The Difference Between Hard Seal and Soft Seal of Butterfly Valve

1.The hard seal of the butterfly valve means that both sides of the seal pair are made of metal materials or harder materials. The hard seal has  high temperature resistance, wear resistance and good mechanical properties. 
The soft seal means that one side of the sealing pair is made of metal material, and the other side is made of elastic non-metal material. The soft seal has better sealing performance, but it is not resistant to high temperatures and easy to be wore.
2.The difference in structure: soft-sealed butterfly valves are mostly centerline. Hard seals are mostly single eccentric, double eccentric, triple eccentric butterfly valves.
3.The soft seal is used in normal temperature environment. Hard seal can be used in low temperature, normal temperature, high temperature and other environments.
4.As a component used to realize flow control in pipeline systems, hard-sealed butterfly valves have been widely used in many fields such as petroleum, chemical industry, metallurgy, and hydropower.

Hard-sealed butterfly valves are mostly used in heating, gas, gas, oil, acid and alkali environments.