The Global Center for Maritime Decarbonization (GCMD) has published a guide to inform interested parties of the dangers of ammonia when it is released at sea.
What happens when liquefied ammonia comes into contact with water?
As GCMD explains, release of liquefied ammonia (-33°C) below the waterline forms ammonium hydroxide (NH₄OH). Ammonium hydroxide solutions are lighter than water, floating on top and slowly diffusing into the water column. As aqueous ammonium hydroxide is colourless up to 30% concentration in water, visual observations of floating or dissolved plumes during spills are difficult. Factors affecting ammonia dissolution in water:
- Rate and extent of ammonia vaporisation
- Heat generated from ammonia dissolving in seawater
- Reactions of ammonium hydroxide with seawater impurities
- Solubility of ammonium hydroxide at the specific sea temperature Previous tests of ammonia release into water have shown that 55-60% of the ammonia dissolved in water.
Therefore, the vapour above remains pungent, stinging, and irritating. A dissolved ammonia plume in seawater can continuously release ammonia vapour depending on current and wind conditions.
Thirty minutes of exposure to ammonia with a concentration of 1,600 parts per million can be lethal. Ammonia also forms ammonium hydroxide upon contact with water, and this can be corrosive. An accidental release of ammonia therefore poses challenges that are very different from those caused by an oil spill.
… explains GCMD CEO, Prof Lynn Loo
Sourcing Safety 4sea
