Unidirectional Knife Gate Valve is a special knife gate valve designed to prevent reverse flow of fluid. Its core function is to force the medium to flow in only one direction through the one-way sealing structure of the knife-shaped gate and the valve seat.
Core Design Features
- Structural Composition
Knife Gate: The thin and sharp gate design can cut off particles, fibers or high-viscosity media (such as slurry, sewage), reducing flow resistance and blockage risks;
One-way sealing valve seat: It only forms a seal when the fluid flows in the forward direction. Under reverse pressure, the gate and the valve seat fit tightly to block the reverse flow;
Packing anti-leakage: Some models use a special packing cavity design (such as a combination of elastic sealing ring and PTFE) to prevent the medium from leaking through the valve stem (more reliable than traditional knife gate valves).
- Working Principle
Forward flow: Fluid pressure pushes the gate to open, and the medium passes through the valve body in the designed direction;
Reverse cutoff: When reverse flow pressure is generated, the gate is pressed against the valve seat sealing surface, forming a mechanical blockage to prevent the medium from flowing back.
- Typical application scenarios
Industrial anti-backflow control: Used in slurry conveying pipelines in the chemical and metallurgical industries to prevent the medium from backflowing and damaging the pump body during shutdown;
Sewage treatment system: When treating sewage containing solid impurities, prevent sediment from flowing back to upstream equipment;
High-pressure slurry system: In the papermaking or food industry, high-pressure working conditions are used to ensure the stability of unidirectional flow.
- Difference from ordinary knife gate valve
Functional focus: Ordinary knife gate valves (Knife Gate Valve) are mainly used for bidirectional medium blocking, while one-way knife gate valves force flow direction through asymmetric sealing structure, which is essentially a composite functional design of "check valve + gate valve";
Sealing requirements: Because it needs to withstand reverse pressure impact, the sealing surface material (such as polyurethane or hard alloy) and structural strength of the one-way valve are required to be higher.
- Selection points
Medium characteristics: Wear-resistant lining (such as rubber or polyurethane) is preferred to deal with fluids containing particles;
Pressure level: The valve seat sealing level needs to be selected according to the maximum reverse pressure to avoid backflow and crushing the sealing surface;
Installation direction: Strictly install according to the flow direction arrow marked on the valve body, otherwise it may fail.