Ball valve for channeling fluid medium e.g. liquid or gaseous medium, has adjusting mechanism to axially press or release one of annular seals against shut-off device at time of valve opening/closing

摘要

Each of a pair of annular seals (34,35) is interposed between a shut-off device (30) and each of two valve housing sections (22,23). The shut-off valve is rotated about a control shaft (36) between closed and opened conditions. An adjusting mechanism axially moves one of the seals (35) to either press against or release from the shut-off device side, at time of valve opening and closing.