The advantages of butterfly valves are simple structure and good sealing effect; the disadvantage is that there is some disturbance to the water flow when the butterfly valve is fully open. Structural Characteristics The basic structural forms of butterfly valves are double offset and triple offset butterfly valves. The operating mechanisms of butterfly valves are usually manual, worm gear, electric, pneumatic, etc. Butterfly valves mainly consist of valve body, disc, shaft, sealing device, bracket, and control device. Manufacturing Guidelines The main function of butterfly valves is to seal water, steam, oil, etc. Therefore, the manufacturing guidelines for butterfly valves are to ensure reliable sealing, accurate and flexible operation. The sealing of butterfly valves mainly includes the main sealing between the valve body and the disc, the bearing composite sealing at the shaft part, and the sealing at the joints of various components. To ensure reliable sealing of butterfly valves, it is necessary to ensure that the dimensions, surface roughness, and positional tolerances of these parts meet the requirements of the drawings. It is also important to ensure that the dimensions, surface roughness, positional tolerances, etc. of all components meet the requirements of the drawings. The application range of butterfly valves is also quite wide. If they are used to control the flow rate, different types and valve body sizes need to be selected. Butterfly valves are widely used not only in general industries such as petroleum, gas, chemical, and water treatment, but also in cooling water systems of thermal power plants.

Line blind valve is a kind of gate valve that cuts off gas medium manually, electrically or pneumatically or hydraulically. It is generally divided into electric blind valve, hydraulic blind valve, closed plug valve and electric open blind valve. Basic Structure Line blind valve is composed of left and right valve bodies, telescopic movement mechanism, fan-shaped valve plate, electric control push rod Ⅰ for driving the valve plate, and electric push rod Ⅱ for clamping and loosening. Principle Introduction Line blind valve has three driving devices, including two manual clamping or loosening devices, and an electric device for opening or closing the gate. When opening or closing the gate, first loosen the two manual devices, and then start the electric device to open or close the gate (special note: the electric device is allowed to open only after the two manual devices are released). After the gate is opened or closed, the two manual devices are clamped, and the pipeline can work. Features Line blind valve, also known as spectacle valve, electric disc valve, is mainly composed of left valve body, right valve body, sector gate, stainless steel bellows, electric transmission device, electric clamping device and other components. The valve body adopts a three-point locking sector gate structure. The sealing adopts stainless steel and rubber sealing ring, which has good sealing performance and long service life. The sealing ring is installed on the gate plate, which is convenient for maintenance and replacement. Line blind valve is operated electrically, with stable operation, flexible start and reliable action.

The ball of floating ball valve is floating. Under the action of medium pressure, the ball can produce certain displacement and press tightly on the sealing surface at the outlet end to ensure the sealing at the outlet end. Structure 1. The valve stem should be inverted, anti-blowout structure. The valve stem of the valve should not be limited by the packing gland fasteners. To be precise, the valve stem will not be separated from the valve due to the loosening of the valve stem sealing fasteners when the valve is under pressure. 2. Anti-static structure. It consists of a stainless steel ball and a spring. One group is placed in the hole at the end of the valve stem, keeping in contact with the ball; the other group is placed on the cylinder of the valve stem, keeping in contact with the valve body, so that the possible static electricity is guided away from the valve body. 3. Fire-safe structural design. When the sealing seat is burned, the main and auxiliary valve bodies should be in contact with the sphere and maintain a certain degree of sealing. The connecting surfaces of the main and auxiliary valve bodies shall adopt gaskets with fire safety functions, such as metal wound gaskets. At the packing seal of the valve stem, when the packing (PTFE) is burned, there should be a graphite ring to prevent the medium from leaking out. 4. There should be a limit mechanism to accurately limit the ball to be in the "open" or "close" position. 5. There should be a platform for installing pneumatic, electric and worm gear actuator brackets on the valve body. Sealing Principle The opening and closing part of the floating ball valve is a sphere with a through hole equal to the diameter of the pipe in the middle. The inlet and outlet ends are each equipped with a sealing seat made of PTFE, and are contained in a metal valve body. When the through hole in the sphere coincides with the pipeline channel, the valve is in the open state; when the through hole in the sphere is perpendicular to the pipeline channel, the valve is in the closed state. When the ball valve is in the closed position, the medium pressure at the inlet end acts on the ball, generating a force to push the ball, making the ball press the sealing seat at the outlet end tightly, and a contact stress is generated on the tapered surface of the sealing seat to form a contact zone. The force per unit area of the contact zone is called the working specific pressure of the valve seal. When this specific pressure is greater than the necessary specific pressure for sealing, the valve is effectively sealed. This kind of sealing method that does not rely on external force is sealed by medium pressure, which is called medium self-sealing.

