What are the common faults of control valves and how to eliminate them?

Some common faults may occur during the use of control valves. Understanding these faults and their elimination methods will help improve the stability of the equipment and extend its service life. The following are some common faults and their elimination methods:

1. The valve cannot be opened or closed
Reason:
Actuator failure: such as insufficient air source, power supply problem or internal fault of the actuator.
Valve stuck: There are foreign objects or corrosion in the valve body, which causes the valve movement to be blocked.
Insufficient air pressure or current: The actuator cannot operate normally.
Troubleshooting method:
Check the air source, power supply or control signal of the actuator to ensure that it is normal.
Clean the inside of the valve, check for foreign objects or dirt, and lubricate it.
Check whether the air pressure, current, etc. of the pipeline system and control system meet the requirements.

2. Valve leakage
Reason:
Damage of seals: Aging or damage of sealing gaskets, O-rings, etc., leading to leakage.
Damage of valve seat: The surface of the valve seat is worn or corroded, and it cannot be completely sealed with the valve core.
Excessive pressure: Exceeding the design pressure range of the valve, resulting in leakage.
Troubleshooting:
Check and replace worn or damaged seals.
Check if the valve seat is damaged, and re-run or replace the valve seat if necessary.
Check the system pressure to ensure that it does not exceed the rated working pressure of the control valve.

3. Failure of control signal
Reason:
Control system failure: damage to the electrical control circuit, sensor or electrical signal transmission problem.
Air source problem: insufficient air source or air pressure fluctuation of the pneumatic control valve.
Troubleshooting:
Check the electrical control circuit and sensor to ensure that the signal input and output are normal.
Check whether the air source is sufficient and the air pressure is stable, and clean or replace the air source if necessary.

4. The valve does not respond to the control signal
Reason:
Actuator failure: such as damage to the electric actuator or insufficient air source of the pneumatic actuator.
Control circuit problem: The control circuit fails, resulting in the inability to transmit the signal.
Troubleshooting:
Check the power supply and air source of the actuator to ensure that it is working properly.
Check the control circuit, including the sensor, signal line and control device, to confirm whether there is any fault.

5. Slow or unstable valve action
Reason:
Unstable air source or power supply: unstable air source pressure or insufficient power supply to the electric actuator.
Unstable control signal: interference in the control system causes unstable signal transmission.
Valve stuck or fouled: fouling or corrosion inside the valve body causes slow action.
Troubleshooting:
Ensure that the air source and power supply are stable, and check whether the air pressure or current is within the valve design range.
Check whether there is interference or failure in the control signal, and clean the control loop.
Clean the inside of the valve, check for fouling or corrosion, and perform necessary maintenance and lubrication.

6. The valve is noisy
Reason:
The fluid flow rate is too high: the fluid flow rate is too fast, resulting in flow noise.
Pneumatic control problem: The air source flow rate of the pneumatic valve is unstable, which may cause increased noise.
Loose valve parts: Loose internal valve parts may also cause noise.
Troubleshooting:
Check the flow setting and adjust the flow control of the valve to avoid excessive flow rate.
Check the air source system to ensure that the air source flow is stable and avoid unnecessary air flow noise.
Check the internal parts of the valve to ensure that all parts are tightened in place to avoid noise caused by looseness.

7. The valve is not sensitive
Reason:
The actuator responds slowly: the internal fault of the actuator leads to untimely response.
Signal transmission problem: the control signal transmission is unstable or the signal strength is insufficient.
Valve body wear: the valve core and valve seat are worn, resulting in the valve opening and closing not being smooth.
Troubleshooting method:
Check the operating status of the actuator to ensure that it responds quickly. If the actuator fails, it needs to be repaired or replaced.
Check the signal transmission path to ensure that there is no interference or attenuation in the signal transmission.
Check whether the valve is worn, and repair or replace the worn parts if necessary.

Summary
The troubleshooting of common faults of control valves mainly involves checking the actuator, seals, air source, electrical control system, etc. to ensure the normal operation of various components and systems of the valve. Regular inspection and maintenance can effectively avoid the occurrence of many faults and improve the working stability and service life of the control valve.