Abstract: At 11:30 a.m. on May 20, 2017, Employee #1, a refrigeration technician, and a coworker were performing pump down of a live ammonia refrigeration line to make the pipe available for replacement. The two employees had checked the line on the roof with a blower and thinking it was clear, went to the engine room to open a valve. The valve was difficult to open, and they believed it was clogged. Employee #1 loosened the valve to see if there was pressure and it popped loose and sprayed ammonia onto his hands and arms, as well as into the air. The employee was hospitalized for treatment after his exposure to the ammonia.