4 ms·

Once corrosion is under control, is that danger actually higher than the risk of a natural gas fuel system leaking and killing a whole crew? Both gases are ligh

Once corrosion is under control, is that danger actually higher than the risk of a natural gas fuel system leaking and killing a whole crew? Both gases are lighter than air, both form explosive mixtures with air (but ammonia-air mixture has much slower flame speed and slower pressure rise than natural gas - for which it makes up with its much higher toxicity). In the end, gas leaks are always bad. But at least you can easily smell an ammonia leak.

iamthemonster 2y ago
No the ammonia toxicity hazard is incredibly severe, it immediately burns your lungs and you die by choking on your own blood as your lungs dissolve. Whereas with natural gas leaks you can reduce the likelihood of ignition by intrinsically safe instrumentation and electrical components. In both cases, gas detection and automated shutdown and sectionalisation helps significantly.
rbanffy 2y ago
> But at least you can easily smell an ammonia leak. IIRC, they add a very nasty smelling chemical to LNG so that leaks are evident before they get explosive. In the case of ammonia, the additive is not really needed, and the toxicity being much higher makes me think that, by the time you realize you are breathing ammonia, it's already too late.
- pbmonster 2y ago
  I know they add a thiol (sulfur compound that smells like rotten eggs) to the city mains for cooking/heating gas. Would be interesting to know if its commonly added to industrial LNG. Because we burn a lot of that - even if you only add a few ppm thiol to natural gas, that's a whole lot of sulfur being burnt...
bluGill 2y ago
If you inhale natural gas it is only deadly (it can cause other problems that are treatable) when it displaces enough oxygen. In open air you are hopefully okay because there is still enough oxygen that you can breath. Ammonia is deadly when inhaled in small quantities. I wouldn't want either, but ammonia is worse if you must choose. I'm not sure how likely fire is in case of a leak.

iamthemonster 2y ago

No the ammonia toxicity hazard is incredibly severe, it immediately burns your lungs and you die by choking on your own blood as your lungs dissolve. Whereas with natural gas leaks you can reduce the likelihood of ignition by intrinsically safe instrumentation and electrical components. In both cases, gas detection and automated shutdown and sectionalisation helps significantly.

rbanffy 2y ago

> But at least you can easily smell an ammonia leak. IIRC, they add a very nasty smelling chemical to LNG so that leaks are evident before they get explosive. In the case of ammonia, the additive is not really needed, and the toxicity being much higher makes me think that, by the time you realize you are breathing ammonia, it's already too late.

pbmonster 2y ago
I know they add a thiol (sulfur compound that smells like rotten eggs) to the city mains for cooking/heating gas. Would be interesting to know if its commonly added to industrial LNG. Because we burn a lot of that - even if you only add a few ppm thiol to natural gas, that's a whole lot of sulfur being burnt...

bluGill 2y ago

If you inhale natural gas it is only deadly (it can cause other problems that are treatable) when it displaces enough oxygen. In open air you are hopefully okay because there is still enough oxygen that you can breath. Ammonia is deadly when inhaled in small quantities. I wouldn't want either, but ammonia is worse if you must choose. I'm not sure how likely fire is in case of a leak.