Throughout my career, I have been taught that to safely “scrub” 1 pound of NH3, 1 gallon of water is required. I have firsthand experience in this ratio working. So I decided to ask Google Gemini+ to explain this ratio.
Looking back at IIAR-2, when we sized a Diffusion Tank for PSV discharge(s), it was always 1 gallon of water per pound of ammonia (e.g., IIAR -2, 5.5.3 Discharge Through a Water Diffusion Tank). This practice carried over when we had to evacuate NH3 from the piping due to a line break. We would determine how many pounds of NH3 needed to be evacuated, and this would determine how many gallons of water we needed. Here is what Gemini+ stated: