**Abstract:**
Based on the working principle of hydraulic control valves, this paper investigates the factors that influence the stable operation of such valves from structural, installation, and environmental perspectives. It proposes an improved design to enhance the stability and reliability of hydraulic control valves. The study emphasizes the importance of optimizing valve structure, ensuring proper installation, and maintaining suitable operating conditions. Keywords: hydraulic level control valve; working principle; stable operation; improvement program.
**1. Introduction**
A hydraulic level control valve is an advanced version of a float valve. When the water level in a tank or reservoir drops, the float valve opens to drain water, allowing the water pressure in the pipeline to decrease. As the water level rises to the set point, the float valve closes, causing the piston to move downward and seal the valve. This stops the water supply, achieving automatic water level control. Due to its low power consumption, simple construction, ease of installation, and durability, it is widely used in various types of clear water tanks for automated water level management. However, due to water quality issues and hydraulic fluctuations, these valves often malfunction, leading to water wastage, excessive pumping, and potentially severe consequences. Enhancing the stability of hydraulic control valves is crucial for ensuring safe and efficient water supply systems.
**2. Internal Structure and Working Principle of Hydraulic Level Control Valve**
The hydraulic level control valve typically consists of a float valve, a control tube, and a hydraulic body. Although the external appearance may vary depending on material, installation orientation (vertical or horizontal), the internal mechanism remains largely consistent. The main components include the inlet chamber, outlet, piston-type valve core, pressure relief cavity, and the relief port. The system operates based on the balance of forces acting on the piston. Key parameters include the inlet pressure $ P_0 $, the pressure relief chamber pressure $ P_1 $, the piston weight $ G $, and the diameters $ D_1 $ and $ D_2 $ at each end of the spool. The flow through the orifice connecting the inlet chamber and the pressure relief chamber has diameter $ d_1 $, while the relief port has diameter $ d_2 $. Friction $ f $ between the spool and the valve chamber, as well as the supporting force $ N $, also play significant roles.
When the water level drops, the float valve opens, allowing water to enter the pressure relief chamber through the small orifice $ d_1 $. Since $ d_1 < d_2 $, the inflow capacity is less than the outflow, reducing $ P_1 $ and the supporting force $ N_1 $. This allows the pressure $ P_0 $ to lift the piston, opening the valve and refilling the tank. When the water level reaches the desired point, the float valve closes, and the pressure in the relief chamber increases, closing the valve again. This cycle ensures continuous, automatic water level regulation.
**3. Factors Affecting Stable Operation**
**3.1 Pressure Relief Chamber Pressure Changes**
During installation, the pressure in the relief chamber must be carefully controlled. The minimum pressure $ C_1 $ determines the valve’s ability to open and close reliably. If the pressure is too low, the spool cannot rise sufficiently, preventing proper valve operation. Conversely, if the pressure is too high, the valve may not close properly, leading to overfilling. Maintaining a balanced pressure is essential for stable performance.
**3.2 Structural Design of the Hydraulic Valve**
The valve’s internal structure, including the piston and spool, must be robust and flexible. A smaller orifice $ d_1 $ reduces head loss and lowers $ C_1 $, enabling faster response. However, if the hole is too small, it can become clogged, disrupting operation. Increasing the diameter of the relief port helps reduce pressure during closure but requires higher inlet pressure $ P_0 $.
**3.3 Installation Considerations**
Proper installation is critical. The control pipe’s diameter and length directly affect the pressure and flow rate. A larger diameter reduces resistance, lowering $ C_1 $, but may reduce available storage space. The length of the control tube should be limited to prevent excessive head loss and delayed closure.
**3.4 Water Quality and Flow Conditions**
The medium must be clean to avoid blockages and corrosion. Dissolved solids can cause fouling, increasing friction and reducing valve efficiency. In areas with hard water, regular maintenance and larger control pipes are recommended to ensure smooth operation.
**4. Improvement Program for Stable Operation**
**4.1 Selecting the Right Valve Model**
Choose a valve that matches the system’s pressure, temperature, and media properties. For regions with high water hardness, such as karst areas, larger orifices and enhanced maintenance are necessary.
**4.2 Proper Installation**
Ensure the valve is installed correctly, with appropriate flanges, pipe sizes, and positioning. Anti-siphon devices and energy dissipation tubes should be included to prevent backflow and noise. Regular checks and adjustments are essential.
**4.3 Routine Maintenance**
Before installation, flush the pipeline thoroughly. During use, perform maintenance 1–2 times per year, more frequently in poor water quality conditions. Cleaning, replacing seals, and checking components help maintain reliable operation.
**5. Conclusion**
Selecting the right hydraulic control valve, installing it correctly, and performing regular maintenance significantly improve its stability and reliability. These steps are vital for ensuring safe and efficient water supply systems. By addressing structural, installation, and operational challenges, we can minimize malfunctions and ensure consistent, trouble-free performance.
**References**
[1] Second Nuclear Design Institute. *Water Supply and Drainage Design Manual*. China Building Industry Press, 2001.
[2] Water Supply Project. *China Building Industry Press*, 1995.
[3] Department of Hydraulics, Southwest Jiaotong University. *Hydraulics*. Xi'an University of Architecture and Technology, 1983.
[4] Wang Yonghui, Huang Tinglin. *Water Physical Chemistry*. Northwestern Polytechnical University Press, 1993.
**About the Author:**
Zhang Hong (born January 1977), male, bachelor's degree, assistant engineer.
Accessories of screw and barrel
ZHEJIANG JINJIA PLASTICS MACHINERY CO., LTD , https://www.jinjiascrew.com