Valve body related faults

1. Wear or damage to the valve core and seat

• Fault manifestationThe valve leakage increases, the regulating performance deteriorates, and the flow or pressure cannot be accurately controlled. For example, in chemical production, three-way regulating valves that could accurately control the flow rate of reactants have large fluctuations in flow rate due to valve core wear, which affects product quality.
• Root cause analysisDuring long-term use, particle impurities in the medium can cause erosion and wear on the valve core and seat; Frequent valve movements can also intensify friction between the valve core and seat, leading to wear and tear.
• solutionDisassemble the valve and check the wear of the valve core and seat. If the wear is light, it can be repaired by grinding; If the wear is severe, new valve cores and seats need to be replaced.

2. Valve stem jamming

• Fault manifestationThe valve is not flexible or even unable to operate. In situations where rapid adjustment of flow or pressure is required, valve stem jamming can cause the system to fail to respond in a timely manner, affecting the stability of the production process.
• Root cause analysisExcessive friction between the valve stem and the packing may be caused by factors such as tight packing pressure, aging packing, or rough surface of the valve stem; Impurities in the medium enter the gap between the valve stem and the valve sleeve, causing jamming.
• solutionAdjust the tightness of the packing appropriately and replace the aging packing; Polish the surface of the valve stem to improve its smoothness; Clean the impurities in the gap between the valve stem and the valve sleeve.

3. Sealing leakage

• Fault manifestationThere is a medium leakage outside the valve, which not only causes waste of medium, but also may pollute the environment and even lead to safety accidents. For example, in the petrochemical industry, the leakage of flammable and explosive media may cause fires or explosions.
• Root cause analysisAging, damage or improper installation of seals; The connecting bolts between the valve body and the valve cover are loose, resulting in poor sealing.
• solutionReplace aging or damaged seals and ensure proper installation; Tighten the connecting bolts again, and if necessary, use a torque wrench to tighten them according to the specified torque value.

Malfunctions related to the execution mechanism

1. Insufficient power of the executing mechanism

• Fault manifestationThe valve cannot reach the predetermined opening and the adjustment accuracy decreases. For example, in systems that require precise temperature control, insufficient actuator power can result in insufficient valve opening, making it impossible to stabilize the temperature at the set value.
• Root cause analysisFor electric actuators, it may be caused by low power supply voltage, motor failure, or damage to the reducer; For pneumatic actuators, it may be caused by insufficient air source pressure, cylinder seal leakage, or piston jamming.
• solutionFor electric actuators, check if the power supply voltage is normal, repair or replace the motor and reducer; For pneumatic actuators, check the air source pressure, repair the cylinder seal or replace the piston.

2. Abnormal position feedback signal

• Fault manifestationThe display of the control system is inconsistent with the actual opening of the valve, which makes it difficult to accurately determine the working status of the valve and affects the adjustment effect.
• Root cause analysisDamage to the position sensor, poor circuit contact, or signal interference can all lead to abnormal position feedback signals.
• solutionCheck the working status of the position sensor and replace damaged sensors; Check the circuit connection to ensure good contact; Take shielding measures to reduce signal interference.

3. Slow action of the executing mechanism

• Fault manifestationThe valve operates slowly and cannot respond to control signals in a timely manner, affecting the dynamic performance of the system.
• Root cause analysisThe internal mechanical components of the actuator may experience sluggish movements due to high friction, poor lubrication, or delayed control signal transmission.
• solutionLubricate and maintain the internal mechanical components of the actuator to reduce friction; Check the control signal transmission line, optimize the signal transmission method, and reduce latency.

Control system related faults

1. Control signal error

• Fault manifestationThe valve opening does not match the control signal, resulting in misoperation. For example, the control signal requires the valve to be closed, but the valve is in the open state.
• Root cause analysisControl signal errors may be caused by incorrect parameter settings, sensor malfunctions, or signal interference in the control system.
• solutionCheck the parameter settings of the control system to ensure they meet the process requirements; Check the working status of the sensor, repair or replace the faulty sensor; Take shielding measures to reduce signal interference.

2. 通信故障

• Fault manifestationThe communication between the control system and the actuator cannot be normal, resulting in the valve being unable to receive control signals. In highly automated systems, communication failures can cause the entire system to become paralyzed.
• Root cause analysisCommunication line faults, mismatched communication protocols, or damaged communication modules can all lead to communication failures.
• solutionCheck the connection status of communication lines, repair or replace damaged lines; Ensure communication protocol matching; Replace the damaged communication module.