The differences between hard-sealed butterfly valves and soft-sealed butterfly valves: Hard-sealed butterfly valve: When both sides of the sealing surface are made of metal materials or other harder materials, it is called "hard seal". This type of seal has poor sealing performance, but it is resistant to high temperatures, abrasion, and has good mechanical properties. For example: steel + steel; steel + copper; steel + graphite; steel + alloy steel; (The steel here may also be cast iron, cast steel, and the alloy steel may also be alloy materials by surfacing or spraying). Soft-sealed butterfly valve: When one side of the sealing pair is a metal material and the other side is an elastic non-metallic material, it is called "soft seal". This type of seal has good sealing performance, but it is not resistant to high temperatures, is prone to wear, and has poor mechanical properties. For example: steel + rubber; steel + tetrafluoroethylene polyethylene, etc. The advantage of the soft-sealed butterfly valve is good sealing performance, and the disadvantage is that it is prone to aging, wear, and has a short service life. The hard-sealed butterfly valve has a long service life, but its sealing performance is relatively worse than that of the soft-sealed one.