Since ball valves typically use rubber, nylon, and Teflon as the seat seal material, their service temperature is limited by the material of the seat seal. The cut-off function of the ball valve is achieved by the metal ball being pressed against the plastic valve seat under the action of the medium (floating ball valve). The valve seat seal is deformed by elastic deformation in a local area under a certain contact pressure. This deformation can compensate for the manufacturing precision and surface roughness of the sphere and ensure the sealing performance of the ball valve.
Since the valve seat seal of the ball valve is usually made of plastic, in the structure and performance of the ball valve, the fire resistance and fireproof of the ball valve should be considered, especially in the petroleum, chemical, metallurgical and other departments, in the flammable and explosive medium. The use of ball valves in equipment and piping systems should pay more attention to fire and fire protection.
Usually, the two-position adjustment, strict sealing performance, mud, wear, shrinkage passage, rapid opening and closing action (1/4 turn open and close), high pressure cutoff (large differential pressure), low noise, cavitation and gasification, Ball valves are recommended for piping systems that have a small amount of leakage into the atmosphere, small operating torque, and low fluid resistance.
Ball valves are also suitable for use in light piping, low pressure cut-off (small differential pressure), corrosive media piping systems. Ball valves are also available in low temperature (deep cold) units and piping systems. In the oxygen piping system of the metallurgical industry, ball valves that have been strictly degreased are used. When the main line in the oil pipeline and the gas pipeline is to be buried underground, a full-bore welded ball valve is required. When a regulating performance is required, a ball valve with a special structure with a V-shaped opening is required. In petroleum, petrochemical, chemical, electric power, urban construction, metal-to-metal sealed ball valves are available for piping systems with operating temperatures above 200 degrees.