What is a knife gate valve?
A knife gate valve is a linear shut-off valve with a flat stainless steel plate that slides guillotine-style through the medium. Unlike a butterfly valve or a wedge gate valve, the knife gate valve has a dead-space-free design and a sharp-edged plate that cuts through fibrous or granular media. Pressure loss in the fully open position is minimal. Fergo offers knife gate valves in uni-directional (FM200) and bi-directional (FB700) sealing for applications with changing pressure direction. The FB700 series uses a U-channel seal with profiled steel-core reinforcement and a plate guide with integrated scraping action. On request Fergo supplies knife gate valves with TA-Luft-compliant stem sealing and fire-safe design for safety-critical applications.
Knife gate valve stainless steel or cast iron — sizes, pressure ratings & materials
Fergo knife gate valves are available from DN50 to DN600, standard PN10 (PN16 and PN25 as special versions). Face-to-face length follows EN 558 Series 20, flange drilling follows EN 1092-1 PN10 — internationally supplemented by MSS SP-81. Key specifications:
- Nominal size: DN50–DN600 (special versions up to DN1200)
- Pressure rating: PN10 standard, PN16/PN25 on request
- Body: grey cast iron GG25 (EN-GJL-250) with epoxy/polyester coating, or stainless steel 1.4408 (CF8M)
- Gate plate: stainless steel 1.4306 (SS304L); in full stainless version 1.4404 (SS316L)
- Spindle: stainless steel 1.4305 (SS303)
- Face-to-face: EN 558 Series 20
- Flange: EN 1092-1 PN10
A knife gate valve stainless steel is the preferred choice for corrosive media, food-grade applications and chemical processing. The cast iron version suits municipal wastewater, pulp and general industrial service.
Seat ring — NBR, EPDM or metallic
The seat ring material determines the service life of your knife gate valve. NBR suits oils and hydrocarbons. EPDM suits water, steam and caustic solutions. A metallic seat handles temperatures above +150 °C and highly abrasive slurries. Check compatibility in advance with our resistance check tool.
- NBR: mineral oils, hydraulic fluids, aliphatic hydrocarbons; FB700 with U-channel seal and profiled steel-core reinforcement
- EPDM: water, steam, caustic solutions, polar solvents; hot-water and wastewater service; FDA-compliant material release available on selected models
- Metallic: temperatures above +150 °C, mining slurries, cement suspensions, vacuum applications
Actuation — handwheel, pneumatic or quick-close
The actuation type depends on switching frequency and level of automation. For manual operation choose a knife gate valve with handwheel — with rising or non-rising stem. For automated processes Fergo supplies pneumatic knife gate valves double-acting or spring-return (fail-to-close), prepared for limit-switch boxes and NAMUR solenoid valves. Safety applications use quick-close levers for instant shut-off. Electric actuators and quarter-turn actuators are also available; mounting follows ISO 5211.
Knife gate valve vs. butterfly valve — when to use which?
| Feature | Knife gate valve | Butterfly valve |
|---|---|---|
| Best for | slurry, fibres, granulates, pastes | clean liquids, gases, HVAC, water treatment |
| Sealing principle | guillotine plate cuts through media | disc rotates 90° inside flow path |
| Dead space | none (full bore) | disc stays in flow path when open |
| Pressure rating | PN10 (PN16 special) | PN6–PN40 |
| Actuation | linear (multi-turn or pneumatic cylinder) | rotary (quarter-turn) |
| Face-to-face | EN 558 Series 20 | EN 558 Series 20 (wafer) |
Choose a knife gate valve when the medium contains solids that would jam a disc. Choose a butterfly valve for clean fluids and gases where compact quarter-turn operation and higher pressure ratings matter.
Applications — wastewater, chemicals, food, pulp & paper
Knife gate valves protect process lines across a wide range of industries. In municipal wastewater and treatment plants, GG25 knife gate valves isolate sludge lines and grit chambers. In the chemical industry, bi-directional stainless steel knife gate valves with PTFE-reinforced packing shut off acids, caustic solutions and solvents. In food and beverage processing, FDA-compliant seal materials and electropolished stainless steel surfaces ensure hygienic operation. In pulp and paper mills, the FB700 series with integrated scraping action handles high-consistency stock. Knife gate valves also serve power plants (fly ash), mining (slurries) and cement production. For applications requiring explosion protection, ATEX versions are available as a special solution.
Knife gate valve in stock — EU-wide delivery
At Fergo you can buy your knife gate valve and receive it directly from stock. All 238 variants — uni-directional and bi-directional, GG25 and stainless steel, handwheel and pneumatic — are ready for dispatch. Standard shipping via DHL reaches customers across Europe within a few working days. Each knife gate valve ships with works certificate, datasheet and declaration of conformity to the EU Pressure Equipment Directive 2014/68/EU. For larger projects the Fergo team coordinates scheduled deliveries, framework agreements and bespoke configurations.
Certificates
Special solutions
Resistance check
FAQ – Your questions, our answers!
Yes, Fergo customises every knife gate valve on request - from the drive to the seal to the anti-corrosion coating. Simply send us your requirements by e-mail or via our enquiry form.
Fergo configures knife gate valves with NBR, EPDM or metallic seals - also with highly resistant combinations such as PTFE-synt./EPDM/PTFE-synt. The selection depends on the medium and the operating conditions.
They are operated manually using handwheels or automatically using pneumatic and electric actuators, suitable for various industrial control systems.
A pneumatically operated knife gate valve uses compressed air to move the valve - ideal for fast, automated processes. The electric knife gate valve, on the other hand, is controlled by a motor drive and is suitable for precise control. Fergo offers both variants in different sizes and designs to suit your needs.
Fergo offers knife gate valves made of stainless steel and grey cast iron with various seals such as NBR, EPDM and PTFE, depending on the application and medium.
A knife gate valve is a shut-off valve that controls the flow in pipework by raising or lowering a plate. It is particularly suitable for viscous, abrasive and fibrous media.
They are used in the chemical industry, food processing, waste water technology, the paper industry and other sectors with demanding media.