Should the relief valve be installed before or after the check valve?

As a hydraulic equipment manufacturer, we often think about the installation order of relief valves and check valves when designing hydraulic systems. Both valves play an important role in hydraulic systems. The relief valve is mainly used to protect the system from damage caused by excessive pressure, while the check valve is used to prevent the reverse flow of oil.

Why is the relief valve often upstream of the check valve?

When the relief valve is used as the main pressure control valve of the system, it is usually connected in parallel at the outlet of the hydraulic pump and before the check valve. At this time, the relief valve directly monitors and limits the output pressure of the pump to prevent excessive pressure caused by sudden load changes or system blockage, and protect the safety of the pump and pipeline. This iron rule is derived from the core safety logic of the hydraulic system: the pressure oil output by the oil pump can only enter the actuator circuit controlled by the check valve after passing through the relief valve. This layout ensures that when the system pressure exceeds the set value, the relief valve can immediately guide the excess flow back to the oil tank to avoid pressure surges that damage pipelines or components.

Exceptions for special situations

Under certain working conditions, the overflow valve needs to be placed after the check valve. For example, in a hydraulic locking circuit, an independent overflow valve is often required behind the locking device composed of two hydraulically controlled check valves. This design not only ensures the reliable locking of the actuator, but also can independently control the impact pressure when unlocking.

Another example is the oil supply circuit of some accumulators. When it is necessary to protect the downstream components of the accumulator, the overflow valve must be installed after the check valve. At this time, the check valve can prevent the accumulator energy from flowing back, while the subsequent overflow valve monitors the working chamber pressure at all times, forming a double protection mechanism.

Conclusion

As a valve block manufacturer, we are well aware that the proper selection of the installation sequence of relief valves and check valves is crucial to the stable operation of the hydraulic system and the protection of components. When designing a hydraulic system, we will comprehensively consider the balance of the entire hydraulic system based on the specific needs and application scenarios of the system, and correctly select the installation sequence to ensure that the hydraulic system can operate safely and efficiently.