Since ball valves are usually made of rubber, nylon and PTFE as seat sealing rings, the temperature at which they are used is limited by the material of the seat seal ring. The cutoff effect of the ball valve is accomplished by pressing the metal sphere under the action of the medium, which is pressed against each other between the plastic seats (floating ball valve). Under the action of certain contact pressure, elastoplastic deformation occurs in local area of seat sealing ring.
This deformation can compensate the spherical manufacturing precision and surface roughness, and ensure the sealing performance of the ball valve.
Also because the ball valve seat seal ring is usually made of plastic, so in the selection of ball valve structure and performance, to consider the ball valve fire resistance and fire prevention, especially in the petroleum, chemical, metallurgy and other sectors, in flammable, explosive media equipment and piping systems using ball valves, should pay attention to fire resistance and fire prevention.
In general, ball valves are recommended in piping systems with double-digit adjustment, strict sealing performance, mud, wear, shrinkage channels, rapid opening and closing movements (1/4 turn opening and closing), high pressure cutoff (large pressure difference), low noise, cavitation and gasification phenomena, small leakage to the atmosphere, small operating torque and small fluid resistance. Ball valves are also suitable for lightweight structures, low pressure cutoff (small pressure difference), corrosive media piping systems. Ball valves can also be selected in low temperature (deep cooling) devices and piping systems. In the metallurgical industry's oxygen piping system, it is necessary to use a ball valve that has been treated with strict skimming. When the line of directors in the pipeline and pipeline is to be laid underground, a full diameter welded ball valve is required. When the adjustment 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, the working temperature of more than 200 degrees of piping system can be selected metal to metal sealed ball valve.
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