Core structural features of knife gate valves
The design of knife gate valves is centered on meeting the needs of cutting off high-viscosity and solid-particle-containing media. Its structure mainly includes the following key components:
Blade-shaped gate disc
The bottom of the gate disc is in the shape of a thin blade, which quickly cuts off fibers or solid particles in the medium through shearing to prevent clogging;
The gate disc is mostly a flat structure with a thin thickness, which reduces the opening and closing resistance and is suitable for compact space installation.
Square or rectangular flow channel
The cross-section of the valve body flow channel is square or rectangular, which is more conducive to the flow of viscous media or suspended media compared to the circular flow channel;
The inner wall of the flow channel is smooth and straight-through design, with small pressure drop and outstanding anti-fouling performance.
Sealing system
Soft seal type: The surface of the gate disc is coated with rubber (such as EPDM, NBR) or polyurethane, relying on elastic deformation to compensate for the gap between the sealing surface and adapt to slight fluctuations in the medium;
Metal seal type: The floating gate disc design is adopted, and the gate disc is assisted to fit the valve seat through the medium pressure to enhance the sealing reliability under high pressure.
Compact valve body and drive mechanism
The valve body is usually a short structure (such as a clamp-type connection) to save installation space;
The drive mode supports manual, pneumatic or electric, with short opening and closing strokes and fast speeds, suitable for frequent operation scenarios.
Typical application scenarios
Impurity-containing medium treatment: slurry pipelines in sewage treatment plants, pulp transportation pipelines in the papermaking industry;
Viscous fluid control: Cutting off high-temperature and high-viscosity media such as asphalt and tar in petrochemicals;
Space-constrained environment: Rapid cutoff requirements in compact pipeline layouts in mining and metallurgical industries.
Performance limitations
Low pressure resistance: Limited by the strength of soft sealing materials, it is usually suitable for low-pressure pipelines below Class 150;
Limited temperature adaptability: The applicable temperature of rubber-sealed knife gate valves generally does not exceed 80°C (special materials are required for high temperatures).
