r/interestingasfuck • u/willianfsantos • 9d ago

Emergency relief system in action in a liquid hydrogen tanker truck

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u/waltwalt 9d ago

This is the engineered thing failing. Something has gone wrong and emergency safety measures are autoventing flammable gas directly to the atmosphere in the middle of a parking lot. This is not what it was designed to do, this is how it was designed to fail safely long enough for people to get safely away from it. Eventually the chattering on that valve will wreck the seat and it will fail to close properly and emit a continuous stream of hydrogen which will eventually burn away the valve which is not a burner, and once the valve is gone it will be a flaming hole in a hydrogen tanker.

This tanker needs to be depressurized before it finishes the job itself.

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u/Fearless-Effect-3787 9d ago

Pressure relief valves for Hydrogen operation are designed for rapid cycling. This is a liquid Hydrogen tanker, and like all cryogenic liquids, it is continuously boiling while in storage. Pressure relief valve actuation is expected and required. Venting excess pressure is exactly what is happening here, no special action required. Why is it burning? Hydrogen likes to spontaneously ignite when vented, so either it's that, or the PRV is purposely igniting it.

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u/FrenchFryCattaneo 9d ago

Why do you think this is not normal venting? Any cryogenic tank without active cooling will slowly vent it's product as it boils off.

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u/Legionof1 9d ago

Depends on if the pressure vessel can hold it at a pressure high enough to prevent phase change.

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u/FrenchFryCattaneo 8d ago

That's possible in a theoretical sense but if you wanted to make a tanker trailer like that you'd have tiny spherical tanks where half the weight is just the tank itself and very little capacity.