Check the coil's condition; if the magnetic force has明显 weakened (which can be verified by testing with a piece of iron), replace it with a qualified coil.

　　Fault phenomenon:

　　After power is applied, the valve core fails to actuate, preventing medium flow and resulting in no system response.

　　Common causes and troubleshooting methods:

　　Electrical circuit malfunction

　　Causes: Power supply not connected (broken wire, loose connection), voltage mismatch (e.g., AC 220V mistakenly connected to DC 24V), coil burnout (overload, short circuit).

　　Exclusion:

　　Use a multimeter to check whether the power voltage is normal and whether the hydraulic manual pump circuit is conducting (pay special attention to inspecting the plug and terminal blocks).

　　Measuring the coil resistance: A normal coil typically has a resistance ranging from tens to thousands of ohms (varying significantly depending on the model). If the resistance reads 0 (indicating a short circuit) or infinite (indicating an open circuit), the coil should be replaced.

　　Electromagnetic brake jamming

　　Cause: Foreign objects (such as rust or impurities) between the iron core and armature, wear or deformation of the iron core causing sticking, or prolonged lack of movement leading to adhesion.

　　Exclusion:

　　After power is cut, disassemble the valve body and clean the iron core, armature, and any impurities or rust remaining inside the valve chamber.

　　Check whether the core surface is smooth; if there are scratches or deformations, replace the core assembly.

　　For valves that have been idle for extended periods, periodically trigger them manually or activate them electrically to prevent sticking.

　　Abnormal medium pressure

　　Cause: For a "pilot-operated solenoid valve," if the inlet medium pressure is too low (below the minimum operating pressure), it cannot push the main spool open.

　　Exclusion:

　　Check whether the pipeline pressure meets the valve's labeled "minimum opening pressure";

　　If the pressure is insufficient, adjust the upstream pressure source or replace it with a valve model suitable for lower pressure.

　　2. Valve fails to close (leaks when power is on or remains conductive after power is off)

　　Fault phenomenon:

　　After power is applied, the valve fails to close completely (resulting in continuous media leakage), or after power is cut off, the valve stem does not return to its original position, allowing the medium to continue flowing.

　　Common causes and troubleshooting methods:

　　Seal damaged or aged

　　Cause: Wear, corrosion, or aging of the valve core sealing gasket (such as rubber rings or metal sealing surfaces), or scratches caused by particles in the medium.

　　Exclusion:

　　Disassemble the valve, inspect the condition of the seals, and replace them with identical models if they are damaged or hardened (note that the material must be compatible with the medium, e.g., oil-resistant, acid- or alkali-resistant).

　　Clean off any impurities adhering to the sealing surface to ensure a tight, secure fit.

　　Valve spool jamming or reset spring failure

　　Cause: The valve core is stuck due to impurities, or the return spring has either fractured from fatigue or lost sufficient elasticity, preventing the valve core from returning to its original position.

　　Exclusion:

　　After disassembly, remove impurities around the valve core and check whether the valve core moves smoothly within the hydraulic valve coil.

　　Replace the broken or insufficiently elastic reset spring (ensure the spring specifications match).

　　Insufficient electromagnetic force

　　Cause: The coil is receiving an abnormally low supply voltage (e.g., AC 220V actually dropping to just 180V), or a partial short circuit in the coil has weakened the magnetic force, preventing it from overcoming the medium pressure and pushing the valve core to close.

　　Exclusion:

　　Measure the actual supply voltage to ensure it falls within the valve's rated voltage range (typically allowing for a ±10% variation);

　　Check the coil's condition; if the magnetic force has明显 weakened (which can be verified by testing with a piece of iron), replace it with a qualified coil.

　　3. Unstable valve operation (frequent on-off cycles, sticking, or delayed response)

　　Fault phenomenon:

　　After being powered on, the system experiences laggy performance—sometimes working intermittently or responding noticeably slower—ultimately affecting system accuracy.

　　Common causes and troubleshooting methods:

　　Unstable power supply or poor contact

　　Causes: Excessive fluctuations in power supply voltage, loose terminal connections, and oxidation of the plug leading to high contact resistance.

　　Exclusion:

　　Use a multimeter to monitor fluctuations in the supply voltage, and install a voltage regulator if necessary.

　　Clean the oxidation layer from the terminal blocks, tighten the connectors, or replace aged joints to ensure reliable electrical connections.

　　Excessive media impurities or abnormal viscosity

　　Cause: Particulate impurities, oil contamination, or crystalline deposits in the medium obstruct the valve stem movement; alternatively, the medium’s viscosity exceeds the valve’s design specifications (e.g., if the oil is too thick).

