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To solve the reliability and maintainability issues of solenoid valves, in addition to giving sufficient consideration in design, strict control of key processes should also be implemented during the manufacturing process. The key manufacturing technologies and implementation methods for high reliability and maintainability solenoid valves include welding, processing, verification testing, and functional testing.
1. Welding
The welding parts of solenoid valves include sleeve, piston, valve head sealing surface welding, piston outer surface welding, and shield sleeve component self welding. Conduct full inspection before, during, and after welding to ensure that the welding quality meets the specified requirements.
2. Mechanical processing
The key technology for mechanical processing of solenoid valves lies in the precision machining of the sealing surfaces of the sleeve, piston, and valve head, as well as the precision machining of the inner hole of the sleeve, the inner and outer surfaces of the piston, and the outer circle of the valve head. These parts have high surface hardness and high dimensional accuracy, making them difficult to process. Firstly, these processing procedures should be identified as critical processes, and process capability assessment must be conducted before manufacturing. Only after passing the assessment can processing be carried out. During the machining process of parts, a control program with designated personnel, equipment, and processes is adopted to ensure the machining quality of the parts.
Principles for selecting specifications and models of solenoid valves
3. Grinding of sealing surface
In order to ensure the sealing performance of its valve seat, the sealing surface must be ground to achieve the required roughness. The contact surfaces between the piston and the sleeve, as well as between the piston and the valve head, should adopt a mating process to ensure that the sealing meets the specified requirements.
Self operated regulating valve (self operated control valve) relies on the pressure and temperature of the medium flowing through the valve as energy to drive the valve disc to change the valve opening, achieving automatic operation of regulating pressure, flow rate, and temperature, without the need for external power supply and secondary instruments. Self operated regulating valves are often used to control the pressure behind the valve. Refrigeration solenoid valves
The difference between pneumatic control valve and self operated control valve:
Self regulating valves can not only control the pressure behind the valve, but also control the pressure in front of the valve in many situations. The self regulating valve is actually a pure proportional control system, which may result in residual errors. The regulating valve controls pressure regardless of the flow rate. But for any type of regulating valve, the direct control is the flow rate. The biggest difference between these two types of valves is that the control valve requires both external energy sources (such as power or gas) as driving energy and external control instrument signals to change the relative position of the valve's shut-off component, thereby achieving a change in fluid flow rate. Self regulating valves, on the other hand, do not require external energy sources or signals from external control instruments. They can achieve pressure regulation solely based on the pressure signal of the regulated medium. The characteristic of self operated pressure regulating valve is that it does not have external driving energy, so the operating force of this product is relatively small.
Refrigeration solenoid valve
1. In terms of regulation: Regulating valves have higher regulation accuracy than self operated valves. The regulation accuracy of self operated regulating valves mainly depends on the accuracy of the spring and diaphragm of the self operated valve. Generally, the final regulation accuracy will not be better than 5%, with a guarantee of 10%. However, the final adjustment accuracy of ordinary regulating valves depends on the accuracy of the meter transmitter and the accuracy of the regulator, and the accuracy of the regulator is very high, and its impact is generally ignored. So the regulation accuracy of self operated valves is definitely much worse than that of ordinary regulation circuits. When the regulation accuracy requirements are high, it is not recommended to use self operated valves.
2. Application: One on-site, one remote transmission, one using medium pressure regulation, and one using instrument air. If the regulating valve is led to DCS control, it can be easily changed to the given value, and can be manually quickly closed or opened, with various related trend records. The self regulating valve cannot be adjusted and can only be operated on site. The degree of intelligence will be greatly reduced. Self operated regulating valves are difficult to adjust the set value, so they are used in situations where the setting does not need to be changed frequently, such as supplying lubricating oil to equipment. Self operated regulating valves require pressure from the process medium, so they are not suitable for use in relatively clean environments where the medium has corrosion, particles, etc.
3. Installation and design: Self operated regulating valves have pre valve pressure control and post valve pressure control. During design, proper spacing should be left for the installation of pressure points. During installation, the self regulating valve actuator on the steam pipeline should be installed downwards, and the pressure point should be connected to the condenser from the bottom of the main pipe. The condenser should be higher than the actuator and lower than the steam main pipe to avoid steam overheating and damage to the valve body. In addition, the actuator should be installed upwards. As self regulating valves are commonly used in gas pipes, the pressure point should be opened from the top of the main pipe at this time.
Scope of use of gas solenoid valve:
The product is suitable for automation pipeline control systems for flammable and explosive media in petrochemical, chemical, gas pipeline networks, industrial kilns, and pipelines.
