Pressure relief valves are components in hydraulic systems that regulate the maximum system pressure and protect against overpressure. The valves ensure safe and efficient operation by monitoring the pressure in the lines. If necessary, they reduce excess pressure.

A pressure relief valve is primarily used for safety. It has the task of limiting the pressure in a system. In this way, it protects the hydraulic components installed in the system and the connected consumers from excess pressure.

In this article, you will learn how pressure relief valves work and how they are used in various applications. Discover how ARGO-HYTOS optimizes the performance and safety of your hydraulic systems with precise and reliable solutions.

What is the basic principle of pressure relief valves?

A pressure relief valve is used in hydraulic systems to limit the pressure in a system. In the rest position, the pressure relief valve is closed. It is set to a specific opening pressure that corresponds to the maximum permissible pressure in the system.

A pressure relief valve reacts to the pressure in the flow direction upstream of the valve. As soon as the pressure in the system reaches the set value, the valve opens and returns the excess volume flow directly to the tank. When the pressure has dropped to a safe level again, the valve closes automatically. This ensures that the hydraulic system remains within safe operating limits and prevents damage to components such as hoses, pumps and cylinders. This extends the service life of the equipment and increases operational safety.

What types of pressure relief valves are there?

Direct operated pressure relief valves and pilot operated pressure relief valves are the two types of pressure relief valves used in hydraulic systems.

Directly controlled pressure relief valves

• The valve opens against a closing force, which is usually applied by a spring. If the pressure drops, the valve closes again. One example of such a valve is the SR1A-B2/HxxL-CE1017 pressure relief valve from ARGO-HYTOS. It increases safety in hydraulic systems thanks to its outstanding stability and low hysteresis.
• These valves are usually used for small to medium volume flows of up to around 60 l/min. They are ideal for applications where precise pressure control and fast response to pressure changes are required.

Pilot operated pressure relief valves

• These pressure relief valves consist of a main stage and a pilot stage. The pilot stage continuously monitors the pressure in the system. If the pressure exceeds the preset value, the main stage opens. As soon as the pressure falls below the set pressure again, the pilot stage closes and the main stage follows. One example is the VPN2-10/MR pressure relief valve from ARGO-HYTOS, which offers high flow rates and excellent pressure control.
• Pilot operated pressure relief valves allow a smaller flow rate spread, resulting in a flatter pressure rise as the flow rate increases. These valves are used for larger volume flows and are particularly suitable for main pressure safety devices.

ARGO-HYTOS offers a wide range of pressure relief valves that are optimized for specific applications as well as for general hydraulic systems. The valves make a significant contribution to the operational safety and efficiency of hydraulic systems. They do this by preventing overpressure situations and thus extending the service life of the components.

Which construction types of pressure relief valves exist?

The choice between poppet and spool designs for pressure relief valves depends on the specific requirements of the application. These include:

• Pressure range
• Volume flow
• Precision of pressure control

Poppet valves are characterized by their tightness and precision. They react quickly to pressure changes. This makes them the first choice for applications where fast and precise pressure control is required.

Spool valves offer better control and enable flatter characteristic curves. This means that the pressure increase is lower as the volume flow increases. They are more robust and can handle larger flow rates, making them suitable for applications where high flow rates are required.

Built-in valves and modular designs offer different advantages depending on the specific application and space requirements. Built-in valves are relatively easy to install. They are compact and space-saving, making them ideal for applications with limited space.

Modular versions offer greater flexibility. They can easily be used and retrofitted in conjunction with Cetop valves. As a result, additional functions such as secondary safety devices and shock valves can be easily integrated. This modularity enables adaptation to different system requirements and provides a flexible solution for complex hydraulic systems.

Application of pressure relief valves in hydraulic systems

Pressure relief valves are used in a wide range of applications in hydraulic systems to ensure safe and efficient operation. Their primary task is to protect the system from overpressure.

For primary protection, pressure relief valves should be located near the pump and secured against unauthorized adjustment. This location ensures that the pressure is controlled immediately before it affects other parts of the system.

For secondary protection, pressure relief valves can be installed at other strategic points in the hydraulic system. For example, they can be placed downstream of other valves or on consumers such as cylinders or motors to provide additional protection. This secondary protection not only protects the components from overpressure. It also serves as protection against external influences or forces that could act on the system.

For applications that fall under the Pressure Equipment Directive 2014/68/EU, such as pressure vessels and systems, ARGO-HYTOS offers special PED-certified and TÜV-tested pressure relief valves. They not only ensure operational safety, but also meet the legal requirements for pressure systems.

The strategic positioning and selection of suitable pressure relief valves are crucial for the protection and durability of hydraulic systems. They make a significant contribution to preventing system failures and ensuring safety in demanding industrial applications.

Examples of the use of pressure relief valves in practice

Pressure relief valves from ARGO-HYTOS are used in a wide range of practical applications. They are used in construction machinery to protect hydraulic systems from overpressure and thus ensure the safety and longevity of the machines. In industrial hydraulic systems, they ensure precise pressure regulation and prevent damage to sensitive components.

They are also used in agricultural technology. There, they ensure the safe operation of hydraulic systems in tractors and other agricultural machinery.

Expert advice on pressure relief valves

The various types of pressure relief valves and their diverse designs offer a tailor-made solution for almost any hydraulic application. Whether for primary or secondary protection or for special requirements in accordance with the Pressure Equipment Directive 2014/68/EU: choosing the right valve is crucial for the efficiency and safety of your hydraulic system.

ARGO-HYTOS offers a wide range of pressure relief valves. They are optimized for both small and large volume flows and impress with their high precision and reliability.

Would you like to find out more about pressure relief valves? Or are you interested in a customized solution for your application? Then get in touch with the experts at ARGO-HYTOS. We offer you comprehensive advice and support in selecting and implementing the most suitable solution for your needs.

Visit our contact page. Get advice from experienced specialists to fully exploit the potential of ARGO-HYTOS pressure relief valves for your company.