Old 12-03-2022, 06:39 AM
  #7  
rickair7777
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Originally Posted by TransWorld View Post
Sorry for lack of clarity.

In electrical power plants, H2 is used for cooling the stator of the generator. After all the welding of the metal is complete, pressure tests with Air and then He are done. Any leaks corrected. Then H2 is introduced. Several leaks with H2 are found that were not found with He. This is typical.

In my previous life, I have witnessed this first hand, on the construction site.

H2 lower flammability limit is 4%. It is not how much fuel leak is tolerable, for cost of fuel losses. It is how far away from the leak it can be set off by a spark or other ignition source.

Unlike Jet A, it requires no vaporization. Unlike methane (CH4, natural gas) H2 is much more susceptible to getting out through tiny leaks.
Yes H2 will leak... I suspect the only practical solution which could hold up to the rigors of aviation will be a an exterior shell around tanks and probably lines and fittings, which is vented overboard with an appropriate airflow (fan on the ground, ram air when airborne). Not really hard or expensive, but another weight and complexity factor which chips away at the practical utility of H2.
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