Knife Gate Valve is a type of shut-off valve designed specifically to handle thick fluids, slurries, powders, and other viscous or abrasive media. It is widely used in industries like mining, pulp & paper, wastewater, and chemical processing.

The knife gate is a uni or bi-directional valve designed for general industrial service applications. The design of the body and seat assures non-clogging shutoff on suspended solids in industries.

Description

1. Structure of Knife Gate Valve

Body: Usually cast in one piece (wafer or lug type), made of stainless steel, ductile iron, or carbon steel.
Gate (Knife Blade): A sharp-edged, thin metal plate (stainless steel or alloy) that moves up and down to cut through the fluid or slurry.
Seat: Soft (EPDM, PTFE, NBR) or metal seat depending on sealing requirements and media.
Stem: Connects the gate to the actuator (manual handwheel, pneumatic, hydraulic, or electric).
Packing / Gland: Prevents leakage around the stem.
Actuator: Handwheel, gear, pneumatic cylinder, hydraulic actuator, or electric motor.
 

2. Features of Knife Gate Valve

“Cutting” Ability: The sharp knife-like gate can cut through solid particles, slurry, fibers, or pulp.
Low Pressure Drop: When fully open, it provides a nearly full-bore flow passage.
Bi-directional or Uni-directional: Some designs seal in one direction, while advanced designs can seal both.
Compact and Lightweight: Slim body design compared to standard gate valves.
Cost-Effective: Lower weight and simpler design make it less expensive than standard gate valves of the same size.
Soft or Metal Seat Options: Soft-seated for tight shut-off, metal-seated for high-temperature or abrasive service.

3. Applications of Knife Gate Valve

Knife gate valves are best suited for on-off service in media that contains solids or requires low-pressure drop. Common uses include:
Mining & Minerals: Slurries with sand, stones, and abrasive particles.
Pulp & Paper Industry: Handling pulp stock, paper slurry, and recycled fibers.
Wastewater Treatment: Sewage, sludge, and solid-laden liquids.
Power Plants: Ash handling systems.
Food & Beverage: Powder, grains, bulk handling.
 

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