Because the ball valve is usually made of rubber, nylon and PTFE as the seat seal, the temperature is limited by the seat seal material. The cut-off function of the ball valve depends on the metal sphere under the action of the medium, the plastic valve seat between the pressure to complete (floating ball valve). In the case of a certain contact pressure, the plastic deformation of the seat seals occurs in the local area. This deformation can compensate the manufacturing precision and surface roughness of the sphere, and ensure the sealing performance of the ball valve.
And because the valve seat seals of the ball valve are usually made of plastic, therefore, in the selection of the ball valve structure and performance, to consider the ball valve fire and fire, especially in the petroleum, chemical, metallurgy and other departments, in flammable, explosive medium equipment and piping system to use the ball valve, should pay attention to fire and fire.
Usually, in the double position adjustment, the sealing performance is strict, mud, wear, necking channel, open and close action quickly (1/4 turn off), high pressure cut-off (big pressure), low noise, gas and gasification phenomenon, a small amount of leakage to the atmosphere, small operating torque, fluid resistance of the pipeline system, recommended the use of ball valve.
Ball valve is also suitable for light structure, low pressure cut-off (small pressure difference), corrosive medium piping system. Ball valves are also available in cryogenic (cryogenic) devices and piping systems. In the metallurgical industry oxygen piping system, the need to use a strict degreasing treatment of the ball valve. The full bore welded ball valve is required to be buried in the pipeline in line with pipelines and gas pipelines. When required to adjust the performance, you need to choose a special structure with V-shaped opening of the ball valve. In petroleum, petrochemical, chemical, electric power, urban construction, the operating temperature of more than 200 degrees in the pipeline system can choose metal to metal sealed ball valve.