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Gaseous hydrogen is molecular hydrogen and does not cause embrittlement, though it can cause a hot hydrogen attack (see below). It is the atomic hydrogen from a chemical attack which causes embrittlement because the atomic hydrogen dissolves quickly into the metal at room temperature. [6] Gaseous hydrogen is found in pressure vessels and pipelines.
Liquid hydrogen also has a much higher specific energy than gasoline, natural gas, or diesel. [12] The density of liquid hydrogen is only 70.85 kg/m 3 (at 20 K), a relative density of just 0.07. Although the specific energy is more than twice that of other fuels, this gives it a remarkably low volumetric energy density, many fold lower.
Hydrogen damage is the generic name given to a large number of metal degradation processes due to interaction with hydrogen atoms. Note that molecular gaseous hydrogen does not have the same effect as atoms or ions released into solid solution in the metal.
The balance of evidence as of 2020 does not indicate that deep stops increase decompression efficiency. Any inert gas that is breathed under pressure can form bubbles when the ambient pressure decreases. Very deep dives have been made using hydrogen–oxygen mixtures , [61] but controlled decompression is still required to avoid DCS. [62]
The Hindenburg disaster is an example of a large hydrogen explosion. Hydrogen safety covers the safe production, handling and use of hydrogen, particularly hydrogen gas fuel and liquid hydrogen. Hydrogen possesses the NFPA 704's highest rating of four on the flammability scale because it is flammable when mixed even in small amounts with ...
In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.
Immediately after an explosive decompression, a heavy fog may fill the aircraft cabin as the air cools, raising the relative humidity and causing sudden condensation. [4] Military pilots with oxygen masks must pressure-breathe, whereby the lungs fill with air when relaxed, and effort has to be exerted to expel the air again.
The autoignition temperature or self-ignition temperature, often called spontaneous ignition temperature or minimum ignition temperature (or shortly ignition temperature) and formerly also known as kindling point, of a substance is the lowest temperature at which it spontaneously ignites in a normal atmosphere without an external source of ignition, such as a flame or spark. [1]