Abstract: On February 27, 2002, a water treatment plant operator, Employee #1, changed a 1-ton container of chlorine using a supplied air respirator and a standby rescuer with a self contained breathing apparatus. He re-entered the chlorine storage room alone, without a respirator, to log numbers from the container after the hook up was completed. Employee #1 jiggled an emergency shut off actuator that was mounted on the outlet valve of the container to ensure that it was well connected. When he did, the yoke connection came loose and liquid chlorine began spraying from the container outlet valve at him. Employee #1 inhaled chlorine gas and he was alone, without visual or voice contact of others and had no personal alarm. He exited the room and donned a self contained breathing apparatus that had an empty air cylinder. Other employees eventually responded to his cries for help. Employee #2, a supervising operator activated a remote emergency shut off on the control board, which failed to operate. Employee #2 then activated another shut off button on a wall outside the chlorine storage room. It closed the container outlet valve and stopped the leak. Employee #1 had used a damaged yoke connection (CGA 820) to connect the chlorine container to flexible "pigtail" tubing. The yoke had been damaged from overtightening by employees. Employee #1 treated himself with oxygen at the scene and was later hospitalized. He returned to work two weeks later.