The knife gate valve, also known as the knife type gate valve or slurry valve, was introduced to China in the 1980s. Its application has expanded from daily use to a wide range of industries in less than 20 years. Initially used in coal preparation, refuse discharge, and sludge handling, it has since been applied in urban sewage treatment, and in industries such as food, hygiene, and pharmaceuticals.
Advantages of Knife Gate Valve
With its compact design, low flow resistance, light weight, and ease of installation and disassembly, the ultra-light knife gate valve has resolved problems such as high flow resistance, heavy weight, difficult installation, and large space requirements typically associated with other valves like gate valves, slab gate valves, ball valves, globe valves, control valves, and butterfly valves. Since its introduction to the market, it has replaced common valves used for shut-off and control.
Selection of Knife Gate Valve
Customers should specify the working conditions, fluid media, operating pressure, fluid temperature, nominal diameter, material, and quantity when purchasing valves.
If there are special requirements, customers should provide drawings and detail these specifications in the contract, so the valves can be customized to meet their needs.
If no specific brand is requested for the driving devices, they will be installed with specified models from the company.
Installation of the Knife Gate Valve
① Ensure there is no dirt or sand in the valve cavity or on the sealing surface before installation.
② Bolts on connections should be tightened evenly.
③ Check that the packing is tightly pressed to ensure sealing and smooth gate operation. Regularly lubricate and tighten bolts.
④ Before installation, verify the models, connection sizes, and flow direction of the valves to ensure they match the purchased specifications.
⑤ Allow sufficient space for the valve’s driving devices during installation.
⑥ Connect the wiring of the driving devices according to the circuit diagram.
⑦ Regular maintenance of knife gate valves is required, and they should not be subjected to impact that could affect their sealing.
Installation Type
Type A and B: Wafer connection type.
Type C and D: Flange connection type.
Please notify the company if you have any specific requirements for connection types.
Maintenance of the Knife Gate Valves
① Do not lift or collide with the handwheel, lever, or drive mechanism.
② The double-disc gate valve should be installed vertically (with the valve stem in a vertical position and the handwheel on top).
③ For gate valves with by-pass valves, the by-pass valve should be opened before the gate opens to balance the differential pressure between the inlet and outlet and
reduce the opening force.
④ The gate valve with a drive mechanism should be installed according to the provided instruction manual.
⑤ Valves that are frequently opened and closed should be lubricated at least once a month.
Sealing Structure Selection
Drawing 1: Uni-directional with hard sealing structure (suitable for high-temperature, low-sealing environments with solid particles).
Drawing 2: Uni-directional movable valve seat with hard sealing structure (suitable for solid particles, abrasion-resistant, with movable seat and cut-off gate).
Drawing 3: Uni-directional movable seat with soft sealing structure (suitable for pipes with slags and fibers, the seat can be replaced).
Drawing 4: Bi-directional soft sealing structure with no grooves (suitable for sewage and tap water pipelines).
Drawing 5: Bi-directional movable seat with hard sealing structure (suitable for silt and powder pipelines, abrasion-resistant, with replaceable seat).
Drawing 6: Bi-directional movable seat with no grooves bottom soft sealing structure (suitable for coal mines, slurry, sewage, and abrasion-resistant, with replaceable seat).
TU Series Bi-directional Sealing Slurry Valve (Non-Rising Stem)
The TU series bi-directional sealing slurry valve (non-rising stem) features a one-piece casting body and a U-type rubber sealing strip lined in the grooves of the valve body and gate edges, achieving zero-leakage standards. This valve is characterized by a lightweight structure, excellent sealing, easy operation, and a smooth cavity design that prevents blockages, ensuring full-bore flow. The valve is widely used in civil sewage treatment, power stations, paper-making, chemical industries, water systems, and sludge discharge in mines.
Suitable Media
The TU series valve is suitable for fluids containing suspended solid particles up to 49% and is commonly used in chemical plants, pumping systems, the food industry, and sewage treatment. The media should be filtered before passing through the valves to avoid damage from large solid particles.
Specification
Nominal Diameters: DN50 ~ DN2000 (custom designs available upon request).
Static Water Pressure Test
Sealing Test: Working pressure x 1.1
Shell Test: Working pressure x 1.5
Working Pressure
DN50-DN250: 10 kg/cm²
DN300-DN400: 6 kg/cm²
DN450: 5 kg/cm²
DN500-DN600: 4 kg/cm²
DN700-DN1200: 2 kg/cm²
Advantageous features:
Comparing with valves of same series, TU series slurry valve has following advantages:
① No grooves in the Valves bottom make no blocking in the cavity so as to have full bore flowing;
② Anti-dropping design of sealing strip makes the valve more durable;
③ Easy opening and closing with nice appearance and excellent sealing performance.
Main Spare Parts List
| Spare parts | Material |
| 1-Body | HT200、QT450、GGG40 |
| 2-Sealing | NBR、EPDM |
| 3-Gland | WCB |
| 4-Yoke | Q235 |
| 5-O-Ring | NBR |
| 6-Packing | PTFE+NBR |
| 7-Disc | 2Cr13、201、304、316(L) |
| 8-StemNut | Brass |
| 9-Stem | 2Cr13、201、304、316(L) |
| 10-Bearing | GCr9 |
| 11-handwheel | GGG40 |
Description of Main Parts and Structural Principles
Body:
The valve body is designed for bi-directional sealing, utilizing one-piece casting. Its full-bore design ensures minimal flow resistance and avoids blockages in the seat area, with a clear, attractive profile.
Disc:
The gate is processed with a mirror surface, reducing friction with the packing and improving the ease of operation and durability. The gate’s edge is smooth, reducing friction with the sealing strip for better sealing and increased wear resistance.
Sealing Materials:
The TU slurry valve’s sealing depends on the pre-tightened friction between the seat sealing strip and the gate edge for bi-directional sealing. The seat sealing strip is made of wear-resistant rubber for long-term durability and effective sealing.
Packing:
The packing design includes PTFE combined with wear-resistant rubber for improved elasticity and sealing performance. This packing design allows for easy adjustment during operation.
Stem:
The valve stem is made from wear-resistant stainless steel (2Cr13) and is available in different materials upon customer request. The stem structure can be either rising or non-rising, with the non-rising option preferred in most cases.
Gland:
The gland is designed to evenly compress the packing for effective sealing. It is made from cast steel or stainless steel depending on the valve body material.
Actuator:
The TU slurry valve can be equipped with various actuators, including handwheels, chain wheels, levers, worm gears, and electric, pneumatic, or hydraulic actuators. Custom brackets allow for flexible actuator choices, offering cost savings and adaptability.
For a detailed catalog of knife gate valves, please contact Eileen.
