WYDave - 9/30/2023 14:29

The answer is "it depends."

Anhydrous presents several different hazards to manage. The first hazard, of course, is what we categorize as "IDLH" (Immediate Danger to Life and Health) from higher (> 35 ppm for > 15 minutes, or 300 ppm in a short time frame) concentrations of the gas.  

The second immediate hazard is possible explosion or deflagration - people often forget (due to the more immediate danger above) that ammonia is flammable in air, and when the concentration gets high enough, it can explode or deflagrate in the right concentrations.

Lastly, there is the issue of contamination in runoff water. A gallon of water can absorb between a pound and two pounds of anhydrous, depending on how well you can disperse the ammonia into the water.

Then there is a problem for firefighters in close enough proximity to the anhydrous escape in applying water to an anhydrous escape is that while our SCBA systems provide protection against anhydrous, bunker gear does not.  

So, long story short: The issue of dousing with water depends on the presentation and which danger(s) the firefighters are trying to mitigate.