Key differences between Safety Valves and Relief Valves

Below is a brief overview of the key differences between a safety valve, a full lift safety valve, and a relief valve:

1. Safety Valve

• Purpose: Primarily used in steam, gas, or vapor applications to protect pressure vessels, boilers, and other equipment from overpressure situations.
• Operation: A safety valve opens suddenly and fully when the set pressure is reached, allowing the excess pressure to escape immediately to prevent damage.
• Response: Quick and automatic—designed to rapidly reduce pressure.
• Usage: Common in steam and gas systems where a rapid release of pressure is essential to avoid equipment damage or explosion.

2. Full Lift Safety Valve

• Purpose: Also used in systems that require fast pressure release but with a more distinct design to open to its full capacity when the set pressure is exceeded.
• Operation: When the pressure reaches the set limit, the valve opens completely (or lifts fully), providing maximum discharge capacity immediately to reduce pressure quickly.
• Response: It has a high lift to release a large volume of excess pressure quickly.
• Usage: Ideal for situations with high-pressure steam and gas where a large, immediate release is needed to stabilize the system quickly.

Difference from Standard Safety Valve: The full lift safety valve lifts fully at once to the maximum possible opening, whereas a standard safety valve may open incrementally or to a lesser degree initially.

3. Relief Valve

• Purpose: Typically used in liquid systems, such as in hydraulic systems or liquid-filled vessels, to prevent excessive pressure that could cause system failure.
• Operation: A relief valve opens more gradually compared to a safety valve, releasing fluid slowly as pressure builds and closing once the pressure normalizes.
• Response: Opens and closes more progressively, which is often preferable for liquid systems where a sudden release could cause additional issues like water hammer.
• Usage: Common in liquid systems where a gradual release is needed to control the flow and prevent damage to pipes and other components.

Key Difference: Unlike safety valves, which are designed to open fully and quickly, relief valves respond more proportionally to the pressure level, making them suitable for liquid systems where a steady pressure release is better than a sudden one.

Summary Table:

Each valve type has a specific function based on the requirements of the system and the medium being used. Safety valves and full lift safety valves are most suited to gaseous systems requiring sudden discharge, while relief valves cater to liquid systems needing controlled pressure release.

At Safety Valves Online we offer a range of safety relief valves and relief valves, which are available to buy online for next day delivery. For any enquiries or assistance, feel free to contact our sales team via phone on +44 (0)1482 601030, or email sales@safetyvalvesonline.com. You can also use the convenient online chat feature on our website to contact us.