SPECIAL TOPIC : Hydrogen & Renewable Energy
Figure 1 : To protect end users in hydrogen applications , ball valves must contain stem seals made from materials that are resistant to long-term wear .
Hydrogen Ball Valves
Hydrogen fuel systems use ball valves to start and stop the flow of hydrogen from one part of the system to the other . If ball valves are specified for specific applications , operators should seek valves with stem seal designs that will resist wear over time , Figure 1 . Trunnion-style ball valves with direct-load designs can
be an excellent choice . Their design enables leak-tight performance each time they are activated , and each time they shut off . Alternatively , bottom loaded stem designs may prevent possible stem blowout , which could enhance the overall safety of the system . Experienced valve suppliers may be able to offer advice on which valves will work best in particular applications . Some ball valves offer two- or three-way functionality , different mounting options , and a range of flow coefficients that can be customized to fit specific needs . Lastly , it is important to make sure that the ball valves selected are compatible with other components within the hydrogen fuel system .
Hydrogen Needle Valves
When the adjustments in a hydrogen system must be more precise , needle valves may be a better option than ball valves . Like ball valves , however , it is important to consider several factors when deciding which ones to specify . Typically , needle valves are all-metal in construction and need significant force to seal properly , Figure 2 . If the specified
needle valve is not able to withstand such pressure , it may deform the needle itself and possibly the seat , leading to potential leaks and expensive repairs . Secondarily , the pressure is usually applied by large air actuators to open and close the valves , which can cause the needle valve to be under intense pressure for as long as two minutes .
To handle such operating conditions , needle valves should be constructed from high-quality 316 stainless steel , which is better able to prevent deformation during repeated use . Not all needle valves are certified to the proper pressure ratings for common hydrogen applications , which means they may not be able to withstand pressures between 350 and 700 bar . A knowledgeable supplier should be able to provide pressure ratings for any needle valves and ensure they are compatible with other hydrogen-qualified components .
Hydrogen Check Valves
Finally , to prevent excess backflow , check valves are often used in essential safety functions at hydrogen refueling stations , Figure 3 . Unlike other general service applications , hydrogen check valves have even more challenging circumstances to endure . For example , check valves often contain springs , which are made with strain-hardened materials that can leave them more vulnerable to hydrogen embrittlement and loss of ductility than those made with high-quality 316 stainless steel .
When used in fluid systems within refueling equipment , check valves are often subjected to large , rapid changes in pressure and temperature , which puts significant stress on their elastomer seals . That is why check valves are more suitable for hydrogen compressors than other hydrogenfueling system infrastructure parts . As always , material integrity is critical as well as compatibility with other components of the system . Suppliers with hydrogen expertise should be able to offer advice on such matters .
Why Choosing the Right Valves Matters
As the hydrogen mobility market continues to grow , the safety , reliability , and durability of its vehicles and refueling infrastructure are paramount . Without appropriate standards , the long-term viability of the market could be in doubt . Ensuring the proper components are selected and specified for all hydrogen systems will enable hydrogen to reach its full potential as an alternative to traditional fossil fuels . Find a fluid systems supplier who can offer a wide range of ball , needle , and check valves specifically designed for hydrogen systems , and consider whether it can offer additional components that can make overall system operation safer and more reliable for both operators and end users . Suppliers should have hydrogen experts available to guide manufacturers on the journey to ensure their components will stand up to the rigors of operating in a hydrogen fuel system environment .
Figure 3 : In hydrogen refueling systems , compressors use check valves to provide a critical safety function by reducing excess backflow that could put consumers at unnecessary risk .
Your Specialist for Overpressure Protection
Figure 2 : It requires large amounts of force to open and close needle valves in hydrogen applications , which means the specified valves must be able to withstand those pressures over time .
All images © 2023 Swagelok .
ABOUT THE AUTHOR
Chuck Hayes is the Principal Applications Engineer for Clean Energy for Swagelok .
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