Unidirectional Knife Gate Valve KG01 for Loaded Fluids and Slurries
The KG01 is a unidirectional knife gate valve in wafer construction, one-piece cast body, available in ductile iron, carbon steel or stainless steel. It is designed for fluids containing suspended solids: slurries, cellulose pulps, mineral concentrates, loaded water. DN 32 to 1400, up to 10 bar.
How does the unidirectional knife gate valve work?
The blade slides vertically in internal guides machined into the body. In the closed position, it presses against the downstream seat. Sealing works in one direction only: upstream pressure keeps the blade in contact with its seat. The directional arrow engraved on the body indicates the correct installation orientation.
This is where “unidirectional” makes sense. No bonnet, no external mechanical seal: the construction is simpler and maintenance less demanding than a bidirectional gate valve. For the vast majority of loaded fluid applications where flow direction is fixed, this is sufficient. When pressure can reverse or exceeds 10 bar, the KGVB bonnet knife gate valve is the right choice.
Technical advantages of the unidirectional knife gate valve
- One-piece cast body: no intermediate joint face liable to leak over time
- Machined internal guides: the blade stays aligned during operation, even under abrasive particle loads
- Integrated closing stops: the blade seats correctly against the seat on every cycle, with no manual adjustment
- Rounded-edge blade: seat wear is distributed evenly, extending seal service life
- Full bore, low pressure drop: nothing obstructs flow in the open position
- Three connection types available: wafer between flanges, lug type with fixing lugs, or flanged
Industrial applications
The unidirectional knife gate valve is the reference valve whenever the fluid contains suspended solids that would clog a conventional valve.
Pulp and paper. Cellulose pulps, liquors, white water loaded with fibres. The cavity-free body prevents fibre build-up. Available seats — EPDM, FKM, PTFE — cover concentrated bases and acid liquors.
Mining. Ore pulps, flotation concentrates. For highly abrasive solids such as silica or quartz, PTFE or metal seats outperform EPDM. Duplex blade recommended for corrosive loaded fluids.
Wastewater treatment and biogas. Sewage sludge, digestate, water loaded with organic matter. Solids concentration up to 5%. Ductile iron body as standard, EPDM or NBR seat depending on pH.
Food and beverage. Food-grade silicone seat and stainless steel body for applications subject to sanitary standards: pumping of purees, concentrated juices, pulpy fluids.
Other applications: silo discharge, ash, industrial powders, chemical plants on low-corrosivity fluids.
KG01 Specifications
- DN: 50 to 1400
- Body: Ductile iron / Carbon steel / SS 316 / SS 304 / Duplex
- Blade: SS 316 / SS 304 / Duplex
- Seat: EPDM / NBR / Silicone / Food-grade silicone / Hypalon / FKM / PTFE / Metal
- End connections: Between flanges PN 10/16 and Class 150 — Wafer / Lug type / Flanged
- Min. temperature: −20 °C
- Max. temperature: +180 °C standard — up to +500 °C with stainless steel body and metal or graphite seat
- Max. pressure: 10 bar standard — above this, see the KGVB bonnet knife gate valve
FAQ — Unidirectional knife gate valve
What is the difference between a unidirectional and bidirectional knife gate valve?
The unidirectional knife gate valve seals on the downstream side only: upstream pressure pushes the blade against its seat. It is suitable whenever flow direction is fixed and pressure is below 10 bar. The bidirectional model — the KGB in the Flowrates range — adds a peripheral seal that provides sealing in both directions.
Is the KG01 suitable for highly abrasive fluids?
With the right materials, yes. For mining pulps and abrasive slurries, a PTFE or metal seat outperforms EPDM. A duplex blade is recommended for corrosive loaded fluids. If particles are particularly hard, consult our engineers before ordering — certain blade profiles wear significantly more slowly in these applications.
What is the maximum solids concentration tolerated?
The KG01 is rated for fluids up to 5% solids by mass concentration. Above this, the risk of clogging during operation increases. For higher concentrations, the KGT through-conduit gate valve or the KGS under-silo valve offer a more open bore and are better suited.
How do I obtain a technical offer?
Submit the DN, upstream and downstream pressures, fluid type, solids concentration and temperature via the configurator or by email. Our engineers will respond with a reference, materials, lead time and firm price within 48 hours.
