Abstract: At approximately 10:00 a.m. on January 13, 1994, employees of Austin Industrial (AI) were helping Mobil Mining Operations purge a liquid anhydrous ammonia line with compressed air. At about 2:30 p.m. the maintenance engineer and the AI superintendent believed they had purged most or all of the ammonia from the line. The AI foreman and Employee #1 took the water truck to dispose of the ammonia/water solution. The maintenance engineer and the AI superintendent discussed flushing the line with water. Neither of them was sure how to do this process, so the maintenance engineer left to confirm the procedure with the hydrostatic testing engineer. The AI superintendent returned to his office to check on another job. The Mobil operator was waiting in the shipping office for the AI foreman and Employee #1 to return. When the AI foreman and Employee #1 returned to the AI field office, the AI superintendent told them to fill the water truck 1/4 to 1/2 full of water because Mobil was considering flushing the line with water. When they returned to the dock, the Mobil operator started back to the dock from the shipping office, and the AI foreman told Employee #1 that he was going to unroll the water hose. Employee #1 told the AI foreman something about going to check the compressed air hose connection. At approximately 3:30 p.m. the AI foreman, who had his back to Employee #1, heard a hissing noise that lasted 3 to 4 seconds. Employee #1 was burned by liquid and vapor ammonia in the face, neck, chest, and left leg. At 3:37 p.m. he received emergency medical treatment from intermediate EMTs on site and from paramedics from American Medical Transport (contractor of Harris County) . He suffered second degree chemical burns to about 36 percent of his body and had great difficulty breathing. At 4:22 p.m. he was taken by Life Flight to Herman Hospital, where he died on February 2, 1994. Since no one witnessed what happened at the time of the release--the AI foreman had his back to Employee #1 and the Mobil operator was donning her ppe at the middle of the dock-- it is uncertain exactly what caused it. Employee #1 may have disconnected the inlet hose while it was still under pressure; or he may have stepped on the inlet hose when he was stepping over the vapor and liquid ammonia lines, causing the hose to disconnect accidentally; or at the time Employee #1 was standing over the connection the inlet hose may have disconnected due to the pressure inside. The AI foreman was wearing either a face shield or a full-face respirator. Employee #1 may have had a respirator available, but no one saw him wearing it.