3 ms·

The explosion happens when you cross the ignition energy threshold. So having a low ignition energy threshold can actually be an advantage as then much less fue

The explosion happens when you cross the ignition energy threshold. So having a low ignition energy threshold can actually be an advantage as then much less fuel is available to drive the explosion. Agreed that doing intrinsic safety for H2 is hell. I did once design a LED sidelight for the relevant class with significant current (redundant electronic energy regulation). So it is possible to do stuff, it just takes more work. The tendency for modern electronics to be very low voltage helps a lot.

dredmorbius 6y ago
More likely: A small amount of the leaked hydrogen encounters an ignition point, igniting the primary mass. The ignition zone is larger, risk is higher.
- Retric 6y ago
  Pure hydrogen can’t burn without oxygen, so you generally get a tiny flare and then a flame based the size of the crack. It’s really about the same risks as using gasoline which almost never causes a significant detonation.
  - dredmorbius 6y ago
    With vehicle, heating, rocket, or aviation applications, quantities involved are nontrivial. Hydrogen's flammable and explosive ratios with oxygen are large, and contrast starkly with other fuels; kerosene (jet/rocket fuel), bunker oil, and deisel, which ignite with difficulty, petrol, which ignites readily but not explosively, and even natural gas which deflagrates rather than explodes under most circumstances. Add in hydrogen's extreme tendency to leak, metal embrittlement, and high pressures and/or low temperatures, and the risks are immense. Particularly at scale, in widespread use, with poor maintenance and inspections.
    - Retric 6y ago
      It’s technically explosive in many situations where the location or net energy released makes that irrelevant. Being significantly lighter than air you might hear a loud bang above the vehicle where gasoline’s foof ends up being significantly more deadly. It’s not strictly better or worse, just different. Diesel for example can be very dangerous in a large open topped container, hydrogen just doesn’t stick around in that environment. PS: Consider what it would take to make a large hydrogen fuel air bomb that’s as effective as it’s hydrocarbon equivalent.

dredmorbius 6y ago

More likely: A small amount of the leaked hydrogen encounters an ignition point, igniting the primary mass. The ignition zone is larger, risk is higher.

Retric 6y ago
Pure hydrogen can’t burn without oxygen, so you generally get a tiny flare and then a flame based the size of the crack. It’s really about the same risks as using gasoline which almost never causes a significant detonation.
- dredmorbius 6y ago
  With vehicle, heating, rocket, or aviation applications, quantities involved are nontrivial. Hydrogen's flammable and explosive ratios with oxygen are large, and contrast starkly with other fuels; kerosene (jet/rocket fuel), bunker oil, and deisel, which ignite with difficulty, petrol, which ignites readily but not explosively, and even natural gas which deflagrates rather than explodes under most circumstances. Add in hydrogen's extreme tendency to leak, metal embrittlement, and high pressures and/or low temperatures, and the risks are immense. Particularly at scale, in widespread use, with poor maintenance and inspections.
  - Retric 6y ago
    It’s technically explosive in many situations where the location or net energy released makes that irrelevant. Being significantly lighter than air you might hear a loud bang above the vehicle where gasoline’s foof ends up being significantly more deadly. It’s not strictly better or worse, just different. Diesel for example can be very dangerous in a large open topped container, hydrogen just doesn’t stick around in that environment. PS: Consider what it would take to make a large hydrogen fuel air bomb that’s as effective as it’s hydrocarbon equivalent.