What Is a Pressure Safety Valve (PSV)

A Pressure Safety Valve (PSV) is a spring-loaded safety device designed to open immediately and fully when system pressure exceeds a predetermined setpoint. It is typically used in compressible fluid systems—such as those involving steam, gas, or vapor—and acts as a last line of defense against catastrophic failure.

Key Features of a PSV

• Rapid "pop" action at set pressure

• Fully opens to relieve excess pressure

• Resets automatically once pressure normalizes

• Used in gas, steam, and vapor systems

• Ensures equipment safety in overpressure situations

PSVs are often required by safety codes and regulations, especially in high-risk environments like power plants, chemical facilities, and gas processing stations.

What Is a Pressure Relief Valve (PRV)

A Pressure Relief Valve (PRV) is a device designed to open gradually as pressure increases, allowing controlled release of excess fluid. PRVs are commonly used in liquid systems, such as water or oil pipelines, where a sudden release could cause system shock or cavitation.

Key Features of a PRV

• Modulates open based on pressure level

• Suitable for incompressible fluids

• Provides gradual and stable relief

• Prevents system overpressure without abrupt discharge

• Often used in hydraulic and liquid transport systems

PRVs play a vital role in maintaining operational balance, protecting pumps, pipes, and storage tanks from sustained pressure buildup.

PSV VS PRV

When to Use PSV vs. PRV

• Use a PSV when working with compressible media (e.g., steam boilers, gas pipelines) where a rapid response is essential to prevent explosions.

• Use a PRV for liquid systems (e.g., cooling loops, water distribution) where stable and continuous pressure control is more important than instant pressure dump.

Avoiding Common Mistakes

• A PRV in a gas system may not relieve pressure fast enough—risking rupture.

• A PSV in a liquid system can cause water hammer or hydraulic shock.

Trust I-Flow for Safety and Performance

Qingdao I-Flow offers a wide range of pressure relief and safety valves, engineered for reliability, fast response, and compliance with global safety codes. Our valves are tested for critical performance and built to handle the demands of chemical, power generation, marine, and industrial HVAC systems.Whether you need a high-capacity PSV for steam protection or a precision PRV for fluid systems, I-Flow delivers the confidence your operations require.