The hydraulic balance valve is a critical hydraulic control component primarily used to prevent loads from sliding uncontrollably due to gravity or external forces, ensuring smooth operation of actuators (such as hydraulic cylinders or hydraulic motors) and enhancing system safety and stability. It allows oil to flow freely in one direction from the directional valve to the load port, while controlling the reverse flow through the pilot assisted overflow function.
Working Principle
Plug in balance valve is essentially an adjustable relief valve with pilot assisted opening.
• Positive flow (load lifting): The oil can flow freely in one direction from the directional valve (port 2) to the load port (port 1), and the one-way valve opens.
• Reverse control (load reduction): When the load decreases, the fluid flow from port 1 to port 2 is controlled by a direct acting pilot assisted relief valve function. The pilot pressure of Port 3 reduces the effective set pressure of the relief valve by the coefficient of action of the pilot ratio, thereby achieving smooth control of the load reduction speed.
• Load holding: When the reversing valve is in the neutral position, the valve closes, preventing hydraulic oil from flowing out of the actuator and preventing the load from moving when there is no pressure supply.
Key Parameters
| Maximum working pressure | 350 bar (approximately 5000 psi) |
| Flow range | 1 - 720 L/min (various models) |
| Pilot ratio | 1.5:1 to 10:1 optional |
| Preset pressure | At least 1.3 times the load pressure |
| Operating Temperature | -20°C to +80°C |
| Leakage rate | Maximum leakage during seat return ≤0.3 cc/min |
| Structural features | Reduce the sensitivity to installation torque to prevent internal components from getting stuck |
| Seal option | Standard nitrile rubber (NBR), with EPDM sealing as an option to accommodate phosphate ester hydraulic oil systems |
Marine crane: Control the smooth movement of the boom lifting, luffing, and slewing mechanisms to prevent the heavy object from sliding out of control.
Ship cargo handling equipment: Such as hatch cover hydraulic systems and lifting platforms, ensuring stable speed during the lifting and lowering process.
Steering gear and stabilizing fin system: Used to maintain the position of the hydraulic actuator and prevent accidental movement caused by wave impact.
Offshore platform lifting system: Provides stable load control and maintenance for the lifting of the legs of a jack-up platform.
Specialized construction machinery: Such as hydraulic circuits for marine excavators, dredging equipment, and other construction machinery.
Operating Essentials
1. Model selection: Choose based on the system's maximum working pressure, flow rate, pilot ratio requirements, and whether there is back pressure.
2. Installation location: It should be installed as close as possible to the hydraulic actuator (cylinder or motor) to provide optimal control effect and prevent pipeline bursting.
3. Back pressure note: The standard 3-port CB series balance valve is strictly prohibited from being used under conditions where back pressure exists at the outlet (port 2), as back pressure will be multiplied and superimposed on the main valve setpoint, seriously affecting control accuracy. In such conditions, the spring chamber vented to atmosphere external relief type (CA or CW series) should be selected.
4. Setting and debugging: The set pressure of the valve needs to be adjusted by professionals on the test bench before installation, and adjusting the screw after installation should be considered as a manual emergency measure.
Advantage
• High reliability: The internal components are heat-treated, making them wear-resistant, impact-resistant, and fatigue-resistant, ensuring a long service life.
• Compact integration: The threaded cartridge design can be directly embedded into the valve block or actuator, saving space and reducing external piping.
• Precise control: Low leakage (≤0.3 cc/min) and adjustable pilot ratio ensure excellent load retention and smooth motion.
• Wide adaptability: Provides a variety of pilot ratios, flow specifications, and sealing options, suitable for special media such as mineral oil and phosphate esters.
