What is a knife gate valve?
When the valve disc of the knife gate valve is closed, its knife edge contacts the valve seat, forming a right angle, thus completely cutting off the fluid path, similar to cutting off a pipe with a knife. Therefore, people call it “knife gate valve”.
Specifically, the valve disk of the knife gate valve is shaped like a knife and can move along the axial direction of the pipe to control the flow of fluid. The valve seat is similar to a gate and can be sealed by contact with the valve disc. In the closed state, the valve disc contacts the valve seat to form a right angle, thus completely cutting off the fluid path and avoiding fluid leakage. In the open state, the valve disc moves upward and separates from the valve seat, allowing fluid to flow through the channel between the valve disc and the valve seat.
The valve disc of a knife gate valve is usually made of cast iron or stainless steel, and the valve seat is usually made of brass or stainless steel. Packing is often used to fill the gap between the valve disc and valve seat to enhance sealing performance. Transmission mechanisms usually include manual and electric, used to control the up and down movement of the valve disc.
Knife gate valves can be divided into various types according to their driving methods: ordinary knife gate valves, hydraulic knife gate valves, electric knife gate valves, pneumatic knife gate valves and hydraulic knife gate valves. Different types of knife gate valves are suitable for different working conditions and occasions.
Knife gate valve is a type of gate valve. Ordinary gate valves may have various problems such as heavy weight, large flow resistance, and difficulty in installation. The emergence of knife gate valve just solves these problems.
The knife gate valve can replace the general cut-off valve and can work under the working pressure of 1.0MPa-2.5MPa and the operating temperature of -29-550℃. The gate plate of the knife gate valve has a shearing function, which can scrape off the adhesive on the sealing surface and automatically remove debris. The stainless steel gate plate can prevent seal leakage caused by corrosion.
Why choose knife gate valve when the medium is mud?
Therefore, knife gate valves are a suitable valve option for handling slurries. In practical applications, the selection needs to be combined with the specific process requirements of the mud and the performance parameters of the valve to ensure the normal operation and processing efficiency of the mud.
The usage occasions and applicable media of knife gate valve are:
1. Mining, coal washing and steel industry – used for washing coal washing pipelines, filtering slurry pipelines, etc., and ash discharge pipelines;
2. Purification device – used for wastewater, mud, dirt and clarified water with suspended solids;
3. Papermaking industry – used for pulp and material-water mixtures of any concentration;
4. Ash removal in power stations – used for ash slurry.
What are the advantages of knife gate valves?
1.Simple structure:
The structure of the knife gate valve is relatively simple, consisting of a valve disc, a valve stem, a valve seat and a flange. It is easy to operate and maintain.
2. Fast opening and closing speed:
Since the valve disc of the knife gate valve is connected to the valve stem, when the valve stem rotates, the valve disc can open or close quickly, and the opening and closing speed is fast.
3. Good sealing performance:
The knife gate valve has good sealing performance between the valve seat and the valve disc, which can effectively prevent medium leakage and external impurities from entering the pipeline.
4.Wide range of application:
Knife gate valves are suitable for working environments under medium and low pressure and normal temperature conditions, and can be used to transport water, oil, gas, steam and other media.
5. Save space:
Because the knife gate valve has a compact structure and takes up less space, it can save pipeline space.
The installation of the knife gate valve is an important part to ensure its normal operation and service life. The following are the things you need to pay attention to when installing the knife gate valve:
1. Before installation, it is necessary to check whether the model, specification, and material of the valve meet the requirements, and confirm the opening direction of the valve and the flow direction of the fluid.
2. During the installation process, attention should be paid to the connection method between the valve and the pipeline, which usually uses flange connection or threaded connection. When connecting flanges, attention should be paid to the selection and installation of flanges to ensure the sealing of the connections.
3. Before installation, the inside of the pipeline should be cleaned to ensure that there are no impurities, iron filings and other substances inside the pipeline to avoid affecting the sealing of the valve.
4. After installation, check whether the valve opens and closes smoothly, and also check the sealing of the valve.
5. During use, the sealing performance of the valve should be checked regularly, and problems such as water leakage and air leakage should be dealt with promptly to ensure the normal use of the valve.
6. Stop valves should be installed upstream and downstream of the knife gate valve so that the valves can be repaired or replaced when necessary.
7. The installation position of the knife gate valve should meet the needs of operation and maintenance, and should avoid direct sunlight and high temperature environment.
