Knife gate valve

Product Overview

The Slurry Knife Gate Valve is a knife‑edge gate valve specifically designed for handling high‑concentration, solid‑particle‑laden, and fibrous slurry media. It is intended only for ON‑OFF service – not for flow regulation. Compared with standard knife gate valves, the slurry knife gate valve features enhanced seat sealing, gate wear resistance, and anti‑clogging flow path design.

It reliably shuts off highly abrasive and settling media such as mineral slurry, pulp, mud, tailings, and coal slurry. The sharp knife‑edge gate cuts through fibers and particles during closure; the body flow path has no recesses and is equipped with extended guides or optional flush ports to prevent solids buildup. The valve has flanged connections, with nominal diameters from DN50 to DN800, pressure ratings PN10/PN16 (Class 150), body materials including carbon steel and stainless steel, and wear‑resistant linings available. Actuators can be manual, electric, or pneumatic.

Product Structure

The Slurry Knife Gate Valve mainly consists of the actuator  and the slurry‑duty valve body assembly.

Actuator:

1. Available in manual (handwheel, bevel gear), electric, or pneumatic.

2. Electric actuator: motor, gearbox, travel limit switches, torque protection, handwheel.

3. Pneumatic actuator: cylinder, solenoid valve, limit switches.

4. All actuators are ON‑OFF type – not for modulation.

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Slurry‑Duty Valve Body Assembly:

1. Body: Cast or fabricated body in carbon steel (WCB), stainless steel (CF8/CF8M), etc. Flanged ends conforming to GB/T 9113, ANSI B16.5, EN 1092‑1, etc. Full‑bore flow path with no recesses. Optional internal wear‑resistant linings (rubber, polyurethane, ceramic).

2. Gate: Stainless steel (304, 316, 310S) knife‑edge gate with a sharp edge. The sealing face and contact areas are hardfaced with Stellite or hard chrome‑plated for high wear resistance. The gate surface is hardened (HRC ≥ 50).

3. Seats: Slurry‑duty seats – available in wear‑resistant rubber (NR, EPDM), polyurethane (PU), or metal hard seal. Typically a bidirectional floating seat design that presses against the gate under media pressure to compensate for wear.

4. Self‑Cleaning Guide Mechanism: Extended guide grooves inside the body and bonnet ensure vertical gate movement and scrape off adhered slurry during gate travel.

5. Flush Ports (optional): Threaded connections (1/2″ or 3/4″) on the body side or bottom to inject water or air after closing to remove residual slurry and prevent drying and sticking.

6. Stem: Stainless steel trapezoidal‑thread stem with optional protective boot to prevent slurry ingress into the threads.

7. Packing Box: Contains wear‑resistant packing (flexible graphite or PTFE) with a wiper ring/dust seal to prevent slurry from entering the packing.

8. Bonnet: Available in enclosed (splash‑proof) or open‑frame (easy cleaning) construction.

The overall design is optimized for slurry services – wear‑resistant, clog‑resistant, and reliable sealing.

Function

1. High‑Wear Shut‑Off: Hardened gate (Stellite hardfacing or chrome plating) combined with wear‑resistant seats (rubber, polyurethane, or metal) makes the valve suitable for highly abrasive media such as mineral slurry and coal slurry.

2. Knife‑Edge Cutting Function: The sharp gate edge cuts through fibers, lumps, and particles during closure, preventing clogging.

3. Self‑Cleaning Flow Path: The recess‑free flow path, together with the scraping action of the gate against the guides, removes adhered slurry. Optional flush ports allow further cleaning.

4. Bidirectional Sealing: The floating seat design ensures that media pressure from either direction presses the seat tightly against the gate, providing bidirectional zero leakage (soft seal) or low leakage (metal seal).

5. Anti‑Sticking Design: Extended guides, hardened gate surfaces, and wiper rings on packing effectively prevent the gate from sticking due to dried slurry.

6. Full‑Bore Low Flow Resistance: When fully open, the gate is completely out of the flow path, minimizing pressure loss and reducing pumping energy.

7. Remote ON‑OFF Control: With electric or pneumatic actuators, remote automatic open/close operation is possible.

8. Manual Emergency Operation: Electric/pneumatic actuators are equipped with a handwheel for manual operation during power or air supply failure.

Working Conditions

1. Applicable Media: Mineral slurry, coal slurry, pulp, tailings, mud, sludge, red mud, phosphate slurry, lime slurry, particle‑laden liquids, etc.

2. Temperature Range: –20°C to +120°C (rubber/polyurethane seats); –29°C to +200°C (PTFE seats); –29°C to +550°C (metal seats).

3. Pressure Rating: PN10, PN16 (Class 150); higher ratings available on request.

4. Nominal Diameter: DN50 – DN800 (2″ – 32″); larger sizes available on request.

5. Installation Orientation: Vertical stem‑up recommended. For settling media, horizontal installation with the valve at a low point is advised.

6. Typical Applications:

   1. Mineral processing slurry transport lines

   2. Coal slurry and ash slag lines in coal‑fired power plants

   3. Pulp and coating slurry lines in paper mills

   4. Sludge discharge in wastewater treatment plants

   5. Red mud lines in alumina refineries

   6. Phosphate slurry and titanium dioxide slurry in chemical plants

   7. Cement slurry and lime slurry lines in building materials industry

Summary

The Slurry Knife Gate Valve, with its hardened wear‑resistant gate, bidirectional floating seats, self‑cleaning flow path, and optional flush ports, is the ideal shut‑off valve for handling highly abrasive, high‑concentration slurry media in mining, power generation, papermaking, chemical, and other industries. Compared with standard knife gate valves, the slurry version offers significantly improved wear resistance, anti‑sticking performance, and sealing reliability, making it suitable for severe services such as mineral slurry, coal slurry, pulp, and mud. With flanged connections, a full‑bore flow path, and optional manual or automated actuators, the Slurry Knife Gate Valve is a durable and efficient professional solution for ON‑OFF pipeline systems that require reliable shut‑off of high‑solids abrasive slurries.