Detailed explanation of failure modes of electric valves
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An electric valve is a control device that relies on an electric actuator to drive the opening and closing of the valve. It is widely used in the fields of fluid transportation and regulation, such as chemical industry, electric power, HVAC, food, water treatment and other systems. However, in actual operation, electric valves also have a certain risk of failure. This article will provide an in-depth analysis of common failure modes of electric valves from multiple perspectives such as structure, signal, and electrical to help users understand and prevent these failures.
The core driving force of electric valves comes from the electric actuator. Once the actuator fails, the entire valve will not operate normally. The most common problems include motor burnout, reduction mechanism stuck, control circuit failure, etc. When the motor is overloaded or runs beyond the rated power for a long time, the winding temperature may rise, eventually causing burnout; and the reduction device may get stuck or rotate poorly if there is poor lubrication, serious gear wear, or foreign matter enters.
Internal jamming of the valve body leads to malfunction
Even if the actuator works normally, if the internal structure of the valve body is blocked, it will still cause the valve to become insensitive or completely fail. Common situations include foreign matter accumulating between the valve core and valve seat, corrosion causing adhesion of the sealing surface, or long-term inactivity causing internal corrosion. For example, in some situations where the medium contains impurities, such as sewage, mineral slurry, etc., the impurities may be deposited around the valve seat, preventing the valve core from being completely closed or opened; if the valve is in a normally closed or normally open state for a long time, the inner wall may be corroded in a humid environment, causing the moving parts to adhere to the fixed parts, causing abnormalities when the actuator is driven.
Abnormal Control Signals Cause Malfunctions
Electric valves usually rely on PLC or DCS systems to send electrical signals for drive control. If the control signal itself is abnormal, it will also cause the valve to malfunction. Possible reasons include loose control signal lines, superposition of interference signals, incorrect program settings, etc. For example, in a strong electromagnetic interference environment, control signals are easily affected by external noise, resulting in abnormal switching commands; if on-site wiring is loose and terminals are in poor contact, signal loss may also occur.
Media Leakage Caused By Seal Failure
Electric valves need to switch repeatedly between open and closed states, and the reliability of the sealing system is the key to ensuring their normal operation. Once the sealing part is aged, deformed, worn or improperly installed, it is easy to cause media leakage. Especially in high temperature, high pressure or corrosive media environments, sealing materials are more likely to fail. For example, rubber sealing rings may soften or harden under high temperature conditions, resulting in a decrease in sealing performance; metal sealing structures may cause the sealing surface to peel off due to medium corrosion.
Potential Failures Caused By Improper Installation
The posture, position, piping stress, environmental conditions, etc. of the electric valve when it is installed will have an important impact on its operational stability. If the installation is not level, the pipe stress is too high, or the pipe is not firmly fixed, the actuator will bear additional mechanical load, and long-term operation may cause cracks in the shell or misalignment of the transmission components; if environmental factors are not considered, such as installation in high humidity or a location prone to rain, the electrical part will be susceptible to moisture and water, eventually leading to short circuit or component damage. Therefore, the failure of many electric valves does not come from the product itself, but from negligence in the installation process, which can easily expose problems in the early stages of use.
