Historically, firefighters have used water to attempt to control an ammonia release. ASTI cautions that there are negative impacts to using water on an ammonia release.

  1. Water sprayed on a leaking pressure vessel of ammonia may increase heat and extend the time frame of the release.
  2. Ammonia and water chemically mix to create ammonium hydroxide. The pH factor of ammonium hydroxide quickly reaches 11.2. The alkaline exposure will cause skin irritation and respiratory threats that are more problem-some than simply letting the ammonia go to atmosphere.
  3. If the aqua ammonia solution finds its way to a live body of water a fish kill may occur, especially when the ammonia traps fish in small stream locations. The threat of nitrates in drinking water is also suspect if large volumes of aqua ammonia drain and pond in open ground area.

ASTI has created a method of mitigating an aerosol release that results in much less life and environmental threat than occurs when using water on an aerosol. Firefighters are trained to cover an aerosol release with a tarp (or salvage cover). The firefighters will use exhaust fans (just as is used to do positive pressure ventilation during a structure fire) to move ammonia vapors away from the firefighters as they move in sync to cover the release; one firefighter at each front-leading corner of the tarp (using a pike pole to extend the tarp forward and over the release without getting into an of the ammonia dense gas aerosol), and a third firefighter, at the rear of the tarp to guide the movement of the tarp over the aerosol stream and then to take charge of anchoring the tarp in place.

Covering an aerosol stream will significantly reduce the downwind threat of an aerosol release. Furthermore the covered ammonia aerosol will cool the tank and reduce the temperature and pressure of the ammonia supply, thus reducing the overall time of the release.

Firefighters dressed in full turnouts, total skin protection (including a Nomex hood), and a SCBA should not experience problems if they work in vapor levels that do not exceed 10,000 PPM (which is considered to be the beginning of the skin redness and irritation when the skin is directly exposed to the ammonia vapor). Technician trained hazmat specialist should wear Level A fully capsulated entry suits with thermal gloves and boots when dealing more directly with controlling an aerosol release.

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About ASTI

Established in 1987, the Ammonia Safety & Training Institute (ASTI) is a 501(c)(3) organization dedicated to making ammonia (NH3) the safest managed hazardous material in the world. Bringing together leaders from industry and public safety organizations with hundreds of years of combined experience, ASTI provides safety management support through effective use of Prevention, Mitigation, Preparedness, Response and Recovery (PMPRR) training. All courses meet OSHA standards.