HIGHLY CLEAN AND HOT VALVE

摘要

A highly clean and high temperature valve apparatus includes a valve driving unit and a valve casing connected to a bonnet supporting a valve stem slidably. A stem portion has one end positioned in a circumferential wall closed at its two ends by upper and lower covers, and supports one end of the valve stem with its other end extending through the lower cover. The stem portion has its ends supported respectively by first and second bellows for closing an axial through hole of the lower cover tightly. A first pipe communicates with a first space isolated by the first bellows, and a second pipe communicates with a second space isolated by the first bellows. The fluid quantities in the first and second spaces are increased or decreased relative to each other, thereby to drive the stem portion supported in a floating state by the first and second bellows.