Ammonia

CAS RN: 7664-41-7

Hazards Summary

The major hazards encountered in the use and handling of ammonia stem from its toxicologic properties and reactivity. Exposure to this colorless gas (liquid, if compressed or in aqueous solution) may occur from its use as a fertilizer, chemical intermediate, alkalizer, metal treating/extraction agent, and common household cleaner. Ammonia is hazardous by all routes (ie, dermal, ingestion, inhalation), with the liquid capable of burning the skin, causing permanent eye damage, or corroding the digestive tract upon contact; and the gas capable of causing severe eye damage, pulmonary edema, and even death from spasm, inflammation, and edema of the larynx. OSHA has established an ammonia Permissible Exposure Level (PEL) of 50 ppm as an 8-hr time-weighted average (TWA). The ACGIH recommends an 8-hr TLV-TWA of 25 ppm. Ammonia levels should be controlled through process enclosure and the use of local exhaust and dilution ventilation, as necessary. While its offensive odor may serve as a warning, to assure against ammonia exposure, workers should wear chemical protective clothing composed of butyl rubber, natural rubber, neoprene, nitrile rubber, or polyvinyl chloride (not Viton), gloves, face protection, and, in emergency situations, a self-contained breathing apparatus. Facilities for quick-drenching the body, as well as eye-wash fountains, should be immediately at hand for the worker. Clothing that becomes wet with liquid ammonia should be placed in closed containers until it can be discarded. While this substance does not burn or ignite readily (autoignition temp: 1204 deg F), containers of ammonia may explode in the heat of a fire. For small fires involving ammonia, extinguish with dry chemical or CO2, and for large fires, use water spray, fog, or foam, taking care to prevent fire control or dilution water from causing pollution. More hazardous than its fire potential is ammonia's reactivity with halogens, interhalogens, and oxidizers. These reactions may be violent and/or may form explosive products. Ammonia should be stored in a cool, well-ventilated location, away from sources of ignition, and separate from other chemicals, particularly oxidizing gases (chlorine, bromine, and iodine) and acids. Aqueous ammonia is commonly containerized in steel drums. Anhydrous ammonia is stored and shipped (prohibited in passenger planes) in pressurized containers, fitted with pressure-relief safety devices, and bearing the label, "Nonflammable Compressed Gas". For small spills of ammonia, isolate 80 feet in all directions from the spill, ventilate the area, and allow vapor or gas to disperse. For large spills, evacuate the area for 160 feet in all directions, and dike to contain the spill for later recovery or disposal and to prevent runoff from causing pollution. Stay upwind and wear positive-pressure breathing apparatus and full protective clothing, as necessary.
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