Abstract: Employee #1 entered the "f" process area that contained a high concentration of solvent chemical vapors. The vapors, trichloroethylene and perchacroethylene, were created by a ruptured disk in a safety valve. The pressure relief disk of the fractional recovery unit ruptured as pressure grew too intense due to an emission control valve being left closed. Employee #1 was overcome by the vapor as a result of not using the proper respiratory protection. Employee #1 was wearing a North, permissible chemical cartridge type respirator rather than the self contained breathing apparatus which was available. Employee #1 had not been instructed in the proper selection and use of respirators and their limitations. Employer did not review the emergency action plan with the employee to cover designated action to take to ensure safety from fire and other emergencies.