Working Principle, Function And Application of Hydraulic Balancing Valve

●Structure and working principle of counterbalance valve

The hydraulic balance valve allows oil to flow freely from port 2 to port 1. We can see from the top structure diagram below that when the pressure of valve 2 is greater than the pressure of port 1, the green part The core moves to valve port 1 under the driving of hydraulic pressure, the check valve opens, and the oil can flow freely from 2 to valve port 1.

The liquid flow from port 1 to port 2 is blocked. Until the pressure of the pilot port reaches a certain value, move the blue spool to the left to open the port flow.

When pilot pressure is not sufficient to open the blue spool, the valve port is closed. The fluid flow from port 1 to port 2 is blocked.

The principle symbols of the balancing valve are as follows;

●The role of the balancing valve

Flow Regulation: Balancing valves regulate the flow rate of fluids, ensuring that each part of the system receives the appropriate amount of fluid. This prevents some areas from being over-supplied while others are under-supplied.

System Efficiency: By maintaining balanced fluid flow, these valves help improve the overall efficiency of the system. This can lead to energy savings, reduced operational costs, and prolonged system lifespan.

Temperature Control: In HVAC systems, balancing valves are essential for maintaining consistent temperatures throughout different zones. They ensure that heated or cooled water is distributed evenly, providing uniform climate control.

Pressure Management: Balancing valves help manage and maintain the desired pressure levels within the system. This is particularly important in hydraulic systems where precise pressure control is required for optimal performance.

System Stability: By ensuring a balanced flow, these valves contribute to the stability of the system, reducing the risk of pressure fluctuations, water hammer, and other potential issues that could cause damage or inefficiency.

Commissioning and Maintenance: Balancing valves facilitate the commissioning process of fluid systems by allowing for precise adjustments to achieve the desired balance. They also make it easier to maintain the system by providing points of measurement and control.

Enhanced Comfort: In applications like HVAC systems, balancing valves improve the comfort of building occupants by ensuring even distribution of heating or cooling, eliminating hot or cold spots.

Preventing Overflows and Shortages: In water distribution systems, balancing valves help prevent overflows in certain areas while ensuring that all regions receive adequate water supply, promoting efficient resource utilization.

Load holding: The balance valve can prevent the undesired downward movement of the hydraulic cylinder. The balance valve allows the operator to lift the weight at a certain speed and keep it in a certain position.

Load control: The balancing valve can prevent the action caused by the load of the actuator before the action of the hydraulic pump, thereby eliminating the cavitation of the actuator and the phenomenon of load out of control.

Safe load: When the pipeline in the hydraulic oil circuit bursts or leaks seriously, the balance valve installed on the actuator can prevent the uncontrolled movement of the moving load.

●Selection Principles of Balance Valve Application

System Requirements

Understand the specific needs of the system, including flow rate, pressure, and temperature. Choose a balancing valve that meets these requirements.

Valve Type

There are various types of balancing valves, including static, dynamic, and pressure-independent valves. Select the type that best suits the application:

①Static Balancing Valves: Manually adjusted and suitable for systems with stable flow requirements.

②Dynamic Balancing Valves: Automatically adjust to changes in system conditions, ideal for variable flow systems.

③Pressure-Independent Valves (PICV): Combine flow control and pressure regulation, offering precise control and efficiency.

Size and Capacity

Ensure the valve size matches the pipe diameter and flow capacity. Incorrect sizing can lead to poor performance and system inefficiency.

Control Accuracy

Choose a valve that offers the desired level of control accuracy. For critical applications, high-precision valves are essential.

Material Compatibility

Ensure the valve material is compatible with the fluid being handled to prevent corrosion and wear. Common materials include brass, bronze, stainless steel, and plastic.

Installation Considerations

Evaluate the installation requirements, including space constraints, accessibility for maintenance, and connection types.

●Pilot Proportion Selection Principles

1.Understanding Pilot Proportion:

The pilot proportion refers to the ratio between the pilot pressure (control pressure) and the main system pressure.

It affects the sensitivity and accuracy of the valve's response to pressure changes.

2. High Pilot Proportion:

Valves with a high pilot proportion offer finer control and greater sensitivity to small pressure changes.

Ideal for applications requiring precise pressure regulation, such as critical HVAC systems and industrial processes with stringent pressure control needs.

3. Low Pilot Proportion:

Valves with a low pilot proportion are less sensitive and respond to larger pressure changes.

Suitable for applications where broad pressure control is sufficient and where rapid pressure changes are less frequent.

4. Application Considerations:

Precision Needs: High pilot proportion valves are preferable for systems requiring tight pressure control and minimal variations.

System Dynamics: In systems with frequent and rapid pressure fluctuations, high pilot proportion valves provide quicker and more precise responses.

General Applications: For less critical applications, low pilot proportion valves may offer a cost-effective solution while still providing adequate control.

The overflow setting value of the balance valve is generally 1.3 times the maximum working pressure, but the required pressure for opening the pilot valve depends on the pilot ratio. The pilot pressure can be calculated according to the following formula:

Pilot pressure = (set value of relief pressure-load pressure) / pilot ratio

To optimize load control and energy utilization, the following methods can be used to select the pilot ratio;

2.5: 1 Select when the load is extremely unstable, such as a long-arm crane.

5: 1 When the load changes and has an unstable effect on the mechanical structure.

10: 1 For applications where the load is relatively stable.