When solenoid valves operate in low-temperature environments, the solidification of the medium is one of the core issues causing operational sluggishness. When the ambient temperature is below the medium's freezing point, the medium may undergo a phase change, transforming from a liquid to a solid or semi-solid state. This can directly block the internal flow channels of the valve body or jam the moving parts of the valve core, preventing the solenoid valve from opening and closing properly. This problem is particularly prominent in hydraulic systems, refrigeration equipment, and polar engineering scenarios, requiring a comprehensive solution through material adaptation, structural optimization, and auxiliary measures.
In low-temperature environments, the impact of medium solidification on solenoid valves is primarily manifested in the obstruction of valve core movement. Traditional greases tend to solidify at low temperatures, significantly increasing the coefficient of friction and causing delays in valve core opening or closing, or even complete jamming. For example, mineral-based greases lose their fluidity at -40°C, increasing frictional resistance several times over and extending valve core actuation time by several seconds, severely affecting system response speed. Furthermore, moisture in the medium freezes and expands at low temperatures, potentially cracking the valve body sealing surface or scratching the valve core surface, exacerbating the risk of leakage. Therefore, selecting a low-temperature resistant lubricant is crucial. For example, polytetrafluoroethylene (PTFE) grease remains stable within a temperature range of -60°C to 150°C, effectively reducing frictional resistance at low temperatures.
The cold resistance of the sealing material directly affects the low-temperature performance of the solenoid valve. Traditional nitrile rubber seals harden and shrink at low temperatures, leading to a decrease in sealing contact pressure and causing media leakage. For example, in a -40°C environment, the hardness of nitrile rubber may increase from Shore A 70A to 95A, losing its elastic sealing ability. In contrast, low-temperature resistant materials such as fluororubber or perfluoroether rubber maintain flexibility within a temperature range of -40°C to 200°C, ensuring stable sealing gaps. Simultaneously, employing an "interference fit seal" design, by allowing for the low-temperature shrinkage of metal components, ensures that the sealing gap remains ≤0.02mm at low temperatures, effectively preventing media leakage.
The structural design of the solenoid valve must fully consider thermal stress and deformation under low-temperature environments. The metal components of the valve body and valve core shrink at low temperatures; if the fit clearance is not properly designed, it may cause the moving parts to jam. For example, if the clearance between the guide sleeve and the valve core is too small, they may completely seize up after low-temperature shrinkage, preventing the valve core from operating. Optimizing the clearance by increasing it from 0.05mm to 0.08mm allows sufficient shrinkage space, preventing low-temperature jamming. Furthermore, adding a dust filter at the valve core to prevent impurities from entering the mating surface also reduces the risk of jamming.
Media characteristic management is crucial for preventing solidification. For water-containing media, a dryer or heater can be installed upstream of the valve to reduce the water content and prevent freezing. For example, in hydraulic systems, installing electric or steam tracing devices can maintain the media temperature above its freezing point, ensuring fluidity. For media whose viscosity changes significantly with temperature, such as hydraulic oil, a low-temperature, low-viscosity model can be selected to reduce flow resistance at low temperatures. Regularly draining residual media from the low points of the valve to prevent freezing is also an important maintenance measure.
The reliability of electrical systems is equally critical in low-temperature environments. Coil insulation materials may become brittle at low temperatures, leading to a decrease in insulation resistance and a risk of short circuits. For example, nylon-framed coils shrink at -40°C, causing the insulating varnish to crack and the insulation resistance to drop from ≥100MΩ to ≤10MΩ. Using low-temperature resistant coil materials, such as polyimide or epoxy resin, ensures stable resistance. Simultaneously, the terminals must be made of low-temperature resistant metal to prevent poor contact due to shrinkage and to prevent overheating and safety hazards during energization.
System auxiliary measures can further improve the low-temperature adaptability of solenoid valves. For example, wrapping the valve exterior with insulation material reduces heat loss; or using electric heat tracing technology to maintain the valve body temperature through heating strips. For extreme low-temperature environments, intelligent solenoid valves with heating functions can be selected, automatically adjusting the heating power through a built-in temperature sensor to ensure the medium remains in a flowing state. Furthermore, optimizing the system design to prevent the medium from stagnating within the valve body for extended periods also reduces the risk of solidification.
Preventing the solenoid valve from jamming due to medium solidification in low-temperature environments requires a comprehensive approach encompassing material selection, structural design, medium management, and system auxiliary measures. By using low-temperature resistant lubricants and sealing materials, optimizing the clearance of moving parts, controlling the characteristics of the medium, enhancing the reliability of the electrical system, and implementing heat preservation and heating measures, the reliability and stability of solenoid valves in low-temperature environments can be significantly improved, meeting the application requirements of extreme working conditions.
