DS Pipe and Steel Supply

Knife Valves

Knife valves, also known as slide valves, are a type of linear motion valve used to control the flow of fluids in piping systems. These valves are designed with a sharp-edged disc or gate that moves back and forth across the flow path to either block or permit the passage of fluid. 

Design and Operation

Knife valves consist of a valve body, a sharp-edged disc or gate, a stem, and an actuator.

The disc or gate is typically flat and sharp-edged, resembling a knife blade. It moves linearly along the flow path to control the flow of fluid. When the valve is fully open, the disc or gate is retracted, allowing fluid to flow unimpeded. Conversely, when the valve is closed, the disc or gate is pushed into the flow path, creating a seal that blocks the fluid flow.

Knife valves can be operated manually using a handwheel or operated automatically using electric, pneumatic, or hydraulic actuators.

Applications of Knife Valves

  • Slurry and Abrasive Fluids: Knife valves are commonly used in applications of slurries, viscous fluids, and abrasive materials. The sharp-edged gate is well-suited for cutting through solids suspended in the fluid, making knife valves ideal for handling abrasive media.
  • High-Pressure and High-Temperature Environments: Knife valves can withstand high pressures and temperatures, making them suitable for applications in challenging environments such as power plants, refineries, and chemical processing plants.
  • Water and Wastewater Treatment: Knife valves find applications in water and wastewater treatment plants for controlling the flow of raw water, treated water, and sludge. They provide reliable shutoff capabilities and can handle varying flow rates encountered in water treatment processes.
  • Mining and Minerals Processing: Knife valves are used in mining operations and mineral processing plants to handle slurries, tailings, and other abrasive materials. They offer efficient flow control and can withstand harsh conditions in mining environments.
  • Pulp and Paper Industry: In the pulp and paper industry, knife valves control the flow of pulp, paper stock, and various chemicals used in the production process. They help to regulate flow rates and maintain process efficiency.