Abstract: At approximately 9:30 a.m.. on April 14, 1997, Employee #2 began to put furnace #3 on flux. Adhering to established procedure, he opened the main upstream chlorine valve first, intending to open the downstream chlorine control valve to control the flow. With no outlet for the gas, which was flowing at 30 psi, the pressure dead-ended in the flowrator and sent the metal float in the flowrator shooting to the top of the Pyrex tube. The float broke through the glass tube, releasing chlorine gas into the face of Employee #2. Employee #1 was approximately 25 ft away, and helped Employee #2 to a safe place. Employee #1 then went to activate the nearest chlorine alarm. On the way, he donned an emergency respirator, but was unable to get it to function, and passed through the chlorine cloud twice again without respiratory protection. Employee #3, in the pit area near the furnace, also was unable to get a nearby respirator to function, and was exposed to chlorine gas. The primary causes of the accident were the employer's failure to implement in sufficient detail the requirements of PSM, failure to perform a hazard analysis of the furnace fluxing procedure, and failure to develop a safe written operation procedure. Factors contributing to employees' injuries included the poor location and inaccessibility of the manual-activation alarms and emergency respirators, and the fact that the respirators did not function properly.