What Is a Control Pressure Valve?
Control pressure valves are essential components in fluid systems, used to manage the pressure of fluids like hydraulic oil. By adjusting the discharge pressure from a pump, these valves prevent damage to system components and piping, often functioning as safety valves.
These valves are broadly classified into five categories:
- Relief Valve (Safety Valve)
- Pressure Reducing Valves
- Sequence Valves, Unloading Valves, Counterbalance Valves
- Brake Valves
- Balancing Valves
Control pressure valves are available in handle type and solenoid type, with the latter offering a broader range of control through external controllers.
Uses of Control Pressure Valves
These valves are primarily used in construction machinery, playing a critical role in hydraulic excavators, bulldozers, wheel loaders, and skid steer loaders. They safeguard hydraulic equipment and piping against damage.
For instance, in hydraulic excavators, control pressure valves are integrated into hydraulic pumps, control valves, and traveling motors, proving indispensable in construction machinery.
Beyond construction, these valves find applications in aircraft and automobiles, essential across various industries.
Principle of Control Pressure Valves
Here, we explore the principles behind relief valves (safety valves) and pressure reducing valves:
- Relief Valve (Safety Valve)
A relief valve activates when fluid pressure exceeds a set threshold, ensuring the safety of equipment and piping. The set pressure is calibrated by adjusting the spring tension. Below this pressure, the valve remains closed due to spring force. Once the fluid pressure surpasses the set level, it overcomes the spring, opening a pathway to a fluid storage container, thereby relieving excess pressure.
- Pressure Reducing Valve
This valve modulates pressure from a high-pressure primary side to a lower, set pressure on the secondary side. The desired pressure level is set by adjusting the spring force. Part of the fluid is directed through a port to a storage container to stabilize the secondary side pressure.