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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.
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.
1、 Working principle of solenoid valve - Introduction
Electromagnetic valve, also known as Electromagnetic value in English, is an automated basic component used to control fluids. It is commonly used in industrial control systems to adjust parameters such as direction, flow rate, and velocity of media. Electromagnetic valves have the characteristics of high precision, good flexibility, multiple models, and wide applications. Electromagnetic valves can be divided into various types, and different electromagnetic valves can play their roles in different positions of the control system.
2、 Working principle of solenoid valve
There is a sealed chamber inside the solenoid valve, with a piston in the middle and two electromagnets on both sides of the chamber. Once the electromagnetic coil is energized, the valve body is attracted to the direction of the energized electromagnet by force; And there are through holes at different positions in the chamber, connecting different oil pipes, so the part of the oil discharge hole can be selected to be opened by controlling the movement of the valve body; Due to the oil inlet being in a normally open state, the movement of the valve body allows hydraulic oil to enter different oil discharge pipes. The pressure of the oil pushes the piston of the cylinder, which in turn pushes the piston rod, thereby driving the mechanical device. By utilizing this principle, it is possible to achieve the function of controlling mechanical motion by controlling the on/off of electromagnetic current.
3、 Working principle of solenoid valve - classification
Electromagnetic valves can be classified into various types based on their functions, such as water solenoid valves, high-pressure solenoid valves, fire solenoid valves, etc. They can also be classified into six types based on valve structure, materials, etc.: direct acting diaphragm structure, pilot diaphragm structure, distributed direct acting piston structure, etc. However, the most important classification method for solenoid valves is based on their principles, which can be divided into three types: direct acting solenoid valves, step-by-step direct acting solenoid valves, and pilot operated solenoid valves. Next, let's take a look at the differences in the principles of these three types of solenoid valves?
4、 Working principle of solenoid valve - direct acting solenoid valve
When the direct acting solenoid valve is powered on, it generates magnetic force through the electromagnetic coil to lift the closing member from the valve seat and open the valve, controlling the movement of the mechanical device; When the power is cut off, the electromagnetic force disappears, and the closing member is re pressed against the valve seat by the spring, causing the valve to close.
5、 Working principle of solenoid valve - pilot operated solenoid valve
When the pilot operated solenoid valve is powered on, the electromagnetic coil generates electromagnetic force to open the pilot hole, causing a sharp drop in pressure in the upper chamber and creating a high pressure difference between the upper and lower parts at the closing part. As a result, the closing part is pushed upward by pressure, and the valve is opened; When the power is cut off, the electromagnetic force disappears, and the pilot hole closes under the action of the spring, forming a pressure difference of high and low at the closing part, which then pushes the closing part downwards and closes the valve.
6、 Working principle of solenoid valve - step-by-step direct acting solenoid valve
The step-by-step direct acting solenoid valve combines the working principles of direct acting and pilot operated solenoid valve switches. When there is no pressure difference at the inlet and outlet or the pressure difference is small enough to push the valve to move, the valve is opened by the action of electromagnetic force (similar to the direct acting solenoid valve); When the pressure difference between the inlet and outlet can push the valve to move, use the pressure to open the valve (similar to a pilot operated solenoid valve); After power failure, when there is no pressure difference or electromagnetic force, the valve closes under the action of the spring.
In summary, the working principle of solenoid valves is to control the valve opening and closing by controlling the power on and off of the solenoid coil, thereby controlling the movement of the mechanical device. The difference in the working principle of the three types of solenoid valves lies in the different ways in which the solenoid coil opens and closes the valve.
There are many factors that affect the service life of solenoid valve products, and corrosion of solenoid valves is one of the important influencing factors. Extending the service life of solenoid valves, improving project safety, and anti-corrosion of solenoid valves are important considerations. How to effectively protect solenoid valve products, and what are the precautions in purchasing? You need to know the following methods.
