Abstract: On May 3, 2009, Employee #1 was finishing up the distillation of a flammable solvent called tetrahydrofuran, while Employee #2 was working nearby. They noticed that a very loud whistling sound began to occur and that a large cloud of solvent vapor was beginning to form in and spread outward. There was an explosion and fire. Both employees sustained second degree burns. Employees #1 and #2 were hospitalized. The boiler room produced steam and hot oil which was pumped out to the Distillation Units to provide the heat. Surveillance videotapes suggested that flammable solvent vapor was drawn into the building became ignited in the Boiler Room.