Research: Types of Knife Gate Valves

🧰 Main Types of Knife Gate Valves

Knife gate valves come in several designs to suit different pressure classes, media characteristics, and installation configurations. Here are the most common types:

1. Unidirectional Knife Gate Valve

• Design: Seals in one flow direction only

• Structure: Single seat against which the gate closes

• Applications: Water, sludge, pulp stock, light slurry

• ✅ Cost-effective and widely used in general industrial service

2. Bidirectional Knife Gate Valve

• Design: Seals in both flow directions

• Structure: Dual seats with center-guided blade

• Applications: Reverse flow systems, wastewater treatment, mining pipelines

• ✅ Enhanced sealing in both upstream and downstream flow

1. U-shaped seat Knife Gate Valve

• Design: Has a rubber U-shaped seat to achieve bidirectional sealing

• Feature: The structure is simple, easy to maintain, and the packing or seat can be replaced to extend the service life

• Applications: Water, sludge, pulp stock, light slurry

• ✅ The U-shaped seat has built-in reinforced steel wire to improve the pressure bearing and sealing performance. O-rings are designed on both sides of the body to facilitate the installation of mating flanges

2. O-shaped seat Knife Gate Valve

• Design: Has one or two O-shaped seat to achieve unidirectinoal or bidirectional sealing

• Feature: Unidirectional or bidirectional seats just selected according to the medium, and suitable materials (NR, EPDM, NBR, PTFE, metal, ceramics) can be customized for different working conditions

• Applications: High-density pulp, fiber slurries, sticky materials

• ✅ The O-shaped seat is easy to replace, low cost of maintenance

3. Through-Conduit Knife Gate Valve

• Design: Has a rectangular gate that matches the pipeline diameter

• Feature: Provides an uninterrupted bore and minimal pressure drop

• Applications: Highly abrasive media, dry bulk, dense slurry

• ✅ Prevents material accumulation in valve body

4. Rubber-Sleeve Knife Gate Valve

• Design: There is a detachable rubber sleeve seat on each side to achieve bidirectional sealing

• Feature: The seat can be lengthened according to the working pressure, with excellent wear resistance and sealing

• Applications: Highly abrasive media, dry bulk, dense slurry

• ✅ Ideal for pulp & paper and viscous slurry systems

5. Heavy-Duty Knife Gate Valve

• Design: Has a bonnet to bear high pressure

• Feature: Has better pressure bearing performance, and can usually be designed and customized according to the working pressure

• Applications: Water, sludge, pulp stock, light slurry

• ✅ Provides higher pressure bearing performance than traditional types

⚙️ Actuation Methods

Knife gate valves can be operated using:

📏 Standards and Pressure Ratings

• Flange Standards: ANSI B16.5, EN1092-1, DIN PN10/PN16

• Design Standards: MSS-SP-81, TAPPI for pulp & paper, ISO 5211 mounting pad

• Pressure Classes: PN10, PN16, PN25, PN40, Class 150, Class 300

• Size Range: DN50–DN1600 (2"–64") or custom-built

🏷️ Seallon Knife Gate Valve Solutions

Seallon offers a full range of high-performance knife gate valves built for rugged industrial environments:

• Unidirectional and bidirectional designs

• Lug, wafer, and through-conduit types

• Metal seat or resilient seat (EPDM, PTFE, NBR)

• Actuator-ready designs: ISO 5211 for pneumatic/electric mounting

• Customized coating: Nickel, epoxy, ceramic for wear resistance

• Industry use: Mining slurry, pulp & paper stock, chemical tank drains, wastewater sludge