Select corrosion-resistant materials based on the type of medium
In practical production applications, solenoid valves face a variety of media types, and even for the same medium, the corrosion rate of materials varies under different pressures, temperatures, and concentrations. For example, aluminum is highly corrosive in concentrated nitric acid with a concentration of over 80%, but its corrosion is not severe in medium to low concentrations of nitric acid. Carbon steel is most severely corroded in sulfuric acid with a concentration of 50%, and when the concentration reaches over 90%, the corrosion sharply decreases. So, when purchasing solenoid valve products, you can analyze the type of medium and the degree of corrosion of materials by different concentrations of media, or consult the manufacturer directly.
Select corrosion-resistant solenoid valves
Corrosion resistant solenoid valves are solutions specifically designed for corrosive media. Many corrosion-resistant solenoid valves use non-metallic materials as the contact surface between the solenoid valve cavity and the media. Materials such as natural rubber and polytetrafluoroethylene not only have good corrosion resistance, but also play a role in saving precious metals as long as the pressure and temperature of the project environment meet the characteristics of the materials.
Surface treatment of solenoid valve
The surface treatment of solenoid valves can be divided into thermal spraying and spray coating. Thermal spraying is one of the techniques for adding a protective layer to the surface of equipment. Thermal spraying is the use of high energy density heat sources, such as gas combustion flames, electric arcs, plasma arcs, electric heating, gas explosions, etc., to heat and melt metal or non-metal materials, and then spray them onto the pre treated basic surface in the form of atomization to form a spray coating. Thermal spraying can improve the corrosion resistance, wear resistance, high temperature resistance and other characteristics of the surface of solenoid valves, extending the service life of products.
Spray coating is a common method, which belongs to non-metallic materials. When applied to metal surfaces or cavities, it can effectively isolate the medium and atmosphere, achieving the purpose of corrosion prevention.
Control corrosive environment
Controlling the corrosive environment is mainly aimed at the working environment where the solenoid valve is located, such as effectively controlling dust, water vapor, smoke, and toxic gases in the environment to maintain cleanliness and dryness.
Electromagnetic valves are widely used in our production. Let's first have a preliminary understanding of electromagnetic valves. Electromagnetic valves are composed of electromagnetic coils and magnetic cores, and are valve bodies containing one or several holes. When the coil is powered on or off, the operation of the magnetic core will cause the fluid to pass through the valve body or be cut off, in order to change the direction of the fluid. The electromagnetic components of the solenoid valve consist of a fixed iron core, a moving iron core, coils, and other components; The valve body is composed of slide valve core, slide valve sleeve, spring base, etc. The electromagnetic coil is directly installed on the valve body, which is enclosed in a sealed tube, forming a simple and compact combination. The solenoid valves we commonly use in production include two position three-way, two position four-way, two position five way, etc. Let's first talk about the meanings of the two: for solenoid valves, it means being energized or de energized, and for the valves being controlled, it means being open or closed.
It consists of valve body, valve cover, electromagnetic components, spring, and sealing structure. The sealing block at the bottom of the moving iron core closes the valve body inlet with the pressure of the spring. After being powered on, the electromagnet is attracted, and the sealing block with a spring on the upper part of the moving iron core closes the exhaust port. The airflow enters the membrane head from the intake port, playing a controlling role. When the power is lost, the electromagnetic force disappears, and the moving iron core leaves the fixed iron core under the action of the spring force, moves downward, opens the exhaust port, blocks the intake port, and the diaphragm head air flows through the exhaust port to be discharged, and the diaphragm returns to its original position. In our oxygen production equipment, there are applications such as emergency shut-off of the membrane regulating valve at the inlet of the turbine expander
When current passes through the coil, excitation is generated, and the fixed iron core attracts the moving iron core. The moving iron core drives the slide valve core and compresses the spring, changing the position of the slide valve core and thus changing the direction of the fluid. When the coil loses power, the slide valve core is pushed by the elastic force of the spring, pushing the iron core back and forth, causing the fluid to flow in the original direction. In our oxygen production, the switch of the forced valve of the molecular sieve switching system is controlled by a two position four-way solenoid valve, and the airflow is supplied to both ends of the piston of the forced valve. So as to control the opening and closing of the forced valve.
