Detailed Explanation of Common Faults and Solutions of Solenoid Valves

Detailed Explanation of Common Faults and Solutions of Solenoid Valves

Fault phenomenon

Treatment method1️⃣

1、The solenoid valve doesn't work after being powered on

First of all, check whether the wiring is intact. Next, confirm whether the coil is broken. By giving the command to open or close the solenoid valve, listen carefully to see if there is any sound of action. If there is no sound, the problem may lie in the circuit or the coil. Further inspect the wiring to confirm whether there are any poor contacts, open circuits or short circuits. If the circuit is normal, it might be that the solenoid valve coil is burned out. The wiring needs to be removed and measured with a multimeter. The reasons for the coil burning out may include moisture leading to a decline in insulation performance, overly hard springs causing excessive reaction force, and insufficient coil turns resulting in inadequate suction force, etc. The burned coil needs to be replaced.

The solenoid valve cannot be opened after being powered on

Check whether the valve cover screws are tightened. If the valve cover gasket has been replaced recently, it is necessary to confirm that the thickness of the gasket is appropriate and the tightness of the screws is consistent. At the same time, check whether the valve core is stuck. If there is a pilot valve, also check whether the valve port of the pilot valve is blocked.

The solenoid valve cannot close after power failure

Similarly, it is necessary to check whether the valve core is stuck or the pilot valve port is blocked. If the solenoid valve cannot close tightly, it is necessary to further check whether the valve core sealing gasket is intact and whether the valve seat is loose.

For valve core jamming or blockage faults, cleaning is an effective solution. It can be cleaned with gasoline or water and then dried with compressed air. When disassembling the solenoid valve, be sure to remember the sequence of each component clearly to avoid errors during reassembly and causing new problems.

The methods for testing the quality of solenoid valves

First, introduce the controlled medium into the solenoid valve, which can be a pressurized liquid or gas (such as air), and the pressure value should be set within the operating pressure range of the solenoid valve. Next, power on the solenoid valve coil. If the controlled medium can achieve state changes from on to off or from off to on, the solenoid valve is in good condition. Otherwise, there might be a malfunction.

Common faults of solenoid valves include short circuits or open circuits in the coil. A multimeter can be used to measure such faults. If the resistance value approaches zero or infinity, it indicates that there is a short circuit or open circuit problem in the coil. However, sometimes, even if the measurement results show that the resistance value is normal, it cannot be completely determined that the coil is in good condition. Therefore, we still need to conduct the final test: Bring a small screwdriver close to the metal rod passed through the solenoid valve coil. If magnetism can be felt after being powered on, the coil is in good condition. Otherwise, the solenoid valve coil needs to be replaced.

2. Plug/socket issues

If the solenoid valve is equipped with a plug and socket, problems with the metal spring of the socket or incorrect plug wiring (such as mistakenly connecting the power cord to the ground wire) may occur, resulting in the power not being delivered to the coil. It is recommended to plug in the plug and then tighten the fixing screw. Make sure that the fixing nut is also tightened after the coil is connected to the valve core stem. If the solenoid valve coil plug is equipped with a power indicator light, it needs to be connected correctly when driven by DC power; otherwise, the indicator light will not light up. At the same time, be careful not to mix power plugs with power indicators of different voltage levels and light-emitting diodes to avoid burning out the light-emitting diodes or short circuits in the power supply. If there is no power indicator light, the solenoid valve coil does not need to distinguish the polarity.

Treatment method:

Correct wiring errors and repair or replace plugs and sockets.

3. Valve core failure

If there is no response when the manual button of the solenoid valve is pressed under normal medium pressure, it indicates that the valve core has been damaged. It is necessary to check whether there are any problems with the medium, such as water accumulation in the compressed air or impurities in the liquid medium, and remove them. If the problem persists, you can try repairing or replacing the valve core, or directly replace the entire solenoid valve.

Fault Phenomenon 2️⃣:

If the coil is the original one and the magnetic field is normal when powered on, but the solenoid valve still does not operate, it may also indicate that the valve core is damaged. At this point, it is also recommended to repair or replace the valve core, or directly replace the entire solenoid valve.

Regarding the maintenance of solenoid valve bodies, due to the wide variety of types, specific methods will not be elaborated here.

Faults and Troubleshooting of Solenoid Valves

①. The solenoid valve does not work after being powered on

First of all, it is necessary to check whether the power connection is good and ensure that the wiring and connectors are correctly connected. Next, check whether the power supply voltage is within the normal working range. If there is a problem, make adjustments. At the same time, check whether the coil is de-soldered or short-circuited. If there is a problem, the coil needs to be re-soldered or replaced. In addition, it is necessary to confirm whether the working pressure difference is appropriate. If it is not, adjustments should be made or the corresponding solenoid valve replaced. If the fluid temperature is too high, a suitable solenoid valve should also be replaced. In addition, if the main valve core and the moving iron core are jammed by impurities, they should be cleaned and the seals replaced. At the same time, filters should be installed. In addition, if the liquid viscosity is too high, the frequency is too high, or the product's lifespan has expired, it may also cause problems. In such cases, the corresponding product should be replaced.

②, the solenoid valve cannot be closed

If the solenoid valve fails to close, it may be due to the damage of the sealing parts of the main valve core or the iron moving core. At this time, they should be replaced immediately. At the same time, it is necessary to confirm whether the fluid temperature and viscosity are too high. If there is a problem, replace the suitable solenoid valve. If impurities enter the solenoid valve and cause the valve core or moving iron core to get stuck, the relevant components should be thoroughly cleaned. In addition, the expiration of the spring's service life or deformation may also affect the closing of the solenoid valve. At this time, the spring should be replaced. In addition, blockage of the throttle hole or balance hole can also cause problems, so the relevant parts need to be cleaned in a timely manner.

