Abstract: A hyperbaric oxygen therapy system having a vertically-oriented pressure vessel and a generally rectangular door opening. The hyperbaric oxygen therapy system also includes a door frame sealingly attached to the door opening and a door panel. The door panel has a shape complementary to that of the door frame and is movable between an open position away from the door opening and a closed position adjacent to the door opening. A door support mechanism is attached to the pressure vessel and movably supports the door panel between the open position and closed position. The hyperbaric oxygen therapy system also includes an interlocking mechanism movable between a locked position when the door panel is in the closed position, wherein the interlocking mechanism extends between and secures the door panel and the door frame, and an unlocked position wherein the interlocking mechanism is retracted from one of the door panel and door frame.