Vacuum ball valve refers to a ball valve whose working pressure is lower than the standard atmospheric pressure and forms a certain vacuum. Its working principle is similar to that of a vacuum butterfly valve, and the valve is opened and closed by rotating the ball fixed on the rotating shaft by 90°. Because the valve body and stem are made of stainless steel in its structure, and the sealing materials such as the valve seat and packing are all polytetrafluoroethylene, it is suitable for working conditions where the medium is air, water, steam, acid, alkali, etc. Features 1. It adopts 1/4 rotary pneumatic or electric actuator, which works smoothly, and the valve switch has electric signal output, which can be used both by hand and by electricity; 2. It not only has simple structure and good sealing performance, but also has small installation size, small driving torque, simple operation, and easy to realize rapid opening and closing; 3. It can be used in a high vacuum state or a low pressure system to achieve the advantages of both positive and negative pressure. Connection Forms (1) Flange connection: This is the most commonly used connection form in valves. According to the shape of the joint surface, it can be divided into the following types: ① Smooth type: used for valves with low pressure, it is more convenient to process; ② Concave-convex type: the working pressure is relatively high, and medium-hard gaskets can be used; ③ Tongue and groove type: gaskets with large plastic deformation can be used, which are widely used in corrosive media and have good sealing effect; ④ Trapezoidal groove type: use oval metal ring as gasket; ⑤ Lens type: The gasket is in the shape of a lens and made of metal; ⑥ O-ring type: It is a relatively new flange connection form developed with the emergence of various rubber O-rings, and its sealing effect is more reliable than ordinary flat washers. (2) Threaded connection: This is a simple connection method, often used in small valves. It is divided into two situations: ① Direct sealing: The internal and external threads directly play a sealing role. ② Indirect sealing: The power of thread tightening is transmitted to the gasket between the two planes, so that the gasket acts as a seal.

Wedge gate valve is a kind of gate valve. It is named for its sealing surface and vertical center line at a certain angle, that is, the two sealing surfaces are wedge-shaped. Wedge gate valves are divided into rising stem wedge gate valves and non-rising stem wedge gate valves. In the rising stem wedge gate valve, the stem moves up and down, and the stem nut is fixed. The non-rising stem gate valve has a fixed stem, and the disc moves up and down to complete the opening and closing. The driving methods include: electric, pneumatic, manual, gas-hydraulic, etc., and the connection methods adopt flange type, welding type, and wafer type. Working Principle The opening and closing part of the wedge gate valve is the wedge, and the movement direction of the gate is perpendicular to the direction of the fluid. Wedge gate valve can only be fully opened and fully closed, not suitable for regulation and throttling. Wedge gate valve generally completes the opening and closing of the valve by moving the valve stem up and down with the rotating hand wheel. Structural Characteristics 1. Compact structure, reasonable design, light and flexible, good rigidity of the valve, smooth passage, small flow coefficient; 2. The sealing surface is made of stainless steel and hard alloy, which has a long service life; 3. With flexible graphite packing, the seal is reliable. Application Range Wedge gate valve is widely used in electric power, petroleum, chemical industry, metallurgy, mining, sewage treatment and other industrial fields, especially in the ash removal and coal washing plant equipment of power stations.

Resilient seated sealing gate valve utilizes the compensation effect of the elastic deformation of the overall rubber covering of the gate to achieve a good sealing effect, and overcomes the problems of poor sealing, water leakage and rust in general gate valves. Resilient seated sealing gate valve can be widely used in tap water, sewage, construction, petroleum, chemical industry, food, medicine, textile, electric power, shipbuilding, metallurgy, energy system and other working conditions, and it is used as a shut-off device on the fluid pipeline. Features of Resilient Seated Sealing Gate Valve: 1. Flat-bottom valve seat, no dirt accumulation, more reliable sealing. 2. The wedge is covered with nitrile rubber as a whole, and the internal parts of the valve are made of corrosion-resistant stainless steel and copper alloy materials, which can be used in the sewage system and adapt to the harsh working environment. 3. Small size, light weight, easy to install and maintain. 4. The valve stem is sealed with three O-rings, which greatly reduces the friction resistance when switching, and the switch is light and water-proof. 5. The valve body is made of precision casting, and the precise geometric dimensions make the valve body tight without any finishing work. 6. The copper nut and the elastic wedge are embedded in the joint, so that the two are closely integrated into one body, and there is no loosening or damage caused by the vibration caused by the water flow. 7. The valve body is coated with powder epoxy resin, which can prevent corrosion and rust of the valve body and can be used in sewage system. 8. The inside of the valve body is coated with non-toxic epoxy resin, and the inner and outer surfaces of the valve are completely covered with rubber, which will not rust or corrode, and can be used for raw drinking.