The flow characteristic curve of a solenoid valve describes the relationship between its opening degree and the relative flow rate of the medium. Under constant pressure differential, this curve directly determines the accuracy and adaptability of the solenoid valve for fluid control. Different characteristic curves alter the flow rate variation with opening degree, causing significant differences in the solenoid valve's regulation accuracy, response speed, stability, and applicable scenarios, thus affecting its overall performance.
A solenoid valve with a linear characteristic curve exhibits a strictly linear relationship between relative flow rate and relative opening degree; that is, the flow rate change caused by a unit change in opening degree is a constant value. This characteristic results in a smoother change in relative flow rate at higher flow rates, while at lower flow rates, the relative flow rate change is more sensitive. Its core advantage lies in its simple control logic, making it suitable for scenarios where high regulation accuracy is not required but rapid response is needed, such as simple fluid on/off control or coarse adjustment of large flow rate systems. However, due to the constant rate of flow change, its regulation capability in the low flow rate range is weak, making it difficult to meet high-precision control requirements.
A solenoid valve with an equal percentage characteristic curve exhibits a relative flow rate change proportional to the current relative flow rate caused by a unit change in opening degree; that is, the amplification factor increases with increasing flow rate. This characteristic allows the solenoid valve to maintain consistent regulation accuracy across different opening degrees: minimal flow rate changes at low flow rates and significant changes at high flow rates. For example, in temperature control of air conditioning systems, an equal percentage characteristic solenoid valve can achieve precise temperature control in low-temperature regions through small opening degree adjustments, while simultaneously responding quickly to load changes in high-temperature regions. Its advantage lies in its uniform regulation capability covering the entire opening range, making it particularly suitable for complex systems requiring dynamic balancing.
A solenoid valve with a parabolic characteristic curve exhibits a flow rate change proportional to the square root of the current relative flow rate caused by a unit change in relative opening degree; the flow rate changes proportional to the square of the stroke. This characteristic lies between linear and equal percentage, combining some advantages of both: it approaches linearity in the small opening range, facilitating initial adjustment; and it approaches equal percentage in the large opening range, improving regulation sensitivity. For example, in water supply systems, parabolic solenoid valves can achieve stable water supply at low flow rates while responding quickly to high flow demands, avoiding pressure fluctuations. Their application is typically in intermediate transition stages where both regulation accuracy and response speed are required.
Solenoid valves with a quick-opening characteristic curve achieve a large flow rate at a small opening. As the opening increases, the flow rate rapidly approaches its maximum value, with subsequent changes in opening having minimal impact on the flow rate. This characteristic makes them excellent in scenarios requiring rapid opening or closing, such as emergency pressure relief of safety valves or rapid shut-off of gas pipelines. While quick-opening solenoid valves sacrifice regulation accuracy for response speed and are generally not used in continuous regulation scenarios, they play an irreplaceable role in systems requiring instantaneous action.
The flow characteristic curve also affects the performance of solenoid valves in terms of system stability and energy consumption optimization. Equal-percentage characteristic solenoid valves effectively reduce system oscillations and improve stability through uniform adjustment precision. Linear characteristic solenoid valves, due to their constant adjustment rate, may cause flow fluctuations in variable load systems. While quick-opening characteristic solenoid valves offer rapid instantaneous action, they may increase system losses due to impact pressure. Furthermore, the selection of the characteristic curve must be considered in conjunction with the media characteristics: high-viscosity fluids require avoiding quick-opening characteristics to prevent valve core jamming, while corrosive media require matching with wear-resistant materials to maintain curve stability.
In practical applications, the selection of the solenoid valve's flow characteristic curve must comprehensively consider system requirements, media characteristics, and control logic. For example, temperature control of reactors in chemical processes requires equal-percentage characteristics for precise adjustment, while rapid opening and closing of fire sprinkler systems relies on quick-opening characteristics. By matching the characteristic curve with the scenario requirements, the solenoid valve can maximize its performance, achieving an optimal balance between stability, response speed, and adjustment precision.
