SD43, SD943, SD643, SD343 (H, F, Y) - PN 6, 10, 16 expansion butterfly valves are suitable for food, medicine, chemical, petroleum, electricity, light textile, paper and other water supply and drainage, gas pipelines with a temperature of s200 "(PTFE seal) or s425C (metal seal) and a nominal pressure of s2.5MPa. They have the function of regulating flow and intercepting flow media, and have the function of compensating for pipeline thermal expansion and contraction.