Ball valve: using

Ball gate made of polished stainless steel is fixed in crane housing on axis perpendicular to pipeline axis. Through hole is made in gate, diameter of which is equal to diameter of connected pipeline or close to it. In the open position, the axes of the pipeline and the holes coincide, and when the ball is rotated by 90 °, the axis of the hole moves to a plane perpendicular to the flow direction, overlapping the flow section with the ball wall. The seal between the polished surface of the ball and the housing is provided with fluoroplastic end rings, which are pressed against the ball by tightening bolts or poppet springs. Ball valves are controlled by means of lever, reduction gear, pneumatic or electric drive. Control with the help of a lever (handle) is used for cranes with a nominal diameter of less than DN125, and at large diameters, due to the high forces necessary for closing, gear drives are installed. Electric ball cranes are used for on-off control, remote control of valves located in inaccessible and remote places, as well as for automation of the technological process. The ball valve is a shut-off valve, it is not designed for proportional control of the medium flow and should not be operated at partial rotation of the ball. Otherwise, tightness of the flow overlap will not be ensured due to abrasive wear of the ball. To open the ball valve, it is required to turn the rod by 90 °, which requires significant torques, therefore electric drives for ball cranes are equipped with reduction mechanisms with a high gear ratio, which significantly complicates the design and increases the cost of the drive.