What is a knife gate valve? What are the key points to consider during installation?

Release time:

2022-04-20

What is a knife gate valve? What are the key points to consider when installing it? A knife gate valve is a common type of electric gate valve, and can also be regarded as a very typical on-off switch. Its shape somewhat resembles an ancient hay cutter, which is why people habitually refer to this type of switch valve as a “knife gate valve.” Many people also call it simply a “knife valve.”

　　The knife gate valve is a common type of electric gate valve and can also be regarded as a very familiar switch. Its shape somewhat resembles an ancient hay cutter, which is why people habitually refer to this type of switch valve as a “knife gate valve.” Many also call it a “knife valve.” The shape of the knife gate valve can be vividly described in this way. Today, knife gate valves are not only used in electrical circuits; rather, they are increasingly employed across most industries in industrial piping systems. Modern knife gate valves are no longer as simple as the blades used in old electrical circuits—they now feature more complex structures and advanced functionalities. Below is an explanation of how a knife gate valve works.

　　The knife gate valve mainly consists of three components: the operating handwheel of the knife gate valve, the outer wall of the valve body, and the internal control mechanism. We primarily operate the knife gate valve by turning its easy-to-handle handwheel, which sets in motion a series of physical actions within the valve body’s internal control mechanism, ultimately enabling the valve to open and close and ensuring its proper functioning for controlling the flow through the pipeline.

The internal structure of a knife gate valve is highly complex. By manually turning the handwheel of the knife gate valve, we set it in motion, which in turn activates the levers and gears inside the valve. Through this coordinated movement, the locking mechanism within the valve can change rapidly, allowing the knife gate valve to open and close depending on the direction of rotation. Moreover, this operation can be completed in a very short time, effectively saving time and enhancing operational efficiency.

　　What should be noted when installing and using knife gate valves?

1. When installing the valve, make sure to leave sufficient space for the valve actuator.

2. Before installing the gate valve, inspect the valve cavity and sealing surfaces to ensure there is no dirt or sand adhering to them.

3. If the gate valve is frequently opened and closed, lubricate it at least once a month.

4. The wiring of the drive unit should be carried out according to the circuit diagram.

5. Gate valves require regular maintenance and must not be subjected to random impacts or compressions, as this could compromise the seal.

6. Handwheels, hand levers, and transmission mechanisms must not be used for lifting purposes, and collisions are strictly prohibited. Therefore, when installing and using knife gate valves, it is important to pay attention to these details to ensure their optimal performance.

Therefore, when installing and using knife gate valves, it is important to pay attention to these details to ensure their proper performance.

The applicable scope of knife gate valves is:

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

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

3. Paper industry – used for pulp and water mixtures of any concentration;

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

　 If you’d like to learn more about knife gate valves, feel free to contact us. We can provide you with detailed information on this topic from various perspectives.

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?