Metal seal butterfly valve means that both sides of the seal pair are made of metal material or other hard materials. The sealing performance is poor, but it is resistant to high temperature, abrasion and 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.

Soft sealing butterfly valve

Soft seal 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 poor mechanical properties. Such as: steel + rubber; steel + tetrafluoroethylene.

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 meatal seal is made of metal and the sealing performance is relatively poor. Although some manufacturers claim to be able to achieve zero leakage, soft seals can not meet the process requirements for a part of corrosive materials, but hard seals can solve this problem, and the two seals can complement each other.

The soft seal is relatively good in terms of tightness, but now the seal of the hard seal can also meet the corresponding requirements. The advantage of the soft seal is that the sealing performance is good, and the disadvantage is that it is easy to age, wear, and has a short service life. The hard seal has a long service life, but the seal is relatively inferior to the soft seal.

The main differences between hard and soft seals are as follows:

Structure

Soft-sealed butterfly valves are mostly in the middle line type, and the metal seals are mostly single eccentric, double eccentric, and three eccentric butterfly valves.

Temperature resistance

The soft seal is used in a normal temperature environment. Metal seals can be used in low temperature, normal temperature, high temperature and other environments.

Pressure

Soft seal low pressure - normal pressure, metal seal can also be used in medium and high pressure conditions.

Sealing performance

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