Solenoid sequence valves

A solenoid sequence valve is a control valve used in hydraulic systems to determine the order in which various functions are activated, based on pressure levels. It ensures that one operation is initiated only after a specific pressure is reached in another part of the system. The sequence valve remains closed under normal conditions and opens only when the pressure reaches a preset value. A common application is with two hydraulic cylinders, where “cylinder two” starts moving only after “cylinder one” is fully extended. Sequence valves are typically used in systems such as lifting equipment, presses, hydraulic grippers, and sequential hatch control.

How a sequence valve works

Sequence cartridges are similar to relief cartridges except the pilot is separately drained so that valve setting is not affected by pressure in the outlet port. When the sequence valve reaches the preset opening pressure, it allows the flow to pass to the next function in the system. Since the spring chamber has a separate drainage, the valve’s function is not affected by any backpressure downstream. To allow for return flow, a check valve is required. Sun Hydraulics offers several combination valves that integrate both sequence and check valve functions – these are identified by the designation SC** in the product code.

Continuously control

Proportionally controlled sequence valves enable continuously regulation of pressure levels and require control via a pilot valve of the RBAP type. These valves use SUN’s T-8A cavities, allowing them to be mounted directly into the main stage valve for a more space-optimized installation. The standard model, RBAP, provides minimal pressure in the de-energized state. For applications where the opposite is desired, an inverted version, RBAN, is also available, which instead delivers the set maximum pressure in the de-energized state.

Different sizes

Sequence valves are available in different sizes, offering flows of up to 480 l/min. They are functionally interchangeable with each other, and within the same flow range, they have the same cavity. The valves are also fully adjustable over a wide pressure regulation range, with a pressure of up to 350 bar, and intermittent operation up to 420 bar (excluding air-piloted valves).

Electric control

To enable electric control, the sequence valve is combined with a solenoid coil. Solenoid coils from Sun Hydraulics are available in various models with different connector types and voltage options, providing high flexibility for adaptation to different applications. The solenoids are compatible with both on/off functions and proportional control. For proportional control, the XMD controller is recommended, which can be easily configured via a mobile app or computer software.