Engineering Better Boil-Off Management

Proportional relief valves bring precise, stable control to the storage and transport of hydrogen and other Group 1 gases.

As clean-energy initiatives gather pace across Europe, liquid hydrogen (LH₂) storage and distribution are moving from pilot projects toward early commercial deployment.  Heavy-duty truck manufacturers and energy suppliers are investing in hydrogen transport infrastructure, while industrial users are adapting long-established cryogenic technologies to meet new performance and safety requirements for hydrogen and other Group 1 gases. In every case, effective boil-off gas (BOG) management remains one of the most demanding engineering challenges.

Even with advanced insulation, LH₂ and other cryogenic fluids stored near -253 ^OC absorb some heat, causing vaporisation and pressure rise within tanks. Whether installed on a truck, mounted in a refuelling station, or positioned at a production facility, each system must maintain precise pressure control to ensure safety and efficiency.

Traditional safety relief valves operate in a binary open-or-closed manner – effective for simple venting but less suited to modern cryogenic applications requiring precise pressure regulation. Proportional relief valves, by contrast, modulate continuously in response to changing pressure, allowing excess gas to be ducted safely to recovery or recirculation systems rather than vented to atmosphere.

In transport applications, this control reduces the risk of gas accumulation in confined areas such as maintenance bays or loading docks while maintaining stable set pressure under fluctuating thermal and load conditions. Their compact, lightweight design supports vehicle integration, and integrated connections simplify installation while minimising leak paths and fugitive emissions.

Reducing boil-off loss – often 0.1% to 0.3% per day for LH₂ - directly improves energy utilisation and process efficiency. Proportional relief valves enable this by maintaining pressure stability and allowing captured vapour to be safely redirected into the system, minimising waste and supporting environmental compliance. 

By offering precise pressure control across hydrogen and other high-purity gases, proportional relief valves enhance safety, reliability, and sustainability across transport and storage applications alike.  

For further information about Parker’s Cryogenic Proportional Relief Valves, please visit https://ph.parker.com/gb/en/product-list/needle-valve-cryogenic-proportional-relief-valve

Contact:

Jacob Hawkins, Innovation Manager

Instrumentation Products Division Europe, Parker Hannifin

Email: jacob.hawkins@parker.com

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