Crane – Closing regulating or switchgear. The main parts are the valve body and closure (stopper) in the form of a cone, cylinder, sphere or disc. For the passage of the medium in the gate provided a through hole or channel different forms, thus providing the required throughput characteristics when using the crane as a control device. Crane control (locking) is done by rotating the tube at 90 . BALL VALVE The largest application received stopcocks. They are used in pipelines transporting natural gas and oil, as well as in municipal supply, the tanks and boilers to determine liquid level, drainage systems, sampling. Ball valve with a stopper in the form of a ball with a through hole for passage of the medium has been widely used for various conditions.
By the principle of closing element sealing ball Cranes can be divided into two main varieties: floating ball and a ball on legs. They are used occasionally and construction of floating ring seals. Spherical cap and body have high strength and rigidity. To tap the ball with a small diameter passage are used most frequently were the construction of floating cork, in which the plug is not connected rigidly with the spindle, and can be displaced from the axis of the spindle. Under pressure protection cap is pressed against the seal ring housing, providing tight shut lock body. At large nominal diameter and the passage of floating cork creates pressures overly large burden on O-rings, making it difficult to work the ball valve, so that in such circumstances is recommended construction crane with a fixed cap. Locking pin plugs can be self-lubricating bearings or bearings, which have recently been in widespread use ball valves. O-rings in ball valves are made of rubber, PTFE or metal. Cranes with a small nominal diameter of the passage typically have manual controls, valves with a large diameter passage provided with pneumo-hydraulic drive.