Because the ball valve usually uses rubber, nylon and polytetrafluoroethylene as the seat sealing ring material, its use temperature is limited by the seat sealing ring material. The cutoff function of the ball valve is completed by pressing the metal ball under the action of the medium with the plastic seat (floating ball valve). Elastoplastic deformation occurs in the sealing ring of the seat under certain contact pressure. This deformation can compensate the manufacturing accuracy and surface roughness of the ball and ensure the sealing performance of the ball valve.
Generally, ball valves are recommended in two-position adjustment, strict sealing performance, mud, wear, shrinking channels, rapid opening and closing action (1/4 turn opening and closing), high pressure cutoff (large pressure difference), low noise, cavitation and gasification phenomenon, small leakage to the atmosphere, small operating torque, and small fluid resistance pipeline systems.
Because the valve seat sealing ring is usually made of plastic, so in the selection of the structure and performance of the ball valve, it is necessary to consider the fire resistance and fire resistance of the ball valve, especially in the petroleum, chemical, metallurgical and other departments, the use of the ball valve in the equipment and pipe system of flammable and explosive media, and attention should be paid to fire resistance and fire protection.
Ball valves are also suitable for lightweight structures, low pressure cut-off (small pressure difference), corrosive media piping systems.
Ball valves are also available in low temperature (cryogenic) devices and piping systems.
In the oxygen piping system of the metallurgical industry, ball valves that have been strictly degreased need to be used.
When the main line in the oil pipeline and gas pipeline needs to be buried underground, the full-diameter welded ball valve should be used.
Ball valves of special structure with V-shaped openings should be selected when regulating performance is required.
In petroleum, petrochemical, chemical, electric power, and urban construction, metal-to-metal sealed ball valves can be selected for piping systems with operating temperatures above 200 ° C.