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As an actuator for automated instruments, solenoid valves have seen a sharp increase in usage in recent years. Their main features are: (1) complete prevention of external leakage, easy control of internal leakage, and safe operation. Internal and external leaks are factors that pose a threat to safety. Other automatic control valves typically extend a valve stem, with electric, pneumatic, or hydraulic actuators controlling the rotation or movement of the valve core. All of this is necessary to address the problem of external leakage in the dynamic sealing of long-term operating valve stems ； Only the solenoid valve operates by using electromagnetic force on an iron core sealed inside a magnetic isolation sleeve; there is no moving seal, so external leakage can be easily prevented. Torque control of electric valves is difficult; internal leakage can occur, and in some cases the head of the valve stem may even break off ； The design of solenoid valves makes it easy to control internal leakage until it is reduced to zero. Therefore, solenoid valves are particularly safe to use, especially for corrosive, toxic, or high/low temperature media. (2) The system is simple, easy to connect to a computer, and inexpensive. Solenoid valves have a simple structure and low cost, and are easier to install and maintain compared to other types of actuators such as control valves. More significantly, the self-control system formed is much simpler and costs much less. Since the solenoid valve is controlled by switch signals, it is very convenient to connect it to an industrial computer. In today’s era of widespread computer use and significantly reduced prices, the advantages of solenoid valves become even more evident. (3) Quick-action, low power consumption, and lightweight design. The response time of solenoid valves can be as short as a few milliseconds, and even pilot-operated solenoid valves can have their response time kept within dozens of milliseconds. Due to its self-contained circuit, it responds more sensitively than other automatic control valves. Well-designed solenoid valves have very low power consumption, making them energy-efficient products ； It is also possible to automatically maintain the valve position simply by triggering the action, with no power consumption at all in normal operation. Solenoid valves have a small size, which saves space and makes them lightweight and attractive in appearance. String 7 (4) Limited adjustment accuracy, limited applicable media. Solenoid valves usually have only two states: on and off; the valve core can only be in two extreme positions and cannot be adjusted continuously. (There are many new concepts aimed at overcoming this limitation, but they are still in the experimental stage), so the precision of adjustment remains somewhat limited. Solenoid valves have high requirements regarding the cleanliness of the medium; media containing particles are not suitable, and any impurities must be filtered out first. Furthermore, viscous media are not suitable, and the viscosity range of media suitable for specific products is relatively narrow. (5) Various models available, with wide applications. Although solenoid valves have certain inherent limitations, their advantages remain very significant; as a result, they are designed in a variety of forms to meet different needs, making them extremely versatile in use. Advances in solenoid valve technology also focus on how to overcome inherent shortcomings and how to make better use of their inherent advantages. In the past, various technical parameters of solenoid valves both domestically and internationally were limited; nowadays, the diameter of solenoid valves in China has been increased to 300 mm ； The medium temperature ranges from as low as --200°C to as high as 450°C℃ ； Operating pressure ranges from vacuum to 25 MPa. The action time ranges from a few dozen seconds to a few milliseconds. The new developments in these technologies are now fully capable of replacing the traditional, bulky and expensive two-position control quick shut-off valves and pneumatic on/off valves; electric on/off valves can also partially replace the pneumatic and electric control valves used for continuous regulation