　　Exclusion:

　　Install a filter upstream of the valve (ensure the filtration accuracy matches the valve core clearance), and clean the filter regularly.

　　Check whether the media viscosity meets the valve requirements, and replace it with a valve model designed for high-viscosity media (e.g., featuring high flow rate and wide-clearance design).

　　Wear of the valve core or valve seat

　　Cause: Long-term, high-frequency operation leads to increased clearance between the valve core and valve seat, or surface wear that creates scratches, compromising smooth movement.

　　Exclusion:

　　After disassembly, inspect the valve core and seat for wear; minor scratches can be polished and repaired.

　　When wear is severe, the valve core assembly or valve body must be replaced entirely.

　　4. Coils overheating or burnout

　　Fault phenomenon:

　　After being powered on, the coil overheats severely (with temperatures exceeding 60°C), even emitting a burning, scorched smell and eventually leading to burnout.

　　Common causes and troubleshooting methods:

　　Overvoltage or prolonged overload

　　Cause: Overvoltage beyond the rated value (e.g., connecting a DC24V valve to a 36V power supply) or prolonged coil energization (due to failure to operate under "intermittent duty cycle") leads to overheating.

　　Exclusion:

　　Verify that the supply voltage matches the valve's rated voltage, and install an overvoltage protection device.

　　If the valve needs to remain open for an extended period, select a "continuous duty" coil model to prevent the intermittent coil from being energized continuously over time.

　　Poor environmental heat dissipation

　　Cause: The valve is installed in a high-temperature environment (such as near a heat source), the coil surface is covered with oil or dust, or poor ventilation leads to heat buildup.

　　Exclusion:

　　Keep away from high-temperature heat sources and clean dirt off the coil surface.

　　Install heat sinks or fans as needed to improve cooling conditions.

　　Internal short circuit in the coil

　　Cause: Aging of the coil insulation layer (due to moisture or high temperatures), combined with loose winding that leads to friction and damage, resulting in turn-to-turn short circuits.

　　Exclusion:

　　Use an insulation resistance tester to check the coil's insulation resistance. If the reading falls below the standard value (typically ≥10 MΩ), the coil must be replaced with a new one.

　　When installing, avoid subjecting the coil to mechanical shock, and in damp environments, opt for a moisture-resistant coil model.

　　5. Media Leakage (Leakage from Outside or Inside the Valve Body)

　　Fault phenomenon:

　　Leakage occurs at the connection between the valve body and piping, or internal sealing failure in the valve leads to media crossover (e.g., air leakage in a 2/3-way valve).

　　Common causes and troubleshooting methods:

　　Poor sealing of the connection

　　Cause: The sealing gasket at the flange/threaded connection was not properly tightened, the gasket has aged, or uneven stress during pipeline installation led to valve body deformation.

　　Exclusion:

　　Retighten the connecting bolts (screwing them on evenly in a diagonal pattern) and replace the aged gasket.

　　Check whether the valve body is deformed due to improper installation. Minor deformations can be repaired, but in severe cases, the valve body will need to be replaced.

　　Internal cavity leakage

　　Cause: Wear on the spool sealing surface, damage to the valve seat O-ring, or blockage of the pilot port in hydraulic directional valves or pilot-operated valves leads to failure of the main valve seal.

　　Exclusion:

　　Disassemble to repair or replace the valve core seals and the valve seat O-rings.

　　Clean out any impurities from the pilot hole (use a thin wire or compressed air to blow them out), ensuring the pilot passage remains unobstructed.

　　6. General Principles for Troubleshooting

　　First electrical, then mechanical: Begin by inspecting the electrical components—such as the power supply, coils, and wiring—to rule out simple issues like power failure or short circuits. Only after addressing these basic problems should you proceed to disassemble the mechanical structure.

　　First external, then internal: Begin by checking the valve body for leaks, ensuring connections are secure, and assessing the environment for any abnormalities (such as high temperatures or humidity), before gradually disassembling the internal components.

　　Condition-based analysis: Based on process conditions such as media type (corrosive, particulate-containing), operating pressure, temperature, and more, determine whether the failure is related to improper selection (e.g., using a standard valve for highly acidic media).

　　Regular maintenance for prevention:

　　Regularly clean the filter to prevent impurities from entering the valve body;

　　For valves that have been out of use for an extended period, periodically power them to ensure smooth operation and prevent seizing.

　　Replace the seals according to the instructions (rubber components typically last 3–5 years).