushing the piston upward, driving the valve stem and gate plate to lift, so that the fluid channel is fully opened.
Close the valve: Compressed air is switched to the upper part of the cylinder, driving the piston to move downward, and the gate is pressed into the valve seat sealing surface through the valve stem to cut off the fluid.
Single-acting actuators rely on spring reset (normally closed or normally open type) when the air is cut off. Double-acting actuators require dual-channel air source control, which has faster response and stable torque.
Manual operation mode
When the air source fails, the opening and closing nut is engaged with the screw by switching the handle, and the handwheel is manually rotated to drive the gate to rise and fall to open and close the valve.
3. Functional characteristics and applicable scenarios
Performance advantages
The wedge gate design can cut off viscous media such as fibers and powders to prevent jamming.
The pneumatic drive has a short response time (usually ≤2 seconds) and supports remote operation of the automation control system.
Typical Applications
Slurry pipeline control in mining and sewage treatment plants
Quick cutoff of high-viscosity fluids in the chemical industry
Flow regulation of sanitary media in food processing
Pneumatic knife gate valves achieve efficient and reliable fluid control through the synergy of pneumatic transmission and mechanical structure, especially suitable for harsh working conditions and high-frequency operation requirements.
