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Overflow valves
An overflow valve, sometimes referred to as a pressure relief or safety valve, is designed primarily as a protective device. Overflow valves are essential components in fluid systems, designed to automatically relieve excess pressure and protect equipment from damage.
Whether used on its own or as part of a complete pressure control setup, an overflow valve is a reliable and essential component in any system where pressure safety is a priority.
Our overflow valves come from the German manufacturer Herose and are suitable for a wide range of flow media and installation environments.
Feel free to contact us and our technical experts will help you to choose the right overflow valve for your specific application.
Principle and use
Overflow valves are essential safety components designed to protect equipment and piping systems from overpressure. When the pressure in a system exceeds a defined limit, the overflow valve opens automatically, allowing excess fluid to be safely diverted—typically back to a tank or vented—until normal pressure is restored. Once the pressure drops, the valve closes again, ensuring continuous system safety without manual intervention.
Overflow valves are often used in conjunction with pressure regulators to ensure stable and safe system operation. While a pressure regulator maintains a constant downstream pressure by adjusting flow, it may not always react quickly enough to sudden spikes or surges. In such cases, the overflow valve acts as a secondary safeguard, stepping in only if the regulated pressure temporarily exceeds the desired limit.
This combination is particularly useful in closed-loop systems, such as hydraulic circuits, compressed air lines, or process gas installations, where there's limited room for pressure to escape.
Overflow Valve vs. Back Pressure Regulator (BPR)
Both overflow valves and back pressure regulators (BPR) control pressure by relieving excess flow, but they serve different purposes. Overflow valves maintain system pressure by bypassing flow to a tank or reservoir, providing basic protection and balance. BPRs, on the other hand, are engineered to maintain a minimum upstream pressure through precise throttling or relief, critical for sensitive processes.
Overflow valves are typically used in hydraulic systems, fuels, or low-viscosity liquids, offering coarse control. BPRs are ideal for gases, liquids, or multi-phase mixtures, ensuring stable pressure even as conditions change. Overflow valves focus on simple flow management with slower, more abrupt operation, while BPRs deliver fast, smooth modulation essential for exact process control.
For example, in hydraulic lifts, overflow valves prevent pressure overload by diverting oil, while BPRs are essential in fields like gas chromatography or pharma production to maintain precise upstream pressure.
Overflow valves offer simple pressure control for general systems; back pressure regulators provide precise upstream regulation for critical, high-sensitivity applications. They are not interchangeable where precision and system safety are essential.
Safety Relief Valve vs. Overflow Valve
The main difference between an overflow valve and a safety relief valve lies in their functions. An overflow valve maintains system pressure by redirecting excess flow back to a reservoir or tank, ensuring system balance during normal operation. In contrast, a safety relief valve (SRV) serves as an emergency protection device, designed to vent fluid or gas quickly when pressure rises to a dangerous level, preventing system damage or explosions. It stays closed under normal operation and only opens during overpressure events.
Overflow valves provide gradual pressure regulation and reset automatically, while safety relief valves typically snap open and may require manual resetting. Overflow valves generally return flow to the system to maintain efficiency, whereas safety relief valves vent externally to prioritize safety. Typical uses for overflow valves include hydraulic systems and fuel circuits, while safety relief valves protect boilers, pressure vessels, and gas tanks.
Overflow valves regulate pressure; safety relief valves protect against overpressure. Choosing the wrong valve can lead to system failure or accidents, making proper selection crucial.
