| It looks like someone declared June 8, 2007 to be | | | | Screening Threshold Quantity (STQ) listed in the |
| the day for serious Anhydrous Ammonia spills from | | | | proposed Appendix A, Chemicals of Interest, to 6 |
| refrigeration systems across the country. There | | | | CFR part 27. Cooling systems having more than 7,500 |
| were three separate instances of significant spills | | | | pounds of Anhydrous Ammonia in the system would |
| reported today. Mount Sterling, KY, Wyalusing, PA, | | | | make that food processing company a ?Chemical |
| and Milwaukie, OR all had releases in the last 24 | | | | Facility? under the rules of this regulation. |
| hours. No one was killed, but a number of people | | | | According to the EPA Risk Management Plan (RMP) |
| were taken to the hospital, businesses were | | | | guidance documents, 7,500 lbs of Anhydrous |
| evacuated, and residents were told to shelter in | | | | Ammonia released in 10 minutes time from a |
| place. | | | | pressurized system (clearly a catastrophic leak, not a |
| There were explosions associated with two of the | | | | faulty valve) will have a plume with a toxic end point |
| incidents. There are reports that the ammonia leak at | | | | 3.2 miles down wind from the site of the leak (Table |
| a Nestle Plant in Kentucky caused an explosion that | | | | 9, 1.5 m/s wind speed). That means that anyone |
| blew down a wall at that plant; no injuries from the | | | | between the leak and 3.2 miles downwind could be |
| explosion or falling debris have been reported. The | | | | exposed to dangerous concentrations of Anhydrous |
| American Cold Storage facility in Oregon had an | | | | Ammonia. |
| unexplained (as yet) explosion result in the ammonia | | | | Rather obviously, from the lack of casualties, none of |
| leak. There were no reports of an explosion | | | | these three release events came any where near |
| associated with the leak at Cargill Taylor Beef Plant in | | | | 7,500 lbs in 10 minute release rate required for a 3.2 |
| Pennsylvania. | | | | mile long toxic plume. There is nothing in any of the |
| Anhydrous Ammonia is favored in many large cooling | | | | available article that tells anything about the release |
| systems because it has better heat transfer | | | | rate for these accidents, but from the description |
| characteristics and is cheaper than the refrigerant | | | | they did not seem to be catastrophic release events. |
| gasses used in home cooling systems and | | | | But what about the explosion caused by the release |
| refrigerators. The problem is that this material is very | | | | in Kentucky? |
| reactive and is classified as a Toxic by Inhalation gas. | | | | Anhydrous Ammonia is a very reactive chemical, and |
| Fortunately, the gas is extremely irritating at well | | | | even by itself can form an explosive mixture when |
| below the toxic level so that when a minor leak | | | | mixed with air at concentrations of 16 to 25% |
| happens, unprotected people evacuate the area | | | | Ammonia in air, though it would require a strong |
| quickly with little urging. A catastrophic leak, however, | | | | ignition source. It reacts to produce explosive |
| can overcome people before they have a chance to | | | | by-products when it mixes with Chlorine, Bromine or |
| get clear. This is partially because many people are | | | | Iodine. Violent reactions occur with Bleach or |
| temporarily blinded by less than lethal concentrations. | | | | Peroxides. It also forms explosive compounds with |
| The food industry has long maintained that they | | | | Gold, Silver and Mercury. So, while explosions are not |
| should not have to comply with any handling | | | | part of the normal operating conditions of |
| restrictions on Anhydrous Ammonia required under | | | | refrigeration systems using Anhydrous Ammonia as a |
| various Federal laws, since they don?t actually handle | | | | refrigerant, an explosion after a significant leak would |
| Anhydrous Ammonia; it stays in a closed system. | | | | not be totally unexpected. |
| During the regulatory comment period they | | | | Just maybe, DHS was correct in setting the STQ limit |
| complained about being required to submit | | | | for Anhydrous Ammonia at a low enough level so |
| information under the new Chemical Facility | | | | that some refrigeration plant users could be labeled |
| Anti-terrorism standards based on the 7,500 pound | | | | as Chemical Facilities. |