Could you please provide a detailed introduction to the features of knife gate valves?

Release time:

2021-11-29

The knife gate valve, also known as the blade gate valve or knife-type gate valve, is suitable for pipelines conveying media such as pulps containing suspended particles and fibrous materials, sewage, coal slurry, and mixtures of fly ash, slag, and cement. It uses a blade-shaped gate that can cut through fibrous materials to effectively shut off these media. The valve body essentially has no internal chamber.

　　The gate rises and falls within a guide groove on the side, and is tightly pressed against the valve seat by protruding lugs at the bottom. If higher media sealing performance is required, an O-ring sealed valve seat can be used to achieve bidirectional sealing. According to the actuation method, knife gate valves are classified into manual knife gate valves, pneumatic knife gate valves, and electric knife gate valves. Knife gate valves feature lightweight, compact design, smooth flow path, low flow resistance, light weight, easy installation, and simple disassembly.

　　Nominal sizes range from DN50 to DN800, and the valve can operate normally under working pressures from 0.6 MPa to 1.6 MPa and service temperatures up to 100℃. The knife-type gate valve’s gate plate features a shearing action that effectively scrapes away adhering substances on the sealing surface, automatically removing debris. The stainless steel gate plate helps prevent sealing leaks caused by corrosion.

　　Product features: Ultra-short structural length saves material and significantly reduces the overall weight of the piping system. It occupies minimal useful space, effectively supports pipe strength, and reduces the likelihood of pipe vibration. The gate plate is made of austenitic stainless steel, greatly enhancing its corrosion resistance and effectively preventing sealing leaks caused by gate plate corrosion.

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.

Pneumatic knife gate valves have a wide range of applications, spanning from ordinary fields to more diverse industries—from coal preparation, gangue removal, and slag discharge in coal-fired power plants to urban wastewater treatment; from general industrial pipelines to pipeline systems used in food, sanitation, and pharmaceutical industries. So, what are the key considerations when installing, using, and maintaining pneumatic knife gate valves?

2023-05-11

Slurry Valve Manufacturer: How are stainless steel knife gate valves good?