Introduction to the various specifications and uses of common valves

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(1) Gate valve: The gate valve is one of the commonly used shut-off valves; it is primarily used to open or close the flow of fluid in a pipeline, and it is not suitable for regulating the flow rate of the fluid. Gate valves are suitable for a wide range of pressures, temperatures, and pipe diameters; they are particularly appropriate for medium- and large-diameter pipelines. Gate valves are used to shut off the flow of media. When fully open, the entire flow is unobstructed. At this point, the pressure loss during medium operation is minimal. Gate valves are generally suitable for situations where frequent opening and closing is not required. And maintain the condition with the gate fully open or fully closed. Not suitable for use as a regulator or throttle. For high-speed flowing media. The partial opening of the gate plate can cause vibration in the gate. Vibration, in turn, may damage the sealing surfaces of the gate and the valve seat. And throttling causes the gate plate to be eroded by the medium. In terms of structural form. The main difference lies in the type of sealing element used. Depending on the type of sealing element. Gate valves are often divided into several different types. Examples include: wedge gate valves, parallel gate valves, parallel double-disc gate valves, wedge double-disc gates, etc. The most commonly used forms are wedge gate valves and parallel gate valves. (II) Globe valves and throttle valves. A globe valve is a commonly used shut-off valve, primarily used to open or close the flow of medium in a pipeline; it is generally not used for flow regulation. Globe valves can be used under a wide range of pressures and temperatures, but they are generally employed in medium- and small-diameter pipelines. (III) Throttle valve: A throttle valve controls the pressure and flow rate of a fluid by altering the cross-sectional area of the flow path. It belongs to the category of control valves; however, due to structural limitations, it lacks the regulatory characteristics of control valves and therefore cannot be used as a substitute for them. Structurally, apart from the valve-opening element and related parts, the globe-type throttle valve is identical to a globe valve. The moving parts of throttle valves are mostly of conical streamlined design. (IV) Butterfly valve: A butterfly valve is a type of valve that uses a circular butterfly plate that rotates along with the valve stem to carry out the opening and closing actions. Butterfly valves are primarily used as shut-off valves, but they can also be designed to have both regulating and shut-off functions. Currently, butterfly valves are being used more and more in low-pressure pipelines of medium and large diameters. The disc of a butterfly valve is installed in the diameter direction of the pipeline. Within the cylindrical channel of the butterfly valve body. The disc-shaped butterfly valve rotates around its axis. The rotation angle is between 0° and 90°. When rotated to 90°. The valve is in the fully open state. Butterfly valves have a simple structure, small size, and light weight. It consists of only a few components. Moreover, it can be quickly opened and closed by just rotating 90°. Easy to operate. At the same time, this valve possesses excellent fluid control properties. When the butterfly valve is in the fully open position. The diaphragm thickness is the only resistance to the flow of the medium through the valve body. Therefore, the pressure drop generated by this valve is very small. Therefore, it has good flow control characteristics. Butterfly valves come in two types of sealing: elastic sealing and metal sealing. Elastic-sealed valve. The sealing ring can be embedded in the valve body or attached around the butterfly plate. Valves with metal seals generally have a longer lifespan than those with elastic seals. But it’s difficult to achieve a complete seal. Metal seals can withstand higher operating temperatures. Elastic seals have the drawback of being limited by temperature. If it is required that the butterfly valve be used for flow control. The most important thing is to choose the correct size and type of valve. The structural principle of butterfly valves makes them particularly suitable for manufacturing large-diameter valves. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemicals, and water treatment. It is also used in the cooling water systems of thermal power plants. The commonly used butterfly valves are wafer-type butterfly valves and flange-type butterfly valves. A wafer butterfly valve connects the valve to two pipe flanges using double-headed bolts. A flanged butterfly valve is a valve that has flanges on it. Bolt the flanges at both ends of the valve to the pipe flanges. The strength performance of a valve refers to its ability to withstand the pressure of the medium. Valves are mechanical products that withstand internal pressure. Therefore, it must have sufficient strength and stiffness. To ensure long-term use without cracking or deformation. (5) Check valve A check valve is a valve that can automatically prevent fluid from flowing in reverse. The valve disc of the check valve opens under the action of fluid pressure, allowing the fluid to flow from the inlet side to the outlet side. When the pressure on the inlet side is lower than that on the outlet side, the valve disc automatically closes under the action of factors such as the fluid pressure difference and its own gravity to prevent backflow of the fluid. The function of a check valve, which is a type of valve, is to allow the fluid to flow in only one direction. And it prevents directional flow. Usually, this type of valve operates automatically. Under the pressure of fluid flowing in one direction. The valve disc opens ； When the fluid flows in the opposite direction. The valve disc acts on the valve seat due to fluid pressure and its own weight. Thereby cutting off the flow. Check valves belong to this type of valve. It includes swing check valves and lift check valves. The swing check valve has a hinge mechanism. There is also a valve disc shaped like a door that rests freely on the inclined valve seat surface. (VI) Ball valve: A ball valve is a type of valve that uses a sphere with a circular opening as the closing element; the sphere rotates along with the valve stem to enable opening and closing. (7) Diaphragm valve: A diaphragm valve is a special type of shut-off valve, whose operating element is a diaphragm made of a soft material that separates the interior chamber of the valve body from the interior chamber of the valve cover. (8) Plug valve: A plug valve is a type of valve that uses a plug with holes as the closing element; this plug rotates along with the valve stem to enable opening and closing. The plug body of a plug valve is usually conical, but it can also be cylindrical. Plug valves feature a simple structure, rapid opening and closing, and low fluid resistance. Gate valves are commonly used in applications where the pressure is not high and the diameter is relatively small. Plug valves are commonly used to stop the flow of a medium, and they can also be used for distributing the medium. Three-way and four-way plug valves are primarily used to change the direction of the medium flow or to distribute it. Safety valve: Safety valves are used in pressurized equipment such as boilers and pressure vessels as overpressure protection devices. When the pressure of the medium inside the protected equipment rises abnormally to a specified value, the valve opens automatically, allowing for complete discharge in order to prevent further pressure increase; it then closes automatically when the pressure drops to another specified value. Pressure reducing valve: A pressure reducing valve is a type of control valve that reduces the inlet pressure to a desired outlet pressure by throttling through the moving part. It is able to maintain a relatively constant outlet pressure even when the inlet pressure and flow rate change, by utilizing the energy of the medium itself. Trap: A trap is used in steam systems and equipment; it functions to automatically remove condensate water, air, and other non-condensable gases, while preventing steam from leaking out.