Solenoid valve as an instrument of automation, in recent years a sharp increase in the amount. The main advantages exist in: 1) the use of safety, the leakage block must be easy to control internal leakage. Internal and external leaks are elements that endanger safety. Other self-control valve stem usually stick out by the electric, pneumatic, hydraulic actuator control spool rotation or movement. This must solve the long-term action of the valve stem seal leakage problems; only the electromagnetic valve is the role of electromagnetic force sealed in the magnetic separation within the sleeve to complete the core, there is no dynamic seal, so easy to block leakage. Electric valve torque control is not easy, prone to internal leakage, and even pulled off the stem head; structure of the solenoid valve easy to control the internal leakage until it drops to zero. Therefore, the use of special safety solenoid valve, especially for corrosive, toxic or high temperature medium. 2) The system is simple, then the computer, the price is low. Solenoid valve itself is simple, the price is low, compared to other types of actuators such as regulating valve easy to install and maintain. Even more remarkable is the composition of the control system is much simpler, the price is much lower. As the solenoid valve is the switch signal control, and industrial computer connection is very convenient. The popularity of today's computers, the price plummeted era, the advantages of the solenoid valve even more pronounced. 3) power is small, lightweight appearance, action express. Solenoid valve response time can be as short as a few milliseconds, even the pilot solenoid valve can be controlled within a few tens of milliseconds. Since the self loop, more responsive than other self-controlled valves. Well-designed solenoid valve coil power consumption is very low, is an energy-saving products; can also be done only trigger action, automatically maintain the valve position, usually do not consume electricity. Solenoid valve small size, saving space, but also lightweight and beautiful. 4) Model diversity, wide range of uses. Designed into a wide range of products to meet a variety of needs, the use of a very wide range. Solenoid valve is relatively speaking, with the above advantages, to a certain extent, there are deficiencies: the regulation accuracy is limited, the applicable medium is limited. Solenoid valve usually only switch two states, the spool can only be in two extreme positions, can not be adjusted continuously, so the adjustment accuracy is subject to certain restrictions. Solenoid valve on the media have a higher cleanliness requirements, including granular media can not be applied, in the case of impurities must be filtered out. In addition, viscous media can not be applied, and the range of viscosities for specific products is relatively narrow. However, as technology advances, the shortcomings of the solenoid valve will gradually narrow the range.