Typical causes of electric valve failure

Electric valves may encounter a variety of faults in the actual application, understanding these typical faults and their causes and solutions, to ensure the stable operation of the system is critical. The following are several common electric valve failure and its solutions：

 

1. Motorized valve can not be opened or closed
Fault phenomenon: The motorized valve cannot open or close normally, it may stay in the middle position and the actuator does not respond.
Possible causes:

• Power supply failure: the motorized valve actuator does not receive power or the power supply voltage is abnormal. Check whether the power cord connector is loose or disconnected, and confirm whether the power supply voltage meets the requirements of the actuator (e.g. 220V or 380V).
• Motor failure: The motor inside the actuator is damaged or overheat protection is activated, resulting in failure to drive the valve. Detect whether the motor is running normally, measure the resistance value of the motor and check whether the motor needs to be replaced.
• Mechanical jamming: there are foreign objects inside the valve or serious wear between the valve stem and the valve body, resulting in mechanical jamming. We can manually operate the valve to detect whether there is mechanical resistance, if so, disassemble it for cleaning or replacement of damaged parts.
• Limit switch malfunction: the travel limit switch is not set correctly or malfunction, resulting in the valve can not reach the set fully open or fully closed position. We can adjust or replace the travel limit switch to ensure that the valve can open and close as required.

 

2. Slow or insensitive action of electric valve
Fault phenomenon:
The response time of the valve is slow, the action is not sensitive, and the set position cannot be reached quickly.
Possible causes:

• Poor lubrication: lack of lubrication of the valve's transmission mechanism, resulting in excessive operating resistance and slow action. Regularly check and replenish the lubricant or grease, especially the valve stem and actuator transmission gear part.
• Torque setting too low: The torque protection value of the actuator is set too low, resulting in the valve stopping operation when it encounters slight resistance during opening and closing. Readjust the torque setting of the actuator to ensure that the valve can operate smoothly under normal working conditions.
• Insufficient power of the actuator motor: the selected motor power of the actuator is insufficient to drive the valve, especially under high pressure or high flow operating conditions. It is necessary to check whether the power of the actuator matches the working requirements of the valve, and replace the actuator with higher power if necessary.

 

3. The electric valve can not feedback the correct position
Fault phenomenon: the valve position signal received by the control system does not match the actual position, and the valve opening feedback is abnormal.
Possible reasons:

• Position sensor failure: the position sensor is damaged or the signal transmission line is faulty, resulting in wrong position signal feedback. Test the signal output of the sensor, check whether the signal line has poor contact, if necessary, replace the position sensor.
• Control system setting problem: the valve stroke in the control system is not set correctly, resulting in the actual opening and control signal inconsistency. Recalibrate the valve stroke settings in the control system to ensure that the system parameters are consistent with the actual working conditions.

 

4. Motorized valve leakage
Failure phenomenon:
Motorized valve in the closed, the pipeline medium is still leaking, can not achieve a complete seal.

Possible causes:

• Wear or aging of seals: aging or wear of the sealing material of the valve, resulting in sealing failure, unable to achieve complete shut-off.
• Inspection measures: Check the condition of the seals regularly and replace the sealing materials such as O-rings, gaskets or sealing seats if necessary.
• Valve closure is not in place: the travel limit switch of the valve is not set accurately, resulting in the valve not being able to reach the fully closed position when closing, resulting in leakage.Adjust the travel limit switch to ensure that the valve is fully in place when closed.
• Pressure fluctuations caused by rebound: In high-pressure systems, after the valve is closed, due to system pressure fluctuations or water hammer phenomenon caused by the valve spool rebound, resulting in leakage. Install a slow-closing device or pressure reducing valve to reduce the impact of pressure fluctuations on the valve.

5. Actuator abnormal noise or vibration
Fault phenomenon:
During the operation of the electric valve, the actuator emits abnormal noise or vibration, which may affect the normal operation of the system.
Possible causes:

• Gear wear: The transmission gears inside the actuator are badly worn, resulting in abnormal noise or vibration during operation.Check the gear system of the actuator, lubricate and replace the worn gears regularly.
• Loose or improper installation: The actuator or valve is not securely mounted or the piping is not adequately supported, resulting in vibration and noise during operation.Check whether the fixing bolts of the actuator and piping support are loose, and make sure that they are firmly installed.

 

6. Motorized valve overheating or actuator overloading
Failure phenomenon:
The temperature of the electric valve actuator is too high during operation, even triggering overheating protection and system shutdown.
Possible reasons:

• Long-time continuous operation: the motorized valve is frequently switched on and off for a long time, resulting in overheating of the actuator motor.
• Check measures: Control the valve operation frequency, avoid long time continuous operation of the actuator, and increase the cooling device if necessary.
• High torque setting: The torque setting of the actuator is too high, resulting in excessive load on the motor and overheating after a long period of operation.

Check measures: Reduce the torque setting of the actuator appropriately to ensure that the motor works within the normal load range.

 

Failure prevention and maintenance recommendations

1. Regular inspection and maintenance: Establish a regular maintenance program for electric valves, and regularly inspect seals, lubrication systems, actuator motors and electrical connections to avoid failures.
2. Environmental control: according to the environment where the electric valve is used, take necessary protective measures, such as dustproof, moisture-proof, explosion-proof, etc., to ensure the stable operation of the electric valve in harsh environments.
3. Training of operators: Ensure that the operation and maintenance personnel have the necessary technical knowledge to be able to find and deal with abnormalities of the motorized valves in time to avoid malfunction due to misoperation.