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Application description of butterfly valve and gate valve under different working conditions

Gate valves and butterfly valves act as switches in the use of the pipeline to regulate the flow. Of course, there are still methods in the matching process of butterfly valves and gate valves. The global valve network teaches you how to choose: gate valves and butterfly valves.
In order to reduce the depth of soil cover in the water supply pipe network, the butterfly valve is usually selected with a larger diameter. The impact on the depth of the soil is not large, and the gate valve is selected. However, the price of the gate valve of the same specification is higher than the price of the butterfly valve. As for the boundary of the caliber, it should be considered according to the specific circumstances. From the use situation in the past ten years, the failure of the butterfly valve is higher than that of the gate valve. Therefore, it is worthy of attention to expand the scope of use of the gate valve when conditions permit.
About gate valves In recent years, many domestic valve manufacturers have developed and imitated soft-sealed gate valves. These gate valves have the following characteristics compared with conventional wedge-type or parallel double-gate gate valves:
The valve body and valve cover of the soft seal gate valve are cast by precision casting method, which is formed once, basically not mechanically processed, and does not use a sealed copper ring to save non-ferrous metals.
There is no pit at the bottom of the soft seal gate valve, no slag is accumulated, and the failure rate of the gate valve opening and closing is low.
The soft seal rubber-lined valve plate is uniform in size and interchangeable.
Therefore, the soft seal gate valve will be a form that the water supply industry is willing to adopt. At present, the soft seal gate valve manufactured in China has a diameter of 1500mm, but most manufacturers manufacture caliber between 80-300mm. There are still many problems in the domestic manufacturing process. Global valve network believes that the key component of the soft-sealed gate valve is the rubber-lined valve plate, and the technical requirements of the rubber-lined valve plate are relatively high. It is not available to all manufacturers in foreign countries, and is often purchased from a reliable manufacturer.
The copper nut block of the domestic soft sealing gate valve is embedded above the rubber-filled valve plate. Similar to the structure of the gate valve, the rubber lining of the valve plate is easily peeled off due to the movable friction of the nut block. The soft sealing gate valve of a foreign company, the copper nut block is embedded in the rubber-lined ram, forming a whole, which overcomes the above shortcomings, but the concentricity of the bonnet and the valve body combination is relatively high.
However, when opening and closing the soft seal gate valve, it should not be closed too much, as long as the water stop effect is achieved, otherwise it is not easy to open or the rubber stripping. A valve manufacturer uses a torsion wrench to control the degree of closure during valve pressure test. The valve operator of the water company should follow this opening and closing method.
What is the difference between the use of butterfly valves in gate valves?
According to the function and use of the gate valve and the butterfly valve, the gate valve has small flow resistance and good sealing performance. Because the valve plate and the medium flow direction of the gate valve are vertical angles, if the gate valve is not in place in the valve plate switch, the medium slams the valve plate to make the valve plate vibrate. It is easy to seal the gate valve and damage it.
The butterfly valve, also known as the flap valve, is a simple regulating valve. The butterfly valve that can be used for the switching control of the low-pressure pipeline medium means that the closing member (valve or disc) is a disc that rotates around the valve shaft to achieve opening and closing. A valve that can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metals, and radioactive media. Mainly cut and throttle on the pipeline. The butterfly valve opening and closing member is a disc-shaped butterfly plate that rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjusting.
The butterfly plate is driven by the valve stem. If it is rotated through 90°, it can be opened and closed once. By changing the deflection angle of the disc, the flow of the medium can be controlled.
Working conditions and medium: Butterfly valve is suitable for conveying various corrosive and non-corrosive fluids in engineering systems such as furnace, gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting and power generation, building water supply and drainage, etc. On the pipe of the medium, used to regulate and cut off the flow of the medium.
The gate valve is a shutter of the opening and closing member. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully open and fully closed. The parameters of the door are different, usually 5°. When the medium temperature is not high. It is 2°52'. Improve the manufacturability and compensate for the deviation of the sealing surface angle during the machining process. This kind of ram is called elastic ram.
When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the ram is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, the external force is forced to press the gate to the valve seat to ensure the sealing of the sealing surface.
Movement mode: The gate of the gate valve moves linearly with the valve stem, also called the open gate valve. Usually, trapezoidal threads are provided on the lifting rod, and the rotary motion is changed into a linear motion by the nut at the top end of the valve and the guide groove on the valve body, that is, the operating torque is changed to the operating thrust. When the valve is opened, when the lifting height of the gate is equal to 1:1 times the diameter of the valve, the passage of the fluid is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a mark, that is, the position where the valve is opened, as its fully open position. In order to consider the temperature change, there is a lock-up phenomenon, usually at the position of the opening to the apex, and then back to 1/2-1 lap as the position of the fully open valve. Therefore, the full open position of the valve is determined according to the position of the gate (ie, stroke). Some gate valve stem nut is set on the gate, and the rotation of the hand wheel drives the valve stem to rotate, so that the gate is lifted. Rotary lever gate valve or dark rod gate valve.

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