Butterfly valve seal refers to the seal on both sides of the metal material are harder or other materials are known as "hard seal." This seal sealing performance is poor, but high temperature, abrasion resistance, good mechanical properties such as : Steel + steel; steel + copper; steel + graphite; steel + alloy steel; (where the steel may also be cast iron, cast steel, alloy steel may also be surfacing, spraying alloy). Soft sealing: the sealing pair is made of metal on one side and flexible non-metallic material on the other side is called "soft seal." This seal has better sealing performance but is not resistant to high temperature and easy to wear, Such as: steel + rubber; steel + PTFE [/ wiki]; etc. Soft seal seat with a certain strength, hardness and temperature performance of non-metallic materials, good sealing performance, Zero leakage can be achieved, but life expectancy and temperature adaptability is poor. Hard seals made of metal, the sealing performance is relatively poor, although there are manufacturers claim that zero leakage can be made. Soft seal part of the corrosive materials can not meet the technical requirements, hard seal can be solved! The two seals complement each other and the soft seal is relatively good in terms of sealing, but now the sealing of the hard seal also meets the corresponding requirements! Soft seal has the advantage of good sealing performance, the disadvantage is easy to aging, wear and tear, short service life. Hard Seal Long service life, but the seal is relatively poor than the soft seal. The structural differences are mainly the following: 1, the structural difference: mostly soft-sealed butterfly valve for the center line of the multi-eccentric single-eccentric, double eccentric, three eccentric butterfly valve 2, temperature: soft seal for room temperature environment . Hard seal can be used in low temperature, room temperature, high temperature and other environments 3, pressure: soft seal low pressure - atmospheric pressure, hard seal can also be used in medium and high pressure conditions 4, sealing performance: soft seal and three eccentric hard seal butterfly valve sealing performance is better , Three eccentric butterfly valve in high pressure and high temperature environment can maintain a good seal. In view of the above features, soft sealing butterfly valve for ventilation dust removal pipeline bidirectional opening and closing and regulation, water treatment, light industry, petroleum, chemical and other industries. Hard seal butterfly valve used for heating, gas supply, and gas, oil, acid and alkali and other environments. With the widespread use of butterfly valves, its easy installation, easy maintenance, the structure of the more obvious features. Electric soft sealing butterfly valve, pneumatic soft sealing butterfly valve, hard sealing butterfly valve in more and more occasions began to replace the electric gate valve, globe valve and so on. Search Keyword: Valve