Because the ball valve is typically used rubber, nylon, and ptfe as seat sealing material, therefore its use temperature is limited by seat sealing material. As function of ball valve is on the metal sphere under the action of medium, the pressure to complete each other between the plastic seat (floating ball valves). Seat sealing under the certain contact pressure effect, elastic-plastic deformation of local region. The deformation can be made of the manufacturing precision and surface roughness of a sphere, to ensure that the ball valve sealing performance.
And as a result of the ball valve seat sealing used plastic, so in the choice on the structure and performance of the ball valve, want to consider the refractory of ball valve and fire prevention, especially in petroleum, chemical industry, metallurgy and other departments, the equipment and piping system of inflammable, explosive medium used in ball valve, more should pay attention to fire and fire prevention.
Usually, in two position adjustment, sealed performance is strict, mud, wear, reducing channel, opening and closing action quickly (1/4 turn open-close), high pressure cut-off (differential pressure), low noise, have spirit cave and gasification phenomenon, into the atmosphere of a small amount of leakage, small operation torque, small fluid resistance of the pipeline system, it is recommended to use ball valves.
Ball valve can also be applied to light structure, low pressure by the (small) differential pressure, corrosive medium in the pipeline system. In low temperature, cryogenic device and also can choose ball valve in the pipeline system. Oxygen piping system in metallurgical industry, the need to use strict degreasing process of ball valve. Mains in the pipeline and gas transmission pipeline should be buried in the ground, the need to use full size welded ball valve. When in requires regulation performance, need to choose the special structure of ball valve with v-shaped opening. In the petroleum, petrochemical, chemical, electric power, city construction, the working temperature above 200 degrees of the piping system can choose metal to metal sealed ball valve.