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Industriearmaturen Knife Gate Valve

Knife Gate Valves in Stainless Steel & GG25 — Buy Online

Knife gate valves in wafer design, stainless steel 1.4408 or grey cast iron GG25, NBR, EPDM or metal seat, DN50 to DN600, PN10, handwheel, pneumatic or quick-closing.

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Knife Gate Valve

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Produktübersicht

Knife Gate Valves: Reliable Shut-Off for Solid-Laden Media

A knife gate valve isolates the flow with a sharp-edged plate that moves down through the medium. The plate cuts fibres, granulates and slurry instead of trapping them. As a result, the valve shuts tight where a disc or ball would clog and jam. This linear design keeps dead space low and, when fully open, adds barely any pressure drop.

Fergo supplies two series. The uni-directional FM200 suits a fixed flow direction, whereas the bi-directional FB700 handles changing pressure directions. The FB700 uses a U-profile seal with a profile steel core and a gate guide with an integrated scraping effect. Both series run from DN50 to DN600 at PN10, with PN16 available on request. Face-to-face lengths follow EN 558 series 20, and flanges follow EN 1092-1 PN10.

Knife gate valves serve municipal wastewater and treatment plants, the chemical and process industry, food and beverage production, as well as pulp, paper and mining. They control sludge, grit, high-consistency stock, fly ash and abrasive slurries. Operators can drive them by handwheel, pneumatic actuator or quick-closing lever. For clean liquids and gases, by contrast, a butterfly valve is usually the more economical choice.

Knife Gate Valves by Actuation

01 Handwheel Knife Gate Valves

The handwheel knife gate valves suit rarely switched isolation points. A rising stem shows the gate position directly, while a non-rising stem saves height above the valve. The FM200 and FB700 both use a body in grey cast iron GG25, a gate in stainless steel 1.4306 and a stem in 1.4305. This design proves itself in treatment plants, silos and process lines from DN50 to DN600.

02 Pneumatic Knife Gate Valves

For automated processes, Fergo supplies pneumatic knife gate valves with a double-acting or spring-return actuator (fail-to-close). The actuators are prepared for NAMUR solenoid valves and limit switch boxes, so the valve integrates directly into the process control system. Actuator mounting follows an ISO 5211 flange. Electric actuators such as the J4C actuator are available as well.

03 Quick-Closing Lever Knife Gate Valves

Safety-critical isolation points need short closing times. Therefore Fergo offers quick-closing lever knife gate valves on the FM200 platform. The lever shuts the gate in a single movement. This design proves itself at silos, dosing plants and emergency shut-off points for granulates and bulk solids.

Materials in Detail: Specifying the Right Knife Gate Valve

Body Materials

1. Grey Cast Iron GG25 / EN-GJL-250 (standard)

  • Application: treatment plants, wastewater, pulp and paper, power stations, mining slurries, cement sludge
  • Temperature: −10 °C to +120 °C (seat dependent) · PN10 standard
  • Advantages: high dimensional stability, good vibration damping, epoxy/polyester coating for corrosion protection, economical for large bores
  • Limitations: not suitable for aggressive or chloride-rich media; more brittle than ductile iron under impact

2. Stainless Steel 1.4408 / CF8M (chemical version)

  • Application: chemical industry, food and beverage processing, pharmaceuticals, aggressive suspensions, chloride-rich media
  • Temperature: −20 °C to +180 °C (seat dependent)
  • Advantages: high corrosion resistance through molybdenum, hygienic surface, durable with acids and alkalis
  • Limitations: higher material cost than GG25, longer lead time on larger sizes

Gate, Stem and Packing

1. Gate Plate Stainless Steel 1.4306 / SS304L, Stem 1.4305 / SS303 (standard)

  • Application: standard combination of the FM200 and FB700 series for water, wastewater, sludge and granulates
  • Temperature: up to +120 °C
  • Advantages: sharp-edged, corrosion-resistant plate with a cutting action; low-maintenance stem; good value for money
  • Limitations: limited resistance to chlorides and strong acids

2. Gate Plate Stainless Steel 1.4404 / SS316L (stainless version)

  • Application: chemical, food and pharmaceutical service, plus chloride-loaded media, paired with the 1.4408 body
  • Temperature: up to +180 °C
  • Advantages: raised pitting and crevice corrosion resistance, acid-resistant, suitable for hygienic applications
  • Limitations: surcharge over the standard plate, project-dependent lead time

3. Spindle Packing PTFE-Synt./EPDM/PTFE-Synt. or PTFE-Synt./NBR/PTFE-Synt.

  • Application: sealing of the stem passage on all FM200 and FB700 versions
  • Temperature: up to +200 °C (PTFE content)
  • Advantages: low stem friction, chemically resistant, adjustable; TA-Luft-compliant version on request
  • Limitations: the elastomer interlayer determines the overall media resistance of the packing

Seat Ring Materials

1. NBR (Nitrile Butadiene Rubber)

  • Application: mineral oils, hydraulic fluids, aliphatic hydrocarbons; on the FB700 as a U-profile seal with profile steel core reinforcement
  • Temperature: −20 °C to +80 °C
  • Advantages: excellent oil resistance, constant sealing pressure through the steel core, economical
  • Limitations: not ozone-resistant, unsuitable for polar solvents and strong acids

2. EPDM (Ethylene Propylene Diene Monomer)

  • Application: water, hot water, wastewater, alkalis and polar solvents; FDA-compliant material approval depending on model
  • Temperature: −30 °C to +120 °C
  • Advantages: high ozone and ageing resistance, wide temperature window, proven in wastewater technology
  • Limitations: not resistant to oils, fats and hydrocarbons

3. Metallic Seat

  • Application: temperatures above +150 °C, highly abrasive media, fly ash, mining slurries, cement sludge, vacuum applications
  • Temperature: up to +400 °C (alloy dependent)
  • Advantages: insensitive to abrasion and heat, no ageing of the sealing element, long service life
  • Limitations: lower leak-tightness than elastomer seats; not suitable for gas-tight isolation

Certificates & Standards for Knife Gate Valves

Fergo knife gate valves comply with the Pressure Equipment Directive 2014/68/EU and carry the CE mark. Face-to-face lengths follow EN 558 series 20, and flanges follow EN 1092-1 PN10. Internationally, the MSS SP-81 standard applies to knife gate valves in stainless steel, and potable and waste water installations follow AWWA C520. Actuator mounting is via an ISO 5211 flange.

Inspection documents to EN 10204 — type 2.2 works certificate or type 3.1 inspection certificate — are available on request. For safety-critical applications, Fergo additionally supplies TA-Luft-compliant stem seals and Fire-Safe designs. A full overview of all certificates is published on the Fergo certificate page. You can verify seat compatibility with your medium beforehand using the Fergo resistance check.

Delivery & Availability

Fergo holds more than 25,000 industrial valves in stock. Over 230 of them are knife gate valves across the FM200 and FB700 series — in every common nominal size, material and actuation type. Orders are picked the same working day. Express shipping therefore delivers within the next working days.

Fergo ships across Europe — including the United Kingdom, the Nordic countries and all other EU member states. Smaller valves travel by parcel service, whereas large-bore and consolidated shipments go by forwarding agent. You will find shipping costs, payment options and express terms on the shipping and payment terms page. For special designs up to DN1200, extended pressure ratings PN16/PN25 or complete automation packages, please contact us through the customised solutions section.