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Pressure Relief Valves

Pressure Relief Valves

Works Well Under Pressure

Pressure relief valves are a critical component of an aircraft’s fuel, hydraulic, and pneumatic systems. These valves can serve one of three functions – safety relief, pressure regulation, or protection against thermal expansion. The Lee PRI® (Pressure Relief Insert) is specifically designed for these functions, helping to guarantee the safety and reliability of your aircraft.

Like all products from The Lee Company, pressure relief valves are small, lightweight, and incredibly durable – enough to serve out the entire 30-year lifespan of an aircraft without replacement. In addition, these products are available in a range of sizes and are engineered to withstand a variety of pressure ranges. We offer sizes from 0.187 inch diameter relief valves up to the 0.812 inch threaded line removable units (LRUs) to offer the appropriate flow and precise opening pressures to meet the specific needs of an application. Zero leak options are available for applications in which eliminating any leakage is critical.

For an unbiased look at relief valve configurations, critical performance characteristics, design challenges and trade-offs, and common failure modes, check out our eBook, An Engineer’s Guide to Selecting a Pressure Relief Valve.

Over half of the products we offer are designed for the unique needs of a specific application. Pressure relief valves can be designed in custom envelopes and configurations with unique cracking pressures, flow rates, leakage specifications, materials, and more. Contact your local Lee sales engineer to discuss your specific needs.

Safety Relief Valves

Safety relief valves are designed to be fast-acting components that protect systems with the potential for sudden pressure spikes. These valves may sit dormant for indeterminate amounts of time before needing to be used, so it’s crucial that they always work as intended. Our safety relief valves are available in low-leak and tight hysteresis configurations. To ensure reliable operation, we 100% test each component for crack, flow point and reseat pressure.

Our safety relief valves are available in 0.187, 0.250, 0.281 and 0.375 inch insert diameters and 0.687 inch threaded configurations. They are constructed entirely of stainless steel and are available screened and unscreened. Built-in damping ensures quiet operation. Cracking pressures ranging from 20 to 5900 psid.

Pressure Regulating Relief Valves

Unlike safety relief valves, pressure regulating valves operate more frequently. The Lee Company offers a “momentum-free” design concept for these applications. These valves compensate for momentum forces that upset the normal force balance of typical direct acting valves. The result is a valve that is stable throughout the operating range. These valves are available in 0.375 and 0.500 inch diameters with cracking pressures from 50-500 psid.

Thermal Relief Valves

When traveling from the cold at an altitude of 30,000 feet to a runway in the desert, rapid temperature change can cause thermal expansion of fluids and potential damage within the system. Thermal relief valves are designed to relieve small volumes of fluid to protect against thermal expansion. Two models are available, the Lee TRI® (Thermal Relief Insert) at 0.187-inch diameter and the High Pressure Lee TRI at 0.250 inch diameter. Due to the small passage size of thermal relief valves, they include an integral CRES low micron filter upstream of the valve seat to prevent internal silting due to ingested contamination.

Zero Leak Relief Valves

Instead of relying on a metal-to-metal seal, these valves incorporate an elastomeric or polymeric seal for a zero leak design, perfect for when leakage is a critical requirement of hydraulic or pneumatic applications. Available in a 0.187 inch diameter for low-pressure applications and a 0.281 inch diameter for cracking pressures ranging from 800 to 4700 psid.

High Pressure Safety Relief Valves

These 0.281 and 0.375 inch diameter relief valves are designed for applications where operating pressures and pressure spikes are too severe for conventional relief valves. Such conditions can lead to instability, erosion, and structural damage of conventional relief valves. High Pressure Safety Relief Valve sizes are available in a range of cracking pressures for system pressures up to 5000 psi.

High Flow Pressure Relief Valve

The Hi-Q PRV is designed for applications that require both a high relief pressure and a high flow rate in a line removable unit (LRU). The valve is offered with minimum cracking pressures from 1000 to 5400 psid and flow rates over 19 GPM, and uses a side inlet flow path to minimize the installation boss size and weight.

Support & Resources

Support & Resources from a Team that Speaks Your Language

Partner with The Lee Company and get much more than just a supplier of top-quality fluid control products. Our reliable technical support team is available every step of the way to help you find solutions, maximize productivity, and drive efficiency across your operations. Check out these aerospace and defense-specific resources to learn more.