Let’s talk about how to install knife gate valves.

Release time:

2022-05-24

The closing and opening element of a knife gate valve is the gate plate, whose direction of motion is perpendicular to the flow direction of the fluid. Manual knife gate valves can only be fully opened or fully closed; they cannot be used for regulation or throttling. The gate has two sealing surfaces. In commonly used gate valves, these two sealing surfaces form a wedge shape. The wedge angle depends on the valve’s specifications and typically measures 50 degrees. The gate of a wedge-type knife gate valve can be either rigid or flexible.

　　The closing and opening element of a knife gate valve is the gate plate, whose direction of movement is perpendicular to the flow direction of the fluid. Manual knife gate valves can only be fully opened or fully closed; they cannot be used for regulation or throttling. The valve has two sealing surfaces. In commonly used gate valves, these two sealing surfaces form a wedge shape. The wedge angle depends on the valve’s specifications and typically measures 50 degrees. The gate of a wedge-type knife gate valve can be either rigid or flexible.

　　The gate can undergo slight deformation to enhance manufacturability and compensate for misalignment of the sealing surfaces during machining. The sealing surfaces are sealed by the pressure of the medium itself. When the knife-type gate valve is closed, the medium pressure presses the sealing surface of the gate against the opposite valve seat, ensuring a tight seal. To close the valve, the gate must be pressed down.

　　The valve seat relies on external force to ensure the sealing performance of the sealing surface. Manual knife gate valves feature a simple and compact structure, reasonable design, ease of fabrication and material savings, reliable sealing, simple and flexible operation, small size, unobstructed flow path, low flow resistance, light weight, convenient installation, and easy disassembly. They can operate under working pressure.

　　The valve operates normally at working temperatures ranging from 10 MPa to 25 MPa and between -29°C and 650°C. The gate of the knife-type gate valve features a shearing action that scrapes off any deposits on the sealing surface, actively removing dust and debris. The stainless steel gate helps prevent leakage caused by corrosion of the sealing elements. This type of valve is typically installed horizontally in pipelines.

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?