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    The differences between soft seal and hard seal of butterfly valves HOME >> NEWS

    For butterfly valves, hard seal means that both sides of the seal are made of metal material or other hard materials. The sealing performance of this seal is poor, but it is resistant to high temperature, abrasion and has good mechanical properties. Such as: steel + steel; steel + copper; steel + graphite; steel + alloy steel. The steel here may also be cast iron, cast steel, alloy steel or alloys for surfacing and spraying.

    The soft seal of the butterfly valve means that the sides of the seal pair are made of metal material and the other side is elastic non-metallic material. The seal has good sealing performance, but is not resistant to high temperature, easy to wear, and has poor mechanical properties. Such as: steel + rubber; steel + PTFE.

    The soft seal seat is made of non-metallic material with certain strength, hardness and temperature resistance. It has good performance and can achieve zero leakage, but its service life and temperature adaptability are relatively poor. The hard seal is made of metal and the sealing performance is relatively poor. Some manufacturers claim that the sealing can achieve zero leakage. Soft seal can not meet the process requirements for a part of corrosive materials, while hard seal can solve this problem, and the two seals can complement each other.

    The differences between hard seal and soft seal is mainly as follows:

    Structure: Soft seal butterfly valves most are the concentric type, and the hard seals are single eccentric, double eccentric, and triple eccentric butterfly valves.

    Temperature resistance: The soft seal is used in a normal temperature environment. Hard seal butterfly valves can be used in low temperature, normal temperature, high temperature and other environments.
    Pressure: Soft seal is used in low pressure - normal pressure. Hard seal can also be used in medium and high pressure conditions.

    Sealing performance: The soft seal and the triple eccentric hard seal butterfly valve have better sealing performance, and triple eccentric butterfly valve can maintain a good seal under high pressure and high temperature environment.

    In view of the above characteristics, the soft seal butterfly valve is suitable for two-way opening and closing and adjustment of the ventilation and dust removal pipeline, including but not limited to water treatment, light industry, petroleum, chemical industry. Hard-sealed butterfly valves are mostly used for heating, gas supply, and gas, oil, acid and alkali environments.