Knife Gate Valves
Knife gate valves are wafer type isolating valves clamped between two flanges, operated by a thin stainless steel knife moving perpendicular to the flow. On closing, the knife cuts through fibres and solids in the line and comes down onto an elastomer seat ring, so it shuts off without clogging on lines carrying sludge, pulp and suspended solids.
The one-piece body is GGG40 ductile iron; the knife and stem are AISI 304 stainless steel, the seat ring is EPDM and the packing is PTFE. The valves are made in PN16 from DN50 to DN600 and used between −10 and +110 °C. Body length is 48 mm at DN50 and 114 mm at DN600; this short length takes up little space in the line even at large sizes.
Main Applications
- Sludge lines in wastewater treatment plants
- Pulp lines in paper and cellulose mills
- Mining and ore processing plants
- Semi-solid product lines in food plants
- Slurry lines in chemical and petrochemical plants
Technical Data
| Type | Wafer, one-piece body |
|---|---|
| Nominal pressure | PN16 |
| Size | DN50 … DN600 |
| Temperature | −10 … +110 °C |
| Media | Fibrous, sludgy and semi-solid fluids |
| Seat elastomer | EPDM (NBR and NR optional) |
| Flow direction | Bi-directional |
| Body length (L) | 48 mm (DN50) · 51 (DN100) · 70 (DN200) · 76 (DN300) · 89 (DN400) · 114 mm (DN500–DN600) |
| Flange bolt circle | 125 mm (DN50) … 770 mm (DN600) |
| Bolts | M16 (DN50–DN125) · M20 (DN150–DN200) · M24 (DN250–DN350) · M27 (DN400) |
| Stem | Rising or non-rising option |
| Operation | Handwheel, gearbox, chain wheel, pneumatic or electric actuator |
Material Options
| Part | PN16 · ductile iron, DN50–DN400 | PN16 · ductile iron, DN500–DN600 |
|---|---|---|
| Body | GGG40 | GGG40 |
| Knife | Stainless AISI 304 | Stainless AISI 304 |
| Seat / sealing ring | EPDM | EPDM |
| Stem | Stainless A276 304 | Depending on model |
| Packing | PTFE | PTFE |
| Gland | Cast steel A216 WCB | Cast steel A216 WCB |
| Yoke | Steel Q235A | Steel Q235A |
| Guide pad | — | PTFE |
| Operation | Handwheel (malleable iron), brass stem nut | Gearbox assembly |
Installation note: The valve can work in any position, but mounting with the knife vertical and the handwheel on top is preferred. On lines needing remote or frequent operation, the valve can be fitted with a pneumatic actuator.
Advantages
Cuts as It Closes
- The knife cuts through fibres.
- Shut-off without clogging on sludge lines.
Short Body
- Only 114 mm long even at DN600.
- Fits tight spaces and existing lines.
Bi-directional
- Flow can come from either side.
- No risk of installing it the wrong way.
Operation Options
- Handwheel, gearbox, chain, actuator.
- Manual or automatic control.
Easy Maintenance
- Simple, easy-to-maintain design.
- PTFE packing can be renewed.
Construction and Design Features
- One-piece GGG40 wafer body
- AISI 304 stainless knife and stainless stem
- Fully sealed body with EPDM seat ring
- PTFE packing and A216 WCB gland
- Handwheel or drive on a Q235A steel yoke
Send the size, medium, solids content and operation method through the Request a Quote form; we will prepare the knife gate valve with a suitable seat elastomer and drive.
How to Choose?
- Define the mediumDetermine fibre, sludge or solids content and confirm the temperature is below 110 °C.
- Choose the elastomerSelect an EPDM, NBR or NR seat ring to suit the medium.
- Determine the sizeChoose the DN of the pipe and check the flange drilling.
- Decide the driveChoose a gearbox for large sizes and a chain wheel or actuator for remote points.
- Plan the installationLeave space for the knife to be vertical with the handwheel on top.
Complementary Products
Why ORFA?
Other Gate Valves
Our Knife Gate Valves
ORFA supplies knife gate valves in a range of pressure classes, sizes and connection types to suit your application. Descriptions, technical specifications, materials and dimension tables are available on each detail page.
Get a quote for your project
Our sales team will prepare the best solution for your needs.