Solenoid valves for medical equipment refer to instruments, equipment, appliances, materials or other related equipment used alone or in combination with human body. It is also the basic element of medical treatment, scientific research, teaching, institutions and clinical work, including professional medical equipment and household medical equipment. At present, as a medical device solenoid valve or medical solenoid valve in blood cell analyzer, biochemical analyzer, urine sediment analysis instruments have been applied. Medical equipment solenoid valve can also be used in environmental protection, spurting code printing, biology, chemistry, inspection and analysis, and many other fields. When selecting solenoid valve, we often consider that components can be very reliable repeated operation, especially to ensure long-term stability, namely repeated performance. It is better that there is no any operation fluctuation or exceptions for a long time period. This is often the first parameter for screening precision components. For example, the selection of solenoid valves used in blood cell sampling channel and counting channel will usually affect the repeatability of the whole machine. In high performance liquid chromatography, the more uniform the response time of the four element gradient solenoid valve is, the easier it is to meet the test requirements. If it is not uniform enough, there will be an intuitive result difference in sensitivity repeatability. In addition, in the analysis and testing instruments, the solenoid valve directly contacts the sample reagent, but most of the micro solenoid valves have internal rubber material, which may swell when contacting the sample reagent. If no pre-compensation is considered in the design, the rubber material will change the parameters and performance of the valve after a long time of use, and even affect the components can not work normally, thus leading to the problem that the whole instrument failure. Experienced component designers will take into account the valve's scope of application, especially the impact of practical applications such as chemical compatibility.