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Gate valves and butterfly valves are both used in pipelines to open and close as well as to regulate flow rate. Of course, there are still methods for selecting butterfly valves and gate valves. In water supply networks, in order to reduce the depth of pipe burial, butterfly valves are generally selected for pipes with larger diameters; for pipes where the burial depth is not significantly affected, gate valves are preferred. However, gate valves of the same specifications are more expensive than butterfly valves. As for the boundary for caliber, it should be determined locally based on specific circumstances. Based on usage over the past decade, butterfly valves experience more failures than gate valves; therefore, it is worth considering expanding the use of gate valves where conditions permit. Regarding gate valves, in recent years many valve manufacturers in China have developed and replicated soft-sealed gate valves. These types of gate valves have the following advantages over traditional wedge-type or parallel double-plate gate valves: The valve body and valve cover of soft-sealed gate valves are manufactured using precision casting methods, resulting in a one-piece structure that requires little to no mechanical processing; moreover, no sealing copper rings are used, which helps save non-ferrous metals. The bottom of the soft-sealed gate valve has no pits, so no residue accumulates, resulting in a low failure rate when opening and closing the valve. The soft-sealed rubber-lined valve discs have uniform dimensions, offering high interchangeability. Therefore, soft-sealed gate valves will be a format favored by the water supply industry. Currently, the diameter of soft-sealed gate valves manufactured in China can reach 1500 mm, but most manufacturers produce valves with diameters ranging from 80 to 300 mm; there are still many issues regarding the manufacturing processes in China. The key component of a soft-seal gate valve is the rubber-lined valve disc, and the technical requirements for such valve discs are quite high; not all manufacturers abroad are able to meet them, so it is common to purchase them from manufacturers with proven quality in order to assemble them. In domestic soft-seal gate valves, the copper nut block is mounted above the rubber-lined valve plate, following a structure similar to that of gate valves; however, the friction caused by the movement of this nut block can easily lead to the peeling off of the rubber lining on the valve plate. In the soft-seal gate valves produced by a foreign company, the copper nut is embedded within the rubber-lined gate plate, forming a single unit that overcomes the aforementioned disadvantages; however, a high degree of concentricity is required between the valve cover and the valve body. However, when opening and closing soft-sealed gate valves, they must not be closed too tightly; it is sufficient to achieve water-blocking effect. Otherwise, it will be difficult to open them or the rubber lining may peel off. A valve manufacturer uses torque wrenches to control the degree of closure during valve pressure testing, and valve operators for water supply companies should also adopt this method of opening and closing valves. What is the difference between butterfly valves and gate valves in usage? In terms of the functions and applications of gate valves and butterfly valves, gate valves have low flow resistance and good sealing performance. Since the valve plate of a gate valve is perpendicular to the direction of the medium flow, if the valve plate does not fully open or close, the impact of the medium on the plate causes it to vibrate; this can easily lead to damage to the seal of the gate valve. A butterfly valve, also known as a flap valve, is a type of control valve with a simple structure. It can be used to switch on and off fluids in low-pressure pipelines. In this type of valve, the closing element (the valve disc or flap) is circular in shape, and it rotates around the valve shaft to enable opening and closing. Such valves can be used to control the flow of various types of fluids, including air, water, steam, various corrosive substances, slurry, oils, liquid metals, and radioactive materials. It mainly serves to cut off and throttle flow in pipes. The operating element of a butterfly valve is a disc-shaped butterfly plate that rotates around its own axis within the valve body, thereby achieving the purpose of opening, closing, or regulating flow. The butterfly plate is driven by the valve stem; turning it 90° completes one cycle of opening and closing. By changing the deflection angle of the butterfly valve, the flow rate of the medium can be controlled. Operating conditions and media: Butterfly valves are suitable for use in pipeline systems in various engineering applications such as blast furnaces, gas production, natural gas, liquefied petroleum gas, municipal gas, hot and cold air systems, chemical processing and smelting industries, as well as power generation and environmental protection projects. They are used to regulate and stop the flow of various corrosive and non-corrosive fluid media. A gate valve consists of a gate as the closing element, whose movement is perpendicular to the direction of the fluid flow. The gate valve can only be in an fully open or fully closed position; the angle at which it operates varies depending on the parameters, usually being 5°, and 2°52’ when the temperature of the medium is not high. By improving its workability and compensating for the deviations in the angle of the sealing surface that occur during processing, this type of gate valve is called an elastic gate valve. When the gate valve is closed, the sealing surface can be sealed solely by the pressure of the medium; that is, it is the pressure of the medium that presses the sealing surface of the gate against the valve seat on the other side to ensure sealing, and this is what is known as self-sealing. Most gate valves use forced sealing; that is, when the valve is closed, external force is required to press the gate against the seat in order to ensure the sealing of the sealing surface. Type of operation: In a gate valve, the gate moves in a straight line along with the valve stem; this type is also known as a straight-stem gate valve. Typically, a trapezoidal thread is present on the lift rod; through the nut at the top of the valve and the guide groove on the valve body, rotational motion is converted into linear motion, that is, the operating torque is transformed into an operating thrust. When the valve is opened, the flow path is completely unobstructed when the lift height of the gate equals 1:1 of the valve’s diameter; however, this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a reference point – that is, the position at which it can no longer be moved – and this is considered its fully open position. To account for locking due to temperature changes, it is common to turn the valve to its full-open position and then reverse it by 1/2–1 turn as the position for a fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (i.e., the stroke). In some gate valves, the stem nut is located on the gate itself; turning the handwheel causes the stem to rotate, thereby lifting the gate. Such valves are known as rotating-stem gate valves or non-rising-stem gate valves.