Some knowledge about the application of the hottes

2022-09-29
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A little understanding of solenoid valve in application

solenoid valve is widely used in our production. We must have encountered many problems related to solenoid valve in the maintenance of production and dealt with various faults. Everyone must have accumulated a lot of experience in dealing with solenoid valve faults, and I deal with solenoid valve faults relatively less than other instrument and control faults in maintenance, Now I will discuss this issue with you, eager to learn more experience from you and improve together. Today's focus:

let's have a preliminary understanding of the solenoid valve. The solenoid valve is composed of solenoid coil and magnetic core. It is a valve body 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, so as to change the direction of the fluid. The electromagnetic components of the solenoid valve are composed of fixed iron core, moving iron core, coil and other components; The valve body is composed of slide valve core, slide valve sleeve, spring base, etc. The solenoid coil is directly installed on the valve body, and the valve body is enclosed in a sealed tube, forming a simple and compact combination. Our commonly used solenoid valves in production include two position three-way, two position four-way, two position five-way, etc. First, let's talk about the meaning of two bits: for the solenoid valve, it means energized and de energized, and for the controlled valve, it means on and off

in the instrument and control system of our oxygen generator, the two position three-way magnetic valve is most used to measure the strength, relative shortening rate and section increase rate of materials under static pressure. It can be used to connect or cut off the gas source in production, so as to switch the pneumatic control membrane head gas circuit

it is composed of valve body, valve cover, electromagnetic components, springs, sealing structures and other components. The sealing block at the bottom of the moving iron core closes the air inlet of the valve body with the help of the pressure of the spring. After power on, the electromagnet is attracted, the sealing block with spring on the upper part of the moving iron core closes the exhaust port, and the air flow enters the membrane head from the air inlet to play a control role. When the power is lost, the electromagnetic force disappears, the moving iron core leaves the fixed iron core under the action of spring force, moves downward, opens the exhaust port, blocks the air inlet, the membrane head gas flows through the exhaust port, and the diaphragm returns to its original position. In our oxygen production equipment, it is used in the emergency cut-off of the membrane regulating valve at the inlet of the turbine expander

the four-way solenoid valve is also widely used in our production, and its working principle is as follows:

when there is current passing through the coil, it will produce excitation, fix the iron core, attract the moving iron core, and the moving iron core will drive the slide valve core and compress the spring, which changes the position of the slide valve core, thus changing the direction of the fluid. When the coil loses power, the slide valve core is pushed by the spring force, and the iron core inlet pump is pushed back to make the fluid flow in the original direction. In our oxygen production, the switch of the forced valve of the molecular sieve switching system is controlled by the two position four-way solenoid valve, and the air flow is supplied to both ends of the piston of the forced valve respectively. So as to control the opening and closing of the forced valve

the failure of the solenoid valve will directly affect the action of the switching valve and the regulating valve. The common failure is that the solenoid valve does not act, which should be checked from the following aspects:

(1) the solenoid valve wiring head is loose or the wire head falls off, the solenoid valve does not reduce the production cost, and the wire head can be tightened

(2) if the solenoid valve coil is burnt out, the wiring of the solenoid valve can be removed and measured with a multimeter. If there is an open circuit, the solenoid valve coil is burnt out

the reason is that the coil is damp, resulting in poor insulation and magnetic leakage, resulting in excessive current in the coil and burning, so it is necessary to prevent rainwater from entering the solenoid valve. In addition, the coil can also be burnt out if the spring is too hard, the reaction force is too large, the coil turns are too few, and the suction is not enough. In case of emergency treatment, turn the manual button on the coil from the "0" position to the "1" position during normal operation to open the valve

(3) the solenoid valve is stuck. The fit clearance between the spool sleeve and the spool of the solenoid valve is very small (less than 0.008, which is widely used in the relevant laboratories of machinery, metallurgy, petroleum, chemical industry, building materials, construction engineering, aerospace, shipbuilding, transportation, and other industrial departments, colleges and universities, scientific research institutions mm). Generally, it is a single piece assembly, and it is easy to get stuck when there are mechanical impurities or too little lubricating oil. The treatment method is to poke the steel wire through the small hole in the head to make it bounce back. The fundamental solution is to remove the solenoid valve, take out the valve core and the valve core sleeve, and clean it with CCI4, so that the valve core can act flexibly in the valve sleeve. During disassembly, pay attention to the assembly sequence and external wiring position of each component, so that the reassembly and wiring are correct, and check whether the oil spray hole of the oil mist is blocked and whether the lubricating oil is sufficient

(4) air leakage. Air leakage will cause insufficient air pressure, making it difficult to open and close the forced valve. The reason is that the sealing gasket is damaged or the slide valve is worn, resulting in gas channeling in several cavities

when dealing with the solenoid valve failure of the switching system, it is necessary to choose an appropriate time to deal with it when the solenoid valve is in power loss. If it cannot be dealt with completely within a switching gap, the switching system can be suspended and dealt with calmly

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