Knife Gate Valve Actuation Method

Release time:

2021-08-30

The ultra-thin knife gate valve, with its advantages of compact size, low flow resistance, light weight, ease of installation, and simple disassembly, has completely solved the longstanding challenges associated with conventional gate valves, flat-plate gate valves, ball valves, globe valves, control valves, butterfly valves, and other similar types of valves—such as high flow resistance, heavy weight, difficult installation, and large footprint. Since the introduction of the knife gate valve, a large number of general-purpose shut-off and control valves have been replaced by it. To date, the United States and Japan are the largest consumers of knife gate valves worldwide.

yingbei Drive types for knife gate valves: manual, chainwheel, electric, pneumatic, hydraulic, bevel gear, electro-hydraulic, and electro-pneumatic, among others. Knife gate valve body styles: exposed stem and concealed stem. Knife gate valve materials: cast iron, cast steel, carbon steel, stainless steel, fluoropolymer-lined, and others. Knife gate valve seals: various materials including hard seals, soft seals, single-sided seals, and double-sided seals.

The ultra-thin knife gate valve, with its advantages of compact size, low flow resistance, light weight, ease of installation, and simple disassembly, has completely solved the longstanding challenges associated with conventional gate valves, flat-plate gate valves, ball valves, globe valves, control valves, butterfly valves, and other similar types of valves—such as high flow resistance, heavy weight, difficult installation, and large footprint. Since the introduction of the knife gate valve, a large number of general-purpose shut-off and control valves have been replaced by it. As of today, the United States and Japan are the world’s largest consumers of knife gate valves.

The application range of knife gate valves is:

1. Mining, coal washing, and the iron and steel industry—used for coal washing pipelines, slurry filtration pipelines, ash discharge pipelines, and more;

2. Purification device—used for wastewater, slurry, sewage, and clarified water containing suspended solids;

3. Paper industry—used for pulp of any concentration and slurry-water mixtures;

4. Power plant ash removal—used for ash and slag slurry.

The vast majority of stainless steel knife gate valves employ forced sealing: that is, when the valve is closed, an external force is applied to forcibly press the gate against the high-pressure valve seat, thereby ensuring a tight seal on the sealing surfaces. Some gates can also be designed to undergo slight deformation, which helps improve their manufacturability and compensate for any misalignment in the sealing surface angles that may occur during the manufacturing process. Such gates are referred to as flexible gates. The majority of knife gate valves rely on forced sealing—meaning that when the valve is closed, an external force is used to press the gate firmly against the high-pressure valve seat, thus guaranteeing a secure seal on the sealing surfaces. Valves of this type are generally installed horizontally in pipelines.

2023-05-11

Next, let’s talk about several operating procedures for knife gate valves.

When a gate valve is closed, the sealing surfaces rely solely on the pressure of the medium to achieve a seal—specifically, the sealing surface of the gate is pressed against the valve seat on the opposite side by the medium’s pressure, thereby ensuring a tight seal. This type of sealing is known as self-sealing. In contrast, most gate valves employ forced sealing: when the valve is closed, an external force must be applied to press the gate against the valve seat in order to guarantee the sealing performance of the sealing surfaces. Such valves should be installed vertically in the pipeline.

2023-05-11

Next, let’s talk about whether knife gate valves have fire-resistant and anti-static requirements.

When an electrostatic knife gate valve is opened or closed, the sphere and the valve seat experience mutual friction. The static electricity generated by this friction tends to accumulate on the sphere—something that is unacceptable for ball valves used in gas, fuel, and chemical pipelines, as it could potentially lead to pipeline explosions. Ball valves with antistatic designs are equipped with static discharge devices.

2023-05-11

Next, let’s talk about some important considerations for the installation, operation, and maintenance of pneumatic knife gate valves.