Manually operated gate valves are easy to operate, and most underground pipeline gate valves rely on manual opening and closing, making them cost-effective and highly competitive. However, the lack of brand recognition and numerous other unfavorable factors mean that this sizable valve market has yet to achieve true market maturity. Worm-gear butterfly valves should be relatively inexpensive. The worm-gear butterfly valve utilizes a gear-lever mechanism. The gears on the valve rotate, driving the lever to open and close the valve disc. Worm-gear butterfly valves have a more efficient and reliable design, making their operation smoother and easier. For some large-diameter valves, they represent an excellent choice; however, opening and closing such valves can take a considerable amount of time. Their price is higher than that of manual butterfly valves but lower than that of electric ball valves or pneumatic butterfly valves. As a general fact, the major difference between a butterfly valve and a gate valve lies in their respective closing mechanisms: a butterfly valve uses a disc-shaped closure member, while a gate valve employs a spherical closure member. The gate valve evolved from the plug valve. It exhibits the same degree of flow resistance. Since the operating power of thermal steam traps comes from steam, and oil in electro-deionized wastewater is highly surface-active emulsified oil, whereas cyclonic separation is a physical, foot-operated degreasing process, the inlet oil concentration of the cyclone must remain within the designed range to ensure proper performance of the cyclonic separation equipment.

　　The manual blind flange valve features a disc-shaped closure member that is either a ring-shaped recessed hole or a sphere with a bore passing through its center. The ratio between the spherical surface and the opening of the flow passage should ensure that, as the sphere rotates, its surface completely fills both the passage and the outlet, thereby effectively blocking fluid flow. Because the valve requires only a small rotation angle and minimal torque to achieve a tight shut-off, it can be fully closed with ease. The valve’s design provides a compact structure and convenient operation and maintenance, making it suitable for handling common working media such as water, organic solvents, acids, and gases. It is also appropriate for extreme operating conditions involving substances like carbon dioxide, hydrogen peroxide, and methane gas, as well as petroleum and butadiene.

　　The gate valve is a new type of gate valve that has become widely used in recent years. It offers the following advantages: low hydraulic friction resistance, with a resistance coefficient equivalent to that of a pipe section of the same length. The upper-end port can be quickly closed to restore pipeline pressure during operation. However, the second injection method, due to its relatively dispersed total dosage of coagulant, cannot achieve the same effectiveness as the first injection method. Therefore, without increasing the cost of heavy media, adopting the second injection method is less than ideal.

　　The manual blind flange valve features a simple structure, compact size, and light weight. It has a compact design and is highly reliable. Currently, the sealing surface material of gate valves commonly uses plastics, offering excellent sealing performance. These valves are also widely used in ultrafiltration systems. They are easy to operate, quick to open and close, and can be fully opened or fully closed with a 90° rotation, making them suitable for remote operation. Maintenance is convenient; the ball valve has a simple structure, and its sealing ring is typically movable, allowing for relatively easy disassembly, replacement, and reinstallation.

　　When fully opened or fully closed, the sealing surfaces of the ball and high-pressure gate valve are isolated from the medium, making it difficult for the medium to cause corrosion of the valve’s sealing surfaces.

　　The application range is broad—from as small as millimeters all the way up to several meters—and the system can apply pressure ranging from high-vacuum pumps to ultra-high-vacuum pumps. A temperature control valve refers to a device installed on the water supply pipe of a heat-pipe radiator, which actually serves as a flow-control mechanism for temperature adjustment.

　　Gate valves are widely used in industries such as crude oil, chemical plants, power generation, papermaking, nuclear energy, aerospace, rocketry, and even in our daily lives.

　　Gate valves can be classified according to their structure.

　　1. Float switch

　　The ball in a gate valve is floating. Under high-pressure conditions, the ball can shift slightly and press against the sealing surface at the inlet and outlet ends, thereby ensuring a tight seal at these ports. The float-ball switch has a simple structure and excellent sealing performance; however, since the entire load borne by the ball—due to the working medium—is transmitted directly to the inlet and outlet sealing rings, it is crucial to ensure that the sealing ring material can withstand the operational loads. This spherical design is commonly used in medium- and low-pressure gate valves.

　　2. Fixed ball valve

　　The ball in a gate valve is fixed and does not move easily once pressed down. By introducing advanced automated machinery, it becomes possible to separate various types of substances—including solid-to-solid, liquid-to-liquid, and even ions in solutions—under different conditions. The manual blind flange valve with a fixed ball features a resilient high-pressure gate valve. After the pressure rises, the high-pressure gate valve moves, pressing the sealing ring against the ball to ensure a tight seal. Typically mounted on the shafts above and below the ball, this type requires low operating torque and is suitable for high-pressure and large-diameter valves. To further reduce the operating torque of the gate valve and enhance the reliability of its sealing performance, skeleton-sealed gate valves have recently been developed. These valves introduce special lubricants between the sealing surfaces, forming a floating oil film that improves sealing effectiveness and reduces operating torque. They are particularly well-suited for high-pressure and large-diameter valves.

　　3. Flexible Gate Valve

　　The ball of the gate valve is made of a flexible material. Both the ball and the seat ring are constructed from metal-composite materials, enabling them to withstand extremely high sealing pressures. The inherent pressure of the medium itself is insufficient to meet the sealing requirements; therefore, external force must be applied. This valve is suitable for use with high-temperature and high-pressure media. The flexible ball is manufactured by cutting flexible grooves into the inner cavity of the sphere, thereby imparting flexibility. When the flow passage is closed, the wedge-shaped seat is used to lift the ball and press it against the high-pressure valve body for effective sealing. Before the ball begins to rotate, the wedge-shaped head is released, allowing the ball to return to its original shape and creating a small gap between the ball and the high-pressure valve body. This gap helps reduce friction on the sealing surface and lowers the operating torque. Depending on the position of the flow passage, gate valves can be classified into straight-through type, three-way type, and angled type. The latter two types of valves are used for distributing media and changing the direction of the flow.

　　Gate valves specify the scope of application; the product manual applies to flanged-end electric (or pneumatic) ball valves. According to their different functions, flotation reagents can be categorized into collectors, frothers, and regulators. This helps maximize the equipment speed and machining accuracy of the workpiece.