Pneumatic solenoid valve is always faulty, how to deal with it correctly?

Pneumatic solenoid valve is always faulty, how to deal with it correctly?

When it comes to solenoid valves, they are now very common in industrial applications, especially in the petroleum and chemical industries, many process pipelines have to install on-off valves, and because the work site is very dangerous, the safety requirements are more stringent than other industries, large chemical enterprises have specialized instrumentation workers, and small electricians are basically responsible for daily management and maintenance.

Here is the pneumatic solenoid valve commonly used in this industry, some are mounted on the cylinder, and some are mounted next to the cylinder with a bracket. Pneumatic solenoid valve can be widely used in these high-risk industries, with fire, explosion-proof, good safety, pollution-free and other advantages, is not available in other transmission components. The basic components are divided into electromagnetic parts and valve body electromagnetic parts; Fixed core, moving core, coil. Valve body; Spool, spool sleeve, spring base.

Basic overview of two-position three-way solenoid valve, two-position four-way solenoid valve and two-position five-way solenoid valve. Two-position three-way solenoid valve working process; The coil gets electricity, the coil excited the electromagnet draws, the sealing block of the charged spring on the upper part of the moving iron core closes the exhaust port with the help of the spring pressure, and the compressed air enters the valve cylinder from the intake port to play a controlling role. When the power is lost, the electromagnetic force disappears, the moving iron core moves downward from the fixed iron core under the force of the spring, the exhaust port is opened, the intake port is closed, and the valve cylinder changes its state due to the loss of air. Two four-way, two five-way solenoid valve working principle is the same as the above principle, but the number of exhaust ports is different. The meaning of the two digits here; For the solenoid valve itself, it is power and power loss, and for the controlled valve, it is open and close. The meaning of several passages; Refers to the number of holes of the solenoid valve, get the physical look at a glance.

The power supply of the solenoid valve has 220V power supply and 24V power supply, and 24V power supply is mostly used in high-risk industries. On the whole, each has its own advantages. The use of 220V power supply is not conducive to on-site explosion protection, but is conducive to long-distance transmission. The reason is that the supply voltage is high, and the voltage drop caused by the transmission cable will not affect the normal operation of the solenoid valve. The use of 24V power supply is conducive to on-site explosion-proof, but the transmission distance is far, and the influence of the voltage drop of the transmission cable on the work of the solenoid valve must be considered. Therefore, it is necessary to calculate the maximum allowable length of the transmission cable according to the minimum working voltage of the solenoid valve.

For example, the 24V power supply is used, the minimum working voltage of the solenoid valve is 20V, the maximum allowable voltage drop of the line is 4V, the rated power is 12W, the polyvinyl chloride insulated sheath control cable is used, the wire diameter is 2.5mm2, and the two-wire system is used. The maximum length of the control cable L is calculated by looking at the table, it is known that the maximum DC resistance of the control cable is 7.1Ω/Km, and because the resistance of the voltage drop generated by the line is R = 8Ω, the maximum allowable length of the control cable is 1.079Km. And because of the use of two-wire control cable, so each control cable length of 539m. Through theoretical calculation, it is known that when the solenoid valve is not lower than the normal working voltage of 20V, the longest line transmission distance of 2.5mm2 can reach 539m.

Common faults occur during the application of the solenoid valve

The solenoid valve connector is loose or off, the coil is burned out, and the solenoid valve is stuck. Solenoid valve wiring loose and fall off, this new fastening, for coil burn, see coil head LED off or insert a metal object into the coil hole is sucked, solenoid valve coil damaged replacement. For the problem of solenoid valve sticking, remove the spool, spool sleeve and spring base, clean it up, and apply grease after cleaning. The reason is that the exhaust port is not equipped with a silencer, the impurities in the air enter the valve, or the compressed air is not clean enough, containing impurities, water, oil and other dirt.

To solve the problem, the exhaust port of the solenoid valve is not installed with a silencer, and the air filter reducing valve should be installed in the front section of the solenoid valve intake. The advantages of the air filter pressure reducing valve can filter out impurities, absorb compressed air containing water, oil, etc., so as to purify the compressed air and avoid unnecessary damage to the solenoid valve body and cylinder.

Air filter pressure reducing valve, in addition to the above can also be adjusted. The compressed air used in general factories is 10 kilograms, that is, 1MPa. If the air filter reducing valve is not installed for pressure regulation, the damage to the cylinder is large, and it is not conducive to the control of the switching speed. Under normal circumstances, the working air source pressure of the valve can meet the switching needs of the valve at about 0.4MPa, so the compressed air from the air compressor station must be depressed and adjusted to the pressure suitable for the valve action, so as to better protect the valve and the control of the switching speed.