Operation and description of an Armstrong Inverted Bucket Steam Trap The inverted bucket is the most reliable steam trap operating principle known. The heart of its simple design is a unique leverage system that multiplies the force provided by the bucket to open the valve against pressure. Since the bucket is open at the bottom, it resists damage from water hammer, and wear points are heavily reinforced for long life. The inverted bucket has only two moving parts-the valve lever assembly and the bucket. That means no fixed points, no complicated linkage. Nothing to stick, bind or clog. Conserves energy even in the presence of wear Armstrong inverted bucket steam traps open and close based on the difference in density between condensate and steam-the inverted bucket principle. They open and close gently, minimizing wear. This simple fact means that inverted buckets are subject to less wear than some other types of traps.