③. Other circumstances

If the solenoid valve has internal leakage, it is necessary to check whether the sealing parts are intact and whether the spring assembly is correct. For external leakage issues, it is necessary to confirm whether the connection points are loose or the seals are damaged, and take corresponding measures to tighten the screws or replace the seals. If noise occurs when powered on, it may be caused by loose fasteners on the head. At this time, the relevant components should be tightened. At the same time, it is necessary to confirm whether the voltage fluctuation is within the allowable range and adjust it to the normal voltage. In addition, if there are impurities or unevenness issues on the core's bonding surface, the relevant components should also be cleaned or replaced in a timely manner.

On-site quick method for judging the quality of solenoid valves

①, check whether the electromagnetic coil of the solenoid valve is faulty.

On the DCS, give the signal to open or close the two-position valve to observe whether the solenoid valve is energized or not. Usually, it can be judged by listening to the sound on site. If no sound can be heard, there might be a problem with the coil. Next, we need to further determine whether the solenoid valve itself is faulty.

②, if the coil is normal, then the problem may lie with the solenoid valve itself.

At this point, we can use a single character to adjust from 1 to 0 at the manual adjustment position and try to open the valve. If it can be successfully opened, it indicates that the problem lies in the coil. Just replace the coil. If it cannot be opened, the solenoid valve needs to be disassembled to check whether the valve core is stuck or blocked by foreign particles. When cleaning, CCL4 or other organic solvents should be used. If the on-site conditions are limited, gasoline or water can also be used as substitutes. After cleaning, it should be dried with instrument air. When disassembling, be sure to remember the sequence of each component clearly to avoid reassembling wrongly.

The quality of an electromagnetic valve mainly depends on the coil and the valve body.

During the test, we can find a 24V power supply and connect it to the coil to observe if there is any noise. If there is a noise, it indicates that the coil and the valve core are normal and can be engaged normally. Next, check for any air leakage. If there is an air source, directly connect it for judgment. If there is no air source, block the air outlet and blow it with your mouth to test. In addition, the inspection of the coil can also be carried out through a multimeter.

After the solenoid valve is powered on, unplug the plug and use a multimeter to measure whether there is electricity.

When the solenoid valve is energized, bring a thin steel wire close to the coil to observe if there is any suction force.

Repeatedly power on and off. Use a thin Allen wrench to gently tap the copper-colored "small pit" on the solenoid valve shaft to feel if it can be normally engaged and eout.

In addition, the condition of the solenoid valve can also be judged by detecting its on-off status. The specific method is to supply power to the solenoid valve coil when the control medium of the solenoid valve (such as pressurized liquid or gas) is introduced, and observe whether the control medium can achieve a state change from on to off or from off to on. If so, the solenoid valve is normal. Otherwise, there might be a malfunction.

Common faults of solenoid valves include short circuits or open circuits in the coil. When conducting the test, first measure its on-off status and resistance value with a multimeter. If the resistance value is abnormal, there may be a short circuit or open circuit. However, sometimes a normal resistance value does not guarantee that the coil is definitely in good condition. Therefore, a final test is required: Place a small screwdriver near the solenoid valve coil. If it feels magnetic after being powered on, the coil is in good condition. Otherwise, the coil needs to be replaced.

In addition, problems with the plug/socket may also cause the solenoid valve to fail to work properly. Therefore, when connecting the plug and socket, make sure the fixing screws are tightened to prevent the power from not reaching the coil. At the same time, if the solenoid valve coil plug is equipped with a light-emitting diode power indicator light, the power supply must be connected correctly when driving the solenoid valve; otherwise, the indicator light may not light up. In addition, it is necessary to avoid swapping the power plugs with power indicators of different voltage levels and light-emitting diodes to prevent problems such as the burning out of light-emitting diodes or power short circuits.

If there is no power indicator light, the solenoid valve coil does not need to distinguish polarity (unlike transistor time relays and intermediate relays for DC coil voltage, the latter of which need to distinguish polarity). If it is found that the solenoid valve cannot work properly, first check whether the wiring is correct, and repair or replace the plug, socket and other components.

Problems with the valve core may cause the solenoid valve to fail. For instance, if the medium pressure is normal but there is no response when the manual button of the solenoid valve is pressed, it indicates that the valve core may be damaged. At this point, it is necessary to check whether there are any problems with the medium, such as removing accumulated water or impurities, and attempting to repair or replace the valve core. If the manual button of the solenoid valve functions normally but the valve core still does not move, it is also necessary to consider replacing the valve core or the entire solenoid valve.

In addition, the problem that the solenoid valve fails to close after power failure may be caused by a variety of reasons. For instance, if the arrow of the solenoid valve body is inconsistent with the direction of fluid flow, it needs to be reinstalled to maintain consistency. If the valve cannot be closed tightly due to debris blockage, the solenoid valve and the filter screen should be cleaned. Problems such as jamming of the moving iron core, spring and main valve core, or damage to the sealing parts also need to be repaired or replaced accordingly.

When dealing with solenoid valve problems, a careful inspection should be carried out and the corresponding handling steps should be followed. If the problem is complex or unsolvable, it is recommended to seek the help of professionals.