Abstract: At approximately 5:00 p.m. on September 10, 2001, Employee #1 was working with a 300-cubic-foot cylinder which contained a mixture of nitrogen and carbon monoxide. He had just finished inspecting the cylinder, found no defects, and noted that the cylinder was not due for hydro testing. Employee #1 connected the cylinder to the filling manifold and began the filling process. When the cylinder reached approximately 1400-1500 psi, he noticed a leak, and approached the cylinder to investigate. The cylinder then ruptured, throwing him across the room. Two coworkers pulled Employee #1 out of the room, and he was transported to Yale-New Haven Hospital, where he was hospitalized with amputations of both lower legs.