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There are many types of butterfly valves, some for quick shut-off and others for continuous regulation. It is mainly used for large-diameter pipes under low pressure for liquids and gases. It is suitable for applications where pressure loss is low, flow regulation is required, and rapid on/off operation is needed. The temperature is usually below 300 degrees, and the pressure is below 40 kg (butterfly valves generally operate at low pressures, such as the basic CL600 grade). The media used are typically water and gases; no special requirements are placed on the media, and particle-based media can also be used. As a sealed butterfly valve, it has seen rapid development in synthetic rubber, making it a new type of shut-off valve. In our country, until the 1980s, they were primarily used as low-pressure butterfly valves, with synthetic rubber used for the valve seats. By the 1990s, due to increasing exchanges with foreign countries, hard-sealed (metal-sealed) butterfly valves saw rapid development. Currently, some valve manufacturers are able to produce medium-pressure metal-sealed butterfly valves stably, which should enable these butterfly valves to find application in a wider range of fields. Butterfly valves can be used to convey and control media such as water, condensate, circulating water, sewage, seawater, air, natural gas, liquefied natural gas, dry powder, slurry, pulp, and mixtures of suspended solids. Butterfly valves are suitable for flow regulation. Since butterfly valves cause relatively high pressure losses in pipelines, about three times those of gate valves, when selecting such valves it is necessary to fully consider the impact of these pressure losses on the pipeline system, as well as the safety of the valve disc under the pressure of the fluid in the pipeline when it is closed. Furthermore, the temperature limitations of the elastic valve seat material at high temperatures must be considered. Butterfly valves have a small structural length and total height, fast opening and closing speeds, and excellent fluid control properties; their structural principle makes them most suitable for producing large-diameter valves. When a butterfly valve is needed for flow control, the most important thing is to select the correct size and type of butterfly valve to ensure its proper and effective operation. Generally speaking, in terms of throttling, regulation, and mud media, short structural length and fast opening/closing speed (rotation speed of 1/4) are required. When low-pressure shutdown (small pressure difference) is required, butterfly valves are recommended. Butterfly valves can be chosen in cases of two-position control, reduced-channel flow, low noise, cavitation, minor leakage to the atmosphere, and abrasive media. When using butterfly valves under special operating conditions such as throttling control, tight sealing, severe wear, or low temperatures (cryogenic conditions), special three-eccentric or double-eccentric butterfly valves require the use of dedicated metal seal strip adjustment devices. The metal-to-metal sealed triple-eccentric butterfly valve can be used not only as a programmable valve in large-scale pressure swing gas separation units, but also in various fields such as petroleum, petrochemicals, chemicals, metallurgy, and power generation; it serves as an excellent alternative to gate valves and globe valves.