Abstract: On September 7, 1993, Employees #1 and #2 climbed to the top of a railroad tank car to determine the effectiveness of a rinsing procedure that used No. 2 diesel fuel heated to 180 degrees Fahrenheit. Employee #1 opened the tank car hatch, leaned into the manway, was overcome, and fell into the tank car. Employee #2 went for help. When he observed his supervisor arriving, he entered the tank car, and was also overcome. Employee #3 arrived at the tank car, summoned a ladder, and entered the tank car unprotected by safety lines, respirators, or other appropriate personal protective equipment. Employee #3 became dizzy and exited the tank car. Employee #3 entered the car a second time, trying various forms of respiratory protection, but all failed. An air-supplied respirator was given to Employee #3, and he entered the tank a third time, tied straps around the chests of Employees #2 and #1, and helped lift them manually out of the tank car. Employee #3 was then assisted out of the tank car. Employee #1 died. Employees #2 and #3 were hospitalized.