Characteristics of gas solenoid valve:
Piston structure; Stable performance; Autocratic coil, long-term power supply, not easy to burn out;
Working principle of rapid shut-off valve:
A: When the valve needs to be opened, first power on the valve, unscrew the protective cover (there is a threaded hole in the middle of the protective cover, which can be used as a handle on the linkage rod), pull the handle firmly, and the valve will open.
B: When the valve needs to be closed, the coil loses power and the valve quickly closes.
Special function of rapid shut-off valve:
◆ Signal feedback: When the valve is opened, the signal common line and the open signal line are connected; When the valve is closed, the signal common line and the closing signal line are connected.
Manual function: When the safety valve needs to be closed, unscrew the manual protective cover and press the manual handle firmly to close the valve.
Generally used in conjunction with gas alarms
Exquisite appearance; Piston structure; Stable performance; Autocratic coil, not easy to burn out;
A: When the valve needs to be opened, unscrew the protective cover (there is a threaded hole in the middle of the protective cover, which can be used as a handle on the linkage rod), pull the handle firmly, and the valve will open.
B: When the valve needs to be closed, the coil should be energized for no more than 2 seconds and the valve should quickly close.
Zhejiang OST TECHNOLOGY Co. LTD. is a professional manufacturer of solenoid valves, specializing in the research and development, design, and manufacturing of various types of miniature solenoid valves.
Received unanimous praise from domestic and foreign customers.
Advantages of our company's solenoid valve products:
1. Free installation on site; Rapid action response; The valve body adopts precision casting technology and has a beautiful appearance.
2. Using original sealing materials, the lifespan is ten times that of similar products.
3. CNC machining ensures the accuracy and reliability of solenoid valves.
4. By using specially sealed coils, the reliability of the valve is improved, with a lifespan of over 2 million cycles.
5. Liquids, gases, and oils can be mixed and used to increase the range of valve applications.
6. A professional electromagnetic valve manufacturer that can satisfy customers before, during, and after sales of electromagnetic valves.
As an actuator of automation instruments, solenoid valves have seen a sharp increase in usage in recent years. This article provides a brief overview of the development trends of mature technologies in China, examining the directions of simplification, intelligence, generalization, and specialization. It also briefly discusses the social factors that affect the development of solenoid valve technology.
The development of the direction of refinement and simplification is essential, and only simplicity can be passed down for a long time. This is also the eternal pursuit of scientists and engineers.
(1) Simplify the control circuit. Previous actuators extensively used pneumatic and electric control circuits, which increased the complexity of the system. Pilot operated solenoid valves, on the other hand, form a control circuit inside the valve that utilizes the working medium itself, with a very simple structure. In the past, multiple technical parameters of solenoid valves at home and abroad were still limited, but now the diameter of solenoid valves in China has been expanded to 300000 mm; The medium temperature ranges from -200 ℃ to 450 ℃; The working pressure ranges from vacuum to 25MPa. The action time ranges from tens of seconds to a few milliseconds. The new development of these technologies can completely replace the bulky and expensive two position control quick shut-off valves, pneumatic switch valves, electric switch valves, and partially replace continuous adjustment pneumatic and electric control valves. (How to better meet the requirements of adjustment accuracy, which will be discussed in the following text). Foreign industries such as textiles, light industry, and urban construction have extensively adopted solenoid valves, while metallurgical and chemical industries have taken the lead in using more and more solenoid valves in auxiliary systems.
Domestic automation professionals are increasingly paying attention to solenoid valves.
(2) When simplifying the operation of the automatic control valve in the pipeline system, some auxiliary valves and fittings must also be equipped on the pipeline. For example, isolating the bypass is a typical installation method that requires three manual valves, with manual valve 1 being the bypass valve and manual backup. And manual valves 2 and 3 are isolation valves, ensuring online maintenance of automatic control valve 5. Of course, two tees 4 and a flexible connector 6 are also required. This piping system takes up a large amount of space, is time-consuming to install, and is prone to leakage. The ZDF series multifunctional solenoid valve cleverly eliminates these additional accessories and still has the function of isolating bypass, thus winning the Geneva International New Technology Gold Award. A filter needs to be installed in front of the automatic control valve. When multiple self-control valves are used in combination, it is often necessary to install one-way valves to prevent interference between pipelines. Now, one-way solenoid valves, combination solenoid valves, and filtered solenoid valves have all played a role in simplifying pipelines.
