At What Pressure Does the Relief Valve Open? Understanding PROTEGO®’s 10% Technology

Engineering Safety Through Precision

Pressure and vacuum relief valves are essential safety components in pressurised storage tank systems, particularly in industries that handle flammable gases or volatile liquids. The exact set pressure at which a relief valve opens is more than just a technical parameter; it also affects operational safety and compliance. PROTEGO®, a market leader in explosion protection and tank safety, uses its 10% technology to revolutionise this critical threshold, offering unrivaled precision protection. This article delves into how PROTEGO®'s approach improves both plant safety and process efficiency.

What Is the Relief Valve Set Pressure?

The set pressure of a relief valve is the calibrated pressure at which it starts to open in order to relieve excess internal pressure or vacuum in the system. To ensure safe, dependable, and code-compliant performance, it must be precisely calibrated in relation to the tank maximum allowable working pressure and vacuum (MAWP/V), specified design pressure/vacuum, operating pressure/vacuum, and system dynamics.

PROTEGO® 10% Technology: A Higher Standard

PROTEGO® has developed a line of relief valves that open reliably at just 10% overpressure, a feature defined as their ‘10% technology.’ In contrast, many traditional valves require as much as 40% or even 100% overpressure to activate. By maintaining a higher setpoint pressure, the PROTEGO® design increases the available tank operating pressure while keeping the valve closed for longer. This reduces leakage, minimises emissions and decreases the number of relieving cycles.

Key Features of PROTEGO®’s 10% Relief Valve Technology

● Tight Operating Band: Opens within 10% overpressure for precise venting
● Minimal Leakage: Enhances emission control and conserves product
● Durability and Repeatability: Designed for long-term performance under harsh operating conditions
● High Flow Capacity: Optimised valve design to allow for high flow capacity

Example: For a set pressure of 100 mbar, a PROTEGO® Pressure and Vacuum Relief valves will be fully open at 110 mbar. This feature is particularly important for storage tanks which have very low MAWP or MAWV available.

How PROTEGO® Achieves 10% Accuracy 

1. Precision Machining of Valve Components 
PROTEGO® ensures superior valve seat leakage tightness by meticulously machining and lapping the valve pallet and seat. Metal-to-metal seals, achieve ultra-flat surfaces that eliminate leakage, which is critical for maintaining tight operational tolerances.

2. Optimised Sealing Options
PROTEGO® uses specialized sealing technologies to meet a variety of pressure requirements. Metal-to-metal seals provide superior mechanical integrity and sealing reliability in higher-pressure environments. Meanwhile, FEP air cushion seals are used for lower-pressure applications where elasticity improves tightness without requiring more lift pressure. Exotic metals, composites and plastics are also available for more demanding applications such as corrosive or polymerizing vapors. These optimized seal configurations consistently surpass the stringent leak-tightness benchmarks established by standards such as API 2000 and EN ISO 28300.

3. Flow-Enhancing Valve Design
The internal configuration of PROTEGO® valves includes a flow-enhancing design that improves efficiency during operation. This streamlined geometry enables a quick transition to full valve lift, resulting in smooth and consistent fluid flow. Utilizing their Flow Test facility, PROTEGO’s approach to flow optimization results in accurate valve sizing and stable flow during venting cycles.

4. Full-Lift Pallet Design
PROTEGO® uses full-lift pallets in its pressure and vacuum relief valves, which can reach full lift and maximum discharge capacity with just 10% accumulation. Unlike many conventional designs that may require as much as 100% overpressure to fully open, this innovative approach ensures rapid, stable, and predictable valve behaviour. The full-lift capability is a critical requirement to achieve over and under-pressure relief whilst optimising process efficiencies and tank emission reduction targets.

Why It Matters

Understanding the pressure at which a relief valve opens is more than just an academic exercise; it is an essential component of plant safety and emissions control. 

PROTEGO®’s 10% Relief Valve Technology ensures that your system vents excess pressure at the appropriate time, protecting people, the environment and your equipment. For more information or to request specifications, visit www.protego.com.