It is an automation basic component used to control fluids. It belongs to an actuator and is not limited to hydraulic and pneumatic. Different solenoid valves play a role in different positions of the control system. The most commonly used ones are check valves, safety valves, directional control valves, speed control valves, etc.
How to deal with solenoid valve failure?
The rated voltages of solenoid valve coils are DC12V, DC24V, AC24V (50/60Hz), AC110V (50/60Hz), AC220V (50/60Hz), and AC380V (50/60Hz). Generally, in electrical design, either AC220V is used (no need to install a switching power supply, low cost, simple circuit and easy maintenance), or DC24V is used (commonly used safety voltage, switching power supply/solenoid valve coil are easy to repair and replace).
Methods for testing the quality of solenoid valves
First, pass the controlled medium (pressurized liquid, gas <air>, the pressure value is the middle value of the solenoid valve's operating pressure range) through the solenoid valve, and then energize the solenoid valve coil. If the controlled medium changes from on to off or from off to on, then the solenoid valve is good, otherwise there is a problem.
What are the common faults of solenoid valves?
1. Coil short circuit or open circuit: Detection method: First use a multimeter to measure its on and off, and the resistance value approaches zero or infinity, which means that the coil is short circuit or open circuit. If the measured resistance value is normal (about tens of ohms), it does not mean that the coil must be good (I once measured a solenoid valve coil resistance of about 50 ohms, but the solenoid valve could not move. After replacing the coil, everything was normal). Please perform the following final test: Find a small screwdriver and place it near the metal rod that passes through the solenoid valve coil, and then energize the solenoid valve. If you feel magnetism, then the solenoid valve coil is good, otherwise it is bad. Treatment method: Replace the solenoid valve coil. 2. There is a problem with the plug/socket: Fault phenomenon: If the solenoid valve is the kind with a plug/socket, there may be problems with the metal reed of the socket (I have encountered this before), problems with the wiring on the plug (such as connecting the power cord to the ground wire), etc., which may prevent the power from being sent to the coil. It is best to develop a habit: after the plug is plugged into the socket, tighten the fixing screw, and tighten the fixing nut on the coil after the valve core rod. If the plug of the solenoid valve coil is equipped with a light-emitting diode power indicator, then when using a DC power supply to drive the solenoid valve, it must be connected correctly, otherwise the indicator will not light up. In addition, do not exchange power plugs with light-emitting diode power indicators of different voltage levels, which will cause the light-emitting diode to burn out/the power supply (replace with a low-voltage plug) to short-circuit or the light-emitting diode to emit very weak light (replace with a high-voltage plug). If there is no power indicator, the solenoid valve coil does not need to distinguish polarity (unlike the transistor time relay with a DC coil voltage and the intermediate relay with a DC coil voltage with a diode/resistor leakage circuit in parallel on the coil <most of these intermediate relays are original Japanese>, which need to distinguish polarity). Solution: Correct the wiring error, repair or replace the plug or socket. 3. Valve core problem: Fault phenomenon 1: When the pressure of the medium passed by the solenoid valve is normal, press the red manual button of the solenoid valve, and the solenoid valve does not respond (the pressure medium does not change on and off), indicating that the valve core must be broken. Solution: Check whether there is a problem with the medium, such as whether there is a lot of water in the compressed air (sometimes the oil-water separator does not play a big role, especially when the pipeline design is poor, there will be a lot of water in the compressed air passed to the solenoid valve), and whether there are a lot of impurities in the liquid medium. Then remove the water or impurities in the solenoid valve and pipeline. If it still doesn't work, please repair (if you have time, patience and it is necessary @_@) or replace the valve core, or simply replace the entire solenoid valve. Fault phenomenon 2: After inspection, the coil is the original coil and the magnetism is normal when the coil is energized, but the solenoid valve still does not move (the function of the manual button of the solenoid valve may be normal at this time), indicating that the valve core is broken. Solution: Please repair or replace the valve core, or simply replace the entire solenoid valve. As for the repair of the solenoid valve body, because there are too many types, I can't say a lot of repair methods, so I won't go into details here.
Solenoid valve failure and troubleshooting
1. The solenoid valve does not work after power on. Check whether the power wiring is bad → Rewire and connect the connector. Check whether the power supply voltage is within the ± working range - → Adjust to the normal position range. Is the coil unsoldered → Reweld the coil short circuit → Replace the coil. Is the working pressure difference inappropriate → Adjust the pressure difference → Or replace the corresponding solenoid valve. The fluid temperature is too high → Replace the corresponding solenoid valve. There are impurities that make the main valve core and the moving iron core of the solenoid valve stuck → Clean, if there is any seal damage, replace the seal and install the filter. The liquid viscosity is too large, the frequency is too high and the life is over → Replace Product 2. The solenoid valve cannot close. The seal of the main valve core or the moving iron core is damaged → Replace the seal. Is the fluid temperature or viscosity too high → Replace the corresponding solenoid valve. Impurities have entered the solenoid valve core or the moving iron core → Clean the spring. The spring life has expired or deformed → Replace the throttle hole. The balance hole is blocked → Clean it in time. The working frequency is too high or the life has expired → Select the product or update the product. 3. Other situations. Internal leakage → Check whether the seal is damaged and whether the spring is poorly assembled. External leakage → The connection is loose or the seal is broken → Tighten the screws or replace the seal. There is noise when the power is on → The fasteners on the head are loose and tightened. The voltage fluctuation is not within the allowable range, adjust the voltage. The iron core suction surface has impurities or is uneven, clean or replace it in time.
Methods for quickly judging the quality of the solenoid valve on site
1. First, check whether the solenoid valve solenoid coil is faulty? Give the two-position valve an open or closed signal on the DCS, and then see whether the solenoid valve is powered on or off. Generally, you can listen to the sound on site. If you can't hear it, then there must be something wrong with the coil. As for whether there is something wrong with the solenoid valve itself? (Explanation below) If there is a problem with the solenoid coil, first check the wiring to see if there is a virtual connection or a short circuit. If there is no problem with the line, the solenoid valve coil is burned out. You can remove the wiring of the solenoid valve and measure it with a multimeter. If it is open, the solenoid valve coil is burned out. The reason is that the coil is damp, causing poor insulation and magnetic leakage, resulting in excessive current in the coil and burning. Therefore, rainwater should be prevented from entering the solenoid valve. In addition, the spring is too hard, the reaction force is too large, the number of coil turns is too small, and the suction force is insufficient, which can also cause the coil to burn out. Second, if the coil is good, then it is a problem with the solenoid valve itself. Generally, you can use a straight line to adjust the manual adjustment position from 1 to 0 to open the valve. If it can be opened, it means that there is indeed a problem with the coil and you can just replace the coil. If it cannot be opened, disassemble the solenoid valve to see if the valve core is stuck or blocked by particles. CCL4 should be used for correct cleaning, but if there are no conditions on site, gasoline can be used, and water can also be used if there is no water. After cleaning, you can use the on-site instrument gas to blow it dry. Be sure to remember the order of the components when disassembling. If you are not careful, it is easy to make mistakes when installing. If you remember the wrong order, even if you have cleaned the solenoid valve, it will still not open even if the solenoid valve is unblocked!
