Safety Valve vs Pressure Relief Valve: What’s the Difference?

In fluid and gas systems, overpressure can lead to catastrophic failures. That’s why pressure protection devices like safety valves and pressure relief valves are essential. But while they’re often used interchangeably, they serve slightly different purposes.

In this article, we’ll explore the differences between safety valves and pressure relief valves, their working principles, and how to choose the right one for your application.

1. What is a Safety Valve?

A safety valve is a fail-safe device designed to automatically release pressure from a system when it exceeds a preset limit, to protect equipment and personnel. It’s commonly used in steam, gas, and high-pressure systems.

①Actuation: Instant “pop-open” release

②Reset: Automatic re-seating after pressure drops

③ Applications: Boilers, pressure vessels, steam lines

Example: In a boiler, if pressure rises above the set limit, the safety valve pops open immediately to discharge steam and prevent explosion.

2. What is a Pressure Relief Valve?

A pressure relief valve (PRV) also protects systems from overpressure, but it operates in a more gradual and controlled manner, typically in liquid systems.

①Actuation: Opens gradually as pressure increases

②Adjustable settings: Often with spring-loaded design

③Applications: Liquid pipelines, pumps, hydraulic systems

Example: In a liquid pumping system, if backpressure builds up, the PRV slowly opens to allow controlled fluid discharge and maintain safe pressure.

3. Key Differences: Safety Valve vs Relief Valve

Feature	Safety Valve	Pressure Relief Valve
Activation style	Sudden “pop” open	Gradual opening
Media type	Mostly gas or steam	Mostly liquid
Typical use cases	Boilers, pressure vessels	Pumps, liquid lines
Reseating behavior	Fast automatic reseating	Slower or adjustable reseating
Sensitivity to pressure	Very sensitive, reacts instantly	Less sensitive, responds proportionally

4. Common Misunderstanding

Many engineers or operators treat safety valves and pressure relief valves as the same – but using the wrong one can reduce system efficiency or even compromise safety.

A safety valve in a liquid system may cause water hammer
A PRV in a steam system may not relieve pressure fast enough

Always choose the correct valve type based on media type and response requirements.

5. Choosing the Right Valve

Use a Safety Valve for:
① Steam
②Gas
③ Systems that require immediate pressure release
Use a Relief Valve for:
① Water or liquid pipelines
② Hydraulic systems
③ Systems requiring stable, controlled relief

DKV – Your Trusted Valve Partner

At DKV Valve, we offer a wide range of high-quality safety valves and pressure relief valves, manufactured to international standards like API, ASME, and CE.

✔ 40+ years of experience
✔ OEM & ODM customization
✔ Fast delivery, global service

📩 Contact us : dkv@dkvchina.com
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