Abstract: At approximately 12:45 p.m. on October 22, 1990, Employee #1, a caustic operator, was responding to a smoking pump in a cooling system for a persulfate crystallizer. The smoke was caused by decomposing potassium persulfate. While he was trying to activate a washing process to unplug the coolers, the pump exploded and Employee #1 was splashed with a hot mixture of potassium persulfate and potassium sulfate. He suffered second- and third-degree burns on about 13 percent of his body, and on November 5, 1990, died in the hospital from a myocardial infarction and a pulmonary embolism due to chemical burns. The cooler system had no provisions for relieving overpressurization. No instrumentation was in operation in the employee's remote control room to alert him that decomposition was occurring.