Abstract: A method and assembly for treating hazardous and/or unknown fluids either liquids or compressed gases contained in a gas cylinder (12) having a cylinder body (14) and a removable fixture (16). The assembly (10) includes a tubular housing (18) having an open end (20). An adjustable carriage assembly (34, 38, 40) is included for supporting the cylinder body (14) in the center of the housing (18). A clamping assembly (30) secures the cylinder body (14) to the carriage assembly (34, 38, 42). An end cap (70) seals the open end (20) of the housing (18). A shaft (72) is rotatably disposed through the end cap (70). The shaft (72) includes a fixture engagement assembly (78) on one end (76) thereof for engaging a portion of the fixture (16) and imparting a rotational force thereto. A motor driven gear box (86) imparts the rotational force to another end (74) of the shaft